Final Exam

Question 1

Describe how Claude Bernard’s notion of “internal milieu” and Walter Cannon’s notion of “homeostasis” may relate to a notion of “stress”.

Answer 1

Claude Bernard’s “internal milieu” means “world within the body”. Physiology acts to buffer the internal world from the external world. Walter Cannon’s notion of homeostasis suggests that physiology acts to maintain balance/constancy in internal milieu.

Question 2

Why is the stress response considered to be “non specific”?

Answer 2

The general stress response is adaptive for dealing with a wide range of physical stressors.

Question 3

What is the Sympathetic Nervous System (SNS) in terms of: a) a key historical proponent, b) their key function, c) their effector hormone(s), d) their speed of onset and duration of action.

Answer 3

The SNS was proposed by Walter Cannon and functions to support a fight or flight response. Its effector hormone is epinephrine and norepinephrine, the onset is rapid with a short duration of action.

Question 4

What is the Hypothalamic Pituitary Adrenal axis (HPA) in terms of: a) a key historical proponent, b) their key function, c) their effector hormone(s), d) their speed of onset and duration of action.

Answer 4

The HPA axis was suggested by Hans Selye and functions as a “General Adaptation Syndrome”. Its effector hormone is cortisol and there is a slow onset with a long duration.

Question 5

Compare and contrast the SNS and the parasympathetic nervous system (PSNS) in terms of the location of the cell bodies, location of the axon terminals, and relative length of the axons of the preganglionic and postganglionic neurons.

In the SNS preganglionic neurons:

Answer 5

In the SNS preganglionic neurons:
-cell bodies in thoracic and lumbar & spinal cord
-short axon length
-axon terminal in ganglia close to spinal cord

Question 6

Compare and contrast the SNS and the parasympathetic nervous system (PSNS) in terms of the location of the cell bodies, location of the axon terminals, and relative length of the axons of the preganglionic and postganglionic neurons.

In the SNS postganglionic neurons:

Answer 6

In the SNS postganglionic neurons:
-cell bodies in ganglia close to spinal cord
-long axon length
-axon terminal near target organ

Question 7

Compare and contrast the SNS and the parasympathetic nervous system (PSNS) in terms of the location of the cell bodies, location of the axon terminals, and relative length of the axons of the preganglionic and postganglionic neurons.

In the PSNS preganglionic neuron:

Answer 7

In the PSNS preganglionic neuron:
-cell bodies located in brain-stem and sacral spinal cord
-long axon length
-axon terminals near target organ

Question 8

Compare and contrast the SNS and the parasympathetic nervous system (PSNS) in terms of the location of the cell bodies, location of the axon terminals, and relative length of the axons of the preganglionic and postganglionic neurons.

In the PSNS postganglionic neuron:

Answer 8

In the PSNS postganglionic neuron:
-cell bodies near target organ
-short axon length
-axon terminals near target organ

Question 9

What neurotransmitters are released by preganglionic and postganglionic neurons of the PSNS and SNS?

Answer 9

All of the preganglionic and postganglionic neurons from the PSNS and SNS release acetylcholine, except for the postganglionic neuron of the SNS which releases norepinephrine.

Question 10

What are two different types of cholinergic receptors?

Answer 10

The two types of cholinergic receptors are nicotinic and muscarinic.

Question 11

What are four different types of adrenergic receptors?

Answer 11

The types of adrenergic receptors are Alpha-1, Alpha-2, Beta-1, and Beta-2.

Question 12

Which type of cholinergic receptor is located on the dendrites and cell body of postganglionic neurons?

Answer 12

Nicotinic cholinergic receptors are located on the dendrites and cell bodies of postganglionic neurons.

Question 13

Which type of cholinergic receptor is located on PSNS target organs?

Answer 13

Muscarinic Cholinergic receptors are located on PSNS target organs.

Question 14

Where are adrenergic receptors located?

Answer 14

Adrenergic receptors are located on the target organs of the SNS.

Question 15

Describe how the effects of the SNS on the following target organs may be beneficial during times of emergency (“fight or flight”): eye, heart, arterioles, bronchial muscle, piloerection, G.I. tract.

