Physiology V01 3.1

Front 1

What are the 4 functions of the nervous system?

Back 1

1. Detect CHANGES OR STIMULI within the internal and external environment
2. Interprets all sensory impulses and determines response (INTEGRATION)
3. Initiates and controls responses to changes in order to maintain HOMEOSTASIS
4. Conceptual THOUGHT

Front 2

What are 2 main divisions of the nervous system?

Back 2

1. CNS: Central NS
2. PNS: Peripheral NS

Front 3

Which are the 2 components of the CNS?

Back 3

1. brain
2. spinal cord

Front 4

What are the collective components of the PNS?

Back 4

1. cranial nerves
2. spinal nerves

Front 5

What are the 2 divisions of the PNS?

Back 5

1. sensory (afferent) division
2. motor (efferent) division

Front 6

What is the function of the sensory (afferent) division of the PNS?

Back 6

carry impulses from receptors to the CNS

Front 7

What are 2 divisions of the sensory (afferent) division of the PNS? Give examples for each classification.

Back 7

1. somatic: muscles, skin, and joints
2. visceral: visceral organs

Front 8

What is the function of the motor (efferent) division of the PNS?

Back 8

carry impulses away from the CNS to the effectors (i.e., muscles or glands that are innervated)

Front 9

What are 2 divisions of the motor (efferent) division of the PNS? Give examples for each classification.

Back 9

1. Somatic: to skeletal muscles
2. Autonomic: to cardiac muscle, smooth muscle, and glands

Front 10

What are 2 further divisions of the autonomic nervous system (a portion of the motor (efferent) division of the PNS)?

Back 10

1. sympathetic
2. parasympathetic

Front 11

What are 2 types of nervous tissue?

Back 11

1. Neuroglia
2. Neurons

Front 12

What are the 6 types of neuroglia?

Back 12

1. ependymal
2. astrocytes
3. oligodendrocytes
4. microglia
5. Schwann cells
6. satellite cells

To remember: Eat At Our Mini Sweet Shop

Front 13

Name the function of this neuroglia and the division of the nervous system in which it is found: ependymal

Back 13

fxn: lines cavities in the CNS-produces cerebrospinal fluid

part of: CNS

Front 14

Name the function of this neuroglia and the division of the nervous system in which it is found: astrocytes.

Back 14

fxn: supports and binds neurons together

part of: CNS

Front 15

Name the function of this neuroglia and the division of the nervous system in which it is found: oligodendrocytes

Back 15

fxn: forms myelin sheaths of neurons

part of: PNS

Front 16

Name the function of this neuroglia and the division of the nervous system in which it is found: microglia

Back 16

fxn: phagocytic cells for protection

part of: CNS

Front 17

Name the function of this neuroglia and the division of the nervous system in which it is found: Schwann cells

Back 17

fxn: forms myelin sheath of neurons

part of: PNS

Front 18

Name the function of this neuroglia and the division of the nervous system in which it is found: satellite cells

Back 18

fxn: supports neurons

part of: PNS

Front 19

What are the 4 types of neuroglia that are part of the CNS?

Back 19

1. ependymal
2. astrocytes
3. oligodendrocytes
4. microglia

Front 20

What are the 2 types of neuroglia that are a part of the PNS?

Back 20

1. Schwann cells
2. satellite cells

Front 21

What is the function of neurons?

Back 21

to generate and conduct action potentials (impulses)

Front 22

What are the 3 components of a neuron's anatomy?

Back 22

1. cell body
2. dendrites
3. axons

Front 23

What does a neuron cell body consist of?

Back 23

contains most of the cytoplasm and organelles

Front 24

What are dendrites of a neuron?

Back 24

extensions of the cell body that carry information TO the cell body

Front 25

What are axons of a neuron?

Back 25

extensions of the cell body that carry impulses AWAY from the cell body

Axon=Away

Front 26

What are 3 ways that neurons can be classified?

Back 26

1. functional
2. anatomical
3. propagation speed [of action potential]

Front 27

What are 3 types of functional neurons?

Back 27

1. afferent (sensory)
2. efferent (motor)
3. association (internuncial)

Front 28

What do afferent (sensory) neurons do?

Back 28

conduct impulses TO the CNS

Front 29

What do efferent (motor) neurons do?

Back 29

conduct impulses AWAY from the CNS

Front 30

What do association (internuncial) neurons do?

Back 30

conduct impulses WITHIN the CNS

Front 31

What are 3 anatomical types of neurons? Give examples of where they are found.

Back 31

1. unipolar- most sensory neurons
2. bipolar- retina, inner ear, olfactory membrane
3. multipolar- brain and spinal cord

Front 32

What are 3 ways that neurons' propagation speed (action potential, ie AP) are classified?

