Brainscape's Knowledge GenomeTM

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


See full index

Physio > Hormone Cell Interaction > Flashcards

Hormone Cell Interaction Flashcards

1
Q

Endocrine hormones

A

. Released by glands into circulation

. Affects distant target cells

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

Neurohormones

A

. Secreted by neurons into circulation

. Influences distant target cells

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

Paracrine

A

. Secreted by cells into ECF affecting neighboring cells of different type

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

Cytokines

A

. Peptides secreted by cells into ECF that function as autocrines, paracrines or endocrine hormones

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

Classes of hormones

A

. Peptides/proteins
. Steroids
. AA derivatives

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

Peptides/proteins hormone class

A

. Synthesized as prohormone or pre-pro-hormone
. Stored in membrane bound secretory vesicles in cytoplasm
. Released by Ca-dependent exocytosis
. Circulate in blood as unbound form: have short half-life times
. Do not cross cell membranes
. Interact w/ membrane receptors
. Second messengers required for signal transduction

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

Steroid hormone class

A

. Lipid soluble
. Readily released as they are synthesized
. Not stored
. Require plasmatic protein transporters
. Interact w/ intracellular receptors to influence protein synthesis

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

Amino acid derivative hormone class

A

. Thyroid hormones: stored in follicle as part of thyroglobulin, cross cell membranes, transported in blood bound to proteins, have intracellular receptors
. Catecholamines: stored in membrane-bound vesicles, don’t cross membranes, transported in blood free or loosely assoc. w/ proteins

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

Competitive antagonist effect on potency and efficacy

A

. Antagonist dec. potency but does not change efficacy

. Degree of shift depends on affinity and receptor coupling of competing chemical

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

Magnitude of biological responses mainly depends on ____

A

Number of hormone-receptor complexes
. Formation of complexes is non-covalent and follows 1st order molecular kinetics
. Affinity constant = [HR]/[H] x [R]

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

Is the hormone considered in [H] free or bound to protein?

A

free

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

Hormone secretion

A

. Most hormones released in short pulsatile bursts
. To inc. secretion the bursts happen more frequently
. Frequency of bursts and oscillations of frequency depends on external factors (light-dark, sleep-wake)

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

Metabolic clearance

A

. Catabolic clearance rate (MCR) of hormone represents the volume of plasma cleared of hormone per unit time
. Occurs primarily via removal and metabolism in liver and kidneys
. Some hormones removed or metabolized after uptake by target cell
. Half-life of hormone is inversely related

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

Hormone half life

A

. Ranges from 2-3 minutes to 6/5 days
. Polypeptide and protein hormones that freely dissolve in plasma H2O generally have a shorter half-life than steroid hormones that are largely bound to transport proteins

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

Affinity in hormones

A

Receptors must have high affinity bc free hormone is in low concentrations

Affinity = [HR]/[H] x [R]

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

Equilibrium dissociation

A

. Concentration of hormone at specified equilibrium conditions that is required for binding to 50% of the receptor sites
. Lower the Kd concentration, the higher the affinity

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

Concentration of receptors

A

. Receptor concentration can be unregulated or downregulated
. They are continuously synthesized and degraded
. Modulation by primary hormone is homologous regulation (low conc. Of primary hormone inc. receptor conc.)
. Modulation by non-primary hormone is heterologous (different hormone inc. another hormone’s receptors in target cell)
. Biological response of target cell is directly proportional to number of occupied receptor sites

18
Q

Exception condition when Kd and ED50 are not equivalent

A

. When the max biological response of target cell occurs despite all receptor sites NOT bring occupies
. Kd is then lower than the ED50

19
Q

T/F endocrine feedback loops are proportional

A

T

. Rate of secretion varies btw 0 and maximal rather than on or off

20
Q

Essential component of feedback loop

A

. Stimulus
. Sensor
. Setpoint: required conc. Of hormone
. Integrating center: comparison of actual and required conc. Of controlled variable occurs (and where error signal develops)
. Effector: mechanism that returns level of controlled variable toward desired setpoint

21
Q

Positive feedback loop

A

. Non-regulatory and unstable
. Deviation from setpoint will be inc. by effector
. Example: parturition: oxytocin stimulates and enhances labor contractions, as baby moves down pressure receptors w/in cervix send signals to produce more oxytocin
. When stimulus to receptor ends, the hormone production stops

22
Q

Permissiveness

A

. Hormone A must be present for full expression of hormone B’s effect

23
Q

Counter regulatory hormones

A

. Different hormones have opposing effects on the same variable

24
Q

Trophic

A

. Hormones stimulate the secretion of another hormone and usually the growth of that endocrine gland

