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Physiology > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

what is a sensory receptor?

A

any structure specialized to detect a stimulus
*some are just bare nerve endings while others are specialized cells adjacent to afferent neurons

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2
Q

what is the purpose of sensory receptors?

A

to convert one form of energy (stimulus) into nerve signals
THIS PROCESS IS CALLED TRANSDUCTION

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3
Q

what is the initial effect of a stimulus on a sensory receptor?

A

-local potential (also called receptor potential)

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4
Q

what happens if the sensory cell is a neuron?

A

action potentials will be generated IF the local potential is strong enough.

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5
Q

what happens if the sensory potential is a separate cell?

A

the local potential will cause it to release a neurotransmitter, which will stimulate the adjacent afferent neuron

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6
Q

4 types of information that sensory receptors transmit:

A
  1. modality
  2. location
  3. intensity
  4. duration
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7
Q

modality (SR info)

A

-type of stimulation (vision, hearing, taste, etc.)
-modality is determined by where the sensory signals end in the brain

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8
Q

location (SR info)

A

-this is also encoded by which nerve fibers carry signals to the brain. a receptive field is the area within which a particular sensory neuron detects stimuli

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9
Q

intensity (SR info)

A

-the number of action potentials per unit time can increase
OR
-greater numbers of neurons may be stimulated

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10
Q

duration

A

encoded by how long the stimulation lasts

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11
Q

what is sensory adaptation?

A

when the firing of the neurons gets slower over time as the stimulus persists

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12
Q

Phasic receptors

A

-generate a burst of action potentials initially and then quickly adapt
-includes receptors for smell, hair movement, skin pressure, and vibrations
-some are activated when the stimulus is applied and again when the stimulus is removed

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13
Q

tonic receptors

A

-adapt more slowly
-includes proprioceptors and pain receptors

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14
Q

how can receptors be classified?

A

-stimulus modality
-distribution of receptors

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15
Q

thermoreceptors

A

heat and cold

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16
Q

photoreceptors

A

light

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17
Q

nociceptors

A

pain

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18
Q

chemoreceptors

A

chemicals (odors, tastes, body fluid composition)

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19
Q

mechanoreceptors

A

-physical deformation caused by vibration, touch, pressure, stretch or tension.
(includes hearing, balance, and many diff. receptors in the skin)

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20
Q

proprioceptors

A

sense the position and movements of the body or its part. found in muscles, tendons and joint capsules.

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21
Q

general sense receptors

A

include widely-distributed receptors in the skin, muscles, tendons, joints, and viscera

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22
Q

special sense receptors

A

limited to the head, are innervated by the cranial nerves. includes vision, hearing, equilibrium, taste and smell

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23
Q

examples of bare dendrites of nerves

A

thermoreceptors, nociceptors, etc.

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24
Q

example of dendrites encapsulated by glial cells or connective tissue. (these are mechanoreceptors that sense touch, pressure, vibration and stretch)

A

pacinian corpuscles. two specialized proprioceptors in this category are muscle spindles and tendon organs

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25
Q

about how many taste buds are there

A

4,000

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26
Q

4 types of papillae

A
  1. filiform papillae
  2. foliate papillae
  3. fungiform papillae
  4. vallate papillae
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27
Q

filiform papillae

A

-tiny spikes with no taste buds
-most abundant papillae, but small
-sense texture of food
-more prominent in other animals and used to groom fur :0

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28
Q

foliate papillae

A

-parallel ridges on the side of the tongue
-not well developed!
-most taste buds here degenerate by ages 2 or 3

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29
Q

fungiform papillae

A

-shaped like a mushroom
-each has about three taste buds
-widely distributed but concentrated at the tip and sides of the tongue
-also sensory for food texture

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30
Q

vallate papillae

A

-large papillae arranged in a V-shape at the rear of the tongue
-each is surrounded by a deep circular trench
-there are only 7 to 10 of these but they contain about half of all taste buds (abt 250 each)

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31
Q

how many cells do taste receptors contain?