Back 32

1. Type A
2. Type B
3. Type C

Front 33

What are characteristics of Type A neurons?

Back 33

-LARGE (4-20 um) MYELINATED axons with speeds up to 140m/s

Front 34

What are characteristics of Type B neurons?

Back 34

-MEDIUM (2-4 um) MYELINATED axons with speeds of about 18m/s

Front 35

What are characteristics of Type C neurons?

Back 35

-SMALL (less than 2um) UNmyelinated axons with speeds of 1m/s

Front 36

What is a transmembrane potential (TP)?

Back 36

the ELECTRICAL POTENTIAL between the inside and outside of a cell membrane

Front 37

What causes a transmembrane potential?

Back 37

a slight excess of (+) charged ions on the OUTSIDE and a slight excess of (-) charged ions on the INSIDE of the membrane.

outside: excess +
inside: excess -

Front 38

What is the range of the transmembrane potential?

Back 38

-10mv to -100 mv

Front 39

What is the resting potential (RP)? Give definition and number.

Back 39

The transmembrane potential of an UNDISTURBED cell

ave: -70mv

Front 40

What are the 4 general features of a resting (non-stimulated) cell?

Back 40

1. HIGH extracellular [Na+] and a LOW intracellular [NA+]
2. HIGH intracellular [K+] and LOW extracellular [K+]
3. INTRAcellular fluid has ANIONS, mostly proteins that cannot cross the membrane
4. the extracellular fluid and the interior of the cell are electrically NEUTRAL

Front 41

What causes the high extracellular and low intracellular [Na+] of a resting cell?

Back 41

1. membrane actively transports Na+ OUT
2. membrane has a LOW permeability to Na+
3. low permeability is the result of FEW open Na+ gates

Front 42

What causes a high intracellular and low extracellular [K+]?

Back 42

1. membrane actively transports K+ IN
2. membrane has a HIGH permeability to K+
3. high permeability is the result of MANY open K+ gates

Front 43

Why are the extracellular fluid and the interior of the cell electrically neutral?

Back 43

1. on the outside, the cations (Na+) are balanced by the anions (Cl-)
2. on the inside, the cations (K+, Na+) are balanced by the anions (proteins)

Front 44

What effect does the cell membrane's permeability to K+ have on the cell resting potential?

Back 44

K+ can constantly diffuse to the OUTSIDE of the membrane, adding positive charges to the outside and leaving the inside slightly negative (hence, a resting potential of -70mv)

Front 45

How does the sodium-potassium pump maintain the resting potential?

Back 45

The Na+-K+ pump returns the Na+ that diffuse in and the K+ that diffuse out (3 to 2), thus maintaining the resting potential

good na-k video: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html

Front 46

What are 2 types of membrane channels? Describe them.

Back 46

1. passive (leak): always open
2. active: can open or close

Front 47

What are 3 types of active membrane channels? Describe them.

Back 47

1. chemically regulated
--->open or close when they bind to specific chemicals

2. voltage regulated
--->open or close when the membrane potential changes

3. membrane regulated
---> open or close in response to distortions of the membrane surface

Front 48

What are graded (local) potentials?

Back 48

changes in the TP that are unable to spread far from the site of stimulation

Front 49

How does a graded potential DEPOLARIZE the cell membrane?

Back 49

if a stimulus causes the opening of the Na+ gates, Na+ will diffuse into the cell and the TP will become LESS negative

Front 50

How does a graded potential HYPERPOLARIZE the cell membrane?

Back 50

If a stimulus causes the opening of K+ gates, K+ will diffuse OUT of the cell and the TP will become MORE negative

Front 51

The degree of depolarization or hyperpolarization will depend upon ...?

Back 51

how MANY Na+ or K+ gates are opened, which in turn depends on the STRENGTH of the stimulus

Front 52

What does the movement of Na+ or K+ generate?

Back 52

a local current

Front 53

What is repolarization? When does it occur?

Back 53

-when the sodium-potassium pump returns the TP BACK TO NORMAl

-occurs when the stimulus is removed.

Front 54

What are action potentials (ie impulses or APs)?

Back 54

Propogated changes in the TP (or RP)

Front 55

What are the 4 stages of AP return to normal?

Back 55

1. depolarization to threshold (the TP that causes voltage-regulated Na+ gates to open, -60mv)

2. once the Na+ gates are open, Na+ diffuses into the cell and the TP depolarizes to +30mv

3. At +30mv, voltage-regulated Na+ gates close, and the voltage-regulated K+ gates open. K+ diffuses out of the cells

4. At -70 mv, voltage-regulated K+ gates close, but because they don't all close at the same time, the membrane becomes temporarily hyperpolarized (over shoot) before returning to normal

*over time, the Na-K pumps return the [Na+] and [K+] to their original distributions across the membrane

Front 56

What are 2 types of AP propogation?

