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LCRS and LSS > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

What is an endocrine gland?

A

A group of cells which secrete messenger molecules directly into the bloodstream

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2
Q

What is a hormone

A

A bioactive messenger molecule secreted by endocrine glands into the blood.

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3
Q

Where is secretin released from and where does it act?

A

Secretin is released from the Small intestine - duodenal ‘S’ cells and acts in the pancreas

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4
Q

What does Secretin do?

A

Stimulates bicarbonate-rich secretions in the pancreas in response to acid chyme from the stomach

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5
Q

Define endocrine

A

A hormone’s action on target cells at a distance

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6
Q

Define paracrine

A

A hormone’s action on nearby target cells

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7
Q

Define autocrine

A

A hormone having an effect on its immediate source (same cell)

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8
Q

Define cryptocrine

A

A hormone having a ‘hidden’ effect within its own cell production

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9
Q

State x3 differences between the endocrine and nervous systems

A

Endocrine = Release of chemical into bloodstream, effect can be on many target cells around the body, longer effect (can be up to days).
Nervous system = Release of chemical across a synapse, effect is restricted to specific target cells innervated (shorter effect within milliseconds).

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10
Q

For a hormone to have an effect what must a tissue have?

A

Tissues must express certain receptors.

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11
Q

Name x5 endocrine glands

A

Pituitary gland, Parathyroid gland, Adrenal gland, Pancreas and gonads.

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12
Q

What is an alternate name for the anterior pituitary gland?

A

Adenohypophysis

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13
Q

What is an alternate name for the posterior pituitary gland?

A

Neurohypophysis

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14
Q

What are the three classifications of hormones?

A

Protein/ polypeptide hormones, steroid hormones and miscellaneous.

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15
Q

All Steroid hormones derive from which compound?

A

Cholesterol

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16
Q

Name in ascending size order from small peptides - intermediate peptides - complex peptides

A

TRH < Insulin < LH

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17
Q

Where are proteins synthesised?

A

In the Rough Endoplasmic reticulum

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18
Q

What is the structure of the hormone before it is active?

A

Pre-hormone to Pro-hormone which is cut and transported to the GA where it is processed by proteolytic enzymes to form the active hormone.

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19
Q

What is the difference between the Pre-hormone and Pro-hormone?

A 
Pre-hormone = shorter (40 aas)
Pro-hormone = longer (240aas)
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20
Q

How is the protein transported from the Golgi Apparatus to the circulation?

A

Protein is stored in vesicles which fuse with the membrane and are moved out of the cell via exocytosis.

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21
Q

What is the difference between a polypeptide and a protein?

A

A polypeptide is a single chain whereas a protein is a more complex structure.

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22
Q

What is the difference between how protein and steroid hormones are exported from the cell?

A

Steroid hormones move freely across the cell membrane whereas protein hormones are packed into secretory granules.

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23
Q

What is the difference between the fatty acid backbone and the steroid backbone?

A

Fatty acid backbone = glycerol

Steroid backbone = cholesterol

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24
Q

Where is ACTH produced?

A

The corticotroph cell within the anterior pituitary gland

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25
Q

Briefly describe the process of ACTH synthesis

A

The amino acid moves from the capillary to the Corticotroph cell cytoplasm where proteins are synthesised on the ribosome. mRNA moves from the Corticotroph nucleus to the cytoplasm on the ribosome and is translated to POMC in the ER. POMC is transported to the GA and processed (cut) by proteolytic enzymes forming ACTH.

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26
Q

Which is the protein hormone pro-hormone?

A

POMC -

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27
Q

What is an example of a protein hormone?

A

ACTH

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28
Q

Which blood vessels are pituitary hormones secreted into?

A

Pituitary capillary

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29
Q

What type of cells are corticotrophs?

A

Endocrine cells

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30
Q

What type of hormone is Cortisol?

A

A steroid hormone

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31
Q

Where is cortisol produced?

A

The adrenal cortex

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32
Q

Name x3 causes of short stature

A

Hypothyroidism, lack in Growth hormone, malnutrition

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33
Q

How would you test for growth hormone levels?

A

Insulin induced hypoglycaemia

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34
Q

How would you test for growth hormone levels?

A

Insulin induced hypoglycaemia.

Take base readings of blood glucose and growth hormone and then give insulin injection.

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35
Q

What would you expect to happen to the osmolarity of urine during a water deprivation test

A

Increased osmolarity

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36
Q

What is an alternative form of vasopressin that can be given as a nasal spray.