A

3 types!
1. taste cells
2. basal cells
3.supporting cells

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32
Q

taste cells

A

-have a tuft of apical microvilli called taste hairs, which serve as receptors for tastants
-the hairs project into the taste pore, they synapse with sensory nerve fibers at their base

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33
Q

basal cells

A

stem cells that replace taste cells

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34
Q

supporting cells

A

have no sensory role; kind of irrelevant!

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35
Q

5 primary taste specializations

A
  1. salty
  2. sweet
  3. umami
  4. sour
  5. bitter
    (and possibly another one associated with fats)
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36
Q

salty

A

-stimulated by metal ions like sodium and potassium

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37
Q

sweet

A

stimulated by organic compounds, especially sugars

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38
Q

umami

A

stimulated by certain amino acids

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39
Q

sour

A

-associated with H+ ions from acids, such as vinegar or citrus fruits

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40
Q

bitter

A

-associated with spoiled foods and with alkaloids (many are poisonous) such as nicotine, caffeine, quinine, and morphine

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41
Q

what are odorants?

A

airborne chemicals

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42
Q

olfactory mucosa

A

-patch of epithelium in the roof of the nasal cavity
-consists of olfactory cells, epithelial supporting cells, and basal stem cells
-neurons with special olfactory hairs that bind odorants

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43
Q

where do the axons of olfactory cells collect into?

A

fascicles, which leave the nasal cavity through the cribriform (nasal) foramina in the ethmoid bone.

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44
Q

how many different kinds of olfactory receptors are present?

A

350 different types

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45
Q

What happens when an odorant binds to a receptor to cause a receptor potential?

A

it leads to the opening of Na+ or Ca+ channels
*which depolarizes the olfactory cell and causes a receptor potential (remember that this is a local potential)

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46
Q

what is hearing?

A

a response to vibrating air molecules

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47
Q

what is sound?

A

an audible vibration of molecules

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48
Q

what is pitch?

A

the sense of whether a sound is high (treble) or low (bass). it is determined by the frequency at which the sound source (and therefore the eardrum) vibrates.

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49
Q

what is loudness?

A

the perception of sound intensity, which is a function of the amplitude of vibration. expressed in decibels (dB). Every 10 dB increase corresponds to a sound with 10 times greater intensity.

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50
Q

what is the external ear?

A

-consists of the pinna
-pinna acts as a funnel to conduct airborne vibrations to the eardrum

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51
Q

what is the auditory canal?

A

-also called external acoustic meatus
-is the passage leading through the temporal bone to the tympanic membrane.

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52
Q

how is the auditory canal protected?

A

-guard hairs on the outer end
-earwax coats guard hairs and waterproofs canal

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53
Q

how is earwax formed?

A

ceruminous and sebaceous glands mix to form cerumen (earwax!)

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54
Q

what is the tympanic membrane?

A

-eardrum!
-separates the auditory canal from the tympanic cavity, also known as the middle ear.

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55
Q

what is the tympanic cavity?

A

-continuous with the nasopharynx via the auditory tube (aka eustachian tube)
-holds the malleus, incus, and stapes.
-the base of the stapes is adjacent to the oval window of the inner ear.

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56
Q

what does the auditory tube do?

A

drains and aerates the middle ear.

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57
Q

what is found in the scala vestibuli and scala tympani?

A

perilymph

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58
Q

what does the cochlea do?

A

-it is the organ of hearing
-a coiled tube that arises from the vestibule
-have 3 fluid-filled chambers

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59
Q

what is found in the cochlear duct?

A

endolymph

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60
Q

what makes up the spiral organ?

A

-hair cells containing stereocilia on apical surface (50 stereocilia on each cell)
-supporting cells
-gelatinous tectorial membrane

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61
Q

where does the tectorial membrane rest on the stereocilia?

A

on top of the stereocilia

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62
Q

why is the spiral organ important?

A

it converts vibrations into nerve impulses

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63
Q

what part of the cochlear duct has high levels of K+ ions

A

the endolymph

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64
Q

what do each of the stereocilia on the inner hair cells have on their tips?

