Part 9

Question 1

Concentration of K+: Is it higher or lower inside the neuron?

Answer 1

HIGHER than outside.

Question 2

Concentration of Na+: higher or lower in the inside of the neuron?

Answer 2

LOWER inside the neuron, therefore HIGHER outside.

Neurons are IMPERMEABLE to Na, so the cell remains polarized.

Question 3

Na+/K+ pump

Answer 3

Gradients are restored by this pump. It uses ATP energy and transports 3 Na+ out for every 2 K+ it transports into the cell.

Question 4

Action Potential

Answer 4

If the cell becomes sufficiently excited or depolarized (inside becomes LESS NEGATIVE), an action potential is generated.

Minimum THRESHOLD membrane potential (usually around -50 mV) is level it is initiated.

Question 5

When does an action potential begin?

Answer 5

When voltage-gated Na+ channels open in response to depolarization, allowing Na+ to rush down its electrochemical gradient INTO the cell, causing rapid depolarization of the segment of the cell.

Question 6

What causes a neuron to be repolarized?

Answer 6

Voltage gated Na+ channels then close and voltage gated K+ channels open, allowing K+ to rush OUTSIDE down its electrochemical gradient.

Question 7

Hyperpolarization

Answer 7

When a neuron shoots past the resting potential and becomes even MORE NEGATIVE than normal.

Question 8

Refractory Period

Answer 8

Immediately after an action potential , it my be difficult or impossible to initiate another action potential.

Question 9

Afferent neurons

Answer 9

Sensory neurons: carry sensory info about external or internal environment TO brain and spinal cord.

Question 10

Efferent neurons

Answer 10

MOTOR neurons: they carry them FROM the brain or spinal cord to various parts of body.

Question 11

Central Nervous system

Answer 11

Consists of Brain and Spinal Cord.

Question 12

Brain

Answer 12

Mass of neurons that resides in the skull.

Consists of OUTER portion called GRAY matter (cell bodies) and INNER WHITE matter (mylelinated axons).

Brain can be divided into FOREBRAIN, MIDBRAIN, and HINDBRAIN

Question 13

Parts of Forebrain

Answer 13

Also called PROSENCEPHALON

Consists of:
Telencephalon and Diencephalon

Question 14

Parts of Telencephalon

Answer 14

1. Cerebral cortex
   - Highly convoluted gray matter that can be seen on the surface of the brain. It processes and integrates sensory input and motor responses and is important in MEMORY and CREATIVE thought.
2. Olfactory Bulb
   - Center for reception and integration of olfactory input.

Question 15

Parts of Diencephalon

Answer 15

1. Thalamus
   - RELAY and INTEGRATION center for spinal cord and cerebral cortex.
2. Hypothalamus
   - Controls VISCERAL function such as HUNGER, THIRST, SEX DRIVE, WATER balance, BLOOD pressure, and TEMPERATURE regulation. Also plays an important role in endocrine system.

Question 16

Parts of Midbrain

Answer 16

RELAY center for VISUAL and AUDITORY impulses. Plas an important role in motor control.

Is also called MESENCEPHALON

Question 17

Parts of Hindbrain

Answer 17

Also called RHOMBENCEPHALON. It is posterior part of brain.

1. Cerebellum
   - Helps modulate MOTOR impulses initiated by cerebral cortex.
   - important in maintenance of BALANCE, HAND-EYE coordination, and the timing of RAPID movements.
2. Pons
   - Act as a RELAY center to allow the cortex to COMMUNICATE with CEREBELLUM.
3. Medulla Oblangata
   - Controls vital functions such as BREATHING, HEART RATE, and GI activity.

Question 18

What is Brainstem?

Answer 18

Midbrain, pons and medulla oblangata

Question 19

Spinal Cord

Answer 19

Elongated extension of the brain.

OUTER WHITE matter: contains motor and sensory axons AND
INNER GRAY matter containing cell bodies.

Question 20

Dorsal Horn

Answer 20

sensory info enters the spinal cord through this.

The cell bodies of these sensory neurons are located in the dorsal root ganglia.

Question 21

Ventral Horn

Answer 21

All motor information exits the spinal cord.

Question 22

Sympathetic Nervous System

Answer 22

Flight or Fight”