Brainscape's Knowledge GenomeTM

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


See full index

Systems: Endocrine AB > Introduction to the Endocrine System > Flashcards

Introduction to the Endocrine System Flashcards

1
Q

Define the endocrine system

A

A system that integrates and controls organ function via the secretion of chemicals (hormones) from cells, tissues or glands which are then carried in the blood to target organs, distal from the site of hormone synthesis, where they influence the activity of that target organ.

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

How can response times within the endocrine system vary?

A

Response may be fast (within seconds) e.g. increased heart rate in response to adrenalin, or slow (over days) e.g. increased protein synthesis in response to growth hormone

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

What should endocrine hormones not be confused with?

A
  • Paracrine
  • Autocrine
  • Exocrine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are paracrine chemicals?

A

Act local to the site of synthesis, do not travel to distant sites e.g. histamine

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

What are autocrine chemicals?

A

Act on/in the same cell that synthesises the hormone e.g. cytokines

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

What are exocrine chemicals?

A

Released from exocrine glands via ducts to the external environment including the GI tract e.g. saliva, sweat, bile

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

What 2 systems communicate and control all body functions?

A
  • Endocrine system

- Nervous system

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

How do hormones travel in endocrine communication?

A

Hormones travel in the blood to their target organs/tissues

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

How do tissues detect hormones in the endocrine system?

A

Tissues detect hormones through the presence of specific receptors for that chemical on/in the cells. No receptor = no response

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

Describe neural communication.

A

Neurotransmitters released from presynaptic neurons travel across the synaptic cleft to the postsynaptic cell to influence its activity

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

What are neurotransmitters?

A

Neurotransmitter is the chemical released by the neuron but, in contrast to hormones, acts locally within the synaptic cleft

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

How is further control achieved within neural communication?

A

The endocrine and nervous systems co-operate intimately to provide further control, particularly for long-term phenomena, e.g. growth.

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

Describe neuroendocrine communication.

A

Endocrine and nervous systems combine. Nerves release hormones which enter blood and travel to their target cells e.g. hypothalamic – posterior pituitary axis

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

Why is the response to any one hormone highly specific?

A

Although all hormones circulate throughout the body in the blood, the response to any one hormone is highly specific because only target cells have receptors for the hormone.

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

What effect does insulin have on skeletal muscle/adipose tissue?

A

Increase glucose uptake

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

What effect does insulin have on the liver?

A
  • Increased glycogenesis

- Decreased gluconeogenesis

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

What is the function of hormones and neurotransmitters?

A

The function of hormones (and NTs) is to bring about changes in the activity of their target cells and tissues, (increase/decrease a particular activity).

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

What are the sites of principal endocrine glands?

A
  • Hypothalamus
  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal glands
  • Gonads
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 6 features of an endocrine hormone?

A
  1. Produced by a cell or group of cells
  2. Secreted from those cells into the blood
  3. Transported via the blood to distant targets
  4. Exert their effects at very low concentrations (act in the range 10-9 -10-12 M)
  5. Act by binding to receptors on target tissues
  6. Have their action terminated, often via negative feedback loops.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the classifications of endocrine hormones?

A
  • Peptide (or protein) hormones
  • Steroid hormones
  • Amine hormones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are peptide/protein hormones composed of?

A

Chains of amino acids

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

What are steroid hormones derived from?

A

Cholesterol

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

What are amine hormones derived from?

A

One of two amino acids (tryptophan or tyrosine)

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

What happens once a peptide hormone is synthesised?

A

Synthesised in advance of need then stored in vesicles until required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Give 3 examples of peptide hormones.

A
  • TRH
  • FSH
  • Insulin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In peptide hormone synthesis, what do the ribosomes produce?

A

Preprohormones which are large and inactive proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What doe preprohormones contain?

A

Preprohormones contain one or more copies of the active hormone in their amino acid sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happen to preprohormones in peptide hormone synthesis?

A

Preprohormones are cleaved into smaller units in the RER to leave smaller but still inactive proteins called prohormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What happen to prohormones in protein hormone synthesis?

A

Prohormones are packaged into vesicles in the golgi apparatus, along with proteolytic enzymes which break the prohormone down into active hormone and other fragments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where are hormones and other fragments stored in peptide hormone synthesis?

A

Hormones and fragments are stored in vesicles in the endocrine cells until release is triggered then all vesicle contents are released into plasma (co-secretion).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Give an example of a clinical use for measuring inactive fragments in plasma?

A

C-peptide in diabetes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is C-peptide?

A

C-peptide is the inactive fragment cleaved from the insulin prohormone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Why are levels of C-peptide in the plasma or urine often measured in diabetes?

A

Levels of C-peptide in plasma or urine are often measured to indicate endogenous insulin production from the pancreas (produced in equal amounts). However, because insulin is metabolised faster, levels of C-peptide are typically about 5x higher than endogenous insulin.

34
Q

Why can peptide hormones be transported via the blood easily?

A

Water soluble so dissolve easily in plasma making transport via the blood simple and easy

35
Q

Why do peptide hormones have to bind to membrane bound receptors to cross the cell membrane?

A

Water solubility means cannot cross cell membrane so bind to membrane bound receptors on target cell.

36
Q

How do most peptide hormones work?

A

Once bound these receptors generally create relatively fast biological responses (seconds to minutes). Most peptide hormones work via modulating either the GPCR or tyrosine kinase linked signalling pathways. These pathways phosphorylate existing proteins in the cell and modify their function

37
Q

Give examples of actions that peptide hormones may have on a cell.

A
  • Open or close ion channels

- Activate or inactivate enzymes

38
Q

Which 2 kinds of cell surface receptor do peptide hormones bind to?

A
  • G Protein Couple Receptor

- Tyrosine Kinase Linked Receptor

39
Q

What happens when a peptide hormone binds to a G protein couple receptor?

A

Activates 2nd messenger system (may alter gene expression) and/or ion channels leading to modification of existing proteins. Rapid response

40
Q

What happens when a peptide hormone binds to a tyrosine kinase linked receptor?

A

Alters gene expression. Slower, longer lasting activity

41
Q

How do steroid hormones differ in their synthesis to other hormones?

A

Unlike the other types of hormones, steroid hormones are synthesized directly as needed, rather than being stored and released.

42
Q

Why are steroid hormones synthesised on demand?

A

This is because they are highly lipophilic (lipid soluble) so cannot be retained within lipid membranes. Once synthesized they diffuse across the membrane into the ISF and the blood.

43
Q

How are steroid hormones transported?

A

Being poorly soluble in water they are transported bound to carrier proteins such as albumin.

44
Q

How is the half life of steroid hormones increased?

A

They are protected from enzymatic degradation as they are stabilised via binding to carrier proteins which increases their half life

45
Q

What are steroid hormones produced by?

A
  • Gonads
  • Placenta
  • Kidney
  • Adrenal cortex
46
Q

What steroid hormones do the gonads produced?

A

Sex steroids

47
Q

What steroid hormones does the placenta produce?

A
  • hCG

- Sex steroids

48
Q

What steroid hormones do the kidneys produce?

A

Vitamin D3

49
Q

What steroid hormones do the adrenal cortex produce?

A

Corticosteroids

50
Q

What determines which specific steroid hormone is produced?

A

Which specific steroid hormone is ultimately produced is determined by different cells having different enzymes synthesising different derivatives of cholesterol

51
Q

Why are the steroid hormone receptors located on the inside of cells?

A

Because steroid hormones are lipophilic they cross the plasma membrane easily, both into and out of cells. As such their receptors are located inside cells (cytoplasmic or nuclear receptors

52
Q

What do steroid hormone receptors trigger?

A

Either activation or repression (inhibition) of gene function within the nucleus = genomic effect.

53
Q

What is the effect of the altered gene function produced by steroid hormones?

A

Genes control the synthesis of protein so these hormones either increase or decrease protein synthesis.

54
Q

Why is there a lag time between hormone release and biological effect?

A

This is a relatively slow process so there is a lag time between hormone release and biological effect (hours to days) but effect persists for around the same time

55
Q

When does some evidence suggest there would be a rapid response to steroid hormones?

A

Some evidences suggests steroids may occasionally bind to cell surface receptors → rapid response.

56
Q

What is the only amine hormone not derived from tyrosine?

A

Melatonin

57
Q

What does melatonin do?

A

Regulates circadian rhythm

58
Q

Give 2 examples of types of amine hormones?

A
  • Catecholamines

- Thyroid hormones

59
Q

Give 3 examples of catecholamines and where they are produced.

A
  • Dopamine from the brain
  • Norepinephrine from neurons
  • Epinephrine from the adrenal medulla
60
Q

What physiologically important fraction of hormone can diffuse across capillary walls?

A

There is a small amount of unbound free steroid/thyroid hormone in the plasma and this is the physiologically important fraction.
Only free hormone can diffuse across capillary walls to target cells.

61
Q

What is the free hormone: hormone= protein complex ration favour?

A

Free hormone : hormone-protein complex ratio much in favour of bound (complexed) hormone

62
Q

What does the Law of Mass Action dictate?

A

The Law of Mass Action dictates that as free hormone leaves the plasma (taken up by cells) more hormone is released from the carriers. Typically only minute quantities of hormone are required for physiological functions

63
Q

What makes up the total plasma [hormone]?

A

Free hormone + complexed hormone = Total plasma [hormone]

64
Q

Give an example of a specific carrier protein.

A

Corticosteroid-binding globulin

65
Q

Give an example of a non-specific carrier protein

A

Albumin

66
Q

What are the advantages of transport via carrier protein?

A
  • Increases solubility required for blood-mediated transport
  • Protects from degradation  increased half life (> 60 min)
67
Q

How is the bound: unbound ratio of hormone maintained?

A
  • As steroid taken up; more is released from carrier
  • Allows for a reservoir of hormone ready for action
  • Prolonged activity
68
Q

Describe peptide and catecholamine hormones.

A
  • Are water soluble, transported in solution in the plasma.
  • Are vulnerable to degradation before they reach their target.
  • Have a short half-life in the plasma, (time taken for [plasma] concentration to fall by a half),usually minutes. Prolonged action therefore requires continued secretion.
69
Q

Describe Steroid and thyroid hormones.

A
  • Are lipophilic, once made they diffuse across the cell membrane into the blood.
  • Circulate in plasma bound to specific transport plasma proteins (eg thryoxine-binding globulin, or albumin) so have longer half-life, usually hours to days.
  • Alter protein synthesis via modifying gene expression thus effect also persists for hours to days.
70
Q

What does the [hormone] in blood depend on?

A

Rate of excretion and rate of removal

71
Q

How are hormones removed form the body?

A

Removal is by excretion or metabolic transformation and mainly occurs in the liver and kidneys

72
Q

Why do catecholamines and peptide hormones have a short half-life?

A

Generally catecholamine and peptide hormones are excreted easily so have a short half-life in plasma, minutes to hours

73
Q

Why do steroid and thyroid hormone take so long to remove form the body?

A

Steroids and thyroid hormones take hours and days to excrete or metabolise, because protein-bound

74
Q

What will most endocrine pathways respond to?

A

Negative feedback relflexes

75
Q

What do some endocrine pathways respond to?

A

Neural feedback loops

76
Q

What mechanisms of control is insulin subject to?

A
  • Plasma [glucose]
  • Autonomic nerve activity
  • Presence of food in the gut
  • Plus additional hormones such as glucagon all influence [insulin]plasma
77
Q

How can hormones influence the ability of target cells to respond?

A
  • Hormones can influence the ability of target cells to respond by regulating the number of hormone receptors
  • May affect not only the hormone’s own receptors but also receptors for other hormones (permissive or antagonistic)
78
Q

Describe up regulation

A

Often after prolonged exposure to low [hormone]plasma we see up-regulation + decrease in number of hormone receptors on target tissues (increases tissue sensitivity to hormone).

79
Q

Describe down regulation.

A

Conversely, often after prolonged exposure to high [hormone]plasma we see down-regulation = increase in receptor number on target tissues (decreases tissue sensitivity to hormone).

80
Q

Permissive effects

A

The presence of one hormone enhances the effect of another eg epinephrine causes only modest lipolysis in adipose tissue, but when thyroid hormones are also present, greatly increased lipolysis occurs.

81
Q

Why is TH permissive to epinephrine?

A

TH increases synthesis of receptors for epinephrine on adipocytes. TH itself has no effect on lipolysis but is permissive to epinephrine.

82
Q

What is the clinical relevance of hormones being released in short bursts?

A

Single values of [hormone] may be misleading. 24 hour monitoring may be required to give the true picture of hormone levels

Systems: Endocrine AB (25 decks)

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