Answer 15

Eye: The pupils dilate with let in more light
Heart: Heart rate increases which increases oxygen delivery to muscles
Arterioles: Shunt blood from skin and GI system to skeletal muscles
Bronchial Muscle: Relax, allows us to breathe deeper
Piloerection: Hair stands up which increases thermal-insulation

Question 16

What is the dual effect of the SNS and the PSNS on male erection and ejaculation?

Answer 16

Activation of the PSNS leads to erection and activation of the SNS leads to ejaculation.

Question 17

What are chromaffin cells?

Answer 17

Chromaffin cells are endocrine cells that mainly secrete adrenaline inside the adrenal medulla.

Question 18

Why is Primatene mist effective in treating asthma?

Answer 18

Primatene Mist has an active ingredient of epinephrine and acts as an effective bronchodilator.

Question 19

Why is a beta-2 selective agonist (e.g. Albuterol) better than Primatene mist for treating asthma?

Answer 19

Albuterol would produce less side effects because it only engages with beta-2 receptors which are found in the lungs, as opposed to epinephrine which can interact with receptors in the heart to also increase heart rate.

Question 20

What does the James-Lange theory of emotion say about the relationship between the physiological stress response and conscious awareness of “stress”?

Answer 20

The James-Lange theory of emotion suggests that we “feel” stressed because of the physiological changes in our body, therefore our physiological response to stress can increase our “emotional stress response”.

Question 21

What were the 3 hallmark symptoms of the General Adaptation Syndrome described by Hans Selye?

Answer 21

1. Adrenal hypertrophy, 2. Shrinkage of the thymus “gland, 3. Ulcers

Question 22

How does chronic stress lead to adrenal hypertrophy?

Answer 22

Chronic activation of the HPA axis leads to increased CRH and ACTH secretion which are trophic factors for the adrenal cortex.

Question 23

How does chronic stress lead to thymic involution?

Answer 23

Thymus is an organ where T-lymphocytes mature. With chronic stress, there is a higher than normal level of cortisol which can kill T cells.

Question 24

What are the two types of receptors for cortisol that are members of the nuclear hormone receptor encoding gene family?

Answer 24

The two subtypes of receptors for cortisol are MR and glucocorticoid receptor (GR).

Question 25

Compare the two cortisol receptors types in terms of distribution in the brain, mechanism of action and relative affinity for cortisol.

Answer 25

MR: high affinity for cortisol, very concentrated in the hippocampus, and is important for the survival of granule neurons GR: lower affinity for cortisol, widely distributed throughout the body

Question 26

What is the relative time course and magnitude of glucocorticoid negative feedback effects?

Answer 26

There is very fast feedback, glucocorticoids can rapidly attenuate the HPA axis response to stress. It is too fast to require changes in gene transcription.

Question 27

What is the relative time course and magnitude of glucocorticoid negative feedback effects?

Answer 27

There is very fast feedback, glucocorticoids can rapidly attenuate the HPA axis response to stress. It is too fast to require changes in gene transcription.

Question 28

Describe the circadian influence on HPA axis activity.

Answer 28

HPA axis activity is lowest during behavioral inactivity (night time for humans) and has a peak right at the time of awakening in anticipation not a reaction.

Question 29

What is Cushing’s syndrome?

Answer 29

Cushing’s syndrome is the result of excessive chronic glucocorticoid levels. It causes “moon face”.

Question 30

Distinguish between a "trait marker" and a "state marker" for a psychiatric disorder.

Answer 30

-Trait marker: (genetics) life-long “symptom” of someone predisposed to a particular disorder -State marker: symptom that is present only during the expression of the disorder (ex: levels of hormones in the blood)

Question 31

What are 2 signs of HPA axis dysregulation present in a large number of depressed individuals?

Answer 31

1. Hypercortisolemia - elevated basal cortisol. 2. Impaired DST result.

Question 32

What is dexamethasone?

Answer 32

A potent synthetic glucocorticoid receptor agonist.

Question 33

What is the dexamethasone suppression test (DST)?

Answer 33

The subject takes 1 mg dexamethasone tablet at bedtime and then the following morning and afternoon blood samples are taken to measure cortisol levels.

