Unit 2: Support System - Nervous System 85
Nervous System
READ: Chapter 12 - pages 221-243
Chapter 13 - pages 248-250
1) What is a nerve impulse?
2) What type of nervous system do humans possess and how is it organized?
3) What type of nervous system do sea stars possess and how is it organized?
4) How does a sensation (one of the senses) illicit a response by the body (e.g.,
placing hand on a hot object brings about a quick removal of the hand from the
surface) ?
A. Nervous Tissue (Chapter 4, page 64-65)
1) Two Cell Types:
a) Neurons -
b) neuroglia (glial cells) -
Unit 2: Support System - Nervous System 86
1. Match the parts of the neuron with their function.
_______ 1. Axon A. contains the nucleus and other
organelles
_______ 2. Dendrites B. sends nerves impulses
_______ 3. Cell body C. receives stimulation
2. What is the function of the neuroglia?
Unit 2: Support System - Nervous System 87
B. Anatomical Design of the Human Nervous System
General Organization -
1. Central Nervous System (CNS) -
Brain -
Spinal cord -
2. Peripheral Nervous System (PNS)-
Nerves -
sensory -
motor -
mixed -
Cranial nerves -
Spinal nerves -
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B. Nervous System & Flow of Nerve Impulses -
General Organization -
Unit 2: Support System - Nervous System 89
1. The Afferent (sensory) Branch Receives & Transmits SENSORY Information
Types of stimuli received-
C___________________________________
O___________________________________
M___________________________________
E____________________________________
T____________________________________
Sensory receptors -
Types of receptors
Receptors Types of stimuli detected
Sensory Neurons -
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2. The CNS Receives SENSORY Nerve Impulses
Sensory nerve impulses enter the CNS at one of two places:
a) Cranial nerves
sensory nerves
motor nerves
mixed nerves
b) Spinal nerves -
dorsal root -
ventral root -
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3) CNS directs SENSORY nerve impulses to regulatory centers of the brain -
Examples:
Respiratory center -
Cardiovascular center-
Muscular coordination -
4. CNS sends MOTOR nerve impulses that govern effectors.
Effector -
Two Types of Motor Neurons -
ÎSomatic motor neurons -
ÏAutonomic motor neurons -
parasympathetic division:
sympathetic division:
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Identify the type of motor neuron that carries the nerve impulse to each
effector and determine whether or not control is voluntary.
Effector Nerve Type Voluntary (Y/N)?
Skeletal muscle
Cardiac muscle
Smooth muscle
Glands
C. Biology of The Nerve Impulse
General observations of excitable cells:
Unit 2: Support System - Nervous System 93
1. Resting Neurons:
Receiving area of neuron -
Nuclear area of neuron -
Conducting area of neuron -
Transmitting area of neuron -
2. Active Neurons
(i) stimulated by a stimulus
(ii) conduction of a nerve impulse
Unit 2: Support System - Nervous System 94
unmyelinated axon myelinated (w/ myelin sheath)
(w/out myelin sheath)
(iii) transmission of a nerve impulse to the next nerve cell.
Unit 2: Support System - Nervous System 95
Detailed view of the junction between nerve cells.
Synapse -
Neurotransmitters -
Neurotransmitter receptors -
Neurotransmitter degradation -
Heroine binds to the neurotransmitter receptors for the endorphins
(neurotransmitters of the brain that produce “runner’s high”) that
block pain sensations and cause euphoric sensations. Heroine will
mimic / not mimic (circle one) the endorphins. Explain .
Organophosphates (used in insecticides and nerve gas) are acetylcholine esterase
inhibitors, inhibiting the enzyme that breaks down acetylcholine (Ach) in the synapse. Ach
stimulates skeletal muscle to contract and slows the heart rate. Nerve gas will cause the
effects of the neurotransmitter to (circle one): increase / decrease / remain the same.
Explain your answer. What are the consequences for skeletal muscles? Heart rate?
Unit 2: Support System - Nervous System 96
D. The Brain -
1.
___________________ 4. ___________________ 7. ___________________
2. ___________________ 5. ___________________ 8. ___________________
3. ___________________ 6. ___________________ 9. ___________________
Parts and Functions:
1. Brainstem = _____________ + __________________ + __________________________
Medulla oblongata -
Pons -
Midbrain
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2. Cerebellum -
3. Diencephalon = ____________________________ + ____________________________
Thalamus -
Hypothalamus -
pituitary gland -
4. Cerebrum -
Left and right halves -
Functional areas -
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Higher mental functions -
Limbic system -
Memory -
Short-term memory -
Long-term memory -
E. Neural Responses to stimuli:
1. Reflex -
a) Somatic
motor reflex
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Trace the path of nerve impulses in a somatic motor reflex:
start: ____________________________ º ____________________________ º
___________________________ º ________________________ º ____________________
(b) Autonomic Motor Reflexes -
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Examples of
Autonomic Nervous
System Reflexes
Sympathetic Division Parasympathetic
(Fight or flight = stress) Division (relax/repose)
Cardiovascular system
heart rate -
Blood pressure -
Respiratory system
bronchiole diameter -
Digestive system
Digestive secretions -
Movement -
Skin
Muscles to hair -
Sweat glands -
2. Complex neural circuits -
Sociobiology -
Evolutionary psychology -