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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
What is neuronal stimuli ?
Stress responses Sympathetic nervous system e.g. Adrenaline
26
What is hormonal stimuli ?
In response to hormones produced by other endocrine glands e.g. pituitary or hypothalamus
27
Describe the relationship between the hypothalamus and pituitary gland in the control of the endocrine system.
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
28
Function of the hypothalamus
Controls release of hormones from the anterior lobe of the pituitary gland
29
What types of hormones are released from the hypothalamus ?
Releasing hormones (GHRH) Inhibitory hormones (GHIH)
30
What does the posterior pituitary do ?
Storage of hormones secreted by neurosecretory cells in the hypothalamus Transported via neuronal axons to the posterior lobe 1. ADH or Vasopressin 2. Oxytocin
31
Results of excess growth hormones
Gigantism Acromegaly
32
Adenohypophysis
(aka) Anterior pituitary Oral ectoderm derived Vascular connection to hypothalamus
33
Neurohypophysis
Posterior pituitary Neuroectoderm derived Direct neural link to hypothalamus
34
What are the 2 major lobes of the pituitary gland ?
Anterior Posterior
35
Where is the pituitary located ?
Hollow of the sphenoid bone
36
What does the anterior lobe consist of ?
Epithelial cells
37
What hormones does the anterior pituitary secrete ?
Growth hormone Thyroid stimulating hormone Adrenocorticotropic hormone Follicle stimulating hormone Luteinising hormone Prolactin
38
What does the posterior lobe consist of ?
Neural tissue
39
Where is the thyroid gland located ?
2 lobes covering the anterolateral surface of the trachea Within the visceral compartment of the neck surrounded by the pre tracheal fascia.
40
What is the largest pure endocrine gland in the body ?
Thyroid gland
41
What are some features of the thyroid gland ?
Innervated by the SNS and PNS
42
Where is thyroglobulin synthesised ?
In follicular cells - stored in the follicle lumen
43
How is thyroid hormone generated ?
Thyroglobulin combines with iodine and endocytosed back into the follicular cells and cleaved to generate Thyroid hormone.
44
Name the 2 types of thyroid hormones
Tri-iodothyronine (T3) - binds 3 iodine Thyroxine (T4) - binds 4 iodine
45
What does thyroxine regulate ?
Rate of metabolism – energy use Protein production – growth & development Sensitivity of cells to other hormones
46
Thyroid disorders
Hypothyroidism Hyperthyroidism Severe hypothyroidism
47
Hypothyroidism
Non-toxic goitre, endemic in particular regions iodine poor soil/ poor diet
48
Hyperthyroidism
Graves disease
49
Severe Hypothyroidism
Due to iodine deficiency Neurological deficits
50
Where is the parathyroid gland located ?
2 pairs of glands Embedded in the posterior aspect of the thyroid gland Develops from the wall of the pharynx
51
What does the parathyroid gland produce ?
Parathyroid hormone
52
Function of parathyroid gland
Regulates calcium homeostasis Promotes conversion of inactive vitamin D to active form.
53
How does the parathyroid gland regulate calcium homeostasis ?
Stimulates osteoclasts to break down bone matrix and increase blood Ca2+ levels
54
Why does the parathyroid gland promote conversion of inactive vitamin D to active form ?
As Vitamin D is required for absorption of Ca2+ from diet
55
Where is the adrenal gland located ?
Superior to the kidneys
56
What is the adrenal gland comprised of ?
Cortex tissue - glandular tissue derived from mesoderm Medulla tissue - sympathetic nervous system derived from the neural crest
57
Layers of the adrenal cortex
Zona : - Glomerulosa : mineralocorticoids - Fasciculata : glucocorticoids - Reticularis : gonadocorticoids Medulla
58
What does the adrenal cortex produce ?
Steroid hormones called corticosteroids - cholesterol is the common precursor
59
Mineralocorticoids
e.g. Aldosterone Homeostasis of Na+ and K+ and water
60
Glucocorticoids
e.g. Cortisol Energy metabolism and glucose availability
61
Gonadocorticoids
Sex steroids Weak androgens which are converted into tissue cells to more potent forms e.g. testosterone and oestrogen
62
What is the cortisol feedback mechanism stimulated by ?
Stress, exercise and hypoglycaemia
63
Cushings syndrome
Excessive cortisol
64
Key effects of the adrenal medulla
Increased BP, heart and respiratory rate Diversion of blood to muscles Glucose mobilisation
65
Where are chromaffin cells found ?
Adrenal medulla
66
Where is the function of chromaffin cells ?
Produce : - Epinephrine - Norepinephrine - Dopamine
67
What is the adrenal medulla the site of ?
Catecholamine synthesis and secretion Direct connection with SNS
68
Where is the pancreas located ?
Partially behind the stomach
69
What type of gland is the pancreas ?
Endocrine and exocrine
70
Function of pancreas
Major role in glucose homeostasis
71
What hormones do the Islets of Langerhans produce ?
Glucagon - in alpha cells Insulin - in beta cells
72
Diabetes mellitus
disorder of the pancreas
73
Gastrin
Digestive enzymes
74
Renin
Helps control your blood pressure and maintain healthy levels of sodium and potassium in your body.
75
Function of Islets of Langerhans
Essential for regulation of blood glucose

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

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