Biology Exam 3

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Biology Exam 3
2013-04-30 15:52:59

Nervous system, reproducive system and endocrine system
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  1. Evaluate the significance of a centrailized nervous system
  2. Dendrite
    Highly branched extensions that recieve signals from other neurons
  3. Axon hillock
    • At the site where the action potential is generated, electrical current depolarizes the neighboring region of the axon membrane
    • Axon joins the cell body at
  4. Synapse
    A junction between an axon and another cell
  5. Axon
    A much longer extension that transmits signals to other cells at synapses
  6. Nerve Net
    • A series of interconnected nerve cells
    • Simple animals like the cnidarians have them
  7. Nerves
    • Bundles that consist of the axons of multiple nerve cells
    • More complex animals have them
  8. Cephalization
    • Bilaterally symmetrical animals exhibits it
    • Clustering of sensory organs at the front end of the body
  9. Ganglia
    Annelids and arthropods have segmentally arranged clusters of neurons
  10. Central Nervous System (CNS)
    • Simple cephalized animals have them
    • Consists of a brain and longitudinal nerve cords
    • Composed of the brain and spinal cord in vertebrates
    • Integration takes place
  11. Peripheral Nervous System (PNS)
    • Composed of nerves and ganglia in vertebrates
    • Brings information into and out of the CNS
  12. Reflex
    The body's automatic response to a stimulus
  13. Neurons
    • Nerve cells that transfer information within the body
    • Use two types of signals to communicate:
    • -Electrical signals (long-distance)
    • -Chemical signals (short-distance)
  14. Ganglia
    Processing of information takes place in simple clusters of neurons 
  15. Brain
    More complex organization of neurons
  16. Nervous systems process information in three stages
    • Sensory input
    • Integration
    • Motor output
  17. Sensory Neurons
    Sensors detect external stimuli and internal conditions and transmit information
  18. Interneurons
    Sensory information is sent to the brain or ganglia, where it integrate the information
  19. Motor Neurons
    Motor output leaves the brain or ganglia via it, which trigger muscle or gland activity
  20. Many animals have a complex nervous system which consists of
    • Central nervous system (CNS) 
    • Peripheral nervous system (PNS)
  21. Cell Body
    Most of a neuron’s organelles are in
  22. Neurotransmitters
    Synaptic terminal of one axon passes information across the synapse in the form of chemical messengers
  23. Presynaptic Cell
    A neuron
  24. Postsynaptic Cell 
    A neuron, muscle, or gland cell
  25. Glia
    Most neurons are nourished or insulated by cells
  26. Membrane Potential
    • Every cell has a voltage (difference in electrical charge) across its plasma membrane
    • Messages are transmitted as changes
  27. Resting Potential 
    Membrane potential of a neuron not sending signals
  28. Equilibrium Potential (Eion)
    Membrane voltage for a particular ion at equilibrium and can be calculated using the Nernst equation
  29. Gated Ion Channels
    Neurons contain it that open or close in response to stimuli
  30. Hyperpolarization
    Increase in magnitude of the membrane potential
  31. Depolarization
    Reduction in the magnitude of the membrane potential 
  32. Graded Potentials
    Changes in polarization where the magnitude of the change varies with the strength of the stimulus
  33. Voltage-gated
    Na+ and K+ channels respond to a change in membrane potential
  34. Action Potential
    • Strong stimulus results in a massive change in membrane voltage
    • Signals that carry information along axons
    • Frequency of it can reflect the strength of a stimulus
  35. Threshold
    Action potential occurs if a stimulus causes the membrane voltage to cross
  36. All-or-none
    Action potential is a brief depolarization of a neuron’s plasma membrane
  37. Refractory Period 
    A result of a temporary inactivation of the Na+ channels
  38. Myelin Sheath
    • In vertebrates, axons are insulated by it, which causes an action potential’s speed to increase
    • Made by glia— oligodendrocytes in the CNS and Schwann cells in the PNS
  39. Nodes of Ranvier
    • Action potentials are formed only at
    • Gaps in the myelin sheath where voltage-gated Na+ channels are found
  40. Saltatory Conduction
    Action potentials in myelinated axons jump between the nodes of Ranvier in a process
  41. Electrical Synapses
    • Electrical current flows from one neuron to another
    • It is rare
  42. Chemical Synapses
    • Chemical neurotransmitter carries information across the gap junction
    • Most synapses are it
  43. Synaptic Vesicles
    Presynaptic neuron synthesizes and packages the neurotransmitter in it located in the synaptic terminal
  44. Synaptic Cleft
    Neurotransmitter diffuses across it and is received by the postsynaptic cell
  45. Postsynaptic potentials fall into two categories
    • Inhibitory postsynaptic potentials (IPSPs)
    • Excitatory postsynaptic potentials (EPSPs)
  46. Inhibitory postsynaptic potentials (IPSPs)
    Hyperpolarizations that move the membrane potential farther from threshold
  47. Excitatory postsynaptic potentials (EPSPs)
    Depolarizations that bring the membrane potential toward threshold
  48. Temporal Summation
    Two EPSPs are produced in rapid succession
  49. Spatial Summation
    EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron add together
  50. Indirect Synaptic Transmission
