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- “message”; electrochemical charge sent along a nerve cell (neuron) change in the internal or external environment that triggers an impulse which ends in a response b. impulse-
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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.
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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