______ suggested that bumps of the skull represented mental abilities
Life support center of the neuron.
Branching extensions at the cell body. Receive messages from other neurons.
Long single extension of a neuron, covered with myelin [MY-uh-lin] sheath to insulate and speed up messages through neurons.
Terminal Branches of axon:
Branched endings of an axon that transmit messages to other neurons.
Depolarization occurs when positive ions enter the neuron, making it more prone to firing an action potential.
occurs when negative ions enter the neuron, making it less prone to firing an action potential.
Each neuron receives depolarizing and hyperpolarizing currents from many neurons.
When the depolarizing current (positive ions) minus the hyperpolarizing current (negative ions) exceed minimum intensity (threshold) the neuron
fires an action potential.
After a neuron fires an action potential it pauses for a short period to recharge itself to fire again.
Sodium-potassium pumps pump positive ions out from the inside of the neuron, making them ready for another action potential.
When the depolarizing current exceeds the threshold, a neuron will fire. If the depolarizing current fails to exceed the threshold, a neuron will not fire.
Intensity of an action potential remains _______ throughout the length of the axon.
a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft.
Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential.
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action.
pathways are involved with regulating mood, sleep, food intake, and pain tolerance.
Low levels of serotonin produce: insomnia, depression, food cravings, increased pain sensitivity, aggression, and poor body-temperature regulation.
Short term surges of dopamine are normally
associated with feelings of pleasure. Abnormally HIGH concentrations of dopamine are associated with schizophrenia.
Delusions (false beliefs)
Hallucinations (false perceptions) Abnormally LOW levels of dopamine are associated with Parkinson’s disease
hand shaking lack of facial expressions, weak voice slowness of movement shuffling steps, muscle stiffness, imbalance, intellectual decline), and
attention deficit disorder.
Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system.
Central Nervous System (CNS):
the brain and spinal cord.
Peripheral Nervous System (PNS):
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
carry incoming information from the sense receptors to the CNS.
carry outgoing information from the CNS to muscles and glands.
provide nutrition to neurons
Oligodendrocytes and Schwann
cells insulate neurons as myelin.
Somatic Nervous System:
The division of the peripheral nervous system that controls the body’s skeletal muscles.
Autonomic Nervous System:
Part of the PNS that controls the glands and other muscles.
Nerves consist of neural
“cables” containing many axons. They are part of the peripheral nervous system and connect muscles, glands, and sense organs to the central nervous system.
Sympathetic Nervous System:
Division of the ANS that arouses the body, mobilizing its energy in stressful situations.
Parasympathetic Nervous System:
Division of the ANS that calms the body, conserving its energy.
(rest and digest)
is the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands.
are chemicals synthesized by the endocrine glands that are secreted in the bloodstream. Hormones affect the brain and many other tissues of the body.
Is called the “master gland.” The anterior pituitary lobe releases hormones that regulate other glands. The posterior lobe regulates water and salt balance.
Thyroid & Parathyroid Glands
Regulate metabolic and calcium rate.
Adrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones (epinephrine and norepinephrine) during stressful and emotional situations, while the adrenal cortex regulates salt and carbohydrate metabolism.
Sex glands are located in different places in men and women. They regulate bodily development and maintain reproductive organs in adults.
A brain lesion experimentally destroys brain tissue to study animal behaviors after such destruction.
An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp.
PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task.
MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue. Top images show ventricular enlargement in a schizophrenic patient. Bottom image shows brain regions when a participants lies.
The Brainstem is the oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival functions.
Medulla [muh-DUL- uh]
The Medulla [muh-DUL- uh] is the base of the brainstem that controls heartbeat and breathing.
is a nerve network in the brainstem that plays an important role in controlling arousal.
Thalamus [THAL-uh- muss]
The Thalamus [THAL-uh- muss] is the brain’s sensory switchboard, located on top of the brainstem. It directs messages to the sensory areas in the cortex and transmits replies to the cerebellum and medulla.
The “little brain” attached to the rear of the brainstem. It helps coordinate voluntary movements and balance.
The Limbic System
The Limbic System is a doughnut-shaped system of neural structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and drives for food and sex. It includes the hippocampus, amygdala, and hypothalamus.
The Amygdala [ah-MIG-dah- la] consists of two almond- shaped neural clusters linked to the emotions of fear and anger.
The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating, drinking, body temperature, and control of emotions. It helps govern the endocrine system via the pituitary gland.
The Cerebral Cortex
The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the body’s ultimate control and information processing center.
Structure of the Cortex
Each brain hemisphere is divided into four lobes that are separated by prominent fissures. These lobes are the frontal lobe (forehead), parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of head).
is the area at the rear of the frontal
lobes that control voluntary movements.
The Sensory Cortex
(parietal cortex) receives information from skin surface and sense organs.