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Medicine Year 1 Semester 1 - Part 2 > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

Where and what do endocrine glands secrete ?

A

Hormones are secreted directly into the bloodstream

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2
Q

What is an endocrine gland ?

A

Ductless glands with a rich blood supply

Endo - internal, Crine - secretions

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3
Q

Name the 8 endocrine glands

A

Pineal gland
Pituitary gland
Parathyroid gland
Thyroid gland
Adrenal gland
Pancreas
Ovary
Testis

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4
Q

What are some functions of endocrine glands ?

A

Cellular metabolism
Growth and development
Sexual development
Homeostasis
Behaviour - mood/sleep

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5
Q

What is an exocrine gland ?

A

May or may not have excretory ducts

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6
Q

Where do exocrine glands secrete ?

A

Externally onto an epithelial surface

Tongue - saliva
Skin - sebum/sweat
GI tract - digestive enzymes

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7
Q

Name the 3 classes of hormones

A

Proteins/ peptides
Steroids
Amino acid derivatives

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8
Q

Describe the half life of proteins

A

They have a short half life of a few minutes, as they are not attached to a carrier protein.

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9
Q

Describe how proteins work ?

A

Note : usually water soluble, readily transported in blood

  1. Bind to plasma membrane receptors on target cells
  2. Signal transduction
  3. Initiate cellular changes (i.e. gene expression)
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10
Q

What are steroids synthesised from ?

A

Cholesterol

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11
Q

Name some examples of steroids

A

Testosterone
Oestrogen
Cortisol

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12
Q

Describe the half life of steroids

A

They have a longer half life than proteins, as they require specific transporter proteins in the blood.

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13
Q

Describe how steroids work ?

A

They readily diffuse across the plasma membrane

Bind to intracellular receptors/transcription factors - modify gene expression.

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14
Q

What are amino acid derivatives modified from ?

A

Tyrosine

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15
Q

Where are catecholamines synthesised in ?

A

Renal medulla

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16
Q

What are catecholamines ?

A

Neurotransmitters

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17
Q

Name some catecholamines

A

Adrenaline
Noradrenaline
Dopamine

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18
Q

Name some thyroid hormones

A

Thyroxine
Tri-iodothyronine

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19
Q

How do all hormones act ?

A

By binding to receptors

e.g. cell membrane receptors - peptides, glycoproteins and catecholamines

e.g. intracellular receptors - steroids and thyroid hormones

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20
Q

Episodic hormones

A

Released in response to physiological demand
e.g. insulin
Jagged lines

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21
Q

Diurnal hormones

A

Released in a predictable pattern over 24 hours
e.g. cortisol
Has a peak in the graph

  • May also respond to episodic stimuli
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22
Q

Constant hormones

A

Fairly constant blood concentrations for normal physiological function.

e.g. thyroxine

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23
Q

Name the 3 types of stimuli that trigger endocrine glands to produce and release their hormones

A

Humoral
Neuronal
Hormonal

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24
Q

What is humoral stimuli ?

A

Circulating molecules in the blood.
SIMPLEST
i.e. critical ions or nutrients

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25
Q

What is neuronal stimuli ?

A

Stress responses
Sympathetic nervous system
e.g. Adrenaline

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26
Q

What is hormonal stimuli ?

A

In response to hormones produced by other endocrine glands

e.g. pituitary or hypothalamus

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27
Q

Describe the relationship between the hypothalamus and pituitary gland in the control of the endocrine system.

A

Hypothalamus and pituitary gland coordinate the endocrine system - orchestrate activity of other endocrine glands

Provides signal amplification - cascades and fine control

Hypothalamus secretes hormones which control release of pituitary hormones

Pituitary hormones stimulate/control many other endocrine glands

Negative feedback system

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28
Q

Function of the hypothalamus

A

Controls release of hormones from the anterior lobe of the pituitary gland

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29
Q

What types of hormones are released from the hypothalamus ?

A

Releasing hormones (GHRH)
Inhibitory hormones (GHIH)

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30
Q

What does the posterior pituitary do ?

A

Storage of hormones secreted by neurosecretory cells in the hypothalamus

Transported via neuronal axons to the posterior lobe

  1. ADH or Vasopressin
  2. Oxytocin
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31
Q

Results of excess growth hormones

A

Gigantism
Acromegaly

32
Q

Adenohypophysis

A

(aka) Anterior pituitary
Oral ectoderm derived
Vascular connection to hypothalamus

33
Q

Neurohypophysis

A

Posterior pituitary
Neuroectoderm derived
Direct neural link to hypothalamus

34
Q

What are the 2 major lobes of the pituitary gland ?

A

Anterior
Posterior

35
Q

Where is the pituitary located ?

A

Hollow of the sphenoid bone

36
Q

What does the anterior lobe consist of ?