    Neurotransmitter binds to a receptor that is not part of an ion channel
  51. Five Major Classes of Neurotransmitters
    • Acetylcholine
    • Biogenic amines
    • Amino acids
    • Neuropeptides
    • Gases
  52. Acetylcholine
    Common neurotransmitter in vertebrates and invertebrates
  53. Acetylcholinesterase
    Activity is terminated by enzymatic hydrolysis
  54. Biogenic Amines include and involved in 
    • Epinephrine
    • Norepinephrine
    • Dopamine
    • Serotonin
    • Modulating synaptic transmission in the CNS
  55. Two amino acids are known to function as major neurotransmitters in the CNS
    • Gamma-aminobutyric acid (GABA) 
    • Glutamate
  56. Neuropeptides
    • Short chains of amino acids
    • Function as neurotransmitters
    • Include substance P and endorphins
  57. Substance P and Endorphins affect
    Our perception of pain
  58. Nitric oxide and Carbon monoxide Gases are
    Local regulators in the PNS
  59. Invertebrates usually have a _______ _______ cord while vertebrates have a ______ ______ cord
    • Ventral Nerve
    • Dorsal Spinal
  60. Central canal of the spinal cord and the ventricles of the brain are hollow and filled with
    Cerebrospinal fluid
  61. Cerebrospinal Fluid
    Filtered from blood and functions to cushion the brain and spinal cord
  62. The brain and spinal cord contain 
    • White matter
    • Gray matter
  63. Gray matter consists of
    • Neuron cell bodies
    • Dendrites
    • Unmyelinated axons
  64. White matter consists of
    Bundles of myelinated axons
  65. Glia have numerous functions
    • Microglia
    • Ependymal cells
    • Oligodendrocytes and Schwann cells
    • Astrocytes
    • Radial glia
  66. Radial glia
    Play a role in the embryonic development of the nervous system
  67. Astrocytes
    Provide structural support for neurons, regulate extracellular ions and neurotransmitters, and induce the formation of a blood-brain barrier that regulates the chemical environment of the CNS
  68. Ependymal cells
    Promote circulation of cerebrospinal fluid
  69. Microglia
    Protect the nervous system from microorganisms
  70. Oligodendrocytes and Schwann cells
    Form the myelin sheaths around axons
  71. Afferent Neurons
    • In the PNS
    • Transmit information to the CNS
  72. Efferent Neurons
    Transmit information away from the CNS
  73. Cranial nerves
    Originate in the brain and mostly terminate in organs of the head and upper body
  74. Spinal nerves 
    Originate in the spinal cord and extend to parts of the body below the head
  75. The PNS has two functional components
    • Motor system 
    • Autonomic nervous system
  76. Autonomic Nervous System
    • Regulates the internal environment in an involuntary manner
    • Has sympathetic, parasympathetic, and enteric divisions
  77. Motor system
    Carries signals to skeletal muscles and is voluntary
  78. The sympathetic and parasympathetic divisions have ___________ effects on target organs
  79. Sympathetic Division
    Correlates with the “fight-or-flight” response
  80. Parasympathetic Division
    Promotes a return to “rest and digest”
  81. Enteric Division
    Controls activity of the digestive tract, pancreas, and gallbladder
  82. All vertebrate brains develop from three embryonic regions
    • Forebrain
    • Midbrain
    • Hindbrain
  83. As a human brain develops further, the most profound change occurs in the _______, which gives rise to the _________
    • Forebrain
    • Cerebrum
  84. Cerebral Cortex
    • Outer portion of the cerebrum
    • Surrounds much of the brain
  85. Brainstem
    • coordinates and conducts information between brain centers
    • Three parts:
    • -The midbrain
    • The pons
    • The medulla oblongata
  86. Midbrain
    Contains centers for receipt and integration of sensory information
  87. Pons
    Regulates breathing centers in the medulla
  88. Medulla Oblongata
    Contains centers that control several functions including breathing, cardiovascular activity, swallowing, vomiting, and digestion
  89. Reticular Formation
    Coreof the brainstem has a diffuse network of neurons
  90. Melatonin
    • Hormone
    • Released by the pineal gland and plays a role in bird and mammal sleep cycles
  91. Cerebellum
    • Important for coordination and error checking during motor, perceptual, and cognitive functions
    • Involved in learning and remembering motor skills
  92. Diencephalon develops into three regions
    • Epithalamus
    • Thalamus
    • Hypothalamus
  93. Epithalamus
    Includes the pineal gland and generates cerebrospinal fluid from blood
  94. Thalamus
    Main input center for sensory information to the cerebrum and the main output center for motor information leaving the cerebrum
  95. Hypothalamus
    • Regulates homeostasis and basic survival behaviors such as feeding, fighting, fleeing, and reproducing
    • Regulates circadian rhythms such as the sleep/wake cycle
    • Receives information from the nervous system and initiates responses through the endocrine system
    • Attached to it is the pituitary gland
  96. Biological clocks
    Require external cues to remain synchronized with environmental cycles
  97. Suprachiasmatic Nuclei (SCN)
    • Mammals usually have a pair of it
    • In the hypothalamus that function as a biological clock
  98. Cerebrum
    Develops from the embryonic telencephalon
  99. The cerebrum has right and left
    Cerebral hemispheres
  100. Each cerebral hemisphere consists of a
    Cerebral cortex (gray matter) overlying white matter and basal nuclei
  101. Basal Nuclei
    Important centers for planning and learning movement sequences
