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MCAT TPR Biology > Nervous and Endocrine Systems > Flashcards

Nervous and Endocrine Systems Flashcards

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1
Q

What is the basic functional and structural unit of the nervous system?

A

Neuron

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2
Q

What are action potentials?

A

electrochemical signals of the nervous system

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3
Q

What is the soma?

A

central cell body

it contains the nucleus and is where most of the biosynthetic activity of the cell takes place

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4
Q

Neurons have ___ axon and ___ dendrites.

A

one

many

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5
Q

Neurons with one dendrite are termed _____, and those with many dendrites are ______.

A

bipolar

multipolar

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6
Q

What direction does an action potential travel?

A

in one direction, dendrites receive the information and the axons carry it away from the cell body

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7
Q

Axons terminate into ______ _____.

A

synaptic knobs- which form connections with target cells

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8
Q

What happens when an action potential reaches the synaptic knob?

A

chemical messengers are released and travel across a very small gap called the synaptic cleft to the target cell

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9
Q

What is the difference between a neuron and a nerve?

A

neuron- single cell

nerve- large bundle of many different axons from different neurons

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10
Q

What is anterograde movement in neurons?

A

from the soma to the axon terminus

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11
Q

What is kinesin?

A

protein motor that drives movement of vesicles and organelles along microtubule in axons

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12
Q

What is the resting membrane potential?

A

-70 mV

electric potential across the plasma membrane, the interior is negatively charged with respect to the exterior

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13
Q

What two membrane proteins are required to establish the resting membrane potential?

A

Na+/K+ ATPase

K+ leak channels

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14
Q

The Na+/K+ ATPase pumps __ sodium ions out of the cell and __ potassium ions into the cell with the hydrolysis of one ____ molecule.

A

3
2
ATP

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15
Q

What form of transport is carried out by the Na+/K+ ATPase?

A

primary active- uses ATP to drive transport against gradient

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16
Q

What do potassium leak channels allow?

A

allow only K+ to flow out of the cell down their gradient, they are open all the time

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17
Q

Why is the resting membrane potential negative?

A

one extra sodium is being pumped out compared to the potassium coming in and the leak channels allow K+ to flow out

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18
Q

Are neurons the only cells with resting membrane potentials?

A

no all cells have it but they are unique in that they use it to generate action potentials, muscle cells also do this

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19
Q

What would happen to the resting membrane potential if potassium leak channels are blocked?

A

it becomes less negative because K+ is stuck in the cell

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20
Q

What would happen to the resting membrane potential if sodium ions were allowed to flow down their concentration gradient?

A

it would become less negative and possibly positive because more sodium ions would flow into the cell

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21
Q

What is depolarization?

A

change in membrane potential from -70 mV to a less negative or even positive number

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22
Q

What is repolarization?

A

returns the membrane potential to normal

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23
Q

Why is the cell polarized?

A

it is negative on the inside and positive on the outside

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24
Q

What do the voltage gated sodium channels allow?

A

they open in response to a change in membrane potential and allow sodium ions to flow down their gradient into the cell to depolarize it (less negative or positive)

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25
Q

What is the threshold potential?

A

-50 mV

threshold needed for an action potential to generate

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26
Q

What happens when threshold is reached? below?

A

the sodium channels are opened fully allowing sodium ions to rush in, down its gradient to depolarize that section of the membrane to about +35 mV before inactivating

below threshold, channels are closed not allowing passage of anything

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27
Q

How does depolarization move down the axon?

A

when one part of the membrane is depolarized, the part next to it gets slightly depolarized until it reaches threshold, in this way it passes it down the axon

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28
Q

If an action potential starts at one end of an axon, can it run out of energy and not reach the end?

A

no, action potentials are continually renewed at each point in the axon, once it starts it will propagate without changing amplitude until it reaches a synapse

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29
Q

What will happen to the voltage gated sodium channels when the membrane potential goes from -70 to -60?

A

none of the channels will open because it has not reached threshold of -50 mV, its all or nothing

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30
Q

What happens in the process of repolarization?

A
  1. voltage gated sodium channels inactivate very quickly shutting off flow of sodium ions into the cell
  2. voltage gated potassium channels open more slowly and stay open longer, as potassium leaves the cell the membrane potential return to negative numbers overshooting resting potential down to -90 mV, then the channels close
  3. potassium leak channels and Na+/K+ ATPase function to bring back to resting membrane potential
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31
Q

What would be the effect if voltage gated potassium channels were inhibited?

A

the membrane potential would still be repolarized but it would take a lot longer

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32
Q

If a toxin prevents voltage gated sodium channels from closing, what will happen?