A

Epithelial cells

37
Q

What hormones does the anterior pituitary secrete ?

A

Growth hormone
Thyroid stimulating hormone
Adrenocorticotropic hormone
Follicle stimulating hormone
Luteinising hormone
Prolactin

38
Q

What does the posterior lobe consist of ?

A

Neural tissue

39
Q

Where is the thyroid gland located ?

A

2 lobes covering the anterolateral surface of the trachea

Within the visceral compartment of the neck surrounded by the pre tracheal fascia.

40
Q

What is the largest pure endocrine gland in the body ?

A

Thyroid gland

41
Q

What are some features of the thyroid gland ?

A

Innervated by the SNS and PNS

42
Q

Where is thyroglobulin synthesised ?

A

In follicular cells - stored in the follicle lumen

43
Q

How is thyroid hormone generated ?

A

Thyroglobulin combines with iodine and endocytosed back into the follicular cells and cleaved to generate Thyroid hormone.

44
Q

Name the 2 types of thyroid hormones

A

Tri-iodothyronine (T3) - binds 3 iodine
Thyroxine (T4) - binds 4 iodine

45
Q

What does thyroxine regulate ?

A

Rate of metabolism – energy use
Protein production – growth & development
Sensitivity of cells to other hormones

46
Q

Thyroid disorders

A

Hypothyroidism
Hyperthyroidism
Severe hypothyroidism

47
Q

Hypothyroidism

A

Non-toxic goitre, endemic in particular regions
iodine poor soil/ poor diet

48
Q

Hyperthyroidism

A

Graves disease

49
Q

Severe Hypothyroidism

A

Due to iodine deficiency
Neurological deficits

50
Q

Where is the parathyroid gland located ?

A

2 pairs of glands
Embedded in the posterior aspect of the thyroid gland
Develops from the wall of the pharynx

51
Q

What does the parathyroid gland produce ?

A

Parathyroid hormone

52
Q

Function of parathyroid gland

A

Regulates calcium homeostasis

Promotes conversion of inactive vitamin D to active form.

53
Q

How does the parathyroid gland regulate calcium homeostasis ?

A

Stimulates osteoclasts to break down bone matrix and increase blood Ca2+ levels

54
Q

Why does the parathyroid gland promote conversion of inactive vitamin D to active form ?

A

As Vitamin D is required for absorption of Ca2+ from diet

55
Q

Where is the adrenal gland located ?

A

Superior to the kidneys

56
Q

What is the adrenal gland comprised of ?

A

Cortex tissue - glandular tissue derived from mesoderm

Medulla tissue - sympathetic nervous system derived from the neural crest

57
Q

Layers of the adrenal cortex

A

Zona :

  • Glomerulosa : mineralocorticoids
  • Fasciculata : glucocorticoids
  • Reticularis : gonadocorticoids

Medulla

58
Q

What does the adrenal cortex produce ?

A

Steroid hormones called corticosteroids - cholesterol is the common precursor

59
Q

Mineralocorticoids

A

e.g. Aldosterone
Homeostasis of Na+ and K+ and water

60
Q

Glucocorticoids

A

e.g. Cortisol
Energy metabolism and glucose availability

61
Q

Gonadocorticoids

A

Sex steroids
Weak androgens which are converted into tissue cells to more potent forms e.g. testosterone and oestrogen

62
Q

What is the cortisol feedback mechanism stimulated by ?

A

Stress, exercise and hypoglycaemia

63
Q

Cushings syndrome

A

Excessive cortisol

64
Q

Key effects of the adrenal medulla

A

Increased BP, heart and respiratory rate

Diversion of blood to muscles

Glucose mobilisation

65
Q

Where are chromaffin cells found ?

A

Adrenal medulla

66
Q

Where is the function of chromaffin cells ?

A

Produce :

  • Epinephrine
  • Norepinephrine
  • Dopamine
67
Q

What is the adrenal medulla the site of ?

A

Catecholamine synthesis and secretion

Direct connection with SNS

68
Q

Where is the pancreas located ?

A

Partially behind the stomach

69
Q

What type of gland is the pancreas ?

A

Endocrine and exocrine

70
Q

Function of pancreas

A

Major role in glucose homeostasis

71
Q

What hormones do the Islets of Langerhans produce ?

A

Glucagon - in alpha cells
Insulin - in beta cells

72
Q

Diabetes mellitus

A

disorder of the pancreas

73
Q

Gastrin

A

Digestive enzymes

74
Q

Renin

A

Helps control your blood pressure and maintain healthy levels of sodium and potassium in your body.

75
Q

Function of Islets of Langerhans

A

Essential for regulation of blood glucose

Medicine Year 1 Semester 1 - Part 2 (37 decks)

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