A

DDAVP (desmopressin)

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37
Q

Concentrated urine has what kind of osmolality?

A

High osmolality

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38
Q

Compare AVP (arginine vasopressin) with DDAVP

A

AVP can only be given by injection whereas DDAVP can be given by nasal spray.
DDAVP is selective for the V2 receptor limiting effects to the kidney. No adverse vasoconstrictive effects.

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39
Q

What can DDAVP be used to treat

A

Diabetes Insipidus

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40
Q

How is Cholesterol carried into cells?

A

By LDLs and their receptors through endocytosis. LDLs are then stored in fatty acid esters and released via esterases. Free cholesterol then moves to the mitochondria via the StAR protein.

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41
Q

What are LDLs stored as within the cell?

A

Fatty acid esters

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42
Q

How is free cholesterol moved into the mitochondria?

A

Via the StAR protein (Steroidogenic acute regulatory protein).

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43
Q

Which is the rate limiting step in steroid synthesis of cholesterol?

A

Moving free cholesterol from the fatty acid ester to the mitochondria via the StAR protein. This is the RLS as cholesterol cannot be made if it is not transported to the mitochondria.

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44
Q

What makes steroids soluble?

A

Their cholesterol backbone

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45
Q

Once cortisol is made from cholesterol, how does it get back into the circulation?

A

Through freely diffusing back to the blood.

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46
Q

Is the pituitary gland part of the brain?

A

No. It is peripheral tissue which sits below the hypothalamus.

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47
Q

In which organelle is POMC made from mRNA?

A

The RER

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48
Q

Which organelle packs POMC into vesicles?

A

The Golgi Apparatus

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49
Q

Which are more soluble - protein or steroid hormones? How does this affect how they are carried within the circulation?

A

Protein hormones are soluble meaning they circulate freely in the blood stream. Steroids are insoluble and so are bound to plasma proteins.

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50
Q

Which plasma protein has low specificity and can bind to many steroid hormones?

A

Albumin

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51
Q

Name x3 specific plasma proteins and what they bind to to carry round in the circulation

A

CBG - Cortisol binding
TBG - Thyroid binding
SHBG - Testosterone/ oestradiol binding

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52
Q

When may CBG and cortisol levels be important to be measured?

A

During pregnancy

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53
Q

Does albumin bind strongly or weakly to proteins?

A

Weakly; non specific.

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54
Q

How is Cortisol bound to CBG?

A

With high affinity. Majority of cortisol’s structure is bound to the CBG - remaining to tissues.

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55
Q

If a steroid hormone is heavily plasma protein bound, can it still access
tissues?

A

Yes, as there is still a component of its structure e.g. cortisol, which is bound to tissues

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56
Q

What are the three things that affect how a hormone is released from its target cell?

A
  1. Number of receptors on target cell
  2. Hormone concentration in circulation
  3. Affinity of hormone by receptor
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57
Q

How does ACTH affect cholesterol release

A

ACTH binds to GPCR on the adrenal cortex causing dissociation of alpha subunit from Gs protein = activates adenylate cyclase and converts ATP to cAMP. Activates PKA which increases activation of StAR and esterases.

ACTH causes esterase and StAR protein activation = increase cholesterol release to the mitochondria.

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58
Q

Describe the mechanism of cortisol work in cell signalling?

A

Cortisol freely diffuses into the cell cytoplasm and binds to glucocorticoid receptors in the cytoplasm. This complex then binds to DNA binding sites and alters DNA transcription and protein synthesis, upregulating and downregulating protein production.

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59
Q

Does Cortisol bind to any receptors to get from the circulation into the cell?

A

No. It passively diffuses.

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60
Q

Which target would cortisol bind to induce negative feedback within the
anterior pituitary?

A

Glucocorticoid receptor; cortisol is functioning meaning anterior pituitary gland is not required to make any more cortisol.

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61
Q

What is another name for the pituitary gland?

A

Hypophysis

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62
Q

What is another name for the anterior pituitary gland?

A

Adenohypophysis

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63
Q

What is another name for the posterior pituitary gland?

A

Neurohypophysis

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64
Q

What does fenestrated mean?

A

Leaky e.g. primary capillary plexus in the anterior pituitary gland = allows communication between the hypothalamic nuclei and the pituitary gland.

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65
Q

Describe the portal circulation in the anterior pituitary gland

A

Superior hypophysial artery feeds into the primary capillary plexus within the median eminence of the anterior pituitary gland. The primary capillary plexus drains into the secondary capillary plexus and then through to the venous system via the cavernous sinus.

