Brainscape's Knowledge GenomeTM

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


See full index

Physiological concepts > Wk8 - endocrinology > Flashcards

Wk8 - endocrinology Flashcards

1
Q

The NS has specificity built into it by the close anatomical relationship between nerve cells and their targets. How does the endocrine system contrast to this?

A

Specificity of a hormone depends on the receptor(s) for that hormone; specificity is built into the receiving end (target organ).

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

State the 3 basic steps of a hormone exerting its effect.

A
  1. Hormone travels through blood, and binds to a receptor at target organ(s).
  2. Binding initiates series of reactions within cell.
  3. Reactions culminate in hormones ‘final effect’.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Detail some basic points which contribute to the COMPLEXITY of the endocrine system. (6)

A
  1. Single endocrine gland produces multiple hormones.
  2. Single hormone may be secreted by more then one gland.
  3. Single hormone may have more then one target tissue (therefor more then one effect).
  4. Single target tissue may be influenced by multiple hormones.
  5. Some chemicals can be both a hormone and NT.
  6. Some hormones are exclusively hormonal, others can perform non-endocrine functions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why does the endocrine system act slowly? (3)

A
  1. Transport depends on BF.
  2. Mechanism of action at target cell is complex.
  3. Hormones remain bound to receptors, therefor prolonging their effectiveness.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What’re the 6 roles of the endocrine system?

A
  1. Regulating organic metabolism (water/ electrolyte balance).
  2. Inducing adaptive changes (cope with stress).
  3. Promoting smooth, sequential growth/ development.
  4. Control reproduction.
  5. Regulate hematopoiesis.
  6. Controlling and integrating circulation with digestion/ absorption (with ANS).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What’re the 3 classes of hormones? (not based on solubility)

A
  1. Peptides/ proteins.
  2. Steroids.
  3. Amines.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

In what ways does the chemical properties of hormones effect the way that they operate? (4)

A
  1. Synthesis.
  2. Secretion.
  3. Transport in blood.
  4. Mechanism of action at target cell.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Summarise the polarity and therefor solubility of the following hormone:
Steroid hormones.

A

Non-polar, lipophillic and hydrophobic. This means they are lipid soluble, NOT water soluble.

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

Summarise the polarity and therefor solubility of the following hormone:
Peptide/ protein hormones.

A

Polar, therefor hydrophillic and lipophobic. This means they are water soluble, NOT lipid soluble.

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

Summarise the polarity and therefor solubility of the following hormone:
Thyroid hormones.

A

Non-polar, lipophillic and hydrophobic. This means they are lipid soluble, NOT water soluble.

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

Summarise the polarity and therefor solubility of the following hormone:
Catecholamines (amines).

A

Polar, therefor hydrophillic and lipophobic. This means they are water soluble, NOT lipid soluble.

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

State polar (P) or non-polar (NP) for the following:

a. ) Steroids.
b. ) Catecholamines.
c. ) Thyroid hormones.
d. ) Peptide/ protein hormones.

A

a. ) Steroids - NP.
b. ) Catecholamines - P.
c. ) Thyroid hormones - NP.
d. ) Peptide/ protein hormones - P.

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

Briefly, how are peptide hormones synthesized?

A
  1. Synthesized as large precursor proteins (in ER).
  2. In travelling to golgi apparatus, preprohormones are pruned.
  3. Golgi apparatus concentrates hormone into packages (vesicles).
  4. Vesicles released via exocytosis.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the precursor to steroid hormones?

A

Cholesterol; which comes majoritively from LDL.

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

What controls the rate of steroid hormone secretion; and why?

A

Rate of steroid hormone secretion is controlled by steroid hormone synthesis - as the body has no mechanisms for storage of steroids. This means as soon as they are synthesized, they immediately diffuse through the cell membrane and into the blood.

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

Briefly explain the process of steroid hormone synthesis. (general answer)

A

Steroid hormones are synthesized from cholesterol, which is found majoritively from LDL. Synthesis of steroid hormones requires modification by certain enzymes which are only found within specific tissues.

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

What occurs to steroid hormones as they travel in the bloodstream and around the body?

A

Steroid hormones undergo further interconversions to become more potent or different hormones.

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

How are amine hormones produced?

A

Most individual amine hormones have unique synthesis and secretory pathways - however they do share features in common:

  1. Derived from AA tyrosine.
  2. None of enzymes directly involved with amine hormone synthesis are located within cell organelles.
  3. All amine hormones are stored until they are secreted.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Percentage wise, how do lipid-soluble hormones travel within the blood?

A

99% - bound.

1% - free.

20
Q

Percentage wise, how do water-soluble hormones travel within the blood?

A

50% - loosely bound.

50% - free.

21
Q

Based on solubility, how can hormones be categorised?

A
  1. Lipophobic peptides and catecholamines.
  2. Lipophillic steroids.
  3. Lipophillic thyoid hormones.
22
Q

What’re the 3 general means by which hormones elicit biological responses? (note: include solubility in answer)

A
  1. Alter cell membrane permeability (few hydrophillic).
  2. Activate secondary messengers (most hydrophillic).
  3. Activating specific genes causing new proteins to be formed (all hydrophobic).
23
Q

What’re the 4 types of receptors on the surface of the cell membrane which lipophobic hormones may bind to?

A
  1. Ligand-gated channels.
  2. Receptor enzymes.
  3. G protein-coupled receptors.
  4. Integrin receptors.
24
Q

Explain the basic steps involved with a hydrophillic hormone binding to a receptor.

