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Regulation
control and coordination of life functions and activities
2 systems involved:
1. nervous- electrical system, brain,spine and nerves
found in multicellular organisms
2. endocrine- chemical system, hormones
found in all organisms
Nervous System:
definitions:
a. stimulus- change in the internal or external environment that
triggers an impulse which ends in a response
b. impulse- “message”; electrochemical charge sent along a nerve
cell (neuron)
c. receptor- structures that detect stimuli
ex) sense organs
d. response- reaction to a stimulus
carried out by the effectors
e. effector-organs of response
include muscles & glands
f. neuron- nerve cell, functional unit of nervous system
a bundle of neurons is a nerve
Parts of a neuron:
1. dendrites- fibers that detect stimuli
generate impulse toward cyton
2. cyton- “cell body”
contains nucleus
3. axon- fibers that send impulse away from cyton to
terminal branches
4. terminal branches- end of axon
contain synaptic knobs that secrete
neurotransmitters
cyton
nucleus
dendrites
node of
axon
Ranvier
terminal
branches
nucleus/Schwann cell
myelin
Schwann cell
(produces
myelin)
Direction of impulse:
synaptic
knobs
definitions cont’d
g. synapse- space between 2 neurons or between neuron & effector
neurons are not connected
h. neurotransmitters-chemicals that aid in the transmission of
impulses across a synapse
ex) acetylcholine
Ntrans. clip
Path of an impulse to brain/spinal cord:
stimulus
(dendrites
of sensory
neuron)
cyton
axon
terminal
branch
synapse
dendrites of
next neuron
…….until it
reaches
brain or
spinal cord
End of notes for neuron quiz
Types of Neurons:
a. sensory- found in sense organs
relay impulse from receptor to brain or spinal cord in
the CNS (Central Nervous System)
b. motor- “neurons of motion”
relay impulse from CNS to effectors
impulse relay causes muscle to contract or gland to
secrete hormones
c. inter- “relays” in brain & spinal cord
interpret & relay impulse between sensory & motor neuron
Reflex
An involuntary, automatic response to a stimulus
•Impulse does NOT travel to the brain
stimulus
sensory
neuron
(receptor)
interneuron
(spinal cord)
motor
neuron
(effector)
RESPONSE
See Awesome Adaptations sheet
Human Nervous System
Functional Organization:
•Central Nervous System (CNS)
brain, spinal cord, interneurons
• Peripheral Nervous System (PNS)
nerves outside of the CNS; sensory and motor neurons
A. Central Nervous System
1.Brain
3 lb. organ, uses 20% of body’s oxygen
100 billion neurons
protected by skull, meninges (tough membrane) and
cerebrospinal fluid (CSF)
Composed of 2 sides called hemispheres
3 major parts:
a. cerebrum
•largest part
• right hemisphere controls the left side of the body & viceversa
•the 2 hemispheres communicate via the nerves of the corpus
callossum
•is convoluted (folded) to increase surface area for information
storage
functions:
1. sensory impulses are interpreted
2. voluntary motor activity (movement) is initiated
3. responsible for thinking, learning & memory
b. cerebellum•located beneath the rear of cerebrum
•coordinates motor activities, maintains balance
•affected by alcohol and if damaged can cause loss of balance
or tremors
c. medulla oblongata- (brainstem)
•connects brain & spinal cord
•controls involuntary actions (heart, digestion, breathing)
cerebrum
hypothalamus
thalamus
corpus
callosum
cerebellum
medulla
spinal cord
Synesthesia
Link:
biomovies
Other brain terms:
gray matter- any region in the brain or spinal cord that contains
cytons
white matter- contains myelin & axons
thalamus- relay area/center btwn. brain & spinal cord
hypothalamus- controls body temp, blood pressure, sleep &
emotions
connected to pituitary gland
acts like a gland by stimulating pituitary
2.Spinal Cordthick nerves protected by vertebrae (backbones)
continuous w/medulla
connects brain to PNS
controls reflexes
covered by meninges
surrounded by CSF
B. Peripheral Nervous System
all nerves outside of CNS
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. sympathetic
antagonists; have
opposite effects
2. parasympathetic
Neurotransmitter
Sympathetic
Parasympathetic
norepinepherine
(excitatory)
prepares for
emergency
acetylcholine
(inhibitory)
returns body to
normal, relaxed state
effects on:
heart
speeds up
slows down
vessels
constricts
(gets small)
dilate
(get big)
eyes
pupils dilate
pupils constrict
Malfunctions of the Nervous System:
A. Cerebral Palsydisease that affects cerebrum and creates problems
w/motor functions, voluntary action and memory
B. Meningitisinflammation of the membranes surrounding the
brain & spinal cord
C. Strokeresults from a hemorrhage (excessive bleeding due to
broken blood vessel) or a blood clot in the cerebrum
D. Polioviral disease of the CNS
may result in paralysis
is preventable by immunization
Nervous System
Central
brain
spinal
cord
Peripheral
autonomic
sympathetic
somatic
parasympathetic
End of info for human n. sys quiz