25
Q

Syngery

A

. Occurs when 2 hormones produce the Sam biological response
. Simultaneously produce a response that is greater than the sum of the individual responses to each hormone

26
Q

Protein hormones are secreted by ____

A

Ca-dependent exocytosis

. Secretory vesicles fuse w/ plasma membrane, vesicle opens releasing contents into extracellular space

27
Q

Peptide hormone transport

A

. Hydrophilic and soluble in plasma

. Do not require transport proteins except somatomedins (IGF)

28
Q

Peptide metabolism

A

. Remain in bloodstream only for a short time after secretion
. Receptor-mediated degradation is 1 pathway for metabolism of some peptide hormones
. For most peptide/protein hormones, kidney and liver are major sites of hormonal degradation
. Polypeptides and lower molecular weight protein hormones are more readily filtered by kidney and excreted
. Polypeptide hormones have a shorter half-life (min) than larger protein hormones (hours)

29
Q

Classes of steroids

A

. Estrogens
. Androgens (testosterone)
. Glucocorticoids (cortisol)
. Mineralcorticoids (aldosterone)

30
Q

Steroids are produced in what locations?

A

. Adrenal cortex
. Testes
. Ovary
. Placenta

31
Q

Steroid synthesis

A

. LDL Major source of cholesterol
. Binding of LDL to membrane receptor causes internalization of LDL-receptor complex via endocytosis
. Cholesterol is then stored in esterified form
. Upon ACTH or LTH stimulation, free cholesterol is released from lipid droplet by cholesterol esterase (activated by PKA)
. Free cholesterol transported to mitochondria by steroidogenic acute regulatory (StAR) protein and internalized by peripheral-type benzo receptor (PBR)
. Cholesterol modified by cytochrome P450s and other enzymes to produce pregnolone (common steroid precursor)

32
Q

Rate limiting step in all steroid synthesis

A

. Conversion of cholesterol to pregnenolone in mitochondria

33
Q

Rate of steroid secretion is controlled by the rate of ____

A

Steroid synthesis

34
Q

Transport of steroids in plasma

A

. Lipophilic (little dissolved in plasma, most bound to transport proteins)
. Hormone bound to protein in equilibrium w/ free hormone in plasma
. Dissociation of hormone from carrier protein is slow process and hormone remains attached to specific carrier as blood transverse capillary beds
. Dissociation of hormone from non-specific protein carriers does occur in capillary beds
. Binding and unwinding keeps free hormone conc. Constant

35
Q

T/F in presence of intact regulatory systems, alterations in hormone-binding proteins do not chronically alter endocrine status bc the free conc. Of hormone is adjusted back to setpoint

A

T

36
Q

Steroid mechanism of action

A

. Receptor in cell nucleus (can be in cytoplasm)
. Binding of hormone to receptor activated DNA-binding domain
. Hormone receptor complex binds to specific sequences of DNA to modify transcription
. Biological effect takes longer compared to response via second messenger production

37
Q

Steroid metabolism

A

. Have long half-life
. Metabolized in series of reduction reactions that primarily take place in liver
. Metabolites conjugated w/ sulfates or glucouronides and secreted into bile or plasma. For excretion via GI or kidneys

38
Q

Enzymes that control formation of eicosanoids

A

. Thromboxane
. Prostacyclines
. Prostaglandins
. Leukotrienes

39
Q

Prostaglandins

A

. Generated from COX enzyme
. Modulate many biological activities
. Type synthesized in a particular tissue is determined by specific complement of enzymes w/in cell
. Interact w/ receptors on local target cells in paracrine or autocrine fashion
. Very short half-life (minutes)

40
Q

Leukotrienes

A

. Generated from arachidonic acid via 5-lipoxygenase
. Classified as LTB4, LTC4, LTD4, LTE4, and LTF4
. Interact w/ receptors on local target cells in paracrine or autocrine way
. LTB4 is important in inflammatory response
. LTC4, D4, and E4 are potent constrictors of smooth mm. In trachea, lung, and arterioles
. Stimulate mucous secretion
. Play role in asthma, gout, IBD, RA, psoriasis, adult respiratory distresss yndrome, and allergies

41
Q

Thromboxanes

A

. Role in hemostasis
. thromboxane A2 is most important
. Platelets convert PGH2 into TA2 which aggregates platelets, induce platelet aggregation, and induce vasoconstriction

42
Q

Prostacyclins

A

. Endothelial cells can convert PGH2 to prostacyclin I2 (PGI2) which inhibits platelet aggregation and dilates blood vessels

Physio (62 decks)

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