A

The hydrophillic hormone binds to receptor, then one of 3 things can happen:

  1. Activation of membrane bound enzyme - this enzyme then activates secondary messenger.
  2. Activation of membrane bound G-protein - which can either activate a secondary messenger or modulate an ion channel.
  3. Activation of receptor enzyme - which can either initiate secondary messenger or activate cellular proteins.
25
Q

t/f: the activated protein kinases and proteins (due to binding of lipophobic hormone) vary between different target cells.

A

True.

26
Q

Why is it that responses to hormones (lipophobic) vary from tissue to tissue, when they mostly all act through the same secondary messenger (cAMP)?

A

Because which protein kinases/ proteins are activated due to the presence of cAMP will vary between tissues!

27
Q

Explain the basic steps involved with a lipophillic hormone bringing about a response in it’s target cell.

A
  1. Lipophillic hormone diffuses directly through plasma and nuclear membranes of target cell; binding with its specific receptor in the nucleus.
  2. Hormone-receptor complex binds to specific segment of DNA (“hormone response element”).
  3. DNA binding activates specific genes, producing mRNA which leaves the nucleus.
  4. mRNA directs synthesis of proteins in cytoplasm.
  5. New proteins (structural or enzymatic) accomplish physiological response to hormone.
28
Q

Despite stark contrast in MOA, state 3 characteristics to both lipohillic/phobic hormones.

A
  1. Actions of hormones are AMPLIFIED.
  2. Hormones REGULATE rates of existing reactions (instead of producing new ones).
  3. Hormone action is SLOW and PROLONGED.
29
Q

Detail factors effecting hormone availability to receptors. (4)

A
  1. Rate of secretion.
  2. Rate of metabolic activation at target cell.
  3. Rate of removal (via metabolic inactivation/ excretion).
  4. Extent of hormone binding to plasma proteins.
30
Q

Are hormones secreted at a constant rate?

A

NO - hormone effect is proportional to concentration in blood; so rate of secretion must be catered to needs of the body (homeostatic control).

31
Q

As hormones are not secreted at a constant rate they must be controlled by certain mechanisms. List these. (4)

A
  1. Negative feedback control.
  2. Neuro-endocrine reflexes.
  3. Diurnal or circadian rhythms.
  4. Hormonal metabolism and excretion.
32
Q

Provide a basic explanation for the following mechanism:

Negative feedback loop.

A

The response counteracts the stimulus; shutting off the response loop.

33
Q

Provide an example of the workings of the following mechanism:
Negative feedback loop.

A

PTH:

  1. Low plasma [Ca+2] sensed by parathyroid cell.
  2. Parathyroid cell releases PTH.
  3. PTH travels in blood, to reach bone and kidney (target organs).
  4. Increased bone and kidney resorption of Ca+2.
  5. Increased plasma [Ca+2], negating the original stimulus.
34
Q

Provide a basic explanation for the following mechanism:

Neuro-endocrine reflexes.

A

These control reflexes with both neural and endocrine components. Basically, a neural stimulus acts on an endocrine integrating centre (via ‘neurohormones’) causing the endocrine gland to release hormones.

35
Q

Provide a basic explanation for the following mechanism:

Circadian rhythms.

A

Circadian rhythms are the 24hr cycle of physiological processes in living beings; hormonal secretion varies with this. These are caused by endogenous oscillators within the brain and entrained by external factors (such as light/ dark cycles). Negative feedback mechanisms operate to maintain whatever set point is established by circadian rhythms.

36
Q

Provide an example of the following mechanism:

Circadian rhythms.

A

Cortisol concentrations rise during the day and fall during the night.

37
Q

Provide a basic explanation for the following mechanism:

Hormonal metabolism + excretion. (extended answer)

A

All hormones eventually metabolised (liver), and excreted (in urine). The time post secretion which a hormone is inactivated depends upon its chemistry:

  1. Hydrophillic - in blood for mins/ hours before inactivated (enzymes).
  2. Hydrophobic - binding of hydrophobic hormones to plasma proteins renders them less vulnerabe to inactivation; so they’re removed more slowly. When they are inactivated they become more soluble in water, dissociate from their plasma protein carriers and can be eliminated in the urine. Steroids take hours, whereas thyroid hormones may take up to a week.
38
Q

Binding of hydrophobic hormones to plasma proteins renders them less vulnerable to inactivation; so they’re removed more slowly. How long do these hormones take for inactivation exactly?

A

Steroids take hours, whereas thyroid hormones may take up to a week.

39
Q

Explain the hormonal interaction of synergism.

A

Synergism occurs when the combined effect of >1 types of hormones is greater then the sum of the individual effects of such hormones.
(basically: because hormones work to achieve same goal the effect is greater; GANGBANG)

40
Q

Provide an example of synergism in hormones.

A

Adrenaline and glucagon both working to increase blood glucose levels together.

41
Q

Explain the hormonal interaction of permissiveness.

A

Permissiveness occurs when one hormone cannot exert it’s full effect unless another hormone is present.
(basically: cuck)

42
Q

Provide an example of permissiveness in hormones.

A

Maturation of reproductive system requires FSH, LH and steroid hormones. However, even if these hormones are present maturation will be delayed unless thyroid hormone is present. These hormones require thyroid hormone to be able to cause maturation of the reproductive system, however thyroid hormone cannot stimulate maturation itself whatsoever (thyroid hormone is kind of acting like a cofactor).

43
Q

What is the correct term for hormone deficiency?

A

Hyposecretion.

44
Q

What is the correct term for hormone’s being in excess?

A

Hypersecretion.

45
Q

Generally speaking, why do endocrine disorders occur?

A

Any of the following:

  1. Hyposecretion.
  2. Hypersecretion.
  3. Decreased responsiveness of target tissue.
  4. Abnormal hormone removal rates.
46
Q

What is the most common cause of endocrine dysfunction?

A

Hyposecretion.

Physiological concepts (12 decks)

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