Biology Exam 3

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Highly branched extensions that recieve signals from other neurons

• 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

A junction between an axon and another cell

A much longer extension that transmits signals to other cells at synapses

• A series of interconnected nerve cells
• Simple animals like the cnidarians have them

• Bundles that consist of the axons of multiple nerve cells
• More complex animals have them

• Bilaterally symmetrical animals exhibits it
• Clustering of sensory organs at the front end of the body

Annelids and arthropods have segmentally arranged clusters of neurons

• 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

• Composed of nerves and ganglia in vertebrates
• Brings information into and out of the CNS

The body's automatic response to a stimulus

• Nerve cells that transfer information within the body
• Use two types of signals to communicate:
• -Electrical signals (long-distance)
• -Chemical signals (short-distance)

Processing of information takes place in simple clusters of neurons 

More complex organization of neurons

• Sensory input
• Integration
• Motor output

Sensors detect external stimuli and internal conditions and transmit information

Sensory information is sent to the brain or ganglia, where it integrate the information

Motor output leaves the brain or ganglia via it, which trigger muscle or gland activity

• Central nervous system (CNS) 
• Peripheral nervous system (PNS)

Most of a neuron’s organelles are in

Synaptic terminal of one axon passes information across the synapse in the form of chemical messengers

A neuron

A neuron, muscle, or gland cell

Most neurons are nourished or insulated by cells

• Every cell has a voltage (difference in electrical charge) across its plasma membrane
• Messages are transmitted as changes

Membrane potential of a neuron not sending signals

Membrane voltage for a particular ion at equilibrium and can be calculated using the Nernst equation

Neurons contain it that open or close in response to stimuli

Increase in magnitude of the membrane potential

Reduction in the magnitude of the membrane potential 

Changes in polarization where the magnitude of the change varies with the strength of the stimulus

Na+ and K+ channels respond to a change in membrane 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

Action potential occurs if a stimulus causes the membrane voltage to cross

Action potential is a brief depolarization of a neuron’s plasma membrane

A result of a temporary inactivation of the Na+ channels

• 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

• Action potentials are formed only at
• Gaps in the myelin sheath where voltage-gated Na+ channels are found

Action potentials in myelinated axons jump between the nodes of Ranvier in a process

• Electrical current flows from one neuron to another
• It is rare

• Chemical neurotransmitter carries information across the gap junction
• Most synapses are it

Presynaptic neuron synthesizes and packages the neurotransmitter in it located in the synaptic terminal

Neurotransmitter diffuses across it and is received by the postsynaptic cell

• Inhibitory postsynaptic potentials (IPSPs)
• Excitatory postsynaptic potentials (EPSPs)

Hyperpolarizations that move the membrane potential farther from threshold

Depolarizations that bring the membrane potential toward threshold

Two EPSPs are produced in rapid succession

EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron add together

Neurotransmitter binds to a receptor that is not part of an ion channel

• Acetylcholine
• Biogenic amines
• Amino acids
• Neuropeptides
• Gases

Common neurotransmitter in vertebrates and invertebrates

Activity is terminated by enzymatic hydrolysis

• Epinephrine
• Norepinephrine
• Dopamine
• Serotonin
• Modulating synaptic transmission in the CNS

• Gamma-aminobutyric acid (GABA) 
• Glutamate

• Short chains of amino acids
• Function as neurotransmitters
• Include substance P and endorphins

Our perception of pain

Local regulators in the PNS

• Ventral Nerve
• Dorsal Spinal

Cerebrospinal fluid

Filtered from blood and functions to cushion the brain and spinal cord

• White matter
• Gray matter

• Neuron cell bodies
• Dendrites
• Unmyelinated axons

Bundles of myelinated axons

• Microglia
• Ependymal cells
• Oligodendrocytes and Schwann cells
• Astrocytes
• Radial glia

Play a role in the embryonic development of the nervous system

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

Promote circulation of cerebrospinal fluid

Protect the nervous system from microorganisms

Form the myelin sheaths around axons

• In the PNS
• Transmit information to the CNS

Transmit information away from the CNS

Originate in the brain and mostly terminate in organs of the head and upper body

Originate in the spinal cord and extend to parts of the body below the head

• Motor system 
• Autonomic nervous system

• Regulates the internal environment in an involuntary manner
• Has sympathetic, parasympathetic, and enteric divisions

