ch 11.4- nervous system

Question 1

neuron

Answer 1

the most basic unit of the nervous
system. It has three parts: the soma (cell body),
dendrites (extensions that receive signals), and the
axon (sends signals out).

Question 2

axon hillock

Answer 2

Area where the axon is connected
to the cell body. Responsible for the summation
of graded potentials.

Question 3

myelin sheath

Answer 3

Fatty insulation of the axon that
speeds up action potential propagation by
stopping ion exchange. The myelin sheath is formed by

oligodendrocytes (in the central
nervous system) and

Schwann cells (in the
peripheral nervous system). Thicker myelinated neurons fire signals faster.

Question 4

nodes of ranvier

Answer 4

Gaps between myelin sheaths
where ion exchange occurs. Propagation of the
action potential occurs here, jumping from gap to
gap (node to node) in a process called saltatory
conduction.

Question 5

steps of action potential

Answer 5

1. At resting potential, the membrane potential of
   the neuron is around -70mV and is maintained by Na+/K+ ATPases, which pump three Na+ ions out and two K+
   ions in, powered by hydrolysis of one ATP. K +leak channels are also present and help maintain resting potential through passive K+ leakage
2. When a stimulus causes threshold potential to
   be reached (around -55mV in neurons),
   voltage-gated Na+ channels open up, letting Na+ in, resulting in depolarization of the neuron. K+ channels are closed.
3. Next is repolarization of the neuron due to the opening of voltage-gated K+ channels, letting K+ out, and the closing of Na channels. This causes the membrane potential to become less positive
   since positive ions are leaving. This is the absolute refractory period: no stimulus can cause an action potential.
4. When the membrane potential becomes even more negative than the normal resting potential, this is known as hyperpolarization. This results in a relative refractory period being established, during which another action potential can be fired, but it requires a much stronger stimulus.
5. The membrane potential returns to normal resting potential through the pumping of Na+ /K+ATPases and K +leak channels.

Question 6

absolute refractory period

Answer 6

refers to the period after the initiation of the action potential during which another action potential cannot be fired no matter how powerful the stimulus is. It is due to the inactivation of voltage-gated Na+ channels after they open.

the period of depolarization and repolarization

Question 7

realative refractory period

Answer 7

refers to the period
after the action potential fires during which a stronger
than normal stimulus could cause another action
potential to be fired. (after repolarization)

Question 8

steps of synaptic transmission

Answer 8

1. Action potential reaches the end of the
   presynaptic axon, causing voltage-gated
   calcium channels to open and letting Ca2+
   ions into the neuron.
2. The Ca2+ ions cause synaptic vesicles to fuse and undergo exocytosis, releasing neurotransmitters into the synapse.
3. The neurotransmitters (described in the table on the next page) bind to ligand-gated ion channels on the postsynaptic neuron, producing graded potentials (depolarizations or hyperpolarizations
   of the membrane).
4. These graded potentials summate at the axon hillock and an action potential will fire if the summation of graded potentials is higher than the threshold potential of neurons.

Question 9

EPSP

Answer 9

An excitatory postsynaptic potential (EPSP) is a
graded potential that depolarizes the membrane.

Question 10

IPSP

Answer 10

An inhibitory postsynaptic potential (IPSP) is a
graded potential that hyperpolarizes the membrane.

Question 11

glutamate

Answer 11

Main ENT of the central nervous system

Question 12

dopamine

Answer 12

Involved in reward motivated behavior

Question 13

epinephrine

Answer 13

● Postsynaptic NT of the sympathetic nervous system
● Constricts blood vessels and dilates bronchioles
● Increases blood flow to skeletal muscles
● Decreases blood flow to smooth muscles

Question 14

norepinepherine

Answer 14

Postsynaptic NT of the sympathetic nervous system

Aids epinephrine in the “fight or flight” response

Question 15

acetylcholine

Answer 15

● Most common NT in the muscular system
● Released from presynaptic motor neurons to signal muscle fibers
● Signals muscle fibers by binding to ligand-gated sodium channels

Question 16

GABA

Answer 16

Gamma-aminobutyric
acid (GABA)

● Main INT of the central nervous system

Question 17

glycine

Answer 17

● INT of the central nervous system

Question 18

seritonin

Answer 18

● INT of the brain

Question 19

frontal lobe

Answer 19

Known for higher function
processes such as decision making, problem
solving, attention and concentration.

Question 20

temporal lobe

Answer 20

Known for speech and hearing.

Question 21

occipital lobe

Answer 21

vision

Question 22

parietal lobe

Answer 22

Known for spatial perception and
sensation.

Question 23

cerebellum

Answer 23

located underneath the occipital
lobe and is responsible for the coordination of
movement.

Question 24

brainstem

Answer 24

midbrain
pons
medulla oblongata
reticular formation

Question 25

midbrain

Answer 25

Relays senses to other parts of brain.

Question 26

pons

Answer 26

Relays messages between the forebrain, cerebellum, and medulla.