Question 34

What is the "normal" response to a DST, and what is the hormonal mechanism for that response?

Answer 34

The normal response to DST is a suppressed basal cortisol level due to increased negative feedback.

Question 35

What is the abnormal response to a DST present in many depressed individuals?

Answer 35

The abnormal response in many depressed individuals is only partial or no suppression of cortisol levels.

Question 36

What is a "free running" rhythm?

Answer 36

Expression of an endogenous rhythm in the absence of entraining cues.

Question 37

What is entrainment?

Answer 37

Environmental periodic cue that synchronizes endogenous rhythm.

Question 38

What were 2 key results pertaining to circadian rhythms illustrated by Michael Siffre living for two months in a cave?

Answer 38

1. Humans might have a free running endogenous period greater than 24 hours. 2. There is a desynchronization of endogenous rhythms.

Question 39

What are 6 characteristics of endogenous "biological clocks"?

Answer 39

1. Inheritance: a number of genes involved 2. Temperature Independence: the endogenous rhythm is largely resistant to temperature fluctuations 3. Resistance to Chemical Intervention: few drugs affect it 4. Limits of Entrainment: phase - no limits in phase shift (only can shift 1 hr. per day) period - can only be lengthened or shortened a little bit 5. Independence of behavioral Feedback: endogenous rhythm continues along even if behavioral responses are prevented 6. Ubiquity of clocks: in all organisms

Question 40

What is Familial Advanced Sleep-Phase Syndrome?

Answer 40

sleep onset, melatonin and temperature rhythms phase advanced and spontaneous awakening phase advanced, may have short endogenous clock due to gene mutations.

Question 41

What are 2 drugs that can increase the circadian period in humans?

Answer 41

Lithium & Alcohol

Question 42

What are 4 pieces of evidence that the suprachiasmatic nucleus (SCN) of the hypothalamus contains circadian pacemaker cells?

Answer 42

1. Lesions of the SCN: abolish expression of endogenous rhythms 2. SCN afferents: direct input form retina 3. SCN neuron activity in culture dish: individual neurons show rhythmic activity pattern 4. “Transplant” SCN cells: transplant restores biological rhythm

Question 43

Describe how the experiment by Ralph, Foster, Davis and Menaker, reported in Science magazine in 1990, was instrumental in establishing that in hamsters the SCN contained circadian pacemaker cells.

Answer 43

Their experiment showed that a lesion of the SCN abolished circadian rhythm, transplant of SCN cell restored a circadian rhythm, and that the restored rhythm had the period of the donor cells.

Question 44

Where is melatonin produced?

Answer 44

Melatonin is produced in the pineal gland.

Question 45

What neurotransmitter is melatonin chemically related to?

Answer 45

Melatonin is chemically related to the monoamine neurotransmitter serotonin.

Question 46

Can melatonin cross the blood brain barrier?

Answer 46

Melatonin can cross the blood brain barrier.

Question 47

Describe the general life-time secretion pattern of melatonin in humans.

Answer 47

Melatonin is highest during childhood, starts to decline around puberty, and is low in old age.

Question 48

What may be the relationship between melatonin and puberty onset?

Answer 48

The decline of melatonin around the time of puberty onset triggers the removal of brakes on GnRH which causes growth and puberty.

Question 49

What is the definition of a hormone? What aspect of this definition distinguishes a hormone from a neurotransmitter?

Answer 49

A hormone is an intercellular chemical signal that produces an effect on a target cell, it differentiates from a neurotransmitter because it travels via the bloodstream as opposed to diffusion.

Question 50

What are some advantages and disadvantages of endocrine versus paracrine intercellular signaling in the body?

Answer 50

There is more efficiency with hormonal signaling because signals can reach more of the body quicker, it is also important during development when not all neural connections have been formed.

Question 51

What is the group of hormones that we have discussed this semester that are not systemic hormones, and why are they not systemic?

Answer 51

Hypothalamic Releasing Hormones are not systemic hormones because they are not secreted in large enough quantities to reach the entire body.

Question 52

What is the group of hormones that we have discussed this semester that are not systemic hormones, and why are they not systemic?