Carries signals to skeletal muscles and is voluntary

Antagonistic

Correlates with the “fight-or-flight” response

Promotes a return to “rest and digest”

Controls activity of the digestive tract, pancreas, and gallbladder

• Forebrain
• Midbrain
• Hindbrain

• Forebrain
• Cerebrum

• Outer portion of the cerebrum
• Surrounds much of the brain

• coordinates and conducts information between brain centers
• Three parts:
• -The midbrain
• The pons
• The medulla oblongata

Contains centers for receipt and integration of sensory information

Regulates breathing centers in the medulla

Contains centers that control several functions including breathing, cardiovascular activity, swallowing, vomiting, and digestion

Coreof the brainstem has a diffuse network of neurons

• Hormone
• Released by the pineal gland and plays a role in bird and mammal sleep cycles

• Important for coordination and error checking during motor, perceptual, and cognitive functions
• Involved in learning and remembering motor skills

• Epithalamus
• Thalamus
• Hypothalamus

Includes the pineal gland and generates cerebrospinal fluid from blood

Main input center for sensory information to the cerebrum and the main output center for motor information leaving the cerebrum

• 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

Require external cues to remain synchronized with environmental cycles

• Mammals usually have a pair of it
• In the hypothalamus that function as a biological clock

Develops from the embryonic telencephalon

Cerebral hemispheres

Cerebral cortex (gray matter) overlying white matter and basal nuclei

Important centers for planning and learning movement sequences

• A thick band of axons
• Provides communication between the right and left cerebral cortices

• In mammals, the cerebral cortex has a convoluted surface
• Previously thought to be required for cognition

Perception and reasoning that form knowledge

• Frontal
• Temporal
• Occipital
• Parietal

• Sensory organs
• Somatosensory receptors

Frontal lobe is active when speech is generated

Temporal lobe is active when speech is heard

Transmits information between the two cerebral hemispheres

More adept at language, math, logic, and processing of serial sequences

Stronger at pattern recognition, nonverbal thinking, and emotional processing

• Differences in hemisphere function
• Linked to handedness

• Emotions are generated and experienced
• Ring of structures around the brainstem that includes:
• -Amygdala
• -Hippocampus
• -Thalamus

Located in the temporal lobe and helps store an emotional experience as an emotional memory

Emergent property of the brain based on activity in many areas of the cortex

• Neurons compete for growth-supporting factors in order to survive
• Only half the synapses that form during embryo development survive into adulthood

• Ability of the nervous system to be modified after birth
• Changes can strengthen or weaken signaling at a synapse

• Short-term memory is accessed
• Plays a role in forming long-term memory, which is stored in the cerebral cortex

• In the vertebrate brain
• Involves an increase in the strength of synaptic transmission
• Involves glutamate receptors

• Schizophrenia
• Depression
• Alzheimer’s disease
• Parkinson’s disease

Characterized by hallucinations, delusions, blunted emotions, and other symptoms

• Major depressive disorder
• Bipolar disorder

Characterized by manic (high-mood) and depressive (low-mood) phases

Patients have a persistent lack of interest or pleasure in most activities

• Mental deterioration characterized by confusion, memory loss, and other symptoms
• Caused by the formation of neurofibrillary tangles and amyloid plaques in the brain

• 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

• 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

• Equipped to respond by binding to specific receptor proteins
• With receptors respond to the signal

• Endocrine system
• Nervous system

Secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior

Conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells

• Hormones
• Local regulators
• Neurotransmitters
• Neurohormones
• Pheromones

• Endocrine signals (hormones) are secreted into extracellular fluids and travel via the bloodstream
• Endocrine glands are ductless and secrete hormones directly into surrounding fluid

• 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.

Class of hormones that originate from neurons in the brain and diffuse through the bloodstream

• 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

• 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

• Polypeptides (proteins and peptides)
• Amines derived from amino acids
• 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

• 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.

Secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors

• 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

• 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

• 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

• 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

a and b

In smooth muscle cells of intestinal blood vessels: triggers different G proteins and different enzymes to cause smooth muscle contraction to restrict blood flow.