A
  • voltage gated potassium channels will open but not close - they normally close by repolarization
  • membrane will not repolarize to normal
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33
Q

What creates the myelin sheath?

A

Schwann cells from the PNS

Oligodendrocytes in CNS

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34
Q

Would an axon be able to conduct action potentials if its entire length were wrapped in myelin?

A

no because no ion can enter or exit where there is myelin

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35
Q

Nodes of Ranvier?

A

periodic gaps in myelin sheath where voltage gated sodium and potassium channels are concentrated

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36
Q

How does the myelin sheath speed up conduction of action potentials?

A

by forcing the action potentials to jump from node to node (saltatory conduction)

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37
Q

Is the amount of energy consumed by Na+/K+ ATPase more in myelinated or unmyelinated axons?

A

more in unmyelinated because it has to maintain the resting potential in the whole membrane whereas in myelinated axons it only has to maintain resting potential in the nodes of Ranvier

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38
Q

What is equilibrium potential?

A

no net movement of ions across the membrane

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39
Q

What is the equilibrium potential of sodium?

A

+50 mV

no more sodium can come in at this point

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40
Q

What is the equilibrium potential for potassium?

A

-90 mV

it is too negative that K+ cannot escape the attraction so potassium is driven in

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41
Q

Are there more potassium or sodium leak channels?

A

potassium because the resting potential is closer to the K+ equilibrium potential

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42
Q

What is the refractory period?

A

short period of time when the neuron is unresponsive to membrane depolarization

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43
Q

What is the absolute refractory period?

A

a neuron will not fire another action potential no matter how strong a membrane depolarization is induced

voltage gated sodium channels are inactivated and will not open again until resting membrane potential is reached and the channels have returned to closed

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44
Q

What is the relative refractory period?

A

a neuron can be induced to transmit an action potential but the depolarization required is greater than normal because the membrane is hyperpolarized

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45
Q

What causes hyperpolarization?

A

caused by the voltage gated potassium channels not closing yet

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46
Q

If voltage gated potassium channels shut more quickly after repolarization than normal, how would this affect the refractory period?

A

absolute- not affected because it is due to the inability of sodium channels to open

relative- would be shorter

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47
Q

What is a synapse?

A

junction between the axon terminus and the dendrites, soma, or axons of a second neuron

could also be axon to organ

two types: electrical and chemical

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48
Q

Electrical synapse?

A

occur when the cytoplasm of two cells are joined by gap junctions so action potentials spread directly from one cell to another

common in smooth muscle and cardiac muscle

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49
Q

Chemical synapse?

A

found at the end of axons where they meet their target cells, action potential is converted into a chemical signal

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50
Q

What are the 8 steps in a chemical synapse?

A
  1. Action potential reaches the end of an axon, the synaptic knob
  2. Depolarization of the presynaptic membrane opens voltage gated calcium channels
  3. Calcium influx into the presynaptic cell causes exocytosis of neurotransmitter stored in secretory vesicles
  4. Neurotransmitter molecules diffuse across the narrow synaptic cleft
  5. Neurotransmitter binds to receptor proteins in the postsynaptic membrane, these receptors are ligand gated ion channels
  6. the opening of these ion channels in the postsynaptic cell alters the membrane polarization
  7. If the membrane depolarization of the postsynaptic cell reaches the threshold of voltage gated sodium channels, an action potential is initiated
  8. Neurotransmitter in the synaptic cleft is degraded and/or removed to terminate the signal
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51
Q

What is a common example of a chemical synapse?

A

neuromuscular junction between neurons and skeletal muscle

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52
Q

What neurotransmitter is released in the neuromuscular junction?

A

acetlycholine (ACh)

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53
Q

What degrades ACh after a synapse?

A

acetylcholinesterase (AChE)

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54
Q

What are some neurotransmitters?

A

Gamma-aminobutyric acid (GABA)
Serotonin
Dopamine
Norepinephrine

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55
Q

If a neurotransmitter, such as ACh, opens a channel that depolarizes the postsynaptic membrane, it is _____.

A

excitatory

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56
Q

Neurotransmitters that induce hyperpolarization are _____.

A

inhibitory

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57
Q

What ultimately determines the effect on the postsynaptic cell?

A

the receptor and its associated ion channels

neurotransmitters can be excitatory and inhibitory depending on the receptors

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58
Q

A presynaptic neuron can release ____ type of neurotransmitter and the postsynaptic neuron can respond to ____ neurotransmitters

A

one

many

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59
Q

If a neurotransmitter causes the entry of chloride into the postsynaptic cell, is it excitatory or inhibitory?