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66
Q

What is a portal network?

A

Where blood drains from the systemic circulation drains from one capillary network to another before returning to the heart.

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67
Q

Where do short hypothalamic neurones project to in the pituitary gland?

A

The median eminence

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68
Q

Where do long hypothalamic neurones project to in the pituitary gland?

A

The neurohypophysis (Posterior pituitary gland).

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69
Q

How do neurosecretions from the hypothalamus get into the pituitary gland?

A

Through the primary capillary plexus.

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70
Q

What are the three types of adenohypophysial hormones?

A

Proteins, Glycoproteins and Polypeptides.

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71
Q

What are examples of glycoprotein hormones and what differentiates between them?

A

LH, FSH and TSH. All made up of alpha and beta subunits. Beta subunits are what differ between them.

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72
Q

How are hormones secreted from the hypothalamus?

A

In a pulsatile fashion

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73
Q

Which hormone stimulates Growth hormone release and which inhibits release?

A

Growth hormone is stimulated by GHRH - Growth hormone releasing hormone and inhibited by somatostatin.

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74
Q

What is another name for the growth hormone?

A

Somatotrophin

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75
Q

Which hormone stimulates Prolactin release?

A

Thyrotrophin releasing hormone - only has minute effects. Must inhibit dopamine for majority of Prolactin stimulation.

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76
Q

Which hormone inhibits Prolactin release?

A

Dopamine

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77
Q

On which organ are many growth hormone receptors found?

A

Hepatocytes = causes production of IGFs which stimulate growth.

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78
Q

Name x3 effects of growth hormone

A

Increased protein synthesis, gluconeogenesis and lipolysis.

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79
Q

Name x3 stimulants of growth

A

Sleep, oestrogens, stress and exercise.

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80
Q

What does T4 stand for and what is another name for it?

A

Triiodothyronine. Thyroxine.

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81
Q

What is characterised by hypothyroidism?

A

High TSH; low T3, T4

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82
Q

What effect does oestrogen have on TRH?

A

Promotes TRH production

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83
Q

Name two hormones which inhibit TRH release from the hypothalamus

A

Glucocorticoids and somatostatin

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84
Q

Where is TSH released from?

A

The anterior pituitary gland

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85
Q

How is the majority of T3 made?

A

From deiodination of T4.

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86
Q

Which hormones increase blood glucose?

A

Glucagon, catecholamines, cortisol, somatotrophin

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87
Q

Which is the most common form of Diabetes?

A

T2DM

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88
Q

What are the islets of langerhans made up of?

A

Alpha, beta and delta cells.

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89
Q

What do delta cells of the islet of langerhans produce?

A

Somatostatin

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90
Q

Name x3 ways insulin reduces blood glucose

A

Increases glycogenesis
Increases glycolysis
Increases glucose uptake back into cells

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91
Q

Does insulin increase or decrease fat production

A

Insulin increases lipogenesis

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92
Q

Does insulin increase or decrease protein synthesis?

A

Insulin increases protein synthesis

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93
Q

Name the main mechanism of glucagon in increasing blood glucose concentration

A

Increases hepatic glycogenolysis.

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94
Q

Through which Glut transporter is glucose brought into cells?

A

Glut 2

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95
Q

What is insulin’s structure made up of?

A

Alpha and a beta chain linked by disulphide bonds. Beta subunits are membrane bound with tyrosine kinase domains.

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96
Q

What is GLP-1?

A

Glucagon like peptide = stimulates insulin, inhibits glucose. Secreted in response to nutrients within the gut and increases satiety.

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97
Q

Is vasopressin produced in the posterior pituitary gland?

A

No; it is produced in the hypothalamus and released from the posterior pituitary gland.

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98
Q

Vasopressin-stimulated water reabsorption involves the insertion of aquaporin-2 molecules into the basal (serosal) membranes of its target renal cells. True or false.

A

False; they are inserted into the apical membranes of renal cells

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99
Q

Oxytocin is a peptide made up of how many amino acids?

A
  1. It is a nonapeptide.
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100
Q

Vasopressin stimulates water reabsorption in the renal proximal tubules. True or false.

A

False;

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101
Q

Vasopressin V1 receptors are linked to the adenyl cyclase-cyclic AMP system. True or false.

A

False; this involvement is with V2 receptors.

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102
Q

Upward growth from the buccal cavity forms which lobe of the pituitary gland?

