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Year 1 > Endocrine > Flashcards

Endocrine Flashcards

1
Q

What are Exocrine Glands?

A

secrete products into ducts which carry the
secretion into cavities, lumen of an organ and outer surface of the body
e.g. sweat glands

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2
Q

What are Endocrine Glands?

A

secrete products into interstitial fluid surrounding the secretory cells, this then diffuses into the capillaries and is carried by the blood to the target organ/receptors.

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3
Q

Define Paracrine…

A

Local hormones which act on neighbouring cells

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4
Q

Define Autocrine…

A

Hormones which act on the same cell that secreted them e.g. Interleukin-2

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5
Q

Define Haemocrine…

A

Hormones which travel from the cell which produced them into the blood

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6
Q

Define Solinocrine….

A

Messenger molecule secreted into hollow lumen of ductal system

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7
Q

Name three water soluble hormones?

A

Amine hormones
Peptide hormones
Protein hormones

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8
Q

Name three lipid soluble hormones?

A

Thyroid hormones
Steriod hormones
Nitric oxide

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9
Q

Examples of amine hormones

A

Catecholamines so adrenaline. nor adrenaline and dopamine

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10
Q

Examples of peptide hormones

A

ADH, oxytocin, insulin

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11
Q

Examples of protein hormones

A

Human growth hormone, parathyorid hormone

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12
Q

Examples of thyroid hormones

A

T3, T4, Calcitonin

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13
Q

Examples of steriod hormones

A

sex hormones, vitamin D, cortisol

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14
Q

nitric oxide can be

A

hormone or neurotransmitter

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15
Q

What is the action of lipid soluble hormones?

A
  • Lipid soluble hormone diffuses from the blood to the lipid bilayer of the plasma membrane
  • target cell binds to the hormone
  • activates receptors located in the nucleus/cytosol
  • the receptor hormone complex then alters gene expression and turns certain genes on/off
  • new proteins are made and alter cell’s activity
  • protein allows response typical of that hormone.
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16
Q

Can water soluble hormones diffuce through the lipid bilayer?

A

no

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17
Q

What is the action of water soluble hormones?

A
  • Hormones bind to receptor on the membrane
  • the hormones act as the first messenger
  • the hormone receptor complex activates G-Protein
  • G protein activates adenylate cyclase
  • Adenylate cyclase converts ATP into cyclic AMP
  • Cyclic AMP activates protein kinases
  • protein kinase phosphorylates other cellular proteins
  • Phosphorylated proteins cause reactions that produce physiological responses.
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18
Q

What does phosphorylates mean?

A

adds a phosphate group

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19
Q

Which hormones do the thyroid gland produce?

A

T3, T4 and calcitonin

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20
Q

Which artery supplies the superior thyroid artery?

A

External carotid artery

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21
Q

Which artery supplies the inferior thyroid artery?

A

Subclavian artery an dthen th thyrocervical trunk

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22
Q

What is the artery that only around 10% of the population have called?

A

Thyroid ima artery

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23
Q

Where does the thryoid ima artery come from

A

brachicephalic trunk of the arch of aorta.

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24
Q

Which cells produce PTH?

A

Chief Cells

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25
Q

What is the overall role of parathyroid hormone?

A

increase blood calcium levels

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26
Q

What are the three OTHER functions of parathyroid hormone?

A
  • -Stimulates osteoclastic activity in the bines to mobile bone calcium so increases calcium in the blood
  • Stimulates absorption ofdietary calcium from the samll intestine
  • Stimulates reabsorption of calcium in the kidney
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27
Q

What controls the parathyroid glands?

A

The calcium levels in the blood

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28
Q

How are thyroid glands regulated?

A
  • The hypothalmus secretes TRH
  • Stimulates TSH in the anterior pituitary
  • Then in the thyroid gland, T3, T4 and calcitonin are stimulated
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29
Q

What cells are in thyroid gland?

A

Follicle cells

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30
Q

Follicle cells are surrounded by….

A

Blood vessels which contain NA+, I-, K+

`

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31
Q

Explain the synthesis of thyroid hormones

A

-Thyroglobulin is proudced in follicle cells in RER
- I- is cotransported with Na+ into the follicle.
-I- enters the colloid via pendrin channel (chloride iondine channel)
- Iodide then gets oxidised into iodine
-Iodine combines with tyrosine in thyroglobulin to form MIT and DIT
- two T2 molecules join to
form T4, or one T1 and one T2 join to form T3.
-T3 and T4 go into the follicle cells and get broken out of the thyroglobulin by lysosomes.