Question 27

medulla oblongata

Answer 27

Heart and breathing rate, blood pressure, toxin sensing. Connects the cerebrum/cerebellum to the spinal cord.

Question 28

reticular formation

Answer 28

Neurons throughout the brainstem that are involved in cortical arousal, and consciousness.

Question 29

during embryonic development, the brain can be divided into what areas

Answer 29

forebrain midbrain hindbrain

Question 30

forebrain of embryo

Answer 30

Telencephalon Diencephalon

Question 31

telencephalon

Answer 31

gives rise to the cerebellum

Question 32

Diencephalon

Answer 32

gives rise to the Thalamus, hypothalamus, and pineal gland

Question 33

midbrain of embryo

Answer 33

develops into the mesencephalon

Question 34

mesencephalon

Answer 34

gives rise to the midbrain

Question 35

hindbrain in embryo

Answer 35

develops into the metencephalon and myencephalon

Question 36

metencephalon

Answer 36

gives rise to pons and cerebellum

Question 37

myencephalon

Answer 37

gives rise to the medulla oblongata

Question 38

what is the limbic system composed of

Answer 38

thalamus, hypothalamus, hippocampus, and amygdala.

Question 39

limbic system

Answer 39

It is responsible for emotion, memory, learning, and motivation.

Question 40

thalamus

Answer 40

The “relay center” of the brain and is located between the cerebrum and the midbrain. Relays sensory and motor signals from the body to the brain.

Question 41

hypothalamus

Answer 41

Regulates hormone secretion in the body.

Question 42

hippocampus

Answer 42

Responsible for memory consolidation.

Question 43

amygdala

Answer 43

Responsible for the emotional reaction to certain scents.

Question 44

peripheral nervous system

Answer 44

The peripheral nervous system is divided into the somatic nervous system (voluntary motor action and sensory input) and the autonomic nervous system (involuntary).

Question 45

autonomic nervous system

Answer 45

The autonomic nervous system can be further divided into the sympathetic nervous system (fight or flight) and the parasympathetic nervous system (rest and digest).

Question 46

sympathetic NS

Answer 46

● Release of sugar into blood for energy. ● Increase in heart rate for oxygen delivery to the brain and muscles. ● Vasodilation of skeletal blood vessels, and vasoconstriction of the digestive system. ● Dilation of bronchi and bronchioles to allow more oxygen into lungs. ● Dilation of the pupil to give the brain more visual information.

Question 47

parasympathetic NS

Answer 47

● Relaxation of muscles. ● Decrease in heart rate. ● Maintenance of homeostasis. ● Increase in gastrointestinal activity. THROUGH THE VAGUS NERVE

Question 48

ganglion

Answer 48

cluster of nerve bodies in the peripheral nervous system. The autonomic nervous system’s neurons are either preganglionic or postganglionic. The preganglionic neuron comes from the central nervous system and synapses with the postganglionic neuron at the ganglion.

Question 49

sympathetic NS preganglionic nerves

Answer 49

Acetylcholine

Question 50

sympathetic NS postganglionic nerves

Answer 50

norepinephrine/ epinephrine also stimulates the adrenal medulla to release NE/E into blood

Question 51

parasympathetic NS preganglionic nerves

Answer 51

acetylcholine

Question 52

parasympathetic NS postganglionic nerves

Answer 52

acetylcholine

Question 53

acetylcholinesterase

Answer 53

is an enzyme that is responsible for the breakdown of acetylcholine via hydrolysis.

Question 54

outer ear

Answer 54

takes in sound waves, and the tympanic membrane transfers the sound from outer ear to middle ear.

Question 55

middle ear

Answer 55

composed of three bony ossicles. The ossicles transfer vibrations through the middle ear and amplify the signal. The vibrations get transmitted from the middle to the inner ear.

Question 56

cochlea

Answer 56

uses fluid and hairs to convert the mechanical signal into a neuronal signal, known as transduction.

Question 57

semicircular canal

Answer 57

has fluid and hairs just like the cochlea but gives information about the person’s movement. It is also the reason we get dizzy.

Question 58

cornea

Answer 58

Transparent; focuses light and protects the eye.

Question 59

iris

Answer 59

controls size of pupil

Question 60

pupil

Answer 60

controls how much light enters the eye

Question 61

lesn

Answer 61

focuses image on the retina

Question 62

retina

Answer 62

Back of the eye that has photoreceptors (rods + cones). ○ Rods function at low levels of light and are responsible for low-light perception. ○ Cones function at high levels of light and are responsible for color perception.

Question 63

fovea

Answer 63

Highest concentration of photoreceptors in the retina. Responsible for high acuity vision.

Question 64

optic nerve

Answer 64

Bundle of axons that transmits visual information to the brain.

Question 65

optic disc

Answer 65

The blind spot of the eye, where the optic nerve passes through to reach the brain.

Question 66

sclera

Answer 66

Protective layer of tissue; the “white part” of the eye.