A

The anterior pituitary gland

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103
Q

Steroid hormones are stored in secretory granules. True or false?

A

False

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104
Q

All anterior pituitary hormones are polypeptides or proteins/glycoproteins. True or false?

A

True.

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105
Q

ADH stimulates the release of corticotrophin (ACTH) from the anterior pituitary. True or false?

A

True.

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106
Q

Where is leptin produced?

A

Adipocytes

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107
Q

Somatostatin inhibits insulin release. True or false?

A

True.

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108
Q

What is the approximate weight of the thyroid gland?

A

25g.

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109
Q

What causes Grave’s disease?

A

Graves’ disease is caused by anti-TSH receptor antibodies

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110
Q

Is hyperthyroidism associated with weight gain or weight loss?

A

Weight loss; increased metabolism. BUT will increase appetite.

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111
Q

Which is the ‘post-prandial’ hormone?

A

Insulin

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112
Q

Name two processes other than gluconeogenesis and glycogenolysis in which we can make glucose?

A

Lipolysis and Proteolysis

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113
Q

Which enzymes are triglycerides broken down by?

A

Lipoprotein lipase

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114
Q

Can fatty acids be used to make glucose?

A

No - only the glycerol component from fatty acids can be used.

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115
Q

Why can the brain not use fatty acids as an energy source?

A

The brain is made of fat so enzymes cannot be used to break down fatty acids as an energy source.

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116
Q

During prolonged fasting, what does the brain use as an energy source?

A

Ketones

117
Q

Does Insulin promote lipolysis or lipogenesis?

A

Lipogenesis

118
Q

In which pathway, does Insulin resistance reside?

A

The PI3/Akt Pathway which has metabolic actions

119
Q

What is the name of the gland which controls calcium metabolism?

A

The Parathyroid Gland

120
Q

What is the adult thyroid gland weight?

A

20g

121
Q

What is the origin of the thyroid?

A

The back of the tongue.

122
Q

Thyroxine deficiency is associated with what?

A

Dysfunction in brain development

123
Q

Define the term ‘Cretin’?

A

An individual with no thyroid gland who has dysfunction in brain development.

124
Q

What is the Guthrie Test used to test for?

A

Phenylketonuria

125
Q

How would you measure thyroid function?

A

Measure TSH via the Heel prick test

126
Q

Where are thyroglobulin and thyroxine found?

A

Within the colloid of the follicular cell in the thyroid gland

127
Q

In which gender is thyroid disease more common?

A

Females

128
Q

What is myxoedema another word for?

A

Primary hypothyroidism

129
Q

When will TSH levels be high?

A

When there is a lack of T3/T4 production i.e. hypothyroidism

130
Q

What is the primary cause of hyperthyroidism?

A

Graves’ Disease. Autoimmune.

131
Q

What is the mechanism of Grave’s disease?

A

Antibodies bind and stimulate the TSH receptor.

132
Q

What is the functional unit of the thyroid gland?

A

The follicular cell

133
Q

What is the iodine form in the blood?

A

I-

134
Q

What type of enzyme converts iodide to iodine?

A

Peroxidase

135
Q

The adrenal cortex is the site of synthesis of catecholamines. True or false.

A

False. Catecholamines are synthesised in the medulla.

136
Q

Where is aldosterone synthesised?

A

In the zona glomerulosa cells

137
Q

When is aldosterone secreted?

A

When there is low blood pressure, aldosterone increases sodium reabsorption to increase blood pressure

138
Q

Cortisol stimulates protein catabolism. True or false?

A

True

139
Q

Addison’s disease can be caused by tuberculosis. True or false?

A

True

140
Q

Hypoglycaemic episodes are common in patients with Cushing’s syndrome. True or false?

A

False; high cortisol = high glucose.

141
Q

Hypoglycaemic episodes are common in patients with Cushing’s syndrome. True or false?

A

False; high cortisol = high glucose. Type 2 Diabetes is often seen in Cushing’s syndrome

142
Q

Cushing’s syndrome can be caused by the excessive use of iodine containing compounds. True or false?

A

False; It may be associated with hyperthyroidism but not caused by it.

143
Q

What is Addison’s disease?

A

Low cortisol characterised by primary adrenal failure.

144
Q

Name x3 Signs/ symptoms you would see in Addison’s disease and why?

A

Pigmentation of skin; High MSH, hypotension; low cortisol, low aldosterone. Dizziness + fatigue; low cortisol = low glucose, hypoglycaemia.

