Nervous System

Question 1

Neuron general function and structure

Answer 1

Function:
- Basic functional units of nervous system.
- Depolarization and repolarization (K+/Na+ pump).
- Requires high amounts of O2.
Structure:
- Dendrites and axons

Question 2

White matter

Answer 2

• Fibers beneath the cortex and corpus callosum.
• Connect two halves of the cerebral cortex.

Question 3

Myelin

Answer 3

Myelin axons conduct impulses faster

Question 4

Dendrites function and structure

Answer 4

Function:
- Receive stimuli from other neurons & conduct the stimuli to the cell body.
- Can serve as sensory receptors for inside/outside body (heat, cold, touch, pressure, physical changes).
Structure:
- Short, numerous, multibranched.

Question 5

Axon function and structure

Answer 5

Function:
- Conduct nerve pulses away from cell toward another neuron or effector cell.
Structure:
- Single, long process; may be covered with myelin.

Question 6

Gray matter

Answer 6

Cerebral cortex; outer layer of the brain

Question 7

Efferent nerves
“Motor Nerves”

Answer 7

• Conduct impulses away from CNS.
• Motor Nerves: cause skeletal muscle contraction and movement.

Question 8

Afferent nerves
“Sensory Nerves”

Answer 8

• Conduct impulses towards CNS.
• Sensory Nerves: conduct sensations from sensory receptors in the skin & other locations in the body to the CNS.

Question 9

Somatic nervous system

Answer 9

Actions under conscious/voluntary control

Question 10

Automatic nervous system

Answer 10

• Controls and coordinates automatic functions.
  Ex: slowing HR in response to low blood pressure.

Question 11

Central nervous system (CNS)

Answer 11

• Brain: Cerebrum, cerebellum, diencephalon, & brainstem.
• Spinal cord

Question 12

Peripheral nervous system (PNS)

Answer 12

• All the nerves that reach every part of the body.
• Somatic & Autonomic nervous system.

Question 13

Sympathetic nervous system

Answer 13

• “Fight or flight” response.
• Epinephrine

Question 14

Parasympathetic nervous sytem

Answer 14

• “Rest & digest” system.
• Acetylcholine

Question 15

Somatic reflexes

Answer 15

Involve contraction of skeletal muscles

Question 16

Autonomic reflexes

Answer 16

Regulate smooth muscle, cardiac muscle, and endocrine glands

Question 17

Withdrawal reflex

Answer 17

Results in contraction or flexing of muscles.
Ex: stepping on lego, so you move your foot off the ground.

Question 18

Palpebral reflex arc

Answer 18

Light tap on the medial canthus of the eye produces a blink of the eyelids

Question 19

Pupillary light reflex (PLR)

Answer 19

Normal response to shining light in the eye of an animal for the iris in both eyes to constrict

Question 20

Cerebrospinal fluid (CSF)

Answer 20

• Fluid between layers of the meninges & in canals & ventricles inside the brain and central canal of spinal cord.
• Provides cushioning function.
• May play role in regulation of autonomic functions such as respiration & vomiting.

Question 21

Cerebrum function & structure
Hint: this is the brainy part of the brain

Answer 21

Function:
- Area of the brain responsible for higher-order behaviors (learning, awareness, etc).
Structure:
- Gray matter: cerebral cortex; outer layer of brain.
- White matter: fibers (connect halves of cerebral cortex) beneath cortex & corpus callosum.
- Gyri: folds in cerebral
- Fissures: deep groves separating gyri

Question 22

Cerebellum function and structure
“Butt of the brain”

Answer 22

Function:
- Responsible for coordinated movement, balance, posture, & complex reflexes.
Structure:
- Caudal to cerebrum

Question 23

Diencephalon (midbrain) function/structure & associated structures

Answer 23

Function/structure:
- Passageway/connection between brain stem & cerebrum.
Associated structures:
- Thalamus: relay station for reg sensory inputs to cerebrum.
- Hypothalamus: interface between nerv. & endocrine system.
- Pituitary: endocrine “master gland”

Question 24

Brain stem function and structure
“Primitive brain”

Answer 24

Function:
- Responsible for basic support functions of the body.
- Connection between brain & the spinal cord.
Structure:
- Composed of the midbrain, pons, & medulla oblongata.
- Many cranial nerves originate from here.

Question 25

Cross extender reflex
“contralateral reflex”

Answer 25

• Prevents individual from falling when withdrawal reflex is stimulated.
• Afferent sensory impulse crosses to other side of spinal cord & stim muscles to extend the opposite limb.

Question 26

Stretch reflex
“ipsilateral reflex”

Answer 26

• Contraction of a muscle in response to its own stretching
• Ex: Patellar ligament (below kneecap) getting tapped. Force causes lig to stretch stimulating contraction of quads. This makes the leg stretch (kick).

Question 27

Sodium (Na+) Potassium (K+) pump

Answer 27

Specialized molecule that pumps Na+ from inside the neuron to outside. They also pump K+ from outside to inside.

Question 28

Depolarization & Repolarization of the Na+/K+ pump
1. Resting state
2. Depolarization
3. Beginning of repolarization
4. Repolarization

Answer 28

1. Resting: Na+ has been pumped in and K+ pumped out the cell, producing a neg charge.
2. Depol: Na+ channel is open, sodium flow into the cell. Produces neg charge OUTside the cell.
3. Beg of repol. Na+ gate is closing whole the K+ gate is open.
4. Repol: K+ gate closes after sufficient amount of potassium has restored neg charge INside the cell.