A

-a single transmembrane protein that acts as a mechanically-gated ion channel

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65
Q

what do tip link proteins do?

A

connect the tips of each of the stereocilia

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66
Q

know the basilar membrane pushes inner hair cells

A

…

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67
Q

what is equilibrium

A

sense of body orientation, movement, and balance

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68
Q

what is in the vestibule in the inner ear?

A

-3 semicircular ducts
-2 chambers called the saccule and utricle

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69
Q

static equilibrium

A

the perception of the orientation of the head in space

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70
Q

dynamic equilibrium

A

the perception of motion and acceleration

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71
Q

what are the saccule and utricle responsible for?

A

static equilibrium and sense of linear acceleration

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72
Q

what do semicircular ducts detect?

A

angular acceleration

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73
Q

saccule structure

A

-patch of hair cells
-supporting cells called a macula
-macula is a vertical structure

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74
Q

utricle structure

A

-patch of hair cells
-supporting cells called a macula
-macula is a horizontal structure

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75
Q

structure of each hair cell in saccule and utricle

A

-has 40-70 stereocilia
-one true cilium called a kinocilium
-tips are embedded in a gelatinous otolithic membrane

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76
Q

semicircular ducts

A

-all 3 ducts are oriented in different planes
-each duct is filled with endolymph
-each duct has a bulge at one end called the ampulla

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77
Q

what is within the ampulla?

A

-a mound of hair cells and supporting cells called the crista ampullaris.
*the hair cells have stereocilia and a kinocilium, all embedded in a gelatinous cap

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78
Q

the cochlear nerve and the vestibular nerve come together to form…?

A

the vestibulocochlear nerve

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79
Q

what is vision?

A

the perception of objects by the light they emit or reflect

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80
Q

what wavelengths can humans see?

A

400 nm to 700 nm. CANNOT see ultraviolet or infrared radiation

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81
Q

eyebrows

A

enhance facial expressions and may offer protection

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82
Q

eyelids

A

protect the eye and blink regularly to moisten the eye *eyelashes are guard hairs

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83
Q

conjunctiva

A

-transparent membrane that covers the inner surface of the eyelid and anterior surface of the eye, except where the cornea is
-secretes a mucous film
-highly vascularized (bloodshot eyes)

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84
Q

lacrimal apparatus

A

-includes the lacrimal (tear) gland and a series of ducts (mainly the nasolacrimal duct) that drain the tears into the nasal cavity

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85
Q

3 layers that form the wall of the eye

A
  1. outer fibrous layer (tunica fibrosa)
  2. the tunica vasculosa
  3. inner tunica interna
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86
Q

outer fibrous layer (tunica fibrosa)

A

-divided into the sclera and the cornea
-sclera- white outer layer
-cornea- modified sclera that is transparent

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87
Q

tunica vasculosa

A

3 regions-
1. choroid- highly vascularized, deeply pigmented layer behind the retina
2. ciliary body- a thickened extension of the choroid that forms a ring around the lens and secretes aqueous humor
3. iris- an adjustable diaphragm that controls the diameter of the pupil

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88
Q

inner tunica interna

A

the retina

89
Q

4 optical components and definition?

A
  1. cornea
  2. aqueous humor
  3. lens
  4. vitreous humor

-all of these components are transparent elements that admit, bend, and focus light rays on the retina

90
Q

aqueous humor

A

-serous fluid found in anterior chamber and posterior chamber

91
Q

lens

A

composed of transparent, flattened cells. held in place by the suspensory ligaments

92
Q

vitreous humor

A

jelly-like material fills the space behind the lens

93
Q

what are the neural components?

A

the retina and the optic nerve

94
Q

retina

A

-an outgrowth of the diencephalon (it’s actually a part of the brain!)
-attached to the rest of the eye only at the optic disc and the ora serrata
-if detached from the choroid, can become blind

95
Q

what does the retina depend on the choroid for?

A

nutrition, oxygen, nutrition, and waste removal

96
Q

what area produces the most detailed images?