  102. Corpus Callosum
    • A thick band of axons
    • Provides communication between the right and left cerebral cortices
  103. Neocortex
    • In mammals, the cerebral cortex has a convoluted surface
    • Previously thought to be required for cognition
  104. Cognition
    Perception and reasoning that form knowledge
  105. Each side of the cerebral cortex has four lobes
    • Frontal
    • Temporal
    • Occipital
    • Parietal
  106.  The cerebral cortex receives input from
    • Sensory organs
    • Somatosensory receptors
  107. Broca’s area
    Frontal lobe is active when speech is generated
  108. Wernicke’s area
    Temporal lobe is active when speech is heard
  109. Corpus Callosum
    Transmits information between the two cerebral hemispheres
  110. Left Hemisphere
    More adept at language, math, logic, and processing of serial sequences
  111. Right Hemisphere
    Stronger at pattern recognition, nonverbal thinking, and emotional processing
  112. Lateralization
    • Differences in hemisphere function
    • Linked to handedness
  113. Limbic System
    • Emotions are generated and experienced
    • Ring of structures around the brainstem that includes:
    • -Amygdala
    • -Hippocampus
    • -Thalamus
  114. Amygdala
    Located in the temporal lobe and helps store an emotional experience as an emotional memory
  115. Consciousness
    Emergent property of the brain based on activity in many areas of the cortex
  116. Two processes dominate embryonic development of the nervous system
    • Neurons compete for growth-supporting factors in order to survive
    • Only half the synapses that form during embryo development survive into adulthood
  117. Neural Plasticity
    • Ability of the nervous system to be modified after birth
    • Changes can strengthen or weaken signaling at a synapse
  118. Hippocampus
    • Short-term memory is accessed
    • Plays a role in forming long-term memory, which is stored in the cerebral cortex
  119. Long-term Potentiation (LTP)
    • In the vertebrate brain
    • Involves an increase in the strength of synaptic transmission
    • Involves glutamate receptors
  120. Disorders of the nervous system include
    • Schizophrenia
    • Depression
    • Alzheimer’s disease
    • Parkinson’s disease
  121. Schizophrenia
    Characterized by hallucinations, delusions, blunted emotions, and other symptoms
  122. Two broad forms of depressive illness are known
    • Major depressive disorder
    • Bipolar disorder
  123. Bipolar Disorder
    Characterized by manic (high-mood) and depressive (low-mood) phases
  124. Major Depressive Disorder
    Patients have a persistent lack of interest or pleasure in most activities
  125. Alzheimer’s Disease
    • Mental deterioration characterized by confusion, memory loss, and other symptoms
    • Caused by the formation of neurofibrillary tangles and amyloid plaques in the brain
  126. Parkinson’s Disease
    • Motor disorder caused by death of dopamine-secreting neurons in the midbrain
    • It is characterized by difficulty in initiating movements, muscle tremors, slowness of movement, and rigidity
  127. Animal Hormones
    • Chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
    • Reach all parts of the body except for target cells
    • Also have different effects in different species
  128. Target Cells
    • Equipped to respond by binding to specific receptor proteins
    • With receptors respond to the signal
  129. Two systems coordinate communication throughout the body
    • Endocrine system
    • Nervous system
  130. Endocrine System
    Secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior
  131. Nervous System
    Conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells
  132. The body is regulated by a variety of different secreted chemical signals including
    • Hormones
    • Local regulators
    • Neurotransmitters
    • Neurohormones
    • Pheromones
  133. Hormones
    • Endocrine signals (hormones) are secreted into extracellular fluids and travel via the bloodstream
    • Endocrine glands are ductless and secrete hormones directly into surrounding fluid
  134. Local Regulators
    • Chemical signals that travel over short distances by diffusion
    • Help regulate blood pressure, nervous system function, and reproduction
    • Divided into two types:
    • –Paracrine signals act on cells near the secreting cell
    • –Autocrine signals act on the secreting cell itself
    • In paracrine signaling, nonhormonal chemical signals called it elicit responses in nearby target cells
    • Many types of cells will only grow, divide and develop if growth factors are present in the extracellular environment.
  135. Neurohormones
    Class of hormones that originate from neurons in the brain and diffuse through the bloodstream
  136. Neurotransmitters
    • Neurons (nerve cells) contact target cells at synapses
    • At synapses, neurons often secrete chemical signals called it that diffuse a short distance to bind to receptors on the target cell
    • Play a role in sensation, memory, cognition, and movement
  137. Pheromones
    • Chemical signals that are released from the body and used to communicate with other individuals in the species
    • Mark trails to food sources, warn of predators, and attract potential mates
  138. Three major classes of molecules function as hormones in vertebrates
    • Polypeptides (proteins and peptides)
    • Amines derived from amino acids
    • Steroid hormones
  139. Lipid-soluble hormones (steroid hormones)
    • Pass easily through cell membranes, while water-soluble hormones (polypeptides and amines) do not.