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32
Q

Role of thyroglobulin

A

Follicular cells, packages into a vesicle and then secreted via exocytosis into the colloid lumen. They have the amino acid tyrosine attached to them also.

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33
Q

What doe T3 and T4 stand for?

A

triiodothyronine (T3)

thyroxine (T4)

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34
Q

Which thyroid hormone is needed more

A

T3 so T4 converts to T3

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35
Q

What is it called when you are T3/T4 deficient?

A

HypOthyroidism - lOw

Hyperthyroidism - high

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36
Q

Which hormones are produced in the anterior pituitary gland?

A 
Growth hormone
Prolactin
ACTH-adrenocorticotropin
LH
FSH
TSH
MSH-melanocyte stimulating hormone
37
Q

Which hormonnes are released from the posterior pituitary gland?

A

ADH/Vasopressin

Oxytcin

38
Q

Name 5 secreting cells in the hypothalmus ?

A
  • Somatotrophs–GH secreting cells
  • Corticotrophs–ACTH secreting cells
  • Thyrotroph-TSH secreting cells
  • Gonadotroph-LH/FSH secreting cells
  • Lactotroph–Prolactin secreting cells
39
Q

Role of Human Growth Hormone?

A
  • targets tissues in liver
  • secreted by Somatotrophs
  • Stimulates tissues to synthesise and secrete insulin like (IGFs)
  • They promote growth of body cells, protein synthesis, tissue repair, lipolysis and elevation of blood glucose concentration.
40
Q

Role of Thyroid stimulating hormone?

A

-targets tissues in thyroid gland
-secreted by thyrotophs
- Stimulates the synthesis and secretion of thyroid
hormones by the thyroid gland.

41
Q

Role of Follicle stimulating hormone?

A
  • targets the ovaries and testes
  • secreted by gonadotophs
  • In females, it initiates development of oocytes and induces ovarian secretion of oestrogen.
  • In males, stimulates testes to produce sperm.
42
Q

Role of Luteinising hormone?

A

-targets the ovaries and testes
-secreted by gonadotrophs
-In females, stimulates secretion of oestrogens and
progesterone, ovulation and formation of corpus luteum.
-In males, stimulates testes to produce testosterone.

43
Q

Role of Prolactin?

A
  • targets mammary glands
  • secreted by Lactotrophs
  • Together with other hormones, promotes milk production by mammary glands.
44
Q

Role of Adrenocorticotropin?

A
  • targets adrenal cortex
  • secreted by Corticotrophs
  • Stimulates secretion of glucocorticoids (mainly cortisol) by adrenal cortex.
45
Q

Role of Mealoncyte stimulating hormone?

A

-targets brain
-secreted by Corticotrophs
-Exact role in humans is unknown but may influence
brain activity; when present in excess it can cause
darkening of the skin

46
Q

Role of Oxytocin?

A

-targest uterus and breasts
-secreted by magnocelluar cells
-Stimulates contraction of smooth muscles of
uterus during childbirth.
-Stimulates contraction of myoepithelial cells in
mammary glands to cause milk ejection.

47
Q

Role of ADH?

A
  • targets kidneys
  • secreted by magnocellular cells
  • Conserves body water by decreasing urine volume
  • decreases water loss through perspiration
  • raises blood pressure by constricting arterioles.
48
Q

Define the main glucose transporters?

A

GLUT 1-brain, erythrocytes (no mitochondria), placenta, foetal tissue
GLUT 2-liver, kidney, intestine, pancreatic beta-cell
GLUT 3-brain
GLUT 4-muscle and adipose tissue (found in vesicle membranes)
GLUT 5-jejunum

49
Q

How does insulin work with GLUT4?

A

Insulin binds to receptor and initiates the recruitment of GLUT4 to the cell surface by initiating a protein kinase cascade

50
Q

How does insulin work with GLUT2?

A

· Insulin accelerates the uptake of blood glucose into the liver by GLUT2.

· The catalytic sites of glucokinase become filled with glucose – converting glucose to glucose 6-phosphate

· The increase in glucose 6-phosphate coupled with insulin action leads to a build-up of glycogen stores

51
Q

Where is insulin produced?