A

the macula lutea, the center of which is called the fovea centralis

97
Q

optic disc

A

-lies medially from the macula lutea
-contains no receptor cells; brain uses visual filling to fill in the gaps
-blood vessels enter and leave via the optic disc

98
Q

how is pupil diameter controlled

A

-the pupillary constrictor
-the pupillary dilator

99
Q

the pupillary constrictor

A

-consists of smooth muscle cells that encircle the pupil. they narrow the pupil

100
Q

the pupillary dilator

A

-consists of contractile myoepithelial cells. when these cells contract the pupils dilate

101
Q

where does the conversion of light energy into action potentials occur?

A

in the retina

102
Q

what is the pigment epithelium?

A

-most posterior part of the retina
-dark layer absorbs stray light so it doesn’t reflect back through the retina

103
Q

what are the three layers of the neural components of the eye?

A
  1. photoreceptor cells
  2. bipolar cells
  3. ganglion cells
104
Q

photoreceptor cells

A

-the rods and cones of these cells absorb light and generate a chemical signal
-they are not neurons
-each rod and cone have an outer segment that points toward the wall of the eye, then an inner segment, a cell body, and synaptic processes

105
Q

in rods, what is each disc filled with?

A

the visual pigment rhodopsin
-rod cells are responsible for night vision and produce images in shades of gray

106
Q

in cones, what is each disc filled with?

A

-the visual pigment photopsin
-cones are responsible for day vision and color vision

107
Q

bipolar cells

A

rods and cones synapse with the dendrites of these cells, which then synapse with ganglion cells

108
Q

ganglion cells

A

these are arranged in a single layer close to the vitreous humor. their axons form the optic nerve.

109
Q

rhodopsin

A

found in rods, and has two parts:
1. a protein called opsin
2. a vitamin A derivative called retinal

110
Q

photopsin

A

found in cones and has the retinal component. The opsin component is modified in different cones which determines the wavelength (color) of light that is absorbed. there are 3 different types of cones.

111
Q

how are nerve signals generated?

A
  1. in the dark, rod cells continuously release neurotransmitter (glutamate) at synapses with bipolar cells
  2. the glutamate inhibits local potentials in the bipolar cells
  3. when the rod receives light, it will stop releasing glutamate. those bipolar cells that were being inhibited by glutamate are now able to be excited and they will release neurotransmitter onto ganglion cells
112
Q

why do we have both rods and cones?

A

-because a single receptor system cannot produce both high sensitivity and high resolution.

113
Q

neural convergence in the retina

A

each bipolar cells receives input from up to 600 rods, and each ganglion cells receives input from several bipolar cells. *this allows for spatial summation, which allows us to detect even at very low light levels.

114
Q

why does lack of neural convergence allow for higher resolution?

A

because the receptive fields are very small.

115
Q

3 kinds of cones

A
  1. short-wavelength (s) cones
  2. medium-wavelength (m) cones
  3. long-wavelength (l) cones
116
Q

how much of our body weight do muscles make up?

A

almost 1/2

117
Q

3 types of muscle

A
  1. skeletal
  2. cardiac
  3. smooth
118
Q

what are muscles specialized to do?

A

convert chemical energy (ATP) to mechanical energy (motion)

119
Q

how many skeletal muscles are there in the human body?

A

more than 600!!

120
Q

functions of muscles (5)

A
  1. movement
  2. stability (maintain posture by preventing unwanted movements)
  3. control of body openings and passages
  4. heat production (skeletal muscles produce 85% of body heat)
  5. glycemic control (muscles absorb and store glucose, and they use a large amount of glucose)
121
Q

what do skeletal muscles include?

A

connective tissue, nerves, and blood vessels

122
Q

are skeletal muscles voluntary or involuntary?

A

voluntary- they will not contract unless stimulated to do so

123
Q

what are skeletal muscle cells also called?

A

muscle fibers

124
Q

why do we see striations in muscles?

A

they are due to an overlapping arrangement of internal contractile proteins

125
Q

what is the cytoplasm in a muscle fiber called?

A

sarcoplasm

126
Q

what is another name for the plasma membrane?