    • The solubility of a hormone correlates with whether receptors are located inside or on the surface of the target cells 
    • Water and lipid soluble hormones differ in their paths through a body:
    • -Water-soluble hormones
    • -Lipid-soluble hormones
  140. Lipid-soluble Hormones
    • Diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells
    • The response to a lipid-soluble hormone is usually a change in gene expression
    • Steroids, thyroid hormones, and the hormonal form of vitamin D enter target cells and bind to protein receptors in the cytoplasm or nucleus
    • Protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes
    • Also can exert different effects in different types of cells.
  141. Water-soluble Hormones
    Secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
  142. Hormone signaling involves three key events
    • Reception: hormone binds to receptor
    • Signal transduction: the signal is amplified and targets the specific cellular machinery needed
    • Response:  the cellular response occurs and a change in the cell occurs
  143. Path for water soluble hormones
    • Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression
    • No carrier proteins are needed for movement thru circulatory system.  Hormone can be stored in vesicles until needed
  144. Hormone can be stored in vesicles until needed. Benefits of storage
    • 1) prevents deactivation
    • 2) provides negative feedback to prevent further production
    • 3) can be released in bursts
    • 4) allows cell to potentially remodel it into other molecules
  145. Multiple Effects of Hormones
    • The same hormone may have different effects on target cells that have
    • –Different receptors for the hormone
    • –Different signal transduction pathways
    • –Different proteins for carrying out the response
    • Tissues vary in response because they may have different receptor types or different signal transduction pathways
  146. Epinephrine has 2 types of receptors
    a and b
  147. a
    In smooth muscle cells of intestinal blood vessels: triggers different G proteins and different enzymes to cause smooth muscle contraction to restrict blood flow.
  148. b
    • In liver cells the pathway activated involves protein kinase A regulation of  glycogen metabolism to increase the amount of free glucose molecules
    • -in blood vessels supplying skeletal muscle, protein kinase A activates a different enzyme to cause smooth muscle relaxation that causes increased blood flow.
  149. Types of local regulators
    • Cytokines and growth factors
    • Nitric oxide (NO)
    • Prostaglandins
  150. Nitric Oxide
    Can act as both a neurotransmitter as well as a very fast acting local regulator.
  151. Prostaglandins
    Modified fatty acids first identified in prostate gland secretions. 
  152. Prostaglandins are produced by many cell types and have varied activities
    • Helps stimulate contraction of smooth muscles of uterus to help sperm reach the egg.
    • Induces labor
    • Promote fever and inflammation and intensify pain sensations.
    • Help regulate aggregation of platelets, an early step in formation of blood clots.
    • Help maintain protective lining of stomach.
  153. Control of the Endocrine system
    Negative feedback and antagonistic hormone pairs are common features
  154. Hormone Pathways
    • Released from an endocrine cell, travel through the bloodstream, and interact with the receptor or a target cell to cause a physiological response.
    • -Signal transduction pathways are involved
    • -Eventually the stimulus is reduced causing the pathway to switch off.
    • A negative feedback loop inhibits a response by reducing the initial stimulus
    • Negative feedback regulates many hormonal pathways involved in homeostasis.
    • -Often requires coordinated regulation of multiple simple hormone pathways.
  155. Insulin and glucagon
    • Control of blood sugar levels
    • Antagonistic hormones that help maintain glucose homeostasis
  156. Pancreas has clusters of endocrine cells called
    Islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin
  157. Most of the tissue of the pancreas secretes
    Digestive enzymes destined for the small intestine
  158. Scattered among pancreas are endocrine cells are
    • alpha cells (which secrete glucagon)
    • beta cells (which secrete insulin)
  159. Insulin reduces blood glucose levels by
    • Promoting the cellular uptake of glucose
    • Slowing glycogen breakdown in the liver
    • Promoting fat storage
  160. Glucagon increases blood glucose levels by
    • Stimulating conversion of glycogen to glucose in the liver
    • Stimulating breakdown of fat and protein into glucose
  161. Diabetes mellitus
    • Best-known endocrine disorder
    • It is caused by a deficiency of insulin or a decreased response to insulin in target tissues
    • It is marked by elevated blood glucose levels
  162. Type I diabetes mellitus
    • Insulin-dependent
    •  Is an autoimmune disorder in which the immune system destroys pancreatic beta cells
  163. Type II diabetes mellitus
    Non-insulin-dependent involves insulin deficiency or reduced response of target cells due to change in insulin receptors (latter being most common).