• 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.

• Cytokines and growth factors
• Nitric oxide (NO)
• Prostaglandins

Can act as both a neurotransmitter as well as a very fast acting local regulator.

Modified fatty acids first identified in prostate gland secretions. 

• 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.

Negative feedback and antagonistic hormone pairs are common features

• 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.

• Control of blood sugar levels
• Antagonistic hormones that help maintain glucose homeostasis

Islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin

Digestive enzymes destined for the small intestine

• alpha cells (which secrete glucagon)
• beta cells (which secrete insulin)

• Promoting the cellular uptake of glucose
• Slowing glycogen breakdown in the liver
• Promoting fat storage

• Stimulating conversion of glycogen to glucose in the liver
• Stimulating breakdown of fat and protein into glucose

• 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

• Insulin-dependent
•  Is an autoimmune disorder in which the immune system destroys pancreatic beta cells

Non-insulin-dependent involves insulin deficiency or reduced response of target cells due to change in insulin receptors (latter being most common).

Individually and together in regulating animal physiology

Composed of the posterior pituitary and anterior 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

• Makes and releases hormones under regulation of the hypothalamus
• Hormone production in it is controlled by releasing and inhibiting hormones from the hypothalamus

Enhances water reabsorption in the kidneys

• 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

Regulates the function of endocrine cells or glands

• Thyroid-stimulating hormone (TSH)
• Follicle-stimulating
• hormone (FSH)
• Luteinizing hormone (LH)
• Adrenocorticotropic hormone (ACTH)

Target nonendocrine tissues

• Prolactin (PRL)
• Melanocyte-stimulating hormone (MSH)

Influences skin pigmentation in some vertebrates and fat metabolism in mammals

Stimulates lactation in mammals but has diverse effects in different vertebrates

• 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

Respond to diverse stimuli in regulating metabolism, homeostasis, development, and behavior

• 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.

• Stimulate metabolism and influence development and maturation
• Proper thyroid function requires dietary iodine for hormone production
• Two Thyroid hormones are:
• -Hypothyroidism
• -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

Low secretion of thyroid hormones, causes weight gain, lethargy, and intolerance to cold

• 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

• Calcitonin
• Parathyroid hormone (PTH)

• Decreases the level of blood Ca2+
• Is released by the thyroid gland
• It stimulates Ca2+ deposition in bones and secretion by kidneys

Response to stress

• Adjacent to the kidneys
• Consistsof two glands:
• -The adrenal medulla (inner portion)
• -Adrenalcortex (outer portion)

Secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)

Catecholamines

• Secreted in response to stress-activated impulses from the nervous system
• They mediate various fight-or-flight responses

• 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

Corticosteroids in response to stress

Triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary

• Glucocorticoids
• Mineralocorticoids

Influence glucose metabolism and the immune system

Affect salt and water balance

Small amounts of steroid hormones that function as sex hormones

• Androgens
• Estrogens
• Progestins
• All three sex hormones are found in both males and females, but in different amounts

Androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system

Muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks

Maintenance of the female reproductive system and the development of female secondary sex characteristics

Preparing and maintaining the uterus

FSH and LH from the anterior pituitary

• 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

• Synthetic chemicals and natural plant compounds that may affect the endocrine system of animals
• Mainly associated with developmental, reproductive and health problems in wildlife

• 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

Some (phytoestrogens) occur naturally in plants (clover, soybeans, legumes); Others are synthetic chemicals.

• 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)

• 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])

• 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

• 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)

Creation of an offspring by fusion of a male gamete (sperm) and female gamete (egg) to form a zygote

Creation of offspring without the fusion of egg and sperm

• Many invertebrates reproduce asexually by it
• Separation of a parent into two or more individuals of about the same size

New individuals arise from outgrowths of existing ones

• Breaking of the body into pieces, some or all of which develop into adults
• Must be accompanied by regeneration

Regrowth of lost body parts

The development of a new individual from an unfertilized egg

• 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

Release of mature eggs at the midpoint of a female cycle

• Each individual has male and female reproductive systems
• Some hermaphrodites can self-fertilize

