Endocrine Physiology

Question 1

What feature allows a target cell to respond to a specific hormone?
A. Its position in the body
B. Electrical membrane charge
C. Presence of specific receptors
D. Quantity of ATP in the cell

Answer 1

Presence of specific receptors

Question 2

Where does the hormone-receptor complex bind in order to initiate gene transcription?
A. Cytoplasm
B. mRNA
C. Hormone response element on DNA
D. Ribosome

Answer 2

Hormone response element on DNA

Question 3

What is the final outcome after mRNA is translated during hormone action?
A. Activation of another hormone
B. Breakdown of the nucleus
C. Synthesis of a specific protein
D. Formation of lipid membranes

Answer 3

Synthesis of a specific protein

Question 4

Which hormone binds to DNA at an estrogen response element?
A. Insulin
B. Estrogen
C. Growth hormone
D. Oxytocin

Answer 4

Estrogen

Question 5

What directly influences the plasma concentration of a free, biologically active hormone?
A. The number of synapses in target tissues
B. The number of mitochondria in endocrine cells
C. Secretion rate, plasma protein binding, activation, and removal rate
D. How long the receptor remains bound to the hormone

Answer 5

a.Secretion rate
b.plasma protein binding
c.activation
d.removal rate

Question 6

What internal system drives rhythmic fluctuations in hormone secretion over time?
A. Enzyme concentration
B. Blood pressure
C. Biological clocks
D. Muscle contraction

Answer 6

Biological clocks

Question 7

What environmental cue helps synchronize circadian hormone rhythms?
A. Noise levels
B. Social interaction
C. Light-dark cycle
D. Oxygen availability

Answer 7

Light dark cycle (Zeitgebers)

Question 8

What hormone is secreted in advance of waking to prepare the body for activity?
A. Oxytocin
B. Cortisol
C. Melatonin
D. Prolactin

Answer 8

Cortisol

Question 9

What is the main function of a tropic hormone?
A. Inhibiting immune responses
B. Stimulating nonendocrine tissues
C. Regulating secretion of another hormone
D. Decreasing receptor sensitivity

Answer 9

Regulating secretion of another hormone

Question 10

What distinguishes a trophic hormone from a tropic hormone?
A. Trophic hormones stimulate cell growth, while tropic hormones regulate other glands
B. Trophic hormones decrease target gland size
C. Tropic hormones are weaker in effect
D. Trophic and tropic mean the same thing

Answer 10

Trophic hormones stimulate cell growth, while tropic hormones regulate other glands

Question 11

What term describes the hormonal interaction where one hormone enhances the responsiveness of a cell to another hormone?
A. Antagonism
B. Synergism
C. Feedback inhibition
D. Permissiveness

Answer 11

Permissiveness

Question 12

What type of hormone interaction results in a greater combined effect than the sum of individual actions?
A. Synergism
B. Antagonism
C. Permissiveness
D. Neutralism

Answer 12

Synergism

Question 13

13. What interaction occurs when progesterone inhibits estrogen’s effects on the uterus during pregnancy?
    A. Permissiveness
    B. Synergism
    C. Antagonism
    D. Entrainment

Answer 13

Antagonism

Question 14

What condition results when a tumor secretes excess hormone despite regulatory feedback?
A. Hyposecretion
B. Hormone resistance
C. Hypersecretion
D. Feedback suppression

Answer 14

Hypersecretion

Question 15

What is a known cause of hormone hyposecretion?
A. Chronic overuse
B. Genetic defects
C. High glucose intake
D. Excess enzymatic activation

Answer 15

Genetic defects

Question 16

The hormone secreted by the pineal gland that is the most critical for regulating circadian rhythms

Answer 16

Melatonin

Question 17

Melatonin synthesis in mammals is most directly regulated by:

Answer 17

Retinohypothalamic input to the SCN

Question 18

The suprachiasmatic nucleus (SCN) acts as:

Answer 18

central circadian peacemaker

Question 19

In mammals, which signaling pathway primarily drives melatonin secretion in darkness?