A

-sarcolemma
-it has numerous tubular infoldings called transverse (T) tubules

127
Q

what is the sarcoplasm made up of?

A

-mostly long strings of proteins, or myofilaments, called myofibrils
-large amount of glycogen as well as myoglobin, which is an oxygen-binding protein

128
Q

what is another name for the smooth endoplasmic reticulum?

A

sarcoplasmic reticulum
-contains really high amounts of calcium

129
Q

2 types of myofilaments

A
  1. thick filaments
  2. thin filaments
130
Q

thick filaments

A

consist of many molecules of the protein myosin

131
Q

thin filaments

A

-consist of two intertwined strands of actin
-each bead of the actin has an active site that can bind to the head of a myosin molecule
-also includes the protein tropomyosin, which covers these active sites when at rest
-each tropomyosin has yet another protein, troponin, bound to it

132
Q

what does the Z line do?

A

-provides anchorage for the thin filaments
-a segment from one Z line to the next is called a sarcomere
-z lines are pulled closer together during contraction

133
Q

when will skeletal muscles contract?

A

when stimulated by somatic motor neurons

134
Q

what is a motor unit?

A

one nerve fiber and all the muscle fibers it innervates

135
Q

what is a neuromuscular junction?

A

the point where a neuron meets a muscle fiber

136
Q

what neurotransmitter is secreted onto skeletal muscle?

A

acetylcholine (ACh)

137
Q

what is acetylcholinesterase

A

-enzyme
-breaks down the ACh after stimulation of the muscle has occurred

138
Q

steps of muscle contraction and know these steps in depth

A
  1. excitation
  2. excitation-contraction coupling
  3. contraction
  4. relaxation
139
Q

what is a muscle twitch?

A

a quick cycle of contraction and relaxation

140
Q

what is threshold in the context of muscle contraction?

A

-minimum voltage necessary to generate an action potential in the muscle fiber

141
Q

what happens as stimulus voltage increases?

A

contraction strength will increase until a maximum contraction strength is reached.

142
Q

what factors can affect the contraction strength of twitches?

A
  1. the stretch of muscle prior to contraction
  2. muscle fatigue
  3. temperature of the muscle
  4. state of hydration
  5. stimulus frequency
143
Q

isometric contraction

A

a contraction without a change in length

144
Q

isotonic contraction

A

involves a change in length (without a change in tension)

145
Q

what are smooth muscle cells called?

A

the myocytes (they are not striated btw)

146
Q

is smooth muscle always innervated?

A

no, but if it is innervated, it would be by the autonomic nervous system

147
Q
A
148
Q

what are varicosities?

A

-neurons swelling along the axon as it branches (the varicosities contain synaptic vesicles)

149
Q

where is smooth muscle found?

A

-walls of organs, walls of blood vessels and airways, and in areas such as the iris and hair follicles

150
Q

factors that make smooth muscle contract:

A
  1. autonomic division/neurotransmitters
  2. chemicals- (smooth muscle can react to hormones, oxygen, CO2, low pH, etc.)
  3. temperature- (cold induces contractions of smooth muscle in hair follicles; warmth relaxes smooth muscles in arteries of the skin)
  4. stretch- (the stomach and urinary bladder contract when stretched)
151
Q

know the steps of smooth muscle contraction

A

!!!!

152
Q

what is the trigger for immediate contraction of smooth muscle contraction?

A

the presence of Ca++ in the cytoplasm

153
Q

4 facts about smooth muscle contraction!

A
  1. smooth muscle is very slow to contract and relax compared to skeletal muscle
  2. smooth muscle often exhibits tetanus, and is very resistant to fatigue
  3. the ATP requirements are much less than that of skeletal muscle
  4. many smooth muscles will exhibit a continual tonic contraction that is called smooth muscle tone
154
Q

how are the nervous system and endocrine system complimentary?

A

nervous system tends to act quickly, while the endocrine system will have longer lasting effects

155
Q

what are hormones?

A

chemical messengers transported thru the bloodstream to target tissues

156
Q

what makes up the endocrine system?

