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Physiology > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

What are the three categories or types of gated ion channels? What causes each to open/close? Give an example of how each is “used” in a cell (i.e. what are they good for?)

A
  1. Mechanically gated ion channels - responds to force
  2. Chemically gated ion channels (ligand) - signaled by a neurotransmitter (hormone)
  3. Voltage-gated ion channels - responds to change in membrane potential
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2
Q

The difference in concentration of this ion has the greatest effect of the RMP.

A

K+

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3
Q

What is the value of the resting membrane potential in a standard neuron?

A

-70mV

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4
Q

Define depolarization.

A

Membrane potential becomes more positive.

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5
Q

Define repolarization.

A

Membrane potential moves back toward the resting membrane potential (RMP)

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6
Q

Define hyperpolarization.

A

Membrane potential becomes lower than resting.

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7
Q

In an axon what is the value of the threshold voltage?

A

-55mV

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8
Q

Name the two ion channels found in axons.

A
  1. Voltage gated sodium (Na+) channels

2. Voltage gated potassium (K+) channels

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9
Q

What causes the ion channels in an axon to open?

A

the threshold voltage of -55mV being met

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10
Q

Action potentials are distinct from one another, explain why this is (mechanism).

A

Once an AP reaches +30mV the inactivation gate inactivates the Na+ channel and K+ exits repolarizing the membrane potential and bringing the AP back towards its RMP of -70mV. There is an absolute refractory period in which no new AP can be formed while the channels reset themselves and it reaches -70mV. Because of this each AP while rise and fall distinctly.

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11
Q

What is the maximum voltage of an action potential? Why?

A

+30mV because the inactivation gate is triggered at that voltage and the Na+ channels close.

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12
Q

Define absolute refractory period. Explain why there is an absolute refractory period (mechanism).

A

The period of time which no new AP can be formed.
It can’t start another AP until the Na+ channel can open again and it must reset to open and it can’t reset until its at -70mV again.

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13
Q

Explain what the all-or-none “law” of an action potential is.

A

All AP’s are the same (+30mV) and are triggered at the threshold of -55mV so you either get on or you don’t.

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14
Q

Where do graded potential occur in a neuron?

A

at synapses

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15
Q

Explain how intensity information is encoded in action potentials.

A

Intensity of reaction is coded in the frequency. All AP’s would be identical but the intensity would be encoded in the signal.

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16
Q

Explain how graded potential are different form action potentials.

A
  1. Graded occur at synapses rather than in the axon.
  2. Graded can be either excitatory (depolarization) or inhibitory (hyperpolarization) while AP’s can only be excitatory to cause depolarization.
  3. Graded use ligand-gated ion channels and G-protein coupled receptor channels; AP’s use votage-gated.
  4. Graded can be of any strength and degrades while AP’s are all-or-none and can self-propagate.
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17
Q

In the PNS, what cell produces myelin? The type of conduction in a myelinated axon is called what?

A

Schwann Cells

Saltatory conduction

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18
Q

Where on a myelinated axon would you find voltage-gated channels? Where on an unmyelinated axon would you find voltage-gated channels?

A

Myelinated axon - at the knodes of Ranvier

Unmyelinated axon - at the axon hillock and all along the axon.

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19
Q

What about an axon allows an action potential to travel fast? About how fast can an AP travel in an axon?

A

Can travel about 100 m/sec (meters per second)

Axons that are larger and myelinated will allow an AP to travel at a higher speed.

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20
Q

The process by which vesicles of neurotransmitter are released from an axon terminal is called what? What ion is most directly responsible for triggering this release?

A

synaptic transmission

Ca+ causes exocytosis

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21
Q

Define ligand

A

chemical that binds to a receptor

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22
Q

All the neurotransmitters that we discussed in lecture are (large/small)? What possible advantage could this have?

A

Small

Advantage - diffuse quickly, easier to make

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23
Q

Define cholinergic receptor.

A

it uses acetylcholine (ACh) as its neurotransmitter.

  • releases ACh at synapse
  • a receptor that binds ACh
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24
Q

Name the 2 types of cholinergic receptors.

A
  1. Nicotinic ACh receptor

2. Muscarinic ACh receptor

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25
Q

Where in the body would you find nicotinic synapses? What ion enters the target cell at a nicotinic synapse? What effect does this have on the target cell?

A

in the CNS at the neuromuscular junction (MEP - motor end plate)
Na+ enters the target cell
effect - depolarization

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26
Q

What enzyme destroys ACh in a cholinergic synapse? Why is this necessary?

A

acetylcholine sterase AChE

it is necessary to avoid prolonged stimulation of synaptic sites throughout the CNS.

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27
Q

Define adrenergic receptor.

A

a receptor that binds norepinephrine and ipinephrine

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28
Q

In the target cell of an adrenergic synapse, the enzyme that converts ATP into cAMP is what? What role does cAMP then have in the target cell?

A

adenylate cyclase

Role - open a channel

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29
Q

List the structures that make up the fibrous layer of the eye.

A

Sclera

Cornea

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30
Q

List the structures that make up the vascular layer of the eye.