A

produced by beta cells in the islets of langerhans

52
Q

Where is glucagon produced?

A

produced by the alpha cells in the islets of langerhans

53
Q

Where is gastrin produced?

A

secreted from G cells

54
Q

Insulin______blood glucose whereas glucagon______blood glucose

A

Decreases

Increases

55
Q

What is hypOglycemia

A

decrease in blood glucose so therefore stimulates glucagon.

56
Q

What stimulates insulin secretion?

A
  • high blood glucosse

- GIP and GLP-1 secretion from the intestine

57
Q

What stimulates glucagon secretion?

A
  • Low blood glucose

- rise in blood amino acids

58
Q

What does glucagon do?

A

Acts on hepatocytes to stimulate glycogenolysis via GCPR, adenylyl cyclase, cAMP, protein kinase A cascade
· Inhibits fatty acid synthesis by reducing production of pyruvate (blocking glycolysis) and stimulates gluconeogenesis

59
Q

What is type 1 diabetes?

A

Results in the beta cells of the pancreatic islets being lost because of an auto-immune process, hence meaning that little or no insulin is produced.

60
Q

What is type 2 diabetes?

A

A condition where peripheral tissues are not responsive to insulin (insulin resistance)
The pancreatic beta cells initially compensate for insulin resistance by increasing production

61
Q

What is the role of adrenaline in glucose level regulation?

A

· During a fasting period, adrenaline is released into circulation from adrenal glands

·promotes the breakdown of glycogen to glucose in skeletal muscle

· Lactate (conjugate base of lactic acid) is released and converted to glucose by the liver

62
Q

What is the role of cortisol (glucocorticoids) in glucose level regulation?

A

· Secreted by the adrenal glands in prolonged fasting (form of stress)

· Cortisol supports the breakdown of glycogen and the conversion of amino acids, lactate, and glycerol to glucose in our liver

· Cortisol promotes protein breakdown of skeletal muscle – supplying amino acids to the liver to be converted to glucose

63
Q

What are the hormones produced fro adrenal glands?

A

Aldosterone
Cortisol
Androgens

64
Q

What are the 3 layers in the adrenal cortex?

A

Zona glomerulosa - Aldosterone
Zona fasciculata - Cortisol
Zona reticularis - Androgens

65
Q

Boisynthesis of Aldosterone

A

· Angiotensin 2 binds to cells of the zona glomerulosa

· This causes Ca2+ to be produced as a second messenger

· This activates protein kinase C which converts cholesterol to pregnenolone

· Pregnenolone is then converted to progesterone then corticosterone in the mitochondria

· Corticosterone is converted aldosterone in the mitochondria – catalysed by K+

66
Q

Biosynthesis of Cortisol

A

· ACTH binds GPCR on cells of the zona fasciculata – activating adenylyl cyclase

· ATP is converted to cAMP which activates PKA

· An LDL binds to an LDL receptor – which along with lipase and PKA converts a cholesterol ester to cholesterol

· In the mitochondria, cholesterol is converted to pregnenolone

· Pregnenolone is converted to 11 deoxycortisol in the cytoplasm

· This then moves back into the mitochondria where is converted to cortisol

· Cortisol leaves the cell and moves to target cells

67
Q

How is the adrenal hormones regulated?

A
  • There is a long term stress in the hypothalmus in the brain stimulates corticotrophin releasing hormone
  • stimulates ACTH to be released in the anterior pituitary
  • ACTH then goes into the blood stream and targets cells specifically in the cortex.
  • These layers have cells that stimulate hormones.
68
Q

Actions of cortisol

A
  • provides a negative feedback to the brain
  • hypERglycaemia
  • Protein breakdown and lipolysis
  • Gluconeogenesis
  • Supression of Immune system
  • Osteoclast stimulation
69
Q

Actions of aldestrone

A
  • important in increasing bp
  • involved in the RAAS System
  • stimuates water and sodium retension
70
Q

Actions of Androgens

A
  • promotes prostrate growth
  • male characteristics like hair
  • Female: sexual drive
71
Q

What happens in the adrenal medulla?

A

It produced catecholamine hormones like adrenaline and nor adrenaline.
involved in the flight and fight response
- the hormones binds to proteins around the liver, lungs, digestive system, muscles

72
Q

Name the insulin receptor?