Answer 19

cAMP-mediated adrenergic signaling

Question 20

MSH secretion from the pars intermedia is involved in:

Answer 20

Melanin dispersion in melanophores

Question 21

The relationship between the pineal gland and the pituitary

Answer 21

The pineal modulates pituitary output via circadian influence

Question 22

The main route through which the SCN communicates photic input to the pineal gland

Answer 22

Multisynaptic sympathetic pathway via the superior cervical ganglion

Question 23

The pineal gland in birds and reptiles retains photoreceptive capabilities due to:

Answer 23

Persistence of pinealopsin

Question 24

Why is MSH functionally more prominent in non-mammalian vertebrates?

Answer 24

Because pigmentation control is critical for camouflage and thermoregulation

Question 25

The photoreceptive pineal organ seen in some non-mammalian vertebrates is evolutionarily homologous to:

Answer 25

The mammalian retina

Question 26

The pituitary is most directly involved in regulating skin pigmentation in ectothermic vertebrates

Answer 26

Pars intermedia

Question 27

What happens to melatonin levels in response to nocturnal light exposure?

Answer 27

They are suppressed

Question 28

Seasonal breeders like hamsters exhibit what kind of adaptation in pineal function

Answer 28

Strong melatonin regulation of gonadal axis

Question 29

The evolutionary trend is observed in the pineal gland from fish to mammals

Answer 29

Shift from direct to indirect photoreception

Question 30

The key evolutionary function of the pineal gland

Answer 30

Integration of photoperiodic cues for seasonal behavior

Question 31

Organ that secretes ecdysone in the circulatory system

Answer 31

Prothoracic glands

Question 32

What concentration level of ecdysone and juvenile hormone triggers larval traits?

Answer 32

High edysone, high juvenile hormone

Question 33

It is the final step of ecdysis that regulates cuticle tanning and wing plasticity

Answer 33

Bursicon

Question 34

Why are primed tissues controlled its rate of function?

Answer 34

Proper larval physiology and timing of metamorphosis

Question 35

When corpora allata were removed early, the larva became:

Answer 35

Premature tiny adult

Question 36

Which enzymes break down the activity of juvenile hormone during pre-final molt?

Answer 36

JH esterase

Question 37

What are the main effects of eclosion hormone in insect development?

Answer 37

a. abdominal movements loosen old cuticle b. peristalsis moves the old cuticle off c. thoracic blood surge, wing expansion movements

Question 38

What is the antagonistic effect of phytoecdysteroids in insect development?

Answer 38

mimics ecdysone that disrupts insect development and reproduction

Question 39

What type of receptor do pheromones bind to ?

Answer 39

G-protein coupled receptors (GPCRs)

Question 40

Premature metamorphosis is regulated by what mechanism of plant defenses

Answer 40

Precocenes (block JH) - destruction of corpora allata cells - no formation of JH

Question 41

It controls hormonal output

Answer 41

anterior pituitary gland

Question 42

Organism that triggers reproduction when melatonin concentration is high

Answer 42

Short day breeders (sheep and deer)

Question 43

It entrain the circadian clock

Answer 43

melanopsin

Question 44

Shifting of one time zones from another leads to:

Answer 44

a. internal rhythm is desynchronized (racing horse) b. brain (three days adjustment period) c. gut and liver (seven days)

Question 45

Pars intermedia is absent to:

Answer 45

birds and cetaceans (whales and dolphins)

Question 46

Regulates the skin coloration via storage granules (melanin)

Answer 46

à - MSH

Question 47

Vasopressin are believed to evolve____ from early vertebrates

Answer 47

arginine vasotocin

Question 48

It lowers the aldosterone levels as it modifies blood flow in the lower limbs

Answer 48

mesotocin (non-mammmalian homolog)

Question 49

What is the role of pituicytes?

Answer 49

direct extension of the hypothalamus

Question 50

Which triggers the release of vasopressin?

Answer 50

high plasma osmolarity