Back 56

1. continuous propogation
2. saltatory conduction

Front 57

Which types of neurons undergo continuous propagation?

Back 57

non-myelinated neurons

Front 58

Describe the process of continuous propagation.

Back 58

1. At the point of the stimulus, an AP occurs (assuming threshold is reached), resulting in LOCAL current flow

2. local current flow depolarizes the adjacent membrane sections to threshold, resulting in an AP in those sections while initial segments return to normal

3. local current flow now develops between these secondary segments of the membrane and the adjacent sections

**The cycle repeats until the AP REACHES THE END OF THE AXON

Front 59

Which types of neurons undergo saltatory conduction?

Back 59

myelinated neurons

Front 60

Describe the process of saltatory conduction.

Back 60

1. In areas of the membrane surrounded by myelin (INTERNODES), the myelin prevents ions from crossing the membrane, thus depolarization can NOT occur

2. depolarization CAN occur in those areas of the membrane NOT covered by the myelin sheath (nodes of Ranvier--1-2 mm apart)

3. Whan an AP occurs in the initial segment, local current flow occurs between there and the next NODE, which causes it to depolarize to threshold, and an AP is produced. This causes local current flow between it and the next node. This cycle continues until the end of the axon.

Front 61

Define threshold stimulus.

Back 61

the SMALLEST stimulus strength required to initiate an impulse

Front 62

Define summation.

Back 62

addition of sub-threshold stimuli so that the threshold is reached

Front 63

Define accomodation.

Back 63

increase in threshold due to a CHRONIC threshold stimulus

Front 64

Define all-or-none law.

Back 64

threshold stimulus (or higher) will cause a MAXIMAL response

Front 65

What are 2 types of synapses?

Back 65

1. excitatory
2. inhibitatory

Front 66

Describe the mechanism of the excitatory synapse.

Back 66

1. AP at the synaptic knob opens voltage-regulated Ca2+ channels

2. Ca2+ diffuses into the cell--->causes release of neurotransmitters from the synaptic vesicles via exocytosis

3. Neurotransmitters diffuse across the synaptic cleft and attach to receptors (chemical-regulated Na+ channels) on the postsynaptic membrane causing the gates to open, allowing Na+ to diffuse in

3. as a result, a graded potential, excitatory postsynaptic potential (EPSP) is generated

4. summation of individual EPSPs occurs at the axon hillock, and if threshold is reached, an AP occurs

Front 67

Describe the mechanism of the inhibitory synapse

Back 67

1. AP at the synaptic knob opens voltage-regulated Ca2+ channels

2. Ca2+ diffuses into the cell--->causes release of neurotransmitters from the synaptic vesicles via exocytosis

**3. Neurotransmitters diffuse across the synaptic cleft and attach to receptors (chemical-regulated K+ channels) on the postsynaptic membrane causing the chemically-regulated gates to open, allowing K+ to diffuse out

**3. as a result, the TP becomes more postive on the outside (hyperpolarization), the new potential is called an inhibitory post synaptic potential (IPSP)

4. IPSP makes the membrane less excitable (inhibited) since it will now take a greater stimulus strength to cause depolarization to threshold

Front 68

Define summation in terms of time and space.

Back 68

def: the addition of EPSPs or IPSPs at the axon hillock

1. temporal: stimuli occurring in rapid succession at a single synapse
2. spatial: results from stimuli acting upon several synapses simultaneously

Front 69

List the 6 categories of transmitter substances.

Back 69

1. Acetylcholine (Ach)
2. Biogenic amine
3. Excitatory amino acids
4. Inhibitory amino acids
5. Neuropeptides
6. Dissolved gases
7. Others

Front 70

Give examples of biogenic amines

Back 70

dopamine, norepinephrine, epinephrine, serotonin

Front 71

Give examples of excitatory amino acids

Back 71

glutamate, aspartate

Front 72

Give examples of inhibitory amino acids

Back 72

gamma aminobutryic acid (GABBA) and glycine

Front 73

Give examples of neuropeptides

Back 73

endorphins, enkelphalins

Front 74

Give examples of transmitter substances that are dissolved gases

Back 74

carbon monoxide (CO), nitric acid (NO)

Front 75

Give examples of transmitter substances that are classified as others

Back 75

ATP, hormones (ADH, insulin, secretin, oxytocin, etc.), prostaglandins