  164. The endocrine and nervous systems act
    Individually and together in regulating animal physiology
  165. Pituitary Gland
    Composed of the posterior pituitary and anterior pituitary
  166. Posterior Pituitary
    • Stores and secretes hormones that are made in the hypothalamus
    • The two hormones released from it act directly on nonendocrine tissues
    • Oxytocin induces uterine contractions and the release of milk
    • Suckling sends a message to the hypothalamus via the nervous system to release oxytocin, which further stimulates the milk glands
  167. Anterior Pituitary
    • Makes and releases hormones under regulation of the hypothalamus
    • Hormone production in it is controlled by releasing and inhibiting hormones from the hypothalamus
  168. Antidiuretic hormone (ADH)
    Enhances water reabsorption in the kidneys
  169. Hormone Cascade Pathway
    • A hormone can stimulate the release of a series of other hormones, the last of which activates a non-endocrine target cell; this is called it
    • The release of thyroid hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland
    • Hormone cascade pathways are usually regulated by negative feedback
  170. Tropic Hormones
    Regulates the function of endocrine cells or glands
  171. The four strictly tropic hormones are
    • Thyroid-stimulating hormone (TSH)
    • Follicle-stimulating
    • hormone (FSH)
    • Luteinizing hormone (LH)
    • Adrenocorticotropic hormone (ACTH)
  172. Non-tropic hormones
    Target nonendocrine tissues
  173. Nontropic hormones produced by the anterior pituitary are
    • Prolactin (PRL)
    • Melanocyte-stimulating hormone (MSH)
  174. Melanocyte-stimulating hormone (MSH)
    Influences skin pigmentation in some vertebrates and fat metabolism in mammals
  175. Prolactin (PRL)
    Stimulates lactation in mammals but has diverse effects in different vertebrates
  176. Growth hormone (GH)
    • Secreted by the anterior pituitary gland and has BOTH tropic and nontropic actions
    • -It promotes growth directly and has diverse metabolic effects
    • -It stimulates production of growth factors
    • -An excess of it can cause gigantism, while a lack of it can cause dwarfism
  177. Endocrine glands
    Respond to diverse stimuli in regulating metabolism, homeostasis, development, and behavior
  178. Thyroid gland
    • Consists of 2 lobes (located on ventral surface of trachea)
    • Secretes 2 hormones, iodothyronine (T3) and thyroxine (T4), which both contain iodine
    • Thyroid hormones are important in development and homeostasis
    • Inherited thyroid deficiency (once referred to as “cretinism”) results in retarded mental development and skeletal growth deficiencies
    • Goiter-enlargement of the thyroid; typically associated with deficiency of iodine in diet.  In some areas of the world, iodine deficiency is severe.
  179. Thyroid Hormone
    • Stimulate metabolism and influence development and maturation
    • Proper thyroid function requires dietary iodine for hormone production
    • Two Thyroid hormones are:
    • -Hypothyroidism
    • -Hyperthyroidism
  180. Hyperthyroidism
    • Excessive secretion of thyroid hormones, causes high body temperature, weight loss, irritability, and high blood pressure
    • Graves’ disease is a form of it in humans
  181. Hypothyroidism
    Low secretion of thyroid hormones, causes weight gain, lethargy, and intolerance to cold
  182. Parathyroid hormone (PTH)
    • Released by the parathyroid glands, increasing the level of blood Ca2+
    • It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys
    • It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food
  183. Two antagonistic hormones regulate the homeostasis of calcium (Ca2+) in the blood of mammals are
    • Calcitonin
    • Parathyroid hormone (PTH)
  184. Calcitonin
    • Decreases the level of blood Ca2+
    • Is released by the thyroid gland
    • It stimulates Ca2+ deposition in bones and secretion by kidneys
  185. Adrenal Hormones
    Response to stress
  186. Adrenal Glands
    • Adjacent to the kidneys
    • Consistsof two glands:
    • -The adrenal medulla (inner portion)
    • -Adrenalcortex (outer portion)
  187. Adrenal Medulla
    Secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)
  188. Epinephrine (adrenaline) and Norepinephrine (noradrenaline) hormones are members of a class of compounds called
  189. Catecholamines
    • Secreted in response to stress-activated impulses from the nervous system
    • They mediate various fight-or-flight responses
  190. Epinephrine and Norepinephrine
    • Trigger the release of glucose and fatty acids into the blood
    • Increase oxygen delivery to body cells
    • Direct blood toward heart, brain, and skeletal muscles, and away from skin, digestive system, and kidneys
    • The release of it occurs in response to nerve signals from the hypothalamus
  191. Adrenal cortex releases a family of steroids called
    Corticosteroids in response to stress
  192. Corticosteroids
    Triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary
  193. Humans produce two types of corticosteroids
    • Glucocorticoids
    • Mineralocorticoids
  194. Glucocorticoids
    Influence glucose metabolism and the immune system
  195. Mineralocorticoids
    Affect salt and water balance
  196. Adrenal Cortex also produces
    Small amounts of steroid hormones that function as sex hormones
  197. The gonads, testes and ovaries, produce most of the sex hormones
    • Androgens
    • Estrogens
    • Progestins
    • All three sex hormones are found in both males and females, but in different amounts
  198. The testes primarily synthesize
    Androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system
  199. Testosterone causes an increase in
    Muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks
  200. Estrogens, most importantly estradiol, are responsible for
    Maintenance of the female reproductive system and the development of female secondary sex characteristics
  201. In mammals, progestins, which include progesterone, are primarily involved in
    Preparing and maintaining the uterus
  202. Synthesis of the sex hormones is controlled by
    FSH and LH from the anterior pituitary
  203. The Pineal Gland
    • Located in the brain, secretes melatonin
    • Light/dark cycles control release of melatonin
    • Primary functions of melatonin appear to relate to biological rhythms associated with reproduction
  204. Endocrine Disruptors
    • Synthetic chemicals and natural plant compounds that may affect the endocrine system of animals
    • Mainly associated with developmental, reproductive and health problems in wildlife
  205. Function of Endocrine Disruptors
    • Mimic the sex steroid hormones      estrogens and androgens (Environmental estrogens)
    • Block, prevent or alter hormone binding to hormone receptors or influence cell signaling pathways (anti-estrogens or anti-androgens)
    • Environmental disruptors (or modulators)
    • 1) alter production/breakdown of natural hormones
    • 2) modify the production/function of hormone receptors
  206. Environmental Estrogens
    Some (phytoestrogens) occur naturally in plants (clover, soybeans, legumes); Others are synthetic chemicals.