A

Choroid
Ciliary Body
Iris

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31
Q

List the structures that make up the Neural/sensory layer of the eye.

A 
(aka retina)
Ganglion cells
Bipolar cells
Photoreceptors
Pigmented epithelium
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32
Q

Name the two fluids that fill the eye. Describe the function of each. Explain why each is necessary.

A

Vitreous humor - helps keep the spherical shape of the eye and helps and the pressure of it keeps the retina in place
Aqueous humor - It maintains the pressure needed to inflate the eye and provides nutrition for the central cornea and lens as they do not have their own blood supply.

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33
Q

What is the function of the iris? Explain the structure of the iris and describe how the iris is controlled.

A

The colored part of the eye which helps regulate the amount of light entering the eye. When there is bright light, the iris closes the pupil to let in less light. And when there is low light, the iris opens up the pupil to let in more light. - The iris has tiny muscles that can either widen (dilate) or narrow (constrict) it.

34
Q

What is the function of the lens? Briefly describe how the lens is controlled.

A

The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances. - The tendons and ciliary muscles help the eye to focus by either relaxing or pulling the lens, allowing it to become either more spherical or flatter in shape.

35
Q

The ability to focus images is properly called what?

A

Accomodation

36
Q

What is the function of the choroid?

A

Nourishes retina and prevents light scattering within the eye.

37
Q

Name the two (main) types of light sensing cells of retina.

A

Rods - very sensitive to light; responsible for black/white vision.
Cones - not very sensitive to light; responsible for color vision

38
Q

The cranial nerve which carries APs to the thalamus is the what?

A

Optic Nerve (II)

39
Q

Briefly explain how sudden and dramatic changes in the intensity of light negatively affect vision.

A

The rhodopsin in the rods is bleached to accommodate the level of light you are currently exposed to and must be sent to the pigmented epithelium to regenerate. If you go from very dark to very light your eye is bleached for the dark and takes a few minutes to be regenerated and compensate for the added light leaving you with a few minutes of poor sight. The same is true in reverse.

40
Q

What is presbyopia?

A

Loss of elasticity of the lens of the eye with age.

41
Q

What is the Snellen eye chart? What is it used for?

A

an eye chart that can be used to measure visual acuity.

42
Q

List the structures that make up the outer ear. What is the function of each?

A

Auricle - the first part of the body to come in contact with auditory stimuli.
Auditory Canal - Funnels sound toward the eardrum and protects the eardrum from injury.
Tympanic membrane - vibrates with the force of the sound wave strike and transmits the vibrations further in, to the bones of the middle ear.

43
Q

List the structures that make up the middle ear. What is the function of each?

A

Tympanic membrane - vibrates with the force of the sound wave strike and transmits the vibrations further in, to the bones of the middle ear.
Tympanic cavity - carry sound from the eardrum and into the inner ear.
Malleus - receives vibrations from the tympanic membrane and transmits this to the incus.
Incus - receives vibrations from the malleus, to which it is connected laterally, and transmits these to the stapes, medially.
Stapes - transmits sound vibrations from the incus to the oval window
Oval window - opening at the head of the cochlea, connecting the middle and inner ear, through which sound vibrations of the stapes are transmitted.

44
Q

Describe the primary function of the Eustachian tube.

A

opening of the eustachian tube equalizes atmospheric pressure in the middle ear; closing of the eustachian tube protects the middle ear from unwanted pressure fluctuations and loud sounds.

45
Q

What is the function of the utricle? What is the function of the saccule?

A

Utricle - contains hair cells that distinguish between degrees of tilting of the head
Saccule - gathers sensory information to orient the body in space. It primarily gathers information about linear movement in the vertical plane, including the force due to gravity.

46
Q

What is the function of the crista ampullaris of a semicircular canal? What is involuntary oscillations of the eye called and what causes it?

A 
function - sense angular acceleration and deceleration
nystagmus is caused the fluid in the inner ear spins as you rotate pushing on the cupula which pushes on the hair. When you stop spinning, the fluid continues to spin.
47
Q

What structural type of neuron is carrying hearing information to the CNS? Where are the cell bodies of these neurons located?

A

Bipolar neurons located in the dorsal root ganglia

48
Q

The hair cells of the cochlea are housed in what membrane? The gelatinous plate within the cochlea is the what?

A

Hair cells - basilar membrane

Gelatinous plate - tectorial membrane

49
Q

Explain how the organ of Corti is able to detect different frequencies of sound.

A

variable stiffness of the basilar membrane

50
Q

Conductive deafness is a common type of hearing loss. List some of the things that might be wrong with a patient’s anatomy that would result in conductive deafness.

A

Conductive deafness occurs when there is a problem conducting sound waves anywhere along the route through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). Damage to any of those structures could result in hearing loss.

51
Q

When a person is speaking the “s” sound is made by causing sound waves of about 8,000 herz. How fast would the tympanic membrane vibrate when hearing an “s”?

A

8,000 cycles per second

52
Q

List the sensors found in the hypothalamus and explain what they detect.

A

Thermoreceptors - monitor the temperature of the body’s blood (core temp)

53
Q

Describe the general neural pathway that the cerebrum uses to influence involuntary functions.