Answer 52

Hypothalamic Releasing Hormones are not systemic hormones because they are not secreted in large enough quantities to reach the entire body.

Question 53

Which neurohormones are effector hormones? Are they produced in magnocellular or parvocellular neurons? Where are the cell bodies and axon terminals located of these neurons?

Answer 53

Effector hormones are produced in large “magnocellular neurons” and the cell body is located in the PVN, with axon terminals in the posterior pituitary gland. Examples of neurohormones that are effector hormones are: vasopressin and oxytocin.

Question 54

Which neurohormones are releasing hormones? Are they produced in magnocellular or parvocellular neurons? Where are the cell bodies and axon terminals located of these neurons?

Answer 54

Releasing Hormones are produced in small “parvocellular neurons” and the cell body is located in the hypothalamic nuclei with axon terminals in the median eminence. Examples of neurohormones that are releasing hormones are: GnRH, dopamine, and thyrotropin releasing hormone.

Question 55

What are 2 examples of a first order neuroendocrine arrangement?

Answer 55

Two examples of a first order neuroendocrine arrangement are oxytocin and vasopressin.

Question 56

What are 5 examples of a second order neuroendocrine arrangement?

Answer 56

Five examples of a second order neuroendocrine arrangement are 1. CRH → stimulates Beta endorphin 2. GnRH → stimulates FSH 3. DA → inhibits prolactin 4. Somatostatin → inhibits GH 5. GHRH → stimulates GH

Question 57

What are 5 examples of a third order neuroendocrine arrangement?

Answer 57

Five examples of a third order neuroendocrine arrangement are: 1. CRH → stimulates ACTH → stimulates cortisol 2. TRH → stimulates TSH → stimulates T3 & T4 3. GnRH → stimulates LH → stimulates progesterone 4. GnRH → stimulates FSH → stimulates estradiol 5. GnRH → stimulates LH → stimulates Testosterone

Question 58

What is a prohormone?

Answer 58

A prohormone is a precursor molecule that may have some hormonal function of its own or can be converted into another hormone.

Question 59

What causes the compensatory hypertrophy after removal of 1 testis?

Answer 59

An initial drop in testosterone from the removal of one testis will cause a decrease in the negative feedback on GnRH, LH, and FSH. This causes their secretion to increase which means the remaining testis will be exposed to high levels and grow bigger.

Question 60

Why does long-term treatment with a GnRH receptor agonist produce “chemical castration”?

Answer 60

The long-term treatments would cause a shut down of LH, FSH, and testosterone because GnRH is normally secreted in a pulsatile fashion rather than tonically. If gonadotrophs are exposed to continuous levels of GnRH they will start to downregulate their GnRH receptors so they are no longer responsive to GnRH which causes chemical castration.

Question 61

Compare the water solubility, ability to pass through cell membranes and ability to penetrate the blood brain barrier of proteins and peptides How do these differences affect whether these hormones can be stored in vesicles and/or interact with intracellular receptors?

Answer 61

Proteins and peptide hormones are water soluble and cannot pass through either cell membranes or the blood brain barrier. Protein and peptide hormones also are stored in vesicles and can only interact with receptors on the surface of a cell.

Question 62

Compare the water solubility, ability to pass through cell membranes and ability to penetrate the blood brain barrier of steroids and thyroid hormones. How do these differences affect whether these hormones can be stored in vesicles and/or interact with intracellular receptors?

Answer 62

Steroids and thyroid hormones are not water soluble, but can pass through cell membranes as well as the blood brain barrier. Steroid and thyroid hormones cannot be stored in vesicles, and rather made “on demand”. They also have intracellular receptors.

Question 63

What are 3 primary processes that contribute to a considerable lag time in the onset of steroid hormone actions at target tissues after stimulation of CRH neurons or GnRH neurons in the hypothalamus?

Answer 63

The 3 primary processes that contribute to a time lag in the onset of steroid actions are the release of the hormone into the blood (3-5 min), the process of the hormone reaching its target cell and modulating gene transcription (5-15 min), and the time difference between the onset of a change in gene transcription and a change in cell function (greater than 1 hour).

Question 64

What determines whether an embryonic gonad develops into a testis or an ovary?