A

glands, tissues and cells that secrete hormones

157
Q

other methods of cell-to-cell communication

A
  1. neurotransmitters- secreted by neurons and bind to receptors on adjacent cells
  2. paracrine messengers- secreted by one cell and diffuse to adjacent cells, where they bind to receptors and cause changes
158
Q

exocrine glands

A

secrete their materials via ducts either onto the surface of the body or into the digestive tract

159
Q

endocrine glands

A

do not utilize ducts and they secrete their materials into the bloodstream. they include a very high density of blood capillaries.

160
Q

what is the hypothalamus?

A

-small area located at the base of the brain
-many functions including some endocrine

161
Q

pituitary gland (hypohysis)

A

-suspended from the floor of the hypothalamus by a stalk called the infundibulum

162
Q

alt. name for the anterior pituitary

A

adenohypophysis
-no direct nervous connection to the hypothalamus, but it is linked to it by the hypophyseal portal system

163
Q

alt. name for the posterior pituitary

A

neurohypophysis
-is an extension of the hypothalamus

164
Q

what two hormones are released from the posterior pituitary

A
  1. oxytocin (OT)
  2. antidiuretic hormone (ADH)
    -produced by neurons in 2 separate nuclei within the hypothalamus
165
Q

oxytocin

A

-responsible for the contraction of myoepithelial cells in breast tissue which results in the expulsion of milk
-surges in both sexes during sexual arousal and orgasm
-essential for contractions during childbirth
-feelings of sexual satisfaction and emotional bonding

166
Q

anti-diuretic hormone (ADH)

A

-increases water retention by the kidneys (reduces urine volume and helps prevent dehydration)
-alcohol inhibits release of ADH
-increase in osmolarity releases ADH
-excessive blood pressure inhibits release of ADH

167
Q

hypothalamic hormones

A
  1. gonadotropin-releasing hormone (GnRH)
  2. thyrotropin-releasing hormone (TRH)
  3. corticotropin-releasing hormone (CRH)
  4. prolactin inhibiting hormone (PIH)
  5. growth hormone-releasing hormone (GHRH)
  6. somatostatin (SST)
168
Q

Gonadotropin-Releasing Hormone (GnRH)

A

Causes the release of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) from the anterior pituitary.

169
Q

Thyrotropin-Releasing Hormone (TRH)

A

Causes the release of Thyroid-Stimulating Hormone (TSH) from the anterior pituitary

170
Q

Corticotropin-Releasing Hormone (CRH)

A

Causes the release of Adrenocorticotropic Hormone (ACTH) from the anterior pituitary

171
Q

Prolactin Inhibiting Hormone (PIH)

A

Inhibits the release of Prolactin (PRL) from the anterior pituitary. This is actually dopamine.

172
Q

Growth Hormone-Releasing Hormone (GHRH)

A

– Causes the release of Growth Hormone (GH)
from the anterior pituitary

173
Q

Somatostatin (SST)

A

-also known as Growth Hormone-Inhibiting Hormone (GHIH)
– Inhibits the release of Growth Hormone (GH) from the anterior pituitary.

174
Q

hormones of anterior pituitary

A
  1. Follicle-Stimulating Hormone
  2. Luteinizing Hormone
  3. Thyroid Stimulating Hormone
  4. Adrenocorticotropic Hormone
  5. Prolactin
  6. Growth Hormone
175
Q

Follicle-Stimulating Hormone

A

In ovaries, stimulates the secretion of ovarian sex hormones (estrogen and progesterone) and causes development of the follicles, which contain eggs. In males, stimulates sperm production.

176
Q

Luteinizing Hormone

A

In females, stimulates
ovulation (and the development of the corpus
luteum). In males, causes secretion of
testosterone.

177
Q

Thyroid Stimulating Hormone

A

Causes growth of
thyroid gland and release of thyroid hormone

178
Q

Adrenocorticotropic Hormone

A

Causes the growth
of the adrenal cortex and the release of cortisol

179
Q

Prolactin

A

Causes the production of milk in breast
tissue. Levels increase greatly during pregnancy
and lactation.