A

inhibitory

chloride is negative so it will make the potential more negative making it harder to reach threshold

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60
Q

If an inhibitor of acetylcholinesterase is added to a neuromuscular junction, what will happen with the postsynaptic membrane?

A

it will be depolarized longer, acetylcholinesterase is not there to degrade ACh so the sodium channels will remain open longer

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61
Q

What causes unidirectional signaling at synapses between neurons?

A

only the postsynaptic cell has receptors for neurotransmitters

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62
Q

What is summation?

A

adding the effect of all the impinging synapses on a nuron, add the stimuli

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63
Q

Excitatory postsynaptic potentials (EPSP)?

A

excitatory neurotransmitters cause postsynaptic depolarization

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64
Q

Inhibitory postsynaptic potentials (IPSP)?

A

inhibitory neurotransmitters cause these

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65
Q

Temporal summation?

A

presynaptic neuron fires action potentials so rapidly that the EPSPs and IPSPs pile up on top of each other

EPSP- additive effect is enough to reach threshold depolarization required to start postsynaptic action potential

IPSP- postsynaptic cell will hyperpolarize, inhibiting action potentials

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66
Q

Spatial summation?

A

All EPSPs and IPSPs from all the synapses on the postsynaptic cell are summed at any give time, if threshold is reached an action potential will fire

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67
Q

What are two types of effectors?

A

muscles and glands

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68
Q

What happens in a reflex?

A

a sensory neuron transmits an action potential to a synapse with a motor neuron in the spinal cord which causes an action to occur, brain is not involved

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69
Q

What happens in the muscle stretch reflex?

A
  • long sensory neuron detects stretching of muscle

- signal is transmitted to a motor neuron cell body in the spinal cord, causing muscle to contract

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70
Q

What is a reflex involving two neurons and one synapse?

A

monosynaptic reflex arc

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71
Q

Inhibitory interneuron?

A

short neuron which forms an inhibitory synapse with a motor neuron causing a muscle to relax (ex. hamstring in knee reflex)

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72
Q

Reciprocal Inhibition?

A

concurrent relaxation of the hamstring and contraction of the quads is an example

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73
Q

If a reflex occurs without the involvement of the brain, how are we aware of the action?

A
  1. sensory neuron also branches to form a synapse with a neuron leading to the brain
  2. other sensory info is received after the action is taken
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74
Q

Somatic division of the PNS?

A

concerned with conscious sensation and deliberate, voluntary movement of skeletal muscle

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75
Q

Autonomic division of the PNS?

A

involuntary process such as digestion, metabolism, circulation, perpiration

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76
Q

Two subdivisions of the autonomic?

A

Sympathetic (fight or flight)

Parasympathetic (rest and digest)

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77
Q

What are some effects of the parasympathetic system?

A
  • Gland and motility (digestion) stimulation
  • relaxation of sphincters
  • bladder contraction (enables urination)
  • constriction of airways
  • decreased heart rate
  • constriction of pupils
  • near vision accommodation
  • erection/ lubrication
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78
Q

What are some effects of the sympathetic system?

A
  • Gland and motility (digestion) inhibition
  • contraction of sphincters
  • bladder relaxation (inhibits urination)
  • relaxation of airways (opens)
  • increased heart rate and blood flow
  • sweating and blushing
  • pupil dilation
  • far vision accommodation
  • release of epinephrine
  • ejaculation/orgasm
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79
Q

The majority of cell bodies are found in the ____.

A

CNS

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80
Q

Cell bodies bunched together in the CNS are called _____. Bunched cell bodies in the PNS are called _____.

A

nuclei

ganglia

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81
Q

Other names for the three subdivisions of the brain:
Hindbrain?
Midbrain?
Forebrain?

A

Rhombencephalon
Mesencephalon
Prosencephalon

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82
Q

What is the function of cerebrospinal fluid?

A

shock absorption for brain

exchange nutrients and waste in CNS

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83
Q

What is the spinal cord responsible for?

A
  • relay info to and from brain
  • simple spinal reflexes (ex. deep tendon reflex)
  • primitive processes like walking, urination, and sex organ function
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84
Q

What does the hindbrain consist of?

A

medulla, pons, cerebellum

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85
Q

Function of Medulla?

A
  • control autonomic processes such as blood pressure, heart rate, respiratory rate, swallowing, vomiting
  • controls reflex reactions such as coughing or sneezing
  • relays sensory info to cerebellum and thalamus
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86
Q

Function of Pons?

