Unit 3- AMSCO

Neuron

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A nerve cell; the basic building block of the nervous system

Cell body

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The part of a neuron that contains the nucleus, the cell’s life support center 

Dendrites

A neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body

Axon

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The neuron extension that passess messages through its branches to other neurons or to muscles or glands 

Myelin sheath

A fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speeds as neural impulses hop from one node to the next

Glial cells

Cells in the nervous system that support, nourish, and protect neurons, they also play a role in learning, thinking, and memory

Action potential

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A neural impulse; a brief electrical charge that travels down the axon 

Threshold

The level of stimulation required to trigger a neural impulse

Refractory period

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In neural processing, a brief resting pause that occurs after an neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state 

All-or-none response

A neuron’s reaction of either firing (with a full-strength response) or not firing

Synapse

The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or cleft

Neurotransmitters

Chemical messengers that cross the synaptic gaps between neurons.

Reuptake

A neurotransmitter’s reabsorption by the sending neuron

Cell body

\#1

Dendrites

\#2

Axon

\#3

Myelin sheath

\#5

Terminal branches

\#6

Dendrites, Cell Body, Axon, Terminal Branches

Order of how impulse travels through a neuron

Resting potential

When a neuron is positively charged on the outside and negatively charged on the inside

Depolarization

When the neuron no longer has a charge difference between the inside and outside of the axon membrane

Excitatory signal exceeding the inhibitory signal by a mimum threshold

What triggers an action potential?

No

Can an action potential happen during the refractory period?

More neurons are triggered and fire more rapidly

How do humans sense the intensity of a stimulus?

Synaptic gap

What is the space between neurons called?

They bind to receptor sites on receiving neurotransmitters

What happens when neurotransmitters cross the synaptic gap?

Brake down, drift away, reabsorbed (reuptake)

What happens to excess neurotransmitters?

Acetylcholine (ACh)

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* Function: Enables muscle action, learning, and memory 
* Malfunction: Alzheimer’s when the neurons that produce this neurotransmitter deteriorate 

Dopamine

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* Function: Influence movement, learning, attention, and emotion 
* Malfunction: Oversupply can cause schizophrenia and undersupply can lead to Parkinson’s 

Serotonin

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* Function: Affects mood, hunger, sleep, and arousal
* Malfunction: Undersupply linked with depression 

Norepinepherine

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* Function: Control alertness and arousal 
* Malfunction:  Depressed mood 

GABA

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* Function: Major inhibitory neurotransmitter 
* Malfunction: undersupply  linked to seizures, tremors, and insomnia

Glutamate

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* Function: Major excitatory neurotransmitter involved in memory 
* Malfunction: Oversupply over stimulates the brain and causes migraines or seizures 

Endorphins

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* Function: Neurotransmitters that influence pain/pleasure perception 
* Malfunction: Oversupply caused by opiates can suppress the body’s natural supply

Agonist

A molecule that increases a neurotransmitter’s action

Anatgonist

A molecule that inhibits or blocks a neurotransmitter’s action

Nervous system

The body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous system

Central nervous system

The brain and the spinal cord

Peripheral nervous system

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The sensory and motor  neurons that connect the central nervous system to the rest of the body 

Nerves

Bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs

Sensory (afferent) neurons

Neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord

Motor (efferent) neurons

Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Interneurons

Neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs

Somatic nervous system

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The division of the peripheral nervous system that controls the body’s skeletal muscles

Autonomic nervous systen

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The part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic divisions arouses and the parasympathetic division calms. 

Sympathetic nervous system

The division of the ANS that arouses the body

Parasympathetic nervous system

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The division of the ANS that calms the body 

Reflex

A simple, automatic response to a sensory stimulus, such as the knee-jerk response

Endocrine system

The body’s slow chemical communication system; a set of glands that secrete hormones into the bloodstream

Hormones

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Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues 

Adrenal glands

A pair of endocrine glands that sit just above the kidneys and secrete hormones that help arouse the body in times of stress

Pituitary glands

The endocrine system’s most influential gland. Under the influence of the hypothalamus, it regulates growth and controls other endocrine glands

Central Nervous System and Peripheral Nervous System

2 major parts of the nervous system

Sensory, motor, interneurons

What are the three types of neurons

Somatic nervous system and autonomic nervous system

Two parts of the peripheral nervous system

Sympathetic nervous system and parasympathetic nervous system

What are the two parts of the autonomic nervous system?

Neural networks

The neruons in the brain that have clustered into work groups

Sensory neuron

A

Interneuron

B

Motor neuron

C

Muscle

D

Similarities between endocrine and nervous system

Hormones and neurotransmitters can be chemically similar

Both produce chemicals that act on receptors elsewhere

endocrine, nervous

The ______ system is slower but the effects last longer than the __ system

Hypothalamus

Brain region controlling pituitary gland

Thyroid gland

Affects metabolism

Adrenal gland

Inner parts help trigger the fight or flight response

Testis

Secrete male sex hormones

Pituitary gland

Secretes many different hormones, some of which affect other glands

Parathyroids

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Help regulate the level of calcium in the blood 

Pancreas

Regulates the level of sugar in the blood

Ovary

Secretes female sex hormones

Pituitary

What is the most influential gland in the endorcine system and it is controlled by the hypothalamus

EEG

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Measures the electrical activity in the brain, information is collected by placing electrodes on the scalp 

MEG

Measures the magnetic fields from the brain’s natural electrical activity

CT/CAT scan

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* Series of X-ray photos taken from different angles and combined into a composite representation of a slice of the brain’s structure 
* Help reveal brain damage

PET scan

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* A visual display of brain activity that detects where a radioactive form of glucose foes while the brain performs a given task 

MRI scan

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* A technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. Shows brain anatomy 

fMRI scan

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* A technique for revealing blood flow, and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as structure

The brainstem

The oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull. It is responsible for automatic survival functions

Medulla

The base of the brainstem

Controls heart rate and breathing

Pons

Above the medulla

Coordinate movement and sleep

The Thalamus

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* Sits atop the brainstem 
* Sensory control center of the brain 
* Receives all information from sense except scent and routes it to the right places in the higher regions of the brain

The Reticular Formation

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* Neuron network that goes from the spinal cord up through to the thalamus 
* Filters incoming stimuli and relays information to other parts of the brain 
* Also controls arousal 

The Cerebellum

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* Extends from the back of the brainstem 
* Enables nonverbal learning and skill memory 
* Judge time, modulate emotions, discriminate sounds and textures 
* Coordinates voluntary movement

The Limbic System

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* Neural system located below the cerebral hemispheres and is associated with emotions and drives 
* Contains the amygdala, hypothalamus, and hippocampus 

Amygdala

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* Linked with aggression and fear 

The hypothalamus

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* Just below the thalamus 
* Influences hunger, thirst, body temperature, and sex drive 
* Helps maintain homeostasis 
* Contains reward centers 

The hippocampus

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* Process conscious, explicit memories
* Decreases in size and function as we grow older 

Brainstem

F, E, and reticular formation

Medulla

F

Pons

E

Thalamus

J

Cerebellum

H

Amygdala

Green section

Hypothalamus

Hippocampus

Pink section

Cerebral cortex

The intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center

Frontal lobes

The portion of the cerebral cortex lying just behind the forehead; involved in speaking, muscle movements, and making plans/judgments

Parietal lobes

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The portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body positions

Motor cortex

An area at the rear of the frontal lobes that controls voluntary movement