  207. Natural Environmental Estrogens (phytoestrogens)
    • Problematic only for organisms which obtain bulk of diet from plant foods
    • In dry, summertime grasses, there are reduced #s of offspring of California Quail and deer mice that feed on these plants
    • Other effects on livestock also seen
    • Short-term exposure (mostly in soybean-based compounds) in humans may protect against some forms of cancer (breast, colon, prostate, liver)
  208. Synthetic Environmental Estrogens
    • Pesticides (herbicides and insecticides, such as DDT, endosulfan, dieldrin, kepone, toxaphene, dicofol, chordane, methoxychlor)􀁡some plastics (bisphenol A)􀁡pharmaceuticals (e.g., drug estrogens: birth control pills)
    • Industrial chemicals (most notably, polychlorinated biphenyls [PCBs])
  209. Possible effects of Environmental Estrogens
    • Women: breast and reproductive organ cancers, endometriosis, pelvic inflammatory diseases, fibrocystic disease of breast
    • Men: poor semen quality (low sperm counts, low ejaculate volume, abnormal/immobile sperm…), testicular cancer, malformed reproductive tissue (undescended testis, etc), prostate disease
  210. Lake Apopka Florida Alligators
    • Lake suffered industrial spill of dicofol and DDT in 1980; also receives agricultural runoff with other pollutants
    • RESULTS: gator population declined severely and reproductive success rates dropped (hatching success fell from 54% in 1983 to 4% in 1988)
    • -Female juveniles had severe ovarian abnormalities (blood estrogen level 2 Xs higher than normal)
    • -Male juveniles were feminized (had smaller than normal penises, abnormal testes; greater than average estrogen level)
  211. Sexual Reproduction
    Creation of an offspring by fusion of a male gamete (sperm) and female gamete (egg) to form a zygote
  212. Asexual Reproduction
    Creation of offspring without the fusion of egg and sperm
  213. Fission
    • Many invertebrates reproduce asexually by it
    • Separation of a parent into two or more individuals of about the same size
  214. Budding
    New individuals arise from outgrowths of existing ones
  215. Fragmentation
    • Breaking of the body into pieces, some or all of which develop into adults
    • Must be accompanied by regeneration
  216. Regeneration
    Regrowth of lost body parts
  217. Parthenogenesis
    The development of a new individual from an unfertilized egg
  218. Sexual reproduction results in genetic recombination, which provides potential advantages
    • An increase in variation in offspring, providing an increase in the reproductive success of parents in changing environments
    • An increase in the rate of adaptation
    • A shuffling of genes and the elimination of harmful genes from a population
  219. Ovulation
    Release of mature eggs at the midpoint of a female cycle
  220. Hermaphroditism
    • Each individual has male and female reproductive systems
    • Some hermaphrodites can self-fertilize
  221. Sex Reversals
    Some species exhibit male to female reversal while others exhibit female to male reversal
  222. Fertilization depends on
    Mechanisms that bring together sperm and eggs of the same species
  223. Mechanisms of fertilization, the union of egg and sperm, play an important part in
    Sexual Reproduction
  224. External Fertilization
    Eggs shed by the female are fertilized by sperm in the external environment
  225. All fertilization requires
    • Critical timing
    • Often mediated by environmental cues
    • Pheromones
    • Courtship behavior
  226. Internal Fertilization
    • Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract
    • Requires behavioral interactions and compatible copulatory organs
    • Species with it provide greater protection of the embryos and more parental care
  227. (Gamete Production and Delivery)
    In most species individuals have
    • Gonads
    • Organs that produce gametes
  228. In many insects, the female has a
    Spermatheca in which sperm is stored during copulation
  229. Cloaca
    • Common opening between the external environment and the digestive, excretory, and reproductive systems
    • Common in non-mammalian vertebrates; mammals usually have a separate opening to the digestive tract
  230. Follicles
    Consist of a partially developed egg
  231. Oocyte
    • Surrounded by support cells
    • Once a month, it develops into an ovum (egg) by the process of oogenesis
  232. Ovulation
    Expels an egg cell from the follicle
  233. The remaining follicular tissue grows within the ovary, forming a mass called
    Corpus Luteum
  234. Corpus Luteum
    • Secretes hormones that help to maintain pregnancy
    • If the egg is not fertilized, it degenerates
  235. The egg cell travels from the ovary to the uterus via an
    Oviduct, or fallopian tube
  236. Cilia in the oviduct convey the egg to the
    Uterus, also called the womb
  237. Endometrium
    • Uterus lining
    • Has many blood vessels
  238. Uterus narrows at the
    Cervix, then opens into the vagina
  239. Vagina
    Thin-walled chamber that is the repository for sperm during copulation and serves as the birth canal
  240. Vulva
    • Vagina opens to the outside at it
    • Consists of the labia majora, labia minora, hymen, and clitoris
  241. Mammary Glands
    • Not part of the reproductive system but are important to mammalian reproduction
    • Small sacs of epithelial tissue secrete milk
  242. The male’s external reproductive organs are
    Scrotum and penis
  243. Gonads
    Produce sperm and hormones, and accessory glands
  244. Testes
