Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology > Introduction to Endocrine Physiology > Flashcards

Introduction to Endocrine Physiology Flashcards

1
Q

The classical definition of a hormone defines one as a chemical messenger from an endocrine gland into the bloodstream and acts on a distant tissue. How does this differ from the modern definition of hormone?

A

The modern definition defines a hormone as any substance released from a cell that acts on another cell, near or far, regardless of the singularity or ubiquity of the source and regardless of the means of conveyance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define autocrine action. Example?

A

Secreting cell and target cell are the same

Ex: prostaglandins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define paracrine action. Example?

A

A hormone is secreted into extracellular space and targets cells in the surrounding area; diffuse short distances

Ex: Somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define endocrine action. Example?

A

A hormone is secreted by specialized endocrine glands/cells directly into the blood; travel long distances

Ex: thyroxine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define neural action. Example?

A

A product of a neuron that is secreted into synaptic spaces; travel short distances

Ex: Acetylcholine & Norepinephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define neuro-endocrine action. Example?

A

A product of a neuron that is released into the blood

Ex: Oxytocin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What six hormones does the anterior pituitary secrete?

A

Follicle-stimulating hormone (FSH)

Leutinizing hormone (LH)

Adrenocorticotropic hormone (ACTH)

Thyroid-stimulating hormone (TSH)

Prolactin (PRL)

Growth hormone (GH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Somatostatin is secreted from what two locations?

A

Hypothalamus

Pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What two receptors are responsible for modulating the secretion of antidiuretic hormone (ADH)? What do they respond to?

A

Stretch receptors signal ADH secretion at low atrial pressures (hypovolemia)

Osmoreceptors signal ADH secretion when ECF osmolarity increases (dehydration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What five hormones function to increase plasma glucose?

A

Growth hormone

Norepinephrine

Epinephrine

Cortisol

Glucagon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When is norepinephrine considered a hormone and when is it considered a neurotransmitter?

A

Hormone: when secreted by the adrenal medulla

Neurotransmitter: when released by sympathetic postganglionic neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the four types of hormones? Which ones are hydrophilic and which ones are hydrophobic?

A

Peptide and protein hormones (Hydrophilic)

Amino acid derivatives (Hydrophilic)

Steroid hormones (Hydrophobic)

Fatty Acid derivatives (Hydrophobic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where are peptide hormones produced? Where are their receptors typically located?

A

Produced by the pituitary gland as releasing factors (except insulin)

Act on receptors on cell surfaces of peripheral endocrine glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the “pre” and “pro” segments of a preprohormone? What are their functions?

A

Pre: signaling peptide sequence; bind to signal recognition complex to pause translation until docked on the ER

Pro: Intervening peptide; holds the final product in the proper orientation; keeps hormone inactive until it is cleaved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the “C-Peptide”? What is its clinical significance?

A

“Pro” segment of pro-insulin

Unknown physiological function

Marker of insulin levels (used to diagnose diabetes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How are peptide hormones stored and transported?

A

Secretory vescicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which hormone type requires use of a secondary messenger? Why?

A

Peptide/protein hormones

Receptors are located the cell surface; cannot freely diffuse through the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

True or false: protein/peptide hormones can be administered orally.

A

False. They will degrade in the stomach.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What hormones are derivatives of tyrosine?

A

Thyroid hormones

Catecholamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where are catecholamines synthesized within the cell (2)? What tissues synthesize them?

A

Synthesized in the cytosol in:

Adrenal medulla

Post-ganglionic fibers of the sympathetic nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In the synthesis of catecholamines, what reaction does tyrosine hydroxylase catalyze?

A

Tyrosine –> DOPA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In the synthesis of catecholamines, what reaction does DOPA decarboxylase catalyze?

A

DOPA –> Dopamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In the synthesis of catecholamines, what reaction does Dopamine β-hydroxylase catalyze?

A

Dopamine –> Norepinephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

In the synthesis of catecholamines, what reaction does PNMT catalyze?

A

Norepinephrine –> Epinephrine

25
Q

What is the rate-limiting step of steroid hormone synthesis? Where does it occur in the cell? What enzyme catalyzes this step?

A

Cholesterol –> Pregnenolone

occurs in the mitochondria

side-chain cleavage enzyme (desmolase)

26
Q

What are the three major types of steroid hormones?

A

Corticosteroids

Sex hormones

Vitamin D

27
Q

What are the two subtypes of corticosteroids? Examples?

A

Glucocorticoids (ex: cortisol)

Mineralcorticoids (ex: aldosterone)

28
Q

Where are corticosteroids synthesized?

A

Adrenal cortex

29
Q

How are steroid hormones transported?

A

Synthesized and immediately diffuses through the cell membrane

Bound to albumin or a specific binding globulin for transport through the blood

30
Q

Where are receptors for steroid hormones located?