145
Q

What is Cushing’s disease?

A

High levels of cortisol. ‘Disease’ means the cause is a pituitary adenoma.

146
Q

What is Cushing’s syndrome?

A

High levels of cortisol characterised generally with weight gain, bruising, proximal myopathy and mood changes. No clear cause

147
Q

What is polydipsia?

A

Increased thirst

148
Q

Which disease is associated with proximal myopathy?

A

Cushing’s disease.

149
Q

One patient complains that the shape of her face has changed and that she has gained a lot of weight ‘around her tummy’. She also mentions that she bruises easily, and that a would on her left shin that she had six months ago has not healed. What is the diagnosis?

A

Cushing’s disease; bruise easily, thin skin, weight gain.

150
Q

Angiotensin I is a potent vasoconstrictor molecule. True or false?

A

False.

151
Q

Testosterone breaks down to form which 2 compounds?

A

Dihydrotestosterone and 17B-Oestradiol.

152
Q

Which enzyme breaks down testosterone to oestrogen?

A

Aromatase

153
Q

Which enzyme breaks down testosterone to dihydrotestosterone?

A

5a-Reductase

154
Q

Give x3 functions of androgens in the fetus?

A
  • Development of male internal and external genitalia.
  • General growth
  • Behavioural effects
155
Q

Give x3 functions of androgens in the adult?

A
  • Spermatogenesis
  • Protein anabolism
  • Secondary sex characteristics
  • Pubertal growth spurt
156
Q

What are oestrogens?

A

Any substance which induces mitosis in the endometrium.

157
Q

Give x5 functions of oestrogens

A
  • Induces LH surge at ovulation
  • Maturation of the follicle during the menstrual cycle
  • Stimulates proliferation of the endometrium
  • Increases renal salt and water reabsorption
  • Stimulates osteoblasts
  • Behavioural influences
158
Q

Which hormone has protective effects on the cardiovascular system and against osteoporosis?

A

Oestrogen

159
Q

What are progestogens?

A

Any substance which induces secretory changes in the endometrium.

160
Q

What is the difference between micro and macro prolactinoma?

A 
Micro-lactinoma = <1cm
Macro-lactinoma = >1cm
161
Q

Where is calcium mainly found?

A

Within the bone as hydroxyapatite crystals

162
Q

Which form of calcium is active?

A

The unbound form

163
Q

Which hormone increases blood calcium?

A

Parathyroid hormone

164
Q

Which hormone decreases blood calcium?

A

Calcitonin

165
Q

What is Calcitriol also known as?

A

1, 25 dihydroxycholecalciferol

166
Q

Where is Calcitonin released from?

A

The parafollicular cells in the thyroid gland.

167
Q

Parathyroid hormone binds to what kind of receptor?

A

GPCR

168
Q

What affect does Parathyroid hormone have on the kidneys?

A

Increases PO4 excretion
Increases Ca2+ reabsorption
Stimulates 1a-hydroxylase activity

169
Q

What are Vitamin D3’s affects on the small intestine?

A

Increases calcium and phosphate reabsorption.

170
Q

What is the Parathyroid hormone’s affects on the bone?

A

Increases osteoclast activity and decreases osteoblasts.

171
Q

Does the PTH increase or decrease osteoclast activity?

A

Increases osteoclastic activity to release calcium.

172
Q

Does Vitamin D3 increase or decrease osteoblast activity?

A

Increases osteoblastic activity

173
Q

What is pseudohypoparathyroidism?

A

PTH resistance - There are sufficient PTH levels but the tissues are resistant to it.

174
Q

Where does the left adrenal vein drain?

A

The renal vein

175
Q

Where does the right adrenal vein drain?

A

The inferior vena cava

176
Q

How many veins does each adrenal gland have?

A

Each adrenal gland has only one vein (but many arteries).

177
Q

Where is cortisol produced?

A

Zona Fasiculata and the Zona Reticularis

178
Q

Where are adrenaline and other catecholamines produced?

A

Adrenal Medulla

179
Q

What makes up the adrenal cortex?

A

The Zona fasciculata, zona glomerulosa and the zona reticularis

180
Q

What is the function of the parathyroid gland?

A

To control calcium metabolism

181
Q

What does an absence of thyroxine do to the basal metabolic rate?

A

Absence of thyroxine causes a decrease in BMR.

182
Q

What is the daily treatment intake of thyroxine?

A

100mg a day

183
Q

What does TRH stand for?