Some species exhibit male to female reversal while others exhibit female to male reversal

Mechanisms that bring together sperm and eggs of the same species

Sexual Reproduction

Eggs shed by the female are fertilized by sperm in the external environment

• Critical timing
• Often mediated by environmental cues
• Pheromones
• Courtship behavior

• 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

• Gonads
• Organs that produce gametes

Spermatheca in which sperm is stored during copulation

• 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

Consist of a partially developed egg

• Surrounded by support cells
• Once a month, it develops into an ovum (egg) by the process of oogenesis

Expels an egg cell from the follicle

Corpus Luteum

• Secretes hormones that help to maintain pregnancy
• If the egg is not fertilized, it degenerates

Oviduct, or fallopian tube

Uterus, also called the womb

• Uterus lining
• Has many blood vessels

Cervix, then opens into the vagina

Thin-walled chamber that is the repository for sperm during copulation and serves as the birth canal

• Vagina opens to the outside at it
• Consists of the labia majora, labia minora, hymen, and clitoris

• Not part of the reproductive system but are important to mammalian reproduction
• Small sacs of epithelial tissue secrete milk

Scrotum and penis

Produce sperm and hormones, and accessory glands

• Consist of highly coiled tubes surrounded by connective tissue
• Male gonads

Seminiferous Tubules

Produce hormones and are scattered between the tubules

• The testes of many mammals are held outside the abdominal cavity in it
• Where the temperature is lower than in the abdominal cavity

Body temperatures of most mammals

• Seminiferous tubules
• Epididymis

• Ejaculation
• Vas deferens
• Ejaculatory duct
• Urethra

Composed of sperm plus secretions from three sets of accessory glands

60% of the total volume of semen

Secretes its products directly into the urethra through several small ducts

Secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra

Composed of three cylinders of spongy erectile tissue

• Vasocongestion
• Myotonia

Increased muscle tension

The filling of tissue with blood

Sexual Intercourse

Characterized by rhythmic contractions of reproductive structures

The production of gametes by meiosis, differs in females and males

Production of mature sperm

Cross-breeds between animals of similar genetics

• 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

Mammalian reproduction

• Hypothalamus
• Anterior Pituitary
• Gonads

Secreted by the hypothalamus and directs the release of FSH and LH from the anterior pituitary

The gonads and the production of sex hormones

• Androgens
• Estrogens
• Progesterone

• –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

Sertoli cells

Nourish developing sperm and are located within the seminiferous tubules

Leydig cells

Secrete testosterone and other androgen hormones, which in turn promote spermatogenesis

Inhibin

Reduces FSH secretion from the anterior pituitary

Cyclic

Menstruation

• –Changes in the uterus define the menstrual cycle (also called the uterine cycle)
• –Changes
• in the ovaries define the ovarian cycle

• Estradiol
• Follicular phase

• Ovulation
• Secondary oocyte

• Corpus luteum
• Luteal phase

• –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

Ectopic

Endometriosis

• 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

• –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

A ball of cells with a cavity

Cleavage

Fertilization of an egg by a sperm, occurs in the oviduct

Prevents menstruation

Condition of carrying one or more embryos in the uterus

Trimesters

• Trophoblast
• Placenta

Identical

Fraternal and genetically distinct

Development of the body organs

Fetus

Labor

The production of milk

The deliberate prevention of pregnancy, can be achieved in a number of ways

• –Preventing release of eggs and sperm
• –Keeping sperm and egg apart
• –Preventing implantation of an embryo

• Rhythm method
• Natural family planning

• –A condom fits over the penis
• –A diaphragm is inserted into the vagina before intercourse

Hormonal contraceptives

• –Tubal ligation ties off the oviducts
• –Vasectomy ties off the vas deferens

Termination of a pregnancy

Assisted reproductive technologies

Eggs with sperm in culture dishes and returns the embryo to the uterus at the 8 cell stage

Intracytoplasmic sperm injection (ICSI)

• 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)

• PNS
• CNS
• Movement
• Environment

• 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

• 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

• 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.

Refractory period

Toward the synaptic terminals

• Bindingof neurotransmitters
• Ligand-gated ion
• Postsynaptic

Postsynaptic potential