Answer 64

The SRY region on the Y chromosome produces the testis determination factor (TDF) that will determine whether the bipotential germinline ridge develops into an ovary or a testis.

Question 65

What determines whether the Wolfian duct or the Mullerian duct continues to develop/differentiate?

Answer 65

All fetuses have both the Mullerian duct and the Wolffian duct. If the Wolfian duct is exposed to testosterone it will continue to develop into the vas deferens and seminal vesicles, if not it will regress. If the Mullerian duct is exposed to mullerian inhibitory hormone (MIH), it will regress. The lack of presence of MIH allowed the Mullerian duct to develop into fallopian tubes & uterus.

Question 66

What determines whether the genital skin differentiates into a vagina or a penis?

Answer 66

The exposure to DHT develops genital skin into a penis and scrotum, the lack of exposure develops a clitoris and vagina.

Question 67

Describe the human menstrual cycle in terms of gonadotropin secretion, ovarian events, estrogen and progesterone secretion, and changes in uterine lining for the follicular phase, the luteal phase and menstruation.

Answer 67

During the follicular phase (days 6-12) there is development of follicles and a mature egg. During this phase there is a steady increase in estrogen, and progesterone remains low. The LH surge occurs around day 13. During the luteal phase (days 15-21), the uterus prepares to receive a fertilized egg. During this phase, estrogen remains at high levels and progesterone increases to high levels. During the menstrual phase, there is a sloughing off of uterine lining which causes bleeding. During this phase, there is very low progesterone & estrogen. A decrease in negative feedback leads to increases in LH & FSH to trigger a new cycle.

Question 68

What are the mechanisms of action by which oral contraceptives prevent pregnancy?

Answer 68

The presence of progesterone in oral contraceptives prevents pregnancy by blocking an LH surge from occurring which is necessary to rupture the Graffian follicle. The mechanism of this process is due to maintaining high negative feedback on LH secretion. Progestin only pills also “lock” the cycle into the luteal phase thereby preventing follicle maturation and ovulation.

Question 69

What are the mechanisms of action by which oral contraceptives prevent pregnancy?

Answer 69

The presence of progesterone in oral contraceptives prevents pregnancy by blocking an LH surge from occurring which is necessary to rupture the Graffian follicle. The mechanism of this process is due to maintaining high negative feedback on LH secretion. Progestin only pills also “lock” the cycle into the luteal phase thereby preventing follicle maturation and ovulation.

Question 70

What is a sexually dimorphic difference between males and females in the neurohormonal control of GnRH secretion?

Answer 70

A sexually dimorphic difference between males and females in the neurohormonal control of GnRH secretion is the presence of absence of a functional surge center. Only females have functional surge centers because they were not exposed to testosterone.

Question 71

What role does the enzyme, aromatase, have in organizational effects of testosterone on the rodent brain?

Answer 71

Aromatase is an enzyme that normally converts testosterone to estradiol in the male rat brain. This conversion is required during the critical period to inhibit the development of a functional surge center.

Question 72

47. Describe briefly the following social effects on rodent reproductive cycles: Lee-Boot effect

Answer 72

The Lee-Boot effect: female mice housed together had lengthened ovarian “inactive” periods.

Question 73

47. Describe briefly the following social effects on rodent reproductive cycles: Whitten effect

Answer 73

The Whitten effect: large numbers of female mice housed together in absence of males show extreme interruptions in estrous cycles.

Question 74

47. Describe briefly the following social effects on rodent reproductive cycles: Bruce effect

Answer 74

Bruce effect: Placing pregnant females with strange males resulted in the termination of their pregnancy and subsequent mating with the new male.

Question 75

47. Describe briefly the following social effects on rodent reproductive cycles: Vandenbergh effect.

Answer 75

Vandenbergh effect: females housed with adult males attain puberty sooner

Question 76

What is meant by a permissive effect of a hormone?

Answer 76

A permissive effect of a hormone is when the presence of a hormone is necessary, but not sufficient on its own to produce a particular effect.

Question 77

How does light suppress melatonin secretion?