A

Thyrotropin releasing hormone

184
Q

What does TSH stand for?

A

Thyroid stimulating hormone

185
Q

What is pretibial myxoedema and when is it seen?

A

Antibodies stimulate growth of the shin in hyperthyroidism.

186
Q

Is goitre seen in hypothyroidism or hyperthyroidism?

A

Both.

187
Q

How do most hyperthyroidism treatments work?

A

Target the peroxidase enzyme

188
Q

What is the name for half-blindness on both temporal lobes?

A

Bi-temporal hemianopia

189
Q

What affect does prolactin have on LH and FSH?

A

Prolactin suppresses LH, FSH.

190
Q

How can high levels of stress cause someone to miss their menstrual cycle?

A

Stress is an inducer of prolactin release as it inhibits dopamine. Prolactin suppresses LH and FSH levels.

191
Q

Define galactorrhoea

A

Excessive or inappropriate production of milk.

192
Q

How can a pituitary tumour cause bitemporal hemianopia?

A

The pituitary tumour impinges upon the optic chiasm disrupting the nerve pathways from the nasal parts of the retina = loss of peripheral vision.

193
Q

Which is the outermost layer of the adrenal cortex?

A

Zona Glomerulosa

194
Q

Which is the innermost layer of the adrenal cortex?

A

Zona Reticularis

195
Q

Mineralocorticoids and glucocorticoids are examples of which sub class?

A

Corticosteroids - produced by the adrenal cortex.

196
Q

How many carbons does cholesterol have?

A

27

197
Q

What is Cholesterol immediately converted to before undergoing further steps to be made into cortisol?

A

Pregnenolone

198
Q

The P450c17 enzyme is involved in which synthesis type?

A

Cortisol synthesis

199
Q

Which enzyme converts testosterone to oestradiol?

A

Aromatase

200
Q

What type of compound is adrenaline?

A

Amine

201
Q

Which hormones are high in Addison’s disease?

A

ACTH and MSH

202
Q

ACTH derives from which compound?

A

POMC - Pro-opiomelanocortin

203
Q

Cortisol can bind to which receptors in comparison with aldosterone?

A

Cortisol can bind to glucocorticoid and mineralocorticoid receptors, whereas aldosterone can only bind to mineralocorticoids receptors.

204
Q

Which enzyme converts cortisol to cortisone?

A

11b-hydroxysteroid dehydrogenase 2 enzyme

205
Q

What percentage of cortisol is plasma protein bound?

A

80%

206
Q

What percentage of aldosterone is plasma protein bound?

A

60%

207
Q

Where is there a high concentration of 11B-hydroxysteroid dehydrogenase 2?

A

The kidney; a lot of active cortisol is converted to cortisone.

208
Q

Where is renin produced?

A

In the granular cells of the kidney

209
Q

Which cells detect varying levels of sodium?

A

The macula densa cells

210
Q

How is angiotensinogen converted to angiotensin II?

A

Angiotensinogen is converted to angiotensin I by Renin and then to angiotensin II by ACE

211
Q

Where is ACE released from?

A

The lungs

212
Q

What is Angiotensin II’s affect on aldosterone?

A

Increases its production

213
Q

What is angiotensin II’s affect on K+ and Na+?

A

Angiotensin II increases aldosterone production which increases tubular Na+ reabsorption in the kidney. Aldosterone increases K+ excretion.

214
Q

Which hormones control cortisol production?

A

CRH (hypothalamus) and ACTH (anterior pituitary gland).

215
Q

What does CRH stand for?

A

Corticotrophin releasing hormone

216
Q

Where is the majority of water reabsorbed under aldosterone control?

A

In the collecting duct

217
Q

Where is the Na+/K+ pump in the kidney?

A

In the distal tubule of the kidney

218
Q

Describe aldosterone’s mechanism of action within the kidney?

A

Aldosterone binds to mineralocorticoid receptors and stimulates Na+ reabsorption into the distal tubule cell of the kidney. Aldosterone drives Na+ out of the collecting duct through Na+ CHANNELS and Na+/K+ ATPase pump.

219
Q

Compare how cortisol binds to cortisol compared with mineralcorticoid receptors?

A

Cortisol binds fully to mineralocorticoid receptors whereas it partially binds to glucocorticoid receptors.

220
Q

How are aquaporins inserted into the distal tubule membrane?

A

When ADH binds to the V2 receptor, Aquaporins 2,3 and 4 are inserted into the membrane which allow H20 to flow through.