A
  • controls antigravity posture and balance
  • connects the spinal cord and medulla to upper regions of brain
  • relays info to cerebellum and thalamus
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87
Q

Function of Cerebellum?

A
  • integrating center

- coordination of complex movement, balance and posture, muscle tone, spatial equilibrium

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88
Q

Function of Midbrain?

A
  • integration of visual and auditory info
  • visual and auditory reflexes
  • wakefulness and consciousness
  • coordinates info on posture and muscle tone
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89
Q

Function of Thalamus?

A
  • relay center for somatic sensation

- relays info between spinal cord and cerebral cortex

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90
Q

Function of Hypothalamus?

A
  • controls homeostatic functions (temp regulation, fluid balance, appetite) through neural and hormonal regulation
  • controls primitive emotions such as anger, rage, sex drive
  • controls pituitary gland
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91
Q

Function of Basal Nuclei?

A
  • regulate body temp and muscle tone
  • coordination of learned movement patterns
  • general pattern of rhythm movements (walking)
  • subconscious adjustments of conscious movements
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92
Q

Function of Limbic system?

A
  • controls emotional states
  • links conscious and unconscious portions of the brain
  • help with memory storage retrieval
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93
Q

Function of Cerebral Cortex?

A
  • four lobes with subfunctions
  • conscious thorough processes and planning, awareness and sensation
  • intellectual function (intelligence, learning, reading, communication)
  • abstract thought and reasoning
  • memory storage and retrieval
  • initiation and coordination of voluntary movement
  • complex motor patterns
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94
Q

Function of Corpus Callosum?

A

connects left and right cerebral hemisphers

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95
Q

What makes up the brainstem?

A

Medulla, Pons, Midbrain

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96
Q

What is the diencephalon?

A

thalamus and hypothalamus

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97
Q

What is included in the forebrain?

A

Diencephalon

Telenchephalon

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98
Q

Left vs Right side?

A

Left- motor functions of right side of body, dominant, speech

Right- motor of left side, visual and spatial reasoning, music

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99
Q

Function of Frontal Lobe?

A

initiates all voluntary movement and are involved in complex reasoning skill and problem solving

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100
Q

Function of Parietal Lobes?

A

general sensations (touch, temp, pressure, vibration) and gustation (taste)

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101
Q

Function of Temporal Lobes?

A

process auditory and olfactory sensation and involved in short term memory

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102
Q

Function of Occipital Lobes?

A

process visual sensation

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103
Q

How many pairs of cranial nerves? spinal nerves?

A

12

31

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104
Q

Cranial nerves convey sensory and motor info to and from the _____. Spinal nerves convey to and from the ____.

A

brainstem

spinal cord

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105
Q

What is the effect the Vagus nerve has on the heart and GI tract?

A

decreases heart rate and increases GI activity (part of parasympathetic system)

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106
Q

All somatic motor neurons innervate what cells? Use what neurotransmitter? Where does it have cell bodies?

A
  • skeletal muscle
  • ACh
  • in the brain stem or ventral portion of spinal cord
107
Q

All somatic sensory neurons have a _____ dendrite extending from a sensory receptor toward the soma, which is located just outside the CNS in a _____ _____ _____.

A

long

Dorsal Root Ganglion

108
Q

What is a dorsal root ganglion?

A

bunch of somatic and autonomic sensory neuron cell bodies located dorsal to the spinal cord, there is a pair for every segment of the spinal cord

109
Q

The dorsal root ganglia is protected within the vertebral column but is outside the ______.

A

meninges so it is outside the CNS

110
Q

The efferents of the autonomic consist of what two neurons?

A

preganglionic- cell body in the brainstem and spinal cord, sends axon to autonomic ganglion outside spinal cord

postganglionic- outside spinal cord, sends axon to effector (smooth muscle or gland)

111
Q

All autonomic preganglionic neurons release what neurotransmitter?

A

ACh

112
Q

All parasympathetic postganglionic neurons release what neurotransmitter?

A

ACh

113
Q

Almost all sympathetic postganglionic release what neurotransmitter?

A

norepinephrine (NE, adrenaline)

114
Q

Location of preganglionic soma in sympathetic? parasympathetic?

A

Thoracolumbar

Craniosacral

115
Q

Preganglionic axon in sympathetic (long or short)? Parasympathetic?

A

symp- short

para- long

116
Q

Which ganglia is close to the cord but far from the target? (sympathetic or para)

A

sympathetic

117
Q

Which ganglia is far from cord but close to the target? (sympathetic or para)

A

parasympathetic

118
Q

Postganglionic axon in sympathetic (long or short)? para?

A

symp- long (NE)

para- short (ACh)

119
Q

Where is the adrenal gland located?

A

above the kidneys (one for each kidney)

120
Q

Why is the adrenal cortex important?

A

endocrine gland that secretes glucocorticoids (cortisol) and mineralcorticoid (aldosterone) and some sex hormones

121
Q

The adrenal medulla is part of the ____ nervous system.

A

sympathetic

it is derived from sympathetic postganglionic neurons and is directly innervated by sympathetic preganglionic neurons

122
Q

Upon activation of the sympathetic system, the adrenal gland is stimulated to release _____.

A

epinephrine (adrenaline-slightly modified NE)

123
Q

T/F

Epinephrine is a hormone.

A

True

it is released into the bloodstream by a ductless gland

124
Q

What are some effects of epinephrine?

A
  • very rapid, short lived
  • sudden flushing and sweating when severely startled
  • stimulation of the heart
  • generally the same as effects of sympathetic system
125
Q

How does the brain know the difference between stimulation of visual receptors and olfactory receptors?

A

based on which sensory neurons are signaling

126
Q

Exteroceptors?

A

sensory receptors that detect stimuli from the outside world

127
Q

Interoceptors?

A

receptors that respond to internal stimuli (baro, chemoreceptors, blood pressure, pH)

128
Q

Mechanoreceptors?

A

respond to mechanical disturbances (ex. Pacinian Corpuscles detect pressure deep in the skin)

129
Q

Why is an auditory hair cell important?

A

mechanoreceptor found in the cochlea of the inner ear that detects vibrations caused by sound waves

130
Q

Why are vestibular hair cells important?

A

mechanoreceptor located in semicircular canals and inner ear that detect acceleration and position relative to gravity

131
Q

Chemoreceptors?

A

respond to particular chemicals

ex: olfactory receptors- detect airborne chemicals and allows us to smell things

gustatory receptors- taste buds

autonomic chemoreceptors in walls of arteries respond to changes in arterial pH

132
Q

Nociceptors?

A
  • pain receptors stimulated by tissue injury
  • generally nerve endings that detect chemical signs of tissue damage
  • can be somatic or autonomic
  • autonomic- dull aching pain (referred pain)
133
Q

Thermoreceptors?

A

detect changes in temp (autonomic and somatic)

134
Q

Electromagnetic receptors?

A
  • stimulated by electromagnetic waves

- only example is rods and cones in eyes(photoreceptors)

135
Q

The nervous system is programmed to respond to ______ stimuli.

A

changing

136
Q

T/F

Nociceptors do not adapt.

A

True

137
Q

Proprioception?

A

awareness of self in space, body part position

138
Q

Muscle spindle?

A
  • mechanoreceptor
  • example of proprioception
  • detects muscle stretch in deep tendon reflex
139
Q

What portion of the CNS requires input from proprioceptors?

A

cerebellum because it coordinates movement

140
Q

What can taste buds detect?

A 
sweet (glucose)
salty (Na+)
bitter (basic)
sour (acidic)
umami (amino acids and nucleotides)
141
Q

Information from taste is transmitted to the brain by what?

A

cranial nerves

142
Q

Why do smells bring back vivid memories?

A

olfactory bulbs are located near centers of the brain important for memory

143
Q

What makes up the outer ear?

A

auricle (pinna) and the external auditory canal

144
Q

What divides the middle ear from the outer ear?

A

tympanic membrane

145
Q

What three bones comprise the middle ear?

A

malleus
incus
stapes

146
Q

What divides the middle and inner ear?

A

oval window

147
Q

What structures make up the inner ear?

A

cochlea
semicircular canals
utricle
saccule

-important for balance

148
Q

What is the round window?

A

membrane covered hole in the cochlea near the oval window which releases excess pressure

149
Q

What is the Eustachian tube?

A

auditory tube, passage from back of throat to middle ear which functions to equalize pressure on both sides of eardrum, is the cause of ear popping

150
Q

Summary from sound to hearing?

A

sound waves -> auricle -> external auditory canal -> tympanic membrane -> malleus, incus, stapes -> oval window -> perilymph -> endolymph -> basilar membrane
-> auditory hair cells -> tectorial membrane -> neurotransmitters stimulate bipolar auditory neurons -> brain -> perception

151
Q

Sound vibrations are first conveyed as air and turn into what?

A

bone and then liquid

152
Q

What is the organ of Corti?

A

basilar membrane, hair cells, tectorial membrane it is the primary site where auditory stimuli are detected

153
Q

What distinguishes pitch?