Answer 77

The retinal ganglion cells that sense light and project directly to the SCN. These intrinsic photosensitive retinal ganglion cells can be activated by blue light and during the dark period can shut down melatonin secretion.

Question 78

What is melanopsin?

Answer 78

Melanopsin is the protein that works with a subset of retinal ganglion cells to detect blue light.

Question 79

What are some symptoms that indicate that a hamster has become refractory to short-day photoperiod?

Answer 79

After 20-30 weeks of short daya photoperiod, hamsters no longer respond to short-day photoperiod.

Question 80

What effect does melatonin have on negative feedback sensitivity of GnRH neurons to gonadal steroids?

Answer 80

Melatonin increases sensitivity of GnRH neurons to negative feedback from gonadal steroids.

Question 81

Is SAD more common in men or women?

Answer 81

More common in women

Question 82

At what time of day is exposure to artificial bright light most effective in treating SAD?

Answer 82

Exposure to light is most effective in treating SAD during the morning.

Question 83

What is some circumstantial evidence for gonadal steroids to have an activational effect on mood in women?

Answer 83

A large proportion of women note changes in mood during time of menstruation, shortly after child birth, around the period of menopause, of using oral contraceptives.

Question 84

What are three hormonal treatment strategies that have been tried to alleviate perimenstrual syndrome, and how effective has each one been?

Answer 84

1. Blocking luteal phase effects by treating with a progesterone antagonist had no benefits. 2. Preventing the entire cycle with GnRH agonist was effective in redcing PMS sympotoms 3. Progesterone and thyroid hormone treatment had posivitve effects

Question 85

What is some circumstantial evidence for gonadal steroids to have an activational effect on aggression?

Answer 85

There are more violent crimes committed by men than women, chemical castration decreases violent acts, male children engage in more rough play, etc.

Question 86

Can norepinephrine be both a neurotransmitter and a hormone?

Answer 86

Norepinephrine is both a hormone, produced by the adrenal glands, and a neurotransmitter

Question 87

What are some potential pathological consequences of chronic stress?

Answer 87

Ulcers, high blood pressure, fatigue, fat redistribution, decreased libido, altered function

Question 88

What are some physical stressors?

Answer 88

starvation, temperature extremes, dehydration, hemorrhage, injury, etc.

Question 89

What are some physiological symptoms of stress?

Answer 89

Sleep problems, fatigue, indigestion, muscle aches, rapid heartbeat.

Question 90

What are 5 kinds of Epi receptors?

Answer 90

Alpha1, Alpha2, Beta1, Beta2, Beta3

Question 91

What are 3 kinds of NE receptors?

Answer 91

alpha1, alpha2, beta1

Question 92

Describe how the Cahill et al., 1994 study supports a role of beta-adrenergic receptor activation in enhanced memory for emotional events.

Answer 92

In this study, a group was given propranolol which blocks adrenergic receptors. This drug selectively impaired memory for the emotional story. This suggests that to remember emotional events the activation of beta-adrenergic receptors is required.

Question 93

Discuss how the Cahill et al. 1994 study may or may not directly support a role of stress-induced hormone secretion to regulate memory for emotional events.

Answer 93

It suggests that when we are stressed and don't activate adrenergic receptors we have an impaired ability to fully recount emotional events.

Question 94

What may be an adaptive function for cytokine effects on HPA axis activity?

Answer 94

The HPA axis may serve as a negative feedback modulator for the immune system— it helps keep the immune system "in check".

Question 95

What is the relationship between the activational and organizational effects of hormones on the nervous system?

Answer 95

During development hormones can organize or determine the structure/interconnections of the nervous system that will permanently alter how the nervous system responds to activational effects of hormones throughout life.

Question 96

Testosterone can be a prohormone for two different hormones. What are the different hormones? What are the enzymes involved? What are the classes of receptors that these two hormones interact with?

Answer 96

Testosterone is a prohormone for both estrogen and DHT. Aromatase converts testosterone into estrogen and alpha-5 reductase converts testosterone to DHT.

Question 97

What is some evidence for sexual dimorphism in human brain anatomy?

Answer 97

Corpus Callosum is larger and anterior commissure is larger in women suggesting that women have more communication between their 2 hemispheres.