221
Q

What actions does cortisol have on glucose?

A

Cortisol increases glucose levels and so increases glycogenolysis, gluconeogenesis and decreases GLUT 4 transport (to keep glucose in blood).

222
Q

What affect do glucocorticoids - cortisol, have on free fatty acids?

A

Cortisol decreases free fatty acids.

223
Q

How does cortisol increase memory function?

A

Cortisol upregulates serotonin 5HT receptors.

224
Q

What affect does cortisol have on inflammation?

A

Cortisol has anti-inflammatory AND immunosuppressive effects.

Anti-inflammatory: decreases leukocyte, monocyte function and complement activation.
Immunosuppressive: decreases complement and lymphocyte function.

225
Q

Where are memories stored?

A

In the Dantate Gyrus

226
Q

What effect would supraphysiological levels of cortisol have on blood pressure?

A

Cortisol would be converted to cortisone by 11b-hydroxysteroid dehydrogenase 2 enzyme. This would increase aldosterone needed ……………..

227
Q

Where are androgens produced in the kidney?

A

Zona Reticularis e.g. DHEA

228
Q

Which are the MAIN steroid hormones in males and females?

A 
Males = androgens
Females = oestrogen and progesterone
229
Q

What is the difference in spermatogonia and oogonia number between males and females?

A

Spermatogonia remain relatively constant through life whereas oogonia are at their maximum at 24 weeks of gestation and after birth decrease.

230
Q

How many oogonia are present at birth?

A

2million; There is rapid atresia of oogonia before birth from the 4-6 million

231
Q

When are oogonia reduced to 0?

A

Menopause

232
Q

Describe spermatogenesis

A

Germ cell > spermatogonia > primary spermatocyte > secondary spermatocyte > spermatid > spermatozoa.

233
Q

Describe oogenesis

A

Germ cell > Oogonia > Primary oocyte > secondary oocyte > obum

234
Q

Describe oogenesis

A

Germ cell > Oogonia > Primary oocyte where 1st meiosis is halted until puberty > secondary oocyte > ovum.

235
Q

When do meiosis and mitosis occur in spermatogenesis/ oogenesis?

A

Spermatogonia > primary spermatocyte = mitosis
Primary spermatocyte > secondary spermatocyte = 1st meiosis
Secondary spermatocyte > spermatid = 2nd meiosis

Oogonia > primary oocyte = mitosis

Primary oocyte > secondary oocyte = 1st meiosis
Secondary oocyte > ovum = 2nd meiosis

236
Q

When does gametogenesis begin in males compared with females?

A

At puberty in males.

237
Q

Which stage of meiosis is halted during oogenesis from the primary oocyte to the secondary oocyte?

A

Prophase

238
Q

Where does spermatogenesis take place?

A

Within the coiled seminiferous tubules

239
Q

Which structure is between the rete testis and epididymis in the testes?

A

The vasa efferentia

240
Q

How do spermatozoa move from the epididymis to the urethra?

A

Through the Vas Deferens via smooth muscle contraction

241
Q

Where do spermatozoa mature?

A

Within the epididymis

242
Q

Describe the structure of the coiled seminiferous tubule

A

Lumen surrounded by sertoli cells connected by tight junctions.

243
Q

Where is the site of testosterone production?

A

The Leydig cell

244
Q

Where are FSH and LH receptors produced?

A

FSH receptors produced in the Sertoli cell

LH receptors produced in the Leydig cell

245
Q

Which cells produce Inhibin in response to FSH?

A

Sertoli cells

246
Q

Describe the structure of the ovaries

A

Ovarian stroma made up of: the Graafian follicle, follicles and remnants of the corpus luteum.

247
Q

What is the Graffian follicle?

A

An ovum, granulosa cells and thecal cells

248
Q

What molecule do oestrogens and progesterones derive?

A

Cholesterol

249
Q

Which are the two phases of the menstrual cycle?

A

The proliferative and secretory phase.

250
Q

Oestrogen is seen predominantly in which phase of the menstrual cycle?

A

The proliferative phase

251
Q

Progesterone is seen predominantly in which phase of the menstrual cycle?

A

The secretory phase

252
Q

Is the basal body temperature higher in the first or second part of the menstrual cycle?

A

The second half.

253
Q

Describe the Ovarian cycle

A

Pre-antral follicle to early antral follicle to late antral follicle to Graafian follicle to ovulation.

254
Q

Which cells produce androgens in the ovaries?

A

Thecal cells.