A

regions of the basilar membrane vibrate, stimulating auditory neurons

basilar membrane is thick (detect high pitch) near the oval window and thin near apex of cochlea (low pitch)

154
Q

What distinguishes loudness of sound?

A

amplitude of vibrations

larger vibrations cause more frequent action potentials

155
Q

If a sensory neuron leading from the ear to the brain fires an action potential more rapidly, how will the brain perceive this change?

A

this would indicate increase in volume of sound

156
Q

If the auditory nerve is severed, can sound still be detected by conductance through bone?

A

no

157
Q

If the bones of the middle ear are unable to move, would this impair the detection of sound by conductance through bone?

A

they are not involved directly in detecting sound, bone conductance can still stimulate the cochlea and result in hearing

158
Q

What are semicircular canals filled with?

A

three tubes filled with endolymph

159
Q

What do semicircular canals detect?

A

rotational acceleration of the head

160
Q

What innervates semicircular canals and where do they send info?

A

afferent neurons

send balance info to pons, cerebellum

161
Q

What do the utricle and saccule do?

A

located in inner ear and monitor static equilibrium and linear acceleration

162
Q

Where is the image formed in the eye?

A

retina

163
Q

What acts as a lens for the eye?

A

cornea, light is refracted as is passes through

refractory index higher than air

164
Q

What is the white of the eye?

A

sclera

165
Q

What is beneath the sclera?

A

choroid- absorbs excess light

166
Q

What is contained in the anterior chamber (just inside cornea)?

A

aqueous humor

167
Q

What is at the back of the anterior chamber?

A
  • iris (colored) with an opening called the pupil

- muscles in iris regulate pupil diameter

168
Q

What is behind the iris?

A
  • posterior chamber contain aqueous humor

- back of posterior chamber is the lens (fine tunes light to focus on retina)

169
Q

What varies the curvature of the lens?

A

ciliary muscle

170
Q

What does light pass through to get from the lens to the retina?

A

vitreous chamber which contains vitreous humor (thick)

171
Q

What does the retina contain to detect light?

A

rods and cones (photoreceptors)

172
Q

What do rods and cones synapse with?

A

nerve cells called bipolar cells (one axon and one dendrite)

173
Q

What do bipolar cells synapse with after rods and cones?

A

ganglion cells whose axons comprise the optic nerve to the occipital lobe

174
Q

What is the optic disk?

A

blind spot (contains no photoreceptors), point on retina where axons from ganglion converge to form the optic nerve

175
Q

What is macula?

A

part of the retina that contains fovea centralis (focal point) which contains only cones for extreme visual acuity

176
Q

What do special pigment proteins contained in rods and cones do when light hits them?

A

changes tertiary structure while absorbing light

177
Q

Retinal?

A

in rods and cones derived from vitamin A

178
Q

In the dark, what is retinal like?

A

several trans double bonds and one cis

179
Q

When retinal absorbs a photon of light what happens?

A

it is converted to all trans form which triggers a series of reactions

180
Q

What is responsible for night vision?

A

rods- more sensitive to dim light and more concentrated in the periphery of the retina

181
Q

What are cones responsible for?

A

require light and are responsible for color vision and high acuity vision, more concentrated in fovea

182
Q

What physical difference allows cones to absorb different colors?

A

each type of cone makes a particular pigment protein which is specialized to change conformation when light of the appropriate frequency strikes it

183
Q

Emmetropia?

A

normal vision

184
Q

Myopia?

A

nearsightedness, too much refraction at the lens or an abnormally long eyeball results in focal length that is too short

185
Q

Hyperopia?

A

farsightedness, too little refraction at the lens or an abnormally short eyeball results in focal length that is too long

186
Q

What can fix myopia?

A

concave (diverging) lens

187
Q

What can fix hyperopia?

A

convex (converging) lens

188
Q

Presbyopia?

A

inability to focus (accommodate), results from loss of flexibility of the lens, aging

189
Q

What is the signal of the endocrine system?

A

hormones, can work over days, not always rapid like action potentials

190
Q

Hormone?

A

molecule which is secreted into the bloodstream by an endocrine gland (ductless), and which has its effects upon distant target cells possessing the appropriate receptor

191
Q

Hormone receptor?

A

polypeptide that possesses a ligand specific binding site

192
Q

What determines tissue specificity of hormone action?

A

whether the cells of a tissue have the appropriate receptor

193
Q

Autocrine?

A

modifies the activity of the cell which secreted them (T cell secretes interlukin 2 which stimulates increased activity of the same T cell)

194
Q

Two classes of hormones?

