Regulationcontrol and coordination of life functions and activities2 systems involved:

1. nervous- electrical system, brain,spine and nerves

found in multicellular organisms2. endocrine- chemical system, hormones found in all organisms

Nervous System:

definitions:

a. stimulus-

“message”; electrochemical charge sent along a nerve cell (neuron)

change in the internal or external environment that triggers an impulse which ends in a responseb. impulse-

c. receptor-structures that detect stimuliex) sense organs

d. response-reaction to a stimuluscarried out by the effectors

e. effector-organs of responseinclude muscles & glands

Parts of a neuron:

f. neuron-nerve cell, functional unit of nervous systema bundle of neurons is a nerve

fibers that detect stimuli generate impulse toward cyton

2. cyton-“cell body” contains nucleus

fibers that send impulse away from cyton to terminal branches

3. axon-

1. dendrites-

4. terminal branches-end of axon

Direction of impulse:

cyton

nucleus

dendritesnode of Ranvier

axon

nucleus/Schwann cell

myelin

Schwann cell (produces myelin)

terminal branches

synaptic knobs

contain synaptic knobs that secrete neurotransmitters

definitions cont’d

g. synapse-space between 2 neurons or between neuron & effectorneurons are not connected

h. neurotransmitters-chemicals that aid in the transmission of impulses across a synapseex) acetylcholine

Path of an impulse to brain/spinal cord:

stimulus(dendrites of sensory neuron)

synapsecyton axon

dendrites of next neuron

…….until it reaches brain or spinal cord

End of notes for neuron quiz

terminal branch

Types of Neurons:

relay impulse from receptor to brain or spinal cord in the CNS (Central Nervous System)

found in sense organs

“neurons of motion” relay impulse from CNS to effectors

b. motor-

a. sensory-

impulse relay causes muscle to contract or gland to secrete hormones

“relays” in brain & spinal cordinterpret & relay impulse between sensory & motor neurons

c. inter-

ReflexAn involuntary, automatic response to a stimulus

•Impulse does NOT travel to the brain

stimulus

interneuron(spinal cord)

motor neuron(effector)

RESPONSE

sensory neuron (receptor)

See Awesome Adaptations sheet

Functional Organization:

Human Nervous System

brain, spinal cord, interneurons

•Central Nervous System (CNS)

• Peripheral Nervous System (PNS)

nerves outside of the CNS; sensory and motor neurons

A. Central Nervous System

1.Brain

100 billion neurons3 lb. organ, uses 20% of body’s oxygen

protected by skull, meninges (tough membrane) and cerebrospinal fluid (CSF)Composed of 2 sides called hemispheres

•the 2 hemispheres communicate via the nerves of the corpus callossum

•largest part

a. cerebrum

•right hemisphere controls the left side of the body & vice-versa

3 major parts:

•is convoluted (folded) to increase surface area for information storage

functions:

•located beneath the rear of cerebrum

b. cerebellum-

•coordinates motor activities, maintains balance

2. voluntary motor activity (movement) is initiated 3. responsible for thinking, learning & memory

•affected by alcohol and if damaged can cause loss of balance or tremors

1. sensory impulses are interpreted

c. medulla oblongata- (brainstem)

•controls involuntary actions (heart, digestion, breathing)

•connects brain & spinal cord

hypothalamus

spinal cordmedulla

cerebellum

corpuscallosum

cerebrum

thalamus

Other brain terms:gray matter-

hypothalamus-

any region in the brain or spinal cord that contains cytons

white matter-

thalamus-

contains myelin & axons

relay area/center btwn. brain & spinal cord

controls body temp, blood pressure, sleep & emotions

acts like a gland by stimulating pituitary connected to pituitary gland

1.Spinal Cord-

thick nerves protected by vertebrae (backbones)

all nerves outside of CNS

continuous w/medulla

controls reflexesconnects brain to PNS

covered by meningessurrounded by CSF

B. Peripheral Nervous System

those connected to brain are cranial nerves 12 pairs servicing head & sense organs

those connected to spinal cord are spinal nerves 31 pairs throughout the body

2 Divisions of the PNS

somatic-nerves that control both voluntary movement (motor neurons) and sense organs (sensory neurons)

autonomic-nerves that control involuntary actions like breathing & heart rate. Made of 2 subdivisions:

1. sympathetic2. parasympathetic

antagonists; have opposite effects

Sympathetic Parasympathetic

Neurotransmitter

effects on:

heart

vessels

eyes

norepinepherine(excitatory)prepares for emergency

speeds up

constricts (gets small)

pupils dilate

acetylcholine(inhibitory)returns body tonormal, relaxed state

slows down

dilate(get big)

pupils constrict

Malfunctions of the Nervous System:

A. Cerebral Palsy-

disease that affects cerebrum and creates problems w/motor functions, voluntary action and memory

results from a hemorrhage (excessive bleeding due to

broken blood vessel) or a blood clot in the cerebrum

C. Stroke-

viral disease of the CNS

inflammation of the membranes surrounding the brain & spinal cord

D. Polio-

B. Meningitis-

may result in paralysis

is preventable by immunization

Nervous System

CentralPeripheral

brain spinal cord

somaticautonomic

sympathetic

parasympathetic

End of info for human n. sys quiz