255
Q

Which cells in the ovaries contain aromatase?

A

Granulosa cells.

256
Q

What is the function of aromatase?

A

Converts androgens to 17B-Oestradiol after ovulation.

257
Q

Testosterone and aldosterone derive from which common compound apart from cholesterol?

A

Progesterone

258
Q

Testosterone is converted to which 2 compounds within the gonads?

A

Dihydrotestosterone and 17B-Oestradiol.

259
Q

Which enzyme is required to make 17B-Oestradiol from testosterone?

A

Aromatase

260
Q

Which enzyme is required to make Dihydrotestosterone from Testosterone?

A

5a-Reductase

261
Q

What is the difference between testosterone and dihydrotestosterone?

A

DHT is more potent.

262
Q

Testosterone is converted to which compound in the testes?

A

TRICK! Depends where in the testes;
Seminiferous tubules=DHT
Sertoli cells =17B-Oestradiol

263
Q

What is seminiferous fluid?

A

Semen

264
Q

Do androgens contribute to protein and bone anabolism or catabolism?

A

Anabolism. (growth)

265
Q

Define oestrogen

A

Any substance which induces mitosis (thickening) in the endometrium (womb).

266
Q

Which is the main oestrogen in pregnancy?

A

Oestriol

267
Q

What is a progesterone?

A

Any substance which induces secretory changes within the endometrium.

268
Q

What is the difference between oestrogen and progesterone effects on Na+ reabsorption.

A

Oestrogen increases Na+ reabsorption. Progesterone decreases Na+ reabsorption; competitive inhibition with aldosterone.

269
Q

Which hormone stimulates the Sertoli cell to make testosterone?

A

LH

270
Q

Testosterone to oestrogen production is what type of reaction?

A

Aromatisation.

271
Q

How many months of unprotected sex must a couple be having without pregnancy to be deemed infertile?

A

12 months

272
Q

Give x3 diseases which may cause infertility

A

Pituitary failure
Ovarian failure
Testicular failure
Prolactinoma

273
Q

What is the term for infrequent periods?

A

Oligomenorrhoea

274
Q

How does the graafian follicle form?

A

It competes with the other follicles by making more oestrogen and gets bigger. There is a positive feedback loop within itself (autocrine). Oestrogen made by follicle stimulates granulosa cells to grow which stimulates further oestrogen production.

275
Q

What is the LH surge on day 14 caused by?

A

The positive feedback and release of extremely high levels of oestrogen. Positive feedback to GnRH and LH.

276
Q

Which hormone does the corpus luteum make?

A

Progesterone

277
Q

Which hormones increase and decrease blood calcium levels?

A

Increased by parathyroid hormone and 1, 25- dihyroxycholecalciferol, decrease by calcitonin.

278
Q

How many Parathyroid glands are there?

A

4

279
Q

PTH binds to receptors on which cell?

A

The osteoblast which activates RANKL on osteoclasts.

280
Q

What is FGF23’s effect on phosphate?

A

FGF23 increases phosphaturia = decreases phosphate reabsorption.

281
Q

What are Trousseau’s sign and Chvostek’s sign and when are they seen?

A

Trousseau’s sign: Tetany in the hands
Chvostek’s sign: facial nerve can be tapped to induce a twitch.
Seen in hypocalcaemia

282
Q

Adenoma can cause what endocrine disorder?

A

Primary hyperparathyroidism; low calcium means more PTH must be produced but there is no negative feedback.

283
Q

What affect will hyperparathyroidism have on the bone, kidney and small intestine

A

Bone fractures
Kidney: Increase PO43- excretion, increase Ca2+ reabsorption, kidney stones
Small intestine: Increase Ca2+ and PO43- absorption = gastric and duodenal ulcers,

284
Q

What is a hormone?

A

A bioactive messenger

285
Q

Name x2 Protein hormones and x2 Steroid hormones

A

Protein hormones = ACTH, Insulin, LH TRH

Steroid hormones = Cortisol, Vitamin D.

286
Q

Where are chromaffin cells found?

A

Within the medulla of the adrenal gland.

287
Q

Where are cortisol, adrenaline, aldosterone and androgens produced?

A

The adrenal gland

288
Q

Aldosterone is what type of substance?

A

Mineralocorticoid

289
Q

Describe the relationship between Serotonin and Cortisol

A

Serotonin increases hippocampus sensitivity to Cortisol.

Cortisol upregulates serotonin 5HT 1A receptor density.

LCRS and LSS (7 decks)

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