180
Q

Growth Hormone

A

Stimulates mitosis and cellular
differentiation in all tissues and thus promotes
growth in general.

181
Q

hormonal axis

A

1.Hypothalamus secretes thyrotropin-releasing
hormone.
2. TRH stimulates the anterior pituitary to secrete
thyroid-stimulating hormone.
3. TSH causes the thyroid gland to secrete thyroid
hormone.
4. TH has effects on target tissues.
5. TH also inhibits the release of TSH from the anterior
pituitary.
6. TH also, to a lesser extent, inhibits the release of
TRH by the hypothalamus.

182
Q

prolactin

A

-milk production and mammary gland growth and development
-causes parental behaviors in a number of species
-affects hair growth and sebaceous gland activity

183
Q

growth hormone

A

-widespread effects on the body
-growth in bone, cartilage, and muscle
-causes liver to release insulin-like growth factors
-need both GH and IGF

184
Q

thyroid gland

A

-largest gland to have a fully endocrine function
-located adjacent to the trachea below the larynx, has a bi-lobed shape
-composed mostly of follicles surrounding thyroglobulin
-thyroglobulin is a protein that is the structural precursor to thyroid hormone

185
Q

thyroid gland

A

-largest gland to have a fully endocrine function
-located adjacent to the trachea below the larynx, has a bi-lobed shape
-composed mostly of follicles surrounding thyroglobulin
-thyroglobulin is a protein that is the structural precursor to thyroid hormone

186
Q

thyroid function

A

Thyroid hormone consists of two tyrosine residues that are
combined together (see below). Either three or four iodines
are attached to form triiodothyronine (T3) or tetraiodothyronine
(T4, Thyroxine). Together, T3 and T4 are called thyroid
hormone.
* When stimulated to do so by thyroid-stimulating hormone,
thyroglobulin is converted into either T4 (90%) or T3 (10%) and
released into the bloodstream.
* T4 gets converted to T3 at the target tissues, and it is T3 that
binds to receptors in the target tissues.

187
Q

physiological roles of thyroid hormone

A

1.growth and development
2. thermogenesis and metabolic rate- increase metabolic rate by increasing production of ATP and heat

188
Q

how many layers does the adrenal cortex have?

A

-3
-each produces different types of steroid hormones

189
Q

2 examples of glucocorticoids

A
  1. cortisol
  2. corticosterone
190
Q

glucocorticoid effects on immune system

A

-stimulate fat and protein catabolism
-stimulate gluconeogenesis
-anti-inflammatory effects
-OVERSECRETION can suppress the immune system

191
Q

stress response steps

A

1.first stages of stress involve release of epinephrine and norepinephrine from sympathetic division (breakdown and use of glucose)
2.aldosterone released to promote sodium and water retention
3.in later stages, cortisol is released from adrenal cortex (cortisol breaks down lipids and proteins to promote gluconeogenesis)

192
Q

what does long-term stress lead to?

A

-inhibition of reproductive function
-suppression of the immune system
-formation of peptic ulcers

193
Q

aldosterone

A

-hormone called a mineralocorticoid because it helps to regulate the levels of electrolytes
-stimulates kidneys to retain sodium and water
-helps to maintain blood volume and blood pressure
-the release is under the control of the renin/angiotensin system (know in depth)

194
Q

main androgen released by adrenal cortex

A

DHEA (dehydroepiandrosterone)
-can be converted to testosterone and dihydrotestosterone
-very important in the development of male reproductive tract
-in men, androgens released testes outweighs amount secreted by adrenal cortex

195
Q

amount of estrogens secreted in women?

A

-in adult women, amount of estrogen released from adrenal cortex is less than from the ovaries
-in post-menopausal women, adrenals become the primary source of estrogens

196
Q

what are the islets of langerhans?

A

-clusters of cells that secrete several hormones, including glucagon and insulin

197
Q

when is glucagon released

A

between meals after the carbohydrates, fats and proteins from our previous meal have been moved into our tissues (it makes sure glucose levels in the blood dont get too low)

198
Q

what does glucagon do?