A

Cerebrum (see, smell, hear, “imagination”)——–>
Limbic System/hypothalamus (emotional brain)—–>
Sympathetic Nervous System (“fight or flight” response)

54
Q

List the major functions of the hypothalamus.

A
  1. Activates the Sympathetic Nervous System
  2. Maintains body temp
  3. Controls Osmolarity
  4. Controls reproductive functions
  5. Controls food intake
  6. Interacts with limbic system
  7. Influences medullary integrating centers
  8. (other) Anterior pituitary gland control
  9. Day/Night
55
Q

Explain how the hypothalamus exerts control over reproductive functions.

A

The hypothalamus:

  1. releases hormones that control the anterior pituitary which releases hormones that control the gonads (testes, ovaries).
  2. controls oxytocin release (childbirth & milk letdown)
  3. Stimulates milk production - prolactin
56
Q

Explain the role of the limbic system in regulating body functions.

A

It is responsible for our emotional lives “emotion brain” and also many higher mental functions, such as learning and formation of memories.
(The limbic system include the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus.)

57
Q

Describe the function of the precentral gyrus.

A

Primary motor cortex - voluntary control of skeletal muscles; regulating somatic motor neurons

58
Q

What does the adrenal medulla secrete?

A

epinephorine and norepiniphorine

59
Q

What does the adrenal cortex secret?

A

cortisol, aldosterone, androgens

60
Q

After ovulation an ovarian follicle is re-organized into a structure called a what? What does it secrete?

A

Corpus Luteum

Secretes estrogen and progesterone

61
Q

Which branch of the nervous system is responsible for causing the pupil to become larger? smaller?

A

larger - sympathetic

smaller - parasympathetic

62
Q

The neurotransmitter released by postganglionic parasympathetic neurons is usually what? what is the specific type of receptor that bind the neurotransmitter at the synapse?

A

ACh

muscarinic receptors

63
Q

List all of the important effectors innervated by the sympathetic nervous system but NOT the parasympathetic.

A 
Most blood vessels
myocardium
adrenal medulla
sweat glands
kidneys
64
Q

Define endocrine gland.

A

Glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct.

65
Q

List each of the major endocrine glands.

A
  1. Anterior pituitary gland
  2. Posterior pituitary gland
  3. Thyroid gland
  4. Adrenal gland
  5. Ovary
  6. Testes
  7. Pancreas
66
Q

What hormones are secreted by the anterior pituitary gland?

A
  1. ACTH (adrenocorticotropic hormone),
  2. FSH - (follicle stimulating hormone),
  3. TSH (thyroid stimulating hormone),
  4. GH (growth hormone),
  5. LH (luteinizing hormone),
  6. PRL (prolactin)
67
Q

What hormones are secreted by the posterior pituitary gland?

A
  1. ADH (antidiuretic hormone),

2. Oxytocin (milk letdown, uterine contractions)

68
Q

What hormones are secreted by the Adrenal gland?

A
  1. Adrenal Medulla (middle portion) - epinephrine and norepinephrine
  2. Adrenal Cortex (outer portion) - cortisol, aldosterone, androgens
69
Q

What hormones are secreted by the thyroid gland?

A

follicular cells produce T3 and T4 (thyroxine)

70
Q

What hormones are secreted by the pancreas?

A
  1. Acinar cells secrete digestive enzymes

2. Islets of Langerhans - Beta cells produce insulin, Alpha cells produce Glucagon

71
Q

What hormones are secreted by the ovaries?

A
  1. Granulosa cells produce estrogen

2. Corpus luteum produces estrogen and progesterone

72
Q

What hormones are secreted by the testes?

A

Interstitial cells (or Leydig cells) produce testosterone

73
Q

Which ion is a critical part of T3 and T4?

A

Iodide/Iodine

74
Q

Explain how the hypothalamus controls the anterior pituitary gland.

A

The anterior pituitary is controlled by releasing hormones (or inhibiting hormones) from the hypothalamus

75
Q

Explain how the hypothalamus controls the posterior pituitary.

A

The posterior pituitary contains axons from the hypothalamus

76
Q

The cells of the thyroid gland that secrete thyroxine are called what?

A

follicular cells.

77
Q

The cells of the testes which secretes testosterone are called what?

A

Interstitial cells (or Leydig cells)

78
Q

The mature stage of development of an ovarian follicle is called a/an what? The cells of the follicle that produce steroids are called what?

A

Graafian follicle

Granulosa cells produce steroids

79
Q

What is PTU and how is it used to treat hyperthyroidism?

A

Propylthiouracil decreases the amount of thyroid hormone produced by the thyroid gland.

80
Q

Explain how a diet low in Iodide could result in a thyroid mass (endemic goiter).

A

A low amount of thyroxine in the blood, due to lack of dietary iodine to make it, gives rise to high levels of thyroid stimulating hormone (TSH), which stimulates the thyroid gland to increase many biochemical processes; the cellular growth and proliferation can result in the characteristic swelling or hyperplasia of the thyroid gland, or goiter.

Physiology (25 decks)

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