A

hydrophilic- peptides, amino acid derivatives, bind to cell surface

hydrophobic- steroid hormones, bind to cell interior

195
Q

Peptide hormones?

A

synthesized in rough ER and modified in Golgi, stored in vesicles until needed, released by exocytosis, cannot cross membrane because hydrophilic

196
Q

How do peptide hormones communicate with the interior of the cell?

A

second messenger cascade

197
Q

Are peptide hormones rapid?

A

yes because they modify the activity of existing enzymes in cytoplasm, duration is brief

198
Q

Two subgroups of peptide hormones?

A

polypeptide

amino acid derivatives

199
Q

Example of polypeptide hormone?

A

insulin

200
Q

Example of amino acid derivative hormone?

A

tyrosine

201
Q

Where are steroid hormones synthesized?

A

from cholesterol in the smooth ER

202
Q

How do steroid hormones reach the bloodstream once made in the cell?

A

they diffuse right through the membrane in the stream because of hydrophobicity

203
Q

How do steroid hormones travel through the bloodstream?

A

they stick to plasma proteins like albumin

204
Q

What holds steroid hormones bound to plasma proteins?

A

hydrophobic interactions

205
Q

How do steroid hormones exert its effects on the target cell?

A

diffusing through the plasma membrane to bind with a receptor in the cytoplasm

206
Q

What do steroid hormones do after binding to the its receptor in the cell?

A

the complex enters the nucleus to regulate transcription to change amount of proteins in the cell, effects are slow (days to weeks)

207
Q

T/F

Regulation of Endocrine system is preplanned.

A

False

hormone levels rise and fall depending on needs

208
Q

Tropic hormones?

A

hormones that regulate hormones

209
Q

Most feedback in the endocrine system is _____.

A

negative

210
Q

What portion of the brain controls much of the endocrine system?

A

Hypothalamus, releases tropic hormones to regulate, it controls the anterior pituitary

211
Q

Hypothalamic pituitary(hypophysial) portal system?

A

mini circulatory system for efficient transport of hypothalamic factors straight to the anterior pituitary

212
Q

What are portal systems?

A

two capillary beds in sequence, allowing for direct communication of nearby structures

-ex. hypothalamic pituitary, hepatic

213
Q

Another name for anterior pituitary? posterior?

A

adenohypophysis

neurohypophysis

214
Q

What is the posterior pituitary composed of?

A

axons which descend from the hypothalamus, these neurons are an example of neuroendocrine cells (neurons which secrete hormones into the bloodstream)

215
Q

Are hormones in the posterior pituitary made by axon termini or somas in the hypothalamus?

A

somas and are transported down the axons

216
Q

Is epinephrine secreted by a duct into the bloodstream?

A

No, endocrine hormones are not secreted through ducts

217
Q

Would an inhibitor of protein synthesis block the action of thyroid hormone?

A

yes because it binds to a receptor that regulates transcription

218
Q

Would the production of ATP by mitochondria be stimulated or repressed by thyroid hormone?

A

stimulated because thyroid hormone stimulates basal metabolic rate throughout the body consuming more ATP so mitochondria would have to make more ATP

219
Q

Would thyroid hormone affect isolated mitochondria directly?

A

no, it affects mitochondria indirectly

220
Q

What type of hormone does the Hypothalamus secrete?

A

releasing and inhibiting factors (peptides)

221
Q

What is the target of hormones secreted by hypothalamus?

A
  • anterior pituitary

- modifies activity

222
Q

What hormones does the Anterior Pituitary secrete?

A
  • Growth (GH, peptide)
  • Prolactin (peptide)
  • Thyroid Stimulating Hormone (TSH, peptide, tropic)
  • Adrenocortiocotropic (ACTH, peptide)
  • Luteinizing (LH, peptide, gonadotropic)
  • Follicle Stimulating (FSH, peptide)
223
Q

What is the target of Growth Hormone (GH)?

A
  • increase bone and muscle growth

- increase cell turnover rate

224
Q

What is the target of Prolactin?

A
  • mammary gland

- milk production

225
Q

What is the target of TSH?

A
  • thyroid

- increase synthesis and release of thyroid hormone

226
Q

What is the target of ACTH?

A

increase growth and secretory activity of adrenal cortex

227
Q

What is the target of LH?

A
  • ovary/ovulation

- testes/testosterone synthesis

228
Q

What is the target of FSH?

A
  • ovary/follicle development

- testes/spermatogenesis

229
Q

What is secreted by the posterior pituitary?

A
  • Antidiuretic Hormone (ADH, vasopressin, peptide)

- Oxytocin (peptide)

230
Q

What is the target of ADH?