    • Consist of highly coiled tubes surrounded by connective tissue
    • Male gonads
  245. Sperm form in these
    Seminiferous Tubules
  246. Leydig cells
    Produce hormones and are scattered between the tubules
  247. Scrotum
    • The testes of many mammals are held outside the abdominal cavity in it
    • Where the temperature is lower than in the abdominal cavity
  248. Production of normal sperm cannot occur at the
    Body temperatures of most mammals
  249. From the ______________ of a testis, sperm pass into the coiled tubules of the _________
    • Seminiferous tubules
    • Epididymis
  250. •During _________, sperm are propelled through the muscular ___________ and the _____________, and then exit the penis through the _______
    • Ejaculation
    • Vas deferens
    • Ejaculatory duct
    • Urethra
  251. Semen
    Composed of sperm plus secretions from three sets of accessory glands
  252. The two seminal vesicles contribute about
    60% of the total volume of semen
  253. Prostate Gland
    Secretes its products directly into the urethra through several small ducts
  254. Bulbourethral Glands
    Secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra
  255. Human Penis
    Composed of three cylinders of spongy erectile tissue
  256. Two reactions predominate in both sexes:
    • Vasocongestion
    • Myotonia
  257. Myotonia
    Increased muscle tension
  258. Vasocongestion
    The filling of tissue with blood
  259. Coitus
    Sexual Intercourse
  260. Orgasm
    Characterized by rhythmic contractions of reproductive structures
  261. Gametogenesis
    The production of gametes by meiosis, differs in females and males
  262. Spermatogenesis
    Production of mature sperm
  263. Hybrid animals
    Cross-breeds between animals of similar genetics
  264. Oogenesis
    • Development of mature oocytes (eggs) and can take many years
    • One egg forms from each cycle of meiosis; in spermatogenesis four sperm form from each cycle of meiosis
    • Ceases later in life in females; spermatogenesis continues throughout the adult life of males
    • Has long interruptions; spermatogenesis produces sperm from precursor cells in a continuous sequence
  265. The interplay of tropic and sex hormones regulates
    Mammalian reproduction
  266. Human reproduction is coordinated by hormones from the
    • Hypothalamus
    • Anterior Pituitary
    • Gonads
  267. Gonadotropin-releasinghormone (GnRH)
    Secreted by the hypothalamus and directs the release of FSH and LH from the anterior pituitary
  268. FSH and LH regulate processes in
    The gonads and the production of sex hormones
  269. The sex hormones are
    • Androgens
    • Estrogens
    • Progesterone
  270. Sex hormones regulate:
    • –The development of primary sex characteristics during embryogenesis: formation of gonad and reproductive organ
    • –The development of secondary sex characteristics at puberty
    • –Sexual behavior and sex drive
  271. FSH promotes the activity of
    Sertoli cells
  272. Sertoli cells
    Nourish developing sperm and are located within the seminiferous tubules
  273. LH regulates
    Leydig cells
  274. Leydig cells
    Secrete testosterone and other androgen hormones, which in turn promote spermatogenesis
  275. Sertoli cells secrete the hormone
  276. Inhibin
    Reduces FSH secretion from the anterior pituitary
  277. In females, the secretion of hormones and the reproductive events they regulateare
  278. If an embryo does not implant in the endometrium, the endometrium is shed in aprocess called
  279. Hormones closely link the two cycles of female reproduction:
    • –Changes in the uterus define the menstrual cycle (also called the uterine cycle)
    • –Changes
    • in the ovaries define the ovarian cycle
  280. Follicle growth and an increase in the hormone _________ characterize the _________ of the ovarian cycle
    • Estradiol
    • Follicular phase
  281. •The follicular phase ends at _________, and the ___________ is released
    • Ovulation
    • Secondary oocyte
  282. •Following ovulation, the follicular tissue left behind transforms into the __________; this is the __________
    • Corpus luteum
    • Luteal phase
  283. Hormones coordinate the uterine cycle with the ovarian cycle
    • –Thickening of the endometrium during the proliferative phase coordinates with the follicular phase
    • –Secretion of nutrients during the secretory phase coordinates with the luteal phase
    • –Shedding of the endometrium during the menstrual flow phase coordinates with the growth of new ovarian follicles
  284. Cells of the uterine lining can sometimes migrate to an abnormal, or ________, location
  285. Swelling of these cells in response to hormone stimulation results in a disorder called
  286. Menopause
    • Cessation of ovulation and menstruation
    • –The endometrium is shed from the uterus in a bleeding called menstruation
    • –Sexual receptivity is not limited to a timeframe
  287. Estrous cycles are characteristic of most mammals:
    • –The endometrium is reabsorbed by the uterus
    • –Sexual receptivity is limited to a “heat” period
    • –The length and frequency of estrus cycles varies from species to species
  288. Blastocyst
    A ball of cells with a cavity
  289. The resulting zygote begins to divide by mitosis in a process called ________
  290. Conception
    Fertilization of an egg by a sperm, occurs in the oviduct
  291. Human chorionic gonadotropin (hCG),
    Prevents menstruation
  292. Pregnancy or gestation
    Condition of carrying one or more embryos in the uterus