A

Tyrosine Kinase Receptor

73
Q

What components make tyrosine kinase receptor?

A

2 alpha subunits
2 betal subunits
2 TYR enzyme (needs to be phosphorylated to be active)

74
Q

Describe the steps in the RAAS system?

A

· Dehydration, Na+ deficiency or haemorrhage cause a decrease in blood volume (and hence BP)

· This stimulates juxtaglomerular cells in the kidney to secrete renin (enzyme)

· Angiotensinogen is a plasma protein secreted by hepatocytes in the liver

· Renin converts angiotensinogen to angiotensin 1

· Angiotensin 1 is converted to angiotensin 2 by angiotensin converting enzyme (ACE) in the lungs

· Angiotensin 2 stimulates the adrenal glands (zona glomerulosa) to secrete aldosterone, the posterior pituitary to secrete ADH and vasoconstriction causing increased BP

Aldosterone:
· Increases cardiac output

· stimulates the kidneys to reabsorb Na+ and increases secretion of H+ and K+ into the urine (retension)

· vasconstricts ateries and arterioles

This is all to increase the blood pressure

75
Q

What is the control mechanism for high calcium?

A

· High blood calcium stimulates parafollicular cells of the thyroid to secrete calcitonin
· Calcitonin inhibits osteoclast activity – so decreases blood calcium

76
Q

What si the control Mechanism for Low Calcium?

A

· Low blood calcium stimulates chief cells of the parathyroid gland to secrete PTH

· PTH stimulates osteoclasts to resorb bone ECM – releasing calcium (and phosphate and magnesium) into the blood

· PTH also stimulates the kidneys to retain more calcium (and phosphate) from urine (but it increases phosphate loss)

· PTH also stimulates the kidneys to synthesise calcitriol (from vitamin D

77
Q

Role of Vitamin D

A

· UV light converts 7-dehydroxycholesterol to vitamin D in the skin

· Vitamin D is also absorbed from the GI tract (via dietary sources)

· In the liver, vitamin D is converted to calcidiol via 25-hydroxylase

· Calcidiol is converted to the active calcitriol in the kidney – stimulated by PTH

· Calcitriol increases osteoclast activity and increases calcium uptake from the GI trac

78
Q

What do sex steroids do?

A

steroid hormones either bind to the extracellular membrane with their transporter or binds directly to genetic material (nuclear hormone)

79
Q

Testosterone Properties (Type of Androgen)

A

· Male sexual characteristics

· Stimulates libido in males and females

· Increases bone thickness and periosteal bone formation

· Increases basal metabolic rate and muscle mass

· Stimulates erythropoiesis (promoting RBC formation)

80
Q

Oestrogen Properties

A

· Female primary and secondary sexual characteristics

· Energy homeostasis and metabolism

· Decreases bone resorption by osteoblasts and osteoclasts

· Decreases the risk of atherogenesis in males and females (atheroma formation)

81
Q

FSH Properties

A

· Stimulates Sertoli cells in males – supports sperm maturation

· Growth and maturation of ovarian follicles

82
Q

LH Properties

A

· Binds to Leydig cells (in males) – stimulating testosterone production

· Stimulates Theca cells (in females) to produce testosterone – which is then converted to oestrogen by adjacent granulosa cells (in the ovary)

83
Q

Aromatase

A

· It catalyses the last steps of estrogen biosynthesis from androgens

· It transforms androstenedione to estrone and testosterone to oestradiol

84
Q

Albumin

A

· Sex hormones are Lipophilic and therefore only weakly water soluble thus specialised transport of steroids in blood is used

· All steroids can be transferred via albumin

85
Q

What is Hypogonadism?

A

reduction or absence of hormone secretion or other physiological activity of the gonads (testes or ovaries

86
Q

What is Klinefelter’s Syndrome (Primary Hypogonadism)?

A

· Genotype – XXY (male)

· No early symptoms but can cause smaller genitalia, enlarge breasts and infertilit

87
Q

What is Turner’s Syndrome (Primary Hypogonadism)?

A

· Genotype – X0

· Female genitalia present, no functional gonads, short stature, amenorrhea and delayed/absent puberty

88
Q

What is Kallmann Syndrome (Secondary Hypogonadism)?

A

· Neurons that stimulate release of GnRH fail to migrate into hypothalamus during development

Year 1 (23 decks)

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