A

-causes glycogenolysis (breakdown of glycogen into glucose)
-gluconeogenesis (formation of glucose from fats and proteins)
*both provide glucose to maintain glucose levels in the blood

199
Q

when is insulin released?

A

-during and immediately following a meal
(targets are the liver, skeletal muscle, and adipose tissue)

200
Q

insulin function

A

-stimulates cells to absorb glucose, fatty acids, and amino acids either to store them or to metabolize them for energy.
-it therefore promotes the synthesis of glycogen, fat, and proteins and enhances cellular growth and differentiation

201
Q

how does leptin affect appetite-regulating centers?

A

-low levels indicate a deficiency in body fat, so it increases appetite and food intake
-high levels of leptin tend to suppress appetite
-also serves as a signal for onset of puberty, which is delayed in individuals with abnormally low body fat

202
Q

receptors found on the surface of target cells

A

peptide hormones and catecholamines

203
Q

receptors found in the cell

A

steroid hormones and thyroid hormone

204
Q

effect timeline or protein hormones vs. steroids or thyroid hormones

A

-protein hormones have very rapid effects
-steroids and thyroid hormones take hours or days

205
Q

know up-regulation v. down-regulation of receptors

A

-upregulation creates a stronger response
-downregulation creates a diminished response

206
Q

2 ways that endocrine disorders can occur

A

-alterations in hormone release
-or due to changes in responsiveness of target tissues

207
Q

hyposecretion

A

inadequate hormone release

208
Q

hypersecretion

A

excessive hormone release

209
Q

growth hormone disorders

A

-gigantism- hypersecretion of growth hormone early in life
-acromegaly- thickening of bones and soft tissues- hypersecretion later in life
-pituitary dwarfism- hyposecretion early in life

210
Q

what is a goiter

A

-overgrowth of the thyroid gland due to excessive release of TSH
-may develop due to dietary deficiency of iodine

211
Q

congenital hypothyroidism

A

-hyposecretion of thyroid secretion from birth
-symptoms- stunted physical development, irreversible brain damage, low body temperature, and lethargy
-childhood hypothyroidism also called cretinism

212
Q

myxedema

A

-adult hypothyroidism
-low metabolic rate, sluggishness and sleepiness, weight gain, thickened/course skin, thickening of the nose, swelling of subcutaneous tissue, mental dullness, and thinning hair

213
Q

Hashimoto’s disease

A

-autoimmune
disorder in which antibodies attack the
thyroid gland and decrease the ability to
produce thyroid hormone. It is the most
common cause of hypothyroidism in North
America.
* A goiter develops.

214
Q

graves disease

A

-most common type of hyperthyroidism
-Due to antibodies that bind to the TSH
receptor on the thyroid gland and cause
overstimulation of the thyroid gland.
* Symptoms include a goiter, elevated
metabolic rate, nervousness, weight loss,
abnormal sweating, and bulging of the
eyes.

215
Q

diabetes mellitus

A

-due to a hyposecretion or lack of effectiveness of insulin
-symptoms: excessive urine output, intense thirst, hunger, hyperglycemia, glucose in urine, and ketones in urine
-long term effects: muscle atrophy and emaciation, osmotic diuresis and electrolyte
deficiencies due to ketonuria, ketoacidosis (which can depress the nervous system and cause diabetic coma), atherosclerosis, blindness, renal failure, and diabetic neuropathy.

216
Q

type 1 diabetes

A

-lack of production of insulin (genetic or caused by disease)
-5-10% of cases in the US
-insulin doses are effective

217
Q

type 2 diabetes

A

-due to insulin resistance
-may be due to genetic mutations
-may be due to obesity

218
Q

main androgen released by adrenal cortex

A

DHEA (dehydroepiandrosterone)
-can be converted to testosterone and dihydrotestosterone
-very important in the development of male reproductive tract
-in men, androgens released testes outweighs amount secreted by adrenal cortex

Physiology (9 decks)

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