  293. Human gestation can be divided into three _________ of about three months each
  294. The outer layer of the blastocyst, called the _________, mingles with the endometrium and eventually forms the __________
    • Trophoblast
    • Placenta
  295. Splitting of the embryo during the first month of development results in genetically ________ twins
  296. Release and fertilization of two eggs results in ___________ twins
    Fraternal and genetically distinct
  297. Organogenesis
    Development of the body organs
  298. All the major structures are present by 8 weeks, and the embryo is called a _____
  299. A complex interplay of local regulators and hormones induces and regulates ______, the process by which childbirth occurs
  300. Lactation
    The production of milk
  301. Contraception
    The deliberate prevention of pregnancy, can be achieved in a number of ways
  302. Contraceptive methods fall into three categories:
    • –Preventing release of eggs and sperm
    • –Keeping sperm and egg apart
    • –Preventing implantation of an embryo
  303. The_________, or ___________, is to refrain from intercourse when conception is most likely
    • Rhythm method
    • Natural family planning
  304. Barrier methods block fertilization with
    • –A condom fits over the penis
    • –A diaphragm is inserted into the vagina before intercourse
  305. Birth control pills are
    Hormonal contraceptives
  306. Sterilization is permanent and prevents the release of gametes:
    • –Tubal ligation ties off the oviducts
    • –Vasectomy ties off the vas deferens
  307. Abortion
    Termination of a pregnancy
  308. Modern technology can provide infertile couples with
    Assisted reproductive technologies
  309. In vitro fertilization (IVF) mixes
    Eggs with sperm in culture dishes and returns the embryo to the uterus at the 8 cell stage
  310. Sperm are injected directly into an egg in a type of IVF called
    Intracytoplasmic sperm injection (ICSI)
  311. Lake Apopka Florida Alligators:
    • Lake suffered industrial spill of dicofol and DDT in 1980; also receives agricultural runoff with other pollutants
    • RESULTS: gator population declined severely and reproductive success rates dropped (hatching success fell from 54% in 1983 to 4% in 1988)
    • female juveniles had severe ovarian abnormalities (blood estrogen level 2 Xs higher than normal)
    • male juveniles were feminized (had smaller than normal penises, abnormal testes; greater than average estrogen level)
  312. •The _____ transmits information to and from the ______ and regulates _______ and the internal __________
    • PNS
    • CNS
    • Movement
    • Environment
  313. Formationof the Resting Potential
    • In a mammalian neuron at resting potential, the concentration of K+ is greater inside the cell, while the concentration of Na+ is greater outside the cell
    • Sodium-potassium pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane
    • These concentration gradients represent chemical potential energy
    • The opening of ion channels in the plasma membrane converts chemical potential to electrical potential
    • A neuron at resting potential contains many open K+ channels and fewer open Na+ channels; K+ diffuses out of the cell
    • Anions (negatively charged ions) trapped inside the cell contribute to the negative charge within the neuron
  314. Modelingof the Resting Potential
    • Can be modeled by an artificial membrane that separates two chambers
    • –The concentration of KCl is higher in the inner chamber and lower in the outer chamber
    • –K+ diffuses down its concentration gradient to the outer chamber
    • –Negative charge builds up in the inner chamber
    • At equilibrium, both the electrical and chemical gradients are balanced
    • The equilibrium potential of K+ (EK) is negative, while the equilibrium potential of Na+ (ENa) is positive
    • The resting potential for an actual neuron is –60 to –80 mV. 
    • The resting potential of the neuron is closer to EK than ENa because there are many open potassium channels but only a small number of open sodium channels.
    • In a resting neuron, the currents of K+ and Na+ are equal and opposite, and the resting potential across the membrane remains steady
  315. Generation of Action Potentials:
    • At resting potential
    • 1.Most voltage-gated Na+ and K+ channels are closed, but some K+ channels (not voltage-gated) are open
    • When an action potential is generated
    • 2.Voltage-gated Na+ channels open first and Na+ flows into the cell (this depolarizes the membrane)
    • 3.During the rising phase, the threshold is crossed, and the membrane potential increases as more Na+ enters the cell.
    • 4.During the falling phase, voltage-gated Na+ channels become inactivated; voltage-gated K+ channels open, and K+ flows out of the cell.  This causes the membrane potential to become increasingly negative.
    • 5.During the undershoot, membrane permeability to K+ is at first higher than at rest, then voltage-gated K+ channels close; resting potential is then restored.
  316. During the ___________ after an action potential, a second action potential cannot be initiated
    Refractory period
  317. Action potentials travel in only one direction:
    Toward the synaptic terminals
  318. Direct synaptic transmission involves ___________ to __________ channels in the ________ cell
    • Bindingof neurotransmitters
    • Ligand-gated ion
    • Postsynaptic
  319. Neurotransmitter binding causes ion channels to open, generating a ___________
    Postsynaptic potential