A
  • kidney/water retention
  • increases blood volume
  • increases blood pressure
231
Q

What is the target of Oxytocin?

A
  • breast/ milk letdown

- uterus/ contraction

232
Q

What is secreted by the Thyroid gland?

A
  • Thyroid hormone (TH, thyroxine, modified amino acid)

- Calcitonin (thyroid C cells, peptide)

233
Q

What is the target of TH?

A
  • Child: necessary for physical and mental development

- Adult: increase metabolic rate and temp

234
Q

What is the target of Calcitonin?

A
  • bone, kidney

- lowers serum (Ca 2+)

235
Q

What is secreted by the parathyroids?

A

Parathyroid Hormone (PTH, peptide)

236
Q

What is the target of PTH?

A
  • bone, kidney, small intestine

- raises serum (Ca 2+)

237
Q

What is secreted by the Thymus?

A

Thymosin (children only, peptide)

238
Q

What is the target of Thymosin?

A

T cell development during childhood

239
Q

What is secreted by the Adrenal Medulla?

A

Epinephrine (modified amino acid)

240
Q

What is the target of Epinephrine?

A

sympathetic stress response (rapid)

241
Q

What is secreted by the Adrenal Cortex?

A
  • Cortisol (glucocorticoid, steroid)
  • Aldosterone (mineralcorticoid, steroid)
  • Sex steroids
242
Q

What is the target of Cortisol?

A
  • longer term stress response
  • increase blood glucose
  • increase protein catabolism
  • decrease inflammation and immunity
243
Q

What is the target of Aldosterone?

A
  • kidney

- increase Na+ reabsorption to increase blood pressure

244
Q

What is secreted by the Endocrine Pancreas (islets of Langerhans)?

A
  • Insulin (beta cells secrete, peptide, absent or ineffective in diabetes mellitus)
  • Glucagon (alpha cells secrete, peptide)
  • Somatostatin (SS, sigma cell secrete, peptide)
245
Q

What is the target of Insulin?

A
  • Decrease blood glucose

- increase glycogen and fat storage

246
Q

What is the target of Glucagon?

A
  • increase blood glucose

- decrease glycogen and fat storage

247
Q

What is the target of Somatostatin?

A

inhibits many digestive processes

248
Q

What is secreted by testes?

A

testosterone (steroid)

249
Q

What is the target of testosterone?

A
  • male characteristics

- spermatogenesis

250
Q

What is secreted by ovaries/placenta?

A
  • Estrogen (steroid)

- Progesterone (steroid)

251
Q

What is the target of Estrogen?

A
  • female characteristics

- endometrial growth

252
Q

What is the target of Progesterone?

A
  • endometrial secretion

- pregnancy

253
Q

What hormone is secreted by the Heart?

A

atrial natriuretic factor (ANF, peptide)

254
Q

What is the target of ANF?

A
  • kidney

- increase urination to decrease blood pressure

255
Q

What hormone is secreted by the Kidneys?

A

erythropoietin (peptide)

256
Q

What is the target of Erythropoietin?

A
  • bone marrow

- increase red blood cell synthesis

257
Q

In humans, vision is due to stimulation of what type of receptor?

A

electromagnetic

258
Q

What is the correct order of events during synaptic transmission?

A
  1. action potential reaches end of axon
  2. voltage gated calcium channels open
  3. Neurotransmitter binds to ligand gated ion channel
  4. Neurotransmitter in synaptic cleft is degraded
259
Q

Which of the following hormones has its receptor located on the cell surface?

Renin
TH
Oxytocin
Aldosterone

A

Oxytocin

-any hormone that is a peptide

260
Q

What could hyperparathyroidism cause?

A
  1. enhance breakdown of bone by osteoclasts and release of Ca 2+ into the bloodstream (weak bones, Increased serum calcium levels)
  2. enhance reabsorption of calcium in nephrons of kidneys
  3. enhance absorption of calcium in small intestine
261
Q

Which would alter gene expression by regulating DNA transcription?

Glucagon
Insulin
Pepsin
Cortisol

A

Cortisol

-anything that is a steroid hormone

262
Q

High blood pressure can be rectified by what?

A
  • decrease in Aldosterone

- ACE (angiostein converting enzyme) inhibitors

263
Q

In which region of the brain is the hippocampus located?

A

temporal lobe

264
Q

What are three normal calcium functions in the cell?

A
  1. memory acquisition and storage
  2. release of synaptic vesicles from the cytoskeleton at the axon terminal
  3. release from the sarcoplasmic reticulum to aid in muscle contraction

MCAT TPR Biology (7 decks)

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