A

Intracellularly

31
Q

True or false: steroid hormones can be administered orally.

A

True

32
Q

Aside from peptide and protein hormones, what specific hormones also have cell surface receptors? (2)

A

Triiodothyronine (T3)

Thyroxine (T4)

33
Q

CYP11A1 is what enzyme? What reaction does it catalyze?

A

Side-chain cleavage enzyme (desmolase)

catalyzes the first reaction in steroidogenesis:

cholesterol –> pregnenolone

34
Q

CYP17 is what enzyme? What reactions does it catalyze? (3)

A

17 alpha-hydroxylase

Pregnenolone –> 17α-OH pregnenolone

Progesterone –> 17α-OH progesterone

cleavage of C17,20 bonds to yield DHEA or androstenedione

35
Q

CYP21A2 is what enzyme?

A

21-hydroxylase

36
Q

CYP19 is what enzyme? What reaction does it catalyze?

A

Aromatase

Testosterone –> estradiol

37
Q

Steroid hormones are synthesized from the enzymatic modification of what molecule?

A

cyclopentanoperhydrophenanthrene (CHL)

38
Q

How are steroid hormones transported?

A

Immediately released from the cell after synthesis

Circulates protein-bound in blood

Interacts with cytoplasmic or nuclear receptors (activate DNA for protein synthesis)

39
Q

The physiologic effects of hormones depend on?

A

Concentration in blood

40
Q

The concentration of hormone as seen by target cells is determined by what three factors? Which is the most highly regulated (*)?

A

*Rate of production

Rate of delivery

Rate of degradation and elimination

41
Q

How is the rate of production and secretion of hormones mediated? (3)

A

Neuroendocrine reflexes

Circadian rhythms

Positive and negative feedback

42
Q

What is the main determinant of the rate of delivery of hormones?

A

Blood flow to a target organ

High blood flow delivers more hormone

43
Q

True or false: rate of degradation (liver) and elimination (kidney) is normally meant to fluctuate.

A

False: any changes in rate of degradation and/or elimination are bad

44
Q

What are the three types of stimuli that control rate of production of hormones?

A

Humoral: pertaining to ECF, blood, or lymph

Neural: direct stimulation of glands by the nervous system

Hormonal: hormone is released in response to another

45
Q

T4 levels are _______ in the winter and _______ in the summer.

A

Increased in the winter

Decreased in the summer

46
Q

What time of the day does cortisol concentration peak?

A

At the beginning of the light cycle

47
Q

What is the pacemaker for most circadian rhythms? Where is it located?

A

Suprachiasmatic nucleus

located in the hypothalamus, superior to the optic chiasma

48
Q

What are some examples of positive feedback?

A

Opening of Na+ channels during depolarization

Ovulation (progesterone)

Birth (oxytocin)

49
Q

What is the HPA axis?

A

Hypothalamic-pituitary-adrenal axis

Negative feedback loop between the hypothalamus, anterior pituitary, and the adrenal cortex that controls the secretion of CRH, ACTH, and cortisol

50
Q

How do binding proteins affect half-life of hormones?

A

Prevent hormones from being degraded, metabolized, or bound to a receptor

51
Q

Which thyroid hormone (T3 and T4) has a greater affinity for its binding protein and which has a greater affinity for its receptor? What are their half-lives?

A

T4: binding protein (6-7 day half-life)

T3: receptor (18 hour half-life)

52
Q

What is half-life?

A

The amount of time required to reduce the amount of a hormone to 1/2 of the original amount

53
Q

What are the three characteristics of receptors?

A

Specificity: receptor can bind a given hormone (+ agonists & antagonists) but not others

Affinity: how well the receptor binds to the hormone (affected by receptor conformation)

Density: changing the number of receptors on the cell surface

54
Q

Define permissiveness. Example?

A

One hormone must be present in adequate amounts for the full effect of another hormone

Ex: thyroid hormone increases epinephrine receptors

55
Q

Define synergism. Example?

A

The combined effect of several hormones is greater than the sum of their separate effects

Ex: counterregulatory hormones on blood glucose

56
Q

Define antagonism. Example?

A

One hormone causes the loss of another hormone’s receptors

Ex: Progesterone causes loss of estrogen receptors on uterine smooth muscle (decreases uterine contractions)

57
Q

Hormone-producing cells in tumors usually do not respond to negative feedback except for _____

A

tumors of the pituitary gland

58
Q

What is the difference between functional and nonfunctional endocrine tumors?

A

Nonfunctional: do not secrete hormone (~25% of endocrine tumors)

Functional: secrete hormones and are named after hormones they secrete (ex: insulinomas secrete insulin)

Physiology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions