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BI0005 > Introduction to the Endocrine System > Flashcards

Introduction to the Endocrine System Flashcards

1
Q

What is endocrinology

A

The study of the endocrine system

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2
Q

What is neuroendocrinology

A

The study of the control of the endocrine system by the nervous system

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3
Q

What is neuroendocrine integration

A

How the two systems interact in order to maintain homeostasis in the body

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4
Q

What is the endocrine system

A

Communication within the body using hormones

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5
Q

What is a hormone

A

A chemical produced by a ductless endocrine gland which is secreted into the blood. It is transported to a target elsewhere in the body where it causes an effect

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6
Q

How do hormones communicate with their target cells

A

They bind to receptors on their target cells

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7
Q

What happens if the appropriate receptor is not present on a cell

A

The hormone cannot affect it

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8
Q

Describe cell membrane receptors

A

A hormone binds to a receptor in the cell membrane which triggers a response in the target cell

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9
Q

Describe receptors in the nucleus

A

Once the hormone has crossed the cell membrane it bind to receptors in the nucleus. Forms a hormone-receptor complex which causes gene expression

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10
Q

What are the two types of receptors on target cells

A

Receptors on cell membranes and receptors in the nucleus

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11
Q

What types of chemical substances are hormones

A
  1. Steroids 2. Proteins/ peptides 3. Amines
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12
Q

Where are steroids synthesised

A

In the adrenal cortex, ovaries, testes and placenta

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13
Q

How are steroids transported

A

They are not very soluble in blood so are transported bound to proteins

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14
Q

How do steroids enter cells

A

They are fat soluble so cross membranes easily and diffuse out of cells

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15
Q

What type of receptors do steroids have

A

Intracellular receptors

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16
Q

Steroids are easily absorbed in the GI tract- True/ False

A

True

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17
Q

Why can steriods be administered orally

A

Because they are easily absorbed in the GI tract

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18
Q

In what form are proteins/ peptides synthesised

A

They are synthesised as ‘prehormones’/ ‘prepeptides’

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19
Q

Where are proteins/ peptides stored

A

They are stored in membrane-bound vesicles/ granules

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20
Q

How are proteins/ peptides transported

A

They circulate unbound in the blood

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21
Q

What type of receptors do proteins/ peptides have

A

Cell membrane receptors

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22
Q

Why can’t proteins/ peptides be administered orally

A

They are too easily digested

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23
Q

What are the two varieties of amines

A
  1. Thyroid hormones 2. Catecholamines
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24
Q

What are thyroid hormones derived from

A

Tyrosine

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25
Q

Do thyroid hormones cross cell membranes

A

Yes

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26
Q

What type of receptors do thyroid hormones have

A

Intracellular receptors

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27
Q

How are thyroid hormones transported

A

They are protein-bound

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28
Q

Where are thyroid hormones stored

A

In thyroid follicles

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29
Q

Can thyroid hormones be administered orally

A

Yes

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30
Q

What are catecholamines derived from

A

Tyrosine

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31
Q

DO catecholamines cross the cell membrane

A

Yes

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32
Q

What type of receptors do catecholamines have

A

Cell membrane receptors

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33
Q

How are catecholamines transported

A

Unbound in the blood

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34
Q

How how catecholamines stored

A

In membrane-bound vesicles/ granules

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35
Q

Can catecholamines be administered orally

A

Yes but their half life is too short

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36
Q

What 5 things does binding hormones to proteins do

A
  1. Prolongs their circulating half-life 2. Prevents them from entering the wrong type of cell 3. Prevents them from being lost through the kidneys 4. Maintains the right concentration of the hormone 5. Acts as a ‘buffer’ against a drop in the secretion of a hormone
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37
Q

How do hormones act on their target cells

A
  1. Receptor binding 2. Initiates intracellular cell-signalling events (2nd messenger hypothesis).
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38
Q

Describe second messenger hypothesis

A

A hormone binds to a receptor which initiates the production of cAMP which are called ‘second messengers’

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39
Q

Which are the male endocrine glands

A
  1. Pituitary gland 2. Thyroid gland 3. Adrenal gland 4. Testis
40
Q

What are the female endocrine glands

A
  1. Pineal gland 2. Thymus 3. Pancreas 4. Ovary
41
Q

What is a very important trace element in thyroid hormones

A

They contain iodine (iodothyronines)

42
Q

What are the 3 thyroid hormones

A
  1. Thyroxine (T4) 2. Triiodothyronine (T3) 3. Reverse T
43
Q

Describe the 3 components of a thyroid gland

A
  1. Colloid
  2. Follicular epithelium
  3. Follice
44
Q

What are the 4 functions of thyroid hormones

A
  1. Maturation, development and growth. 2. Metabolism (Control basic metabolic rate). 3. Skeletal muscle (calcium availability). 4. Cardiovascular system
45
Q

Describe the stages of thyroid hormone production

A
  1. Thyroglobulin (TG) couples to a follicular cell membrane by thyroid peroxidase.
  2. TG enclosed by lysosome containing proteolytic enzymes.
  3. Iodinated tyrosines (MIT and DIT) are then deiodinated.
  4. Tyrosine and iodine are recycled.
46
Q

What two endocrine tissues are located within the adrenal gland

A
  1. Adrenal cortex 2. Adrenal medulla
47
Q

Which two catecholamines are secreted by the adrenal medulla

A
  1. Noradrenaline 2. Adrenaline
48
Q

What controls the adrenal medulla

A

The sympathetic nervous system

49
Q

Which do receptors do adrenaline and noradrenaline act on

A

Alphareceptors and betareceptors

50
Q

What effects to adrenaline and noradrenaline have on betareceptors

A
  1. Metabolic 2. Cardiovascular 3. Bronchodilation
51
Q

What effects to adrenaline and noradrenaline have on alphareceptors

A
  1. Metabolic 2. Cardiovascular 3. Sweating 4. Dilation of pupils 3. Sphincter contractor
52
Q

What 3 groups of hormones does the adrenal cortex produce

A
  1. Mineralocorticoids 2. Glucocorticoids 3. Sex hormones
53
Q

Give an example of a mineralocorticoids and explain what they do

A

Aldosterone. Regulate mineral metabolsim- retention of Na+ and water resorption by the kidney. Secretion of H+ and K+

54
Q

Give an example of a glucocorticoid and explain what they do

A

Cortisol. Regulates blood glucose levels

55
Q

Give an example of a sex hormone and explain what they do

A

Weak androgens that can be converted into more potent sex hormones (androgens) such as testosterone and oestrogens, especially in women

56
Q

Describe the pancreas

A

The pancreas is both an exocrine and endocrine gland

57
Q

What is the endocrine part of the pancreas called

A

Islets of Langerhans

58
Q

What are the 3 types of cells of the Islets of Langerhans

A
  1. Alpha cells 2. Beta cells 3. Delta cells
59
Q

What do alpha cells produce and what is the function of this hormone

A

Glucagon- a catabolic hormone which can mobilise stores of glycogen, fat and protein to act as energy sources during food deprivation

60
Q

What do beta cells produce and what is the function of this hormone

A

Insulin- an anabolic hormone which causes the uptake and use of glucose from the blood during times of excess nutrient availability

61
Q

What do delta cells produce and what is the function of this hormone

A

Somatostain- inhibits growth hormone and gastrin

62
Q

Describe what happens when there are low blood glucose levels

A

Detected by the pancreas -> glucagon is released by alpha cells > liver releases glucose into blood -> achieve normal blood glucose levels

63
Q

Describe what happens when there are high blood glucose levels

A

Detected by the pancreas -> beta cells release insulin -> fat cells take in glucose from the blood -> achieve normal blood glucose levels

64
Q

Why must the levels of Ca2+ be tightly regulated

A

Because it can become very toxic to cells

65
Q

What percentage of Ca2+ is found in the bones and teeth

A

99%

66
Q

What percentage of Ca2+ is found intracellulary

A

0.9%

67
Q

What percentage of calcium is found in the ECM

A

0.1%

68
Q

What is half of free Ca2+ bound to

A

Proteins or PO4(3+)

69
Q

How much calcium is freely diffusible

A

About half is freely diffusible and can take part in chemical reactions- this must be tightly regulated

70
Q

What happens in terms of neuromuscular excitability when Ca2+ levels decrease

A

Over excitability of nerves and muscles

71
Q

What happens in terms of neuromuscular excitability when Ca2+ levels increase

A

Depressed the excitability of nerves and muscles

72
Q

What is the function of Ca2+ in cardiac and smooth muscle

A

Excitation-contraction coupling. Ca2+ entry into these tissues initiated the contractile mechanism

73
Q

What happens when Ca2+ enters nerves and cells that secrete peptide hormones

A

It triggers the secretory process

74
Q

What increases Ca2+ levels

A

Parathormone (PTH)

75
Q

What is parathormone produced by

A

The parathyroid gland

76
Q

What does parathormone do

A

Increase levels of Ca2+ and so prevents hypocalcaemia

77
Q

Apart from parathormone what else is involved in the regulation of Ca2+

A

Calcitonin and vitamin D

78
Q

Which parts of the body does parathromone regulate the exchange of Ca2+

A

In the bone, kidneys and intestine

79
Q

Which are the two main cells involved in reproductive endocrinology

A

Leydig cells Sertoli cells

80
Q

Label the leydig and sertoli cells

A

Diagram

81
Q

What are sertoli cells involved in

A

Maturation of sperm by producing peptodes that act as hormones

82
Q

What do leydig cells produce

A

Testosterone which is a steroid hormone and an androgen

83
Q

What are the effects of testosterone before birth

A

Regulates differentiation and development of internal and external genitalia

84
Q

What are the effects of testosterone at puberty

A
  1. Regulates growth and maturation of the internal and external genitalia. 2. Development of secondary sexual characteristics (hair, deep voice, muscle growth). 3. Initiates and maintains spermatogenesis. 4. Develops sex drive.
85
Q

What are the other effects of testosterone

A
  1. Aggression 2. Bone growth and fusion of epiphyses
86
Q

Label the parts of the female reproductive endocrinology system

A

Diagram

87
Q

What do the ovaries do

A
  1. Produce eggs (oogenesis). 2. Secrete the female sex hormones oestrogen and progesterone
88
Q

What do oestrogen and progesterone help to promote

A

They help to promote fertilisation and get the reproductive system ready for pregnancy

89
Q

What are the functions of oestrogen

A

Similar to those of progesterone (secondary sexual characteristics etc.)

90
Q

What is the menstrual cycle controlled by

A

A very complex series of interactions between hormones

91
Q

What are the components of the menstrual cycle synthesised by

A

The ovary, anterior part of the pituitary gland that the hypothalamus of the brain

92
Q

What are the 3 aspects of the endocrinology of pregnancy

A
  1. Development of the placenta 2. Implantation of the fertilised ovum. 3. Birth (parturition).
93
Q

What is the posterior lobe of the pituitary gland attached to

A

The hypothalamus at the base of the brain

94
Q

What does the anterior pituitary gland regulate

A

Several physiological processes: stress, growth, reproduction, lactation

95
Q

How many hormones does the pitutitary gland secrete and what do these hormones do

A

Secretes 9 hormones that regulate homeostasis

BI0005 (21 decks)

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