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Semester 2 Biology Revision > Endocrine System > Flashcards

Endocrine System Flashcards

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1
Q

What is a hormone?

A

Mediator molecule that is released in one part of the body but regulates the activity of cells in other parts of the body.

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2
Q

How do hormones travel around the body?

A

Enter interstitial fluid and travel in the blood stream.

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3
Q

To be able to cause a response, what must hormones do?

A

Bind to a receptor.

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4
Q 
Differences between the endocrine system and the nervous system:
Messages
Duration of Response
Area of Response
Example of Controlled Processes
A

E: Slow N: Fast
E: Chemical impulses in blood stream N: Electrical impulses- Nerves.
E: May take years N: Few Seconds
E: Many organs- Widespread N: One area of body- localised.
E: Growth and Reproductive system development. N: Reflex- Blinking.

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5
Q

How do receptors world for hormones?

A

Supply and Demand Basis- Receptor Upregulated and Downregulated.

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6
Q

Upregulation of receptor? When does this happen?

A

Receptors are synthsised.

Hormones levels are low.

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7
Q

Downregulation of receptors? When does this happen?

A

Receptors are broken down.

Hormone levels are high.

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8
Q

What are the three types of lipid soluble hormones?

A

Steroid Hormones- Cholesterol backbone with small changes in R group which change function.
Thyroid Hormones- T3 and T4- Tyrosine and Iodine.
Nitric Oxide- NO.

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9
Q

Lipid Soluble Hormone Mechanism:

A
  1. Lipid soluble hormone diffuses into cell.
  2. Hormone binds to receptor in cell. In nucleus receptor hormone complex is activated and alters gene expression.
  3. Newly formed mRNA directs synthesis of specific proteins on ribosomes.
  4. New proteins alter the cells activity.
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10
Q

Lipid Soluble Hormones are Liophilic and undergo Constitutive secretion. What do these words mean?

A

Hormones which are able to diffuse through the cell membrane.
Proteins secreted from cell continuously.

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11
Q

How do lipid soluble hormones travel around the body?

A

Free in blood or attached to globulin carrier.

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12
Q

Circulating Hormone.

A

Long lasting.

Secreted by Kidneys and Liver and travel to distant sites via blood.

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13
Q

Local Hormones.

A

Do not circulate in the blood.
Produced by nerve and gland cells which bind to neighbouring cells or to same cells that produced the hormones.
Activated/ Inactivated quickly.

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14
Q

Paracrine Signalling.

A

Cell signalling in which cell produces a signal to induce change in near by cells.

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15
Q

Autocrine Signalling.

A

Cell signalling in which the cell that secreted the hormone binds to receptors on that cell so there is a change in that cell.

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16
Q

Synergistic Hormones

A

2 Hormones produce greater effect that their individual effects.

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17
Q

Antagonistic Hormones

A

Act to return to normal body conditions from extreme opposites.

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18
Q

How responsive hormone interactions on depend on what?

A
  1. Hormone Concentration in blood.
  2. Receptor Density.
  3. Other hormones (Permissive effect- depends on 2nd hormone- promote enzyme activation or have effect on receptor density.)
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19
Q

What are peptide hormones degraded by? Where does the inactive breakdown products go?

A

Plasma Enzymes. Urine.

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20
Q

What are lipid hormones degraded by?

A

Lipid hormones which are bound to globulins deactivated by passage through the liver.

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21
Q

On a target cell now many receptors are there per hormone?

A

2000- 10000

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22
Q

What are the three types of water soluble hormones? Name a few examples.

A
  1. Amine Hormones- Retain NH3+ eg. histamine, serene and epinerine.
  2. Peptide/ Protein Hormones- ADH, Oxytocine, insulin, hGH and Parathyroid hormone.
  3. Eicosanoid Hormone deprived from arachidonic acid. Eg. Prostaglandins and Leukotriene’s.
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23
Q

Water Soluble Hormone Mechanism:

A
  1. Binding of hormone (first messenger) to receptor activates G protein– activates adenylate cyclase.
  2. Activated adenylate cyclase converts ATP to cAMP (Second Messenger).
  3. cAMP activates protein kinases.
  4. Protein kinases phosphorylates cellular proteins.
  5. Millions of phosphorylated proteins cause reactions that produce a physiological response.
  6. Phosphodiesterase inactive cAMP.
24
Q

What is Negative Feedback?

A

Acts to oppose the condition/ stimulus that triggered it. Eg High Blood Glucose Concentration.

25
Q

What is Positive Feedback?

A

Amplifings starting signal so process can be pushed to completion. Eg: Giving Birth.

26
Q

What is the hypothalamus?

A

Endocrine Gland- link between nervous and endocrine system.

27
Q

What is the pituitary gland nicknamed? Why?

A

Master gland because it releases hormones which control other endocrine tissues.

28
Q

How are hypothalamic neurosecretory cells regulated?

A
  1. Negative feedback by hormones from target glands decreases activity of pituitary gland.
  2. Corticotrophs, Thyrotrophs and Gonadontrophs secreted less when blood levels of their target hormones rise.
29
Q

What is the most abundant cell in the anterior pituitary gland?

A

Somatotrophs.

30
Q

What do Somatotrophs do?

A

Release hGH which promotes the release of proteins IGS.

31
Q

Somatotrophs are regulated by blood glucose. Explain how this happens when low blood glucose levels are recognised.

A
  1. Low blood glucose.
  2. Stimulates release of GHRH (hypothalamus) which stimulates secretion of hGH.
  3. hGH and IGFs speed up release in liver.
  4. Blood glucose normal.
  5. Increases too much- hyperglycaemia inhibits release of GHRH.
32
Q

Somatotrophs are regulated by blood glucose. Explain how this happens when high blood glucose levels are recognised.

A
  1. High blood glucose levels.
  2. Stimulates release of GHIH inhibits the secretion of hGH.
  3. Low levels of hGH and IGFs slows the release of glucose in liver.
  4. Blood glucose= Normal.
  5. Continues to fall hypoglycaemia which inhibits release of GHIH.
33
Q

What is the Diabetogenic effect of hGH?

A

Stimulates hyperglycaemia so insulin secreted constantly and Beta cells burn out= DIABETES.

34
Q

Where are Oxytocin and ADH secreted, stored and released?

A

Secreted- Hypothalamus.

Stored in vesicles in axon and release by exocytosis- Posterior Pituitary Gland.

35
Q

What makes up the thyroid gland?

A

Thyroid Follicies.

36
Q

Where is the thyroid gland located?

A

Right and left lateral lobes either side of trachea. Connected by isthmus.

37
Q

Mechanism for the release of hormones from the thyroid gland.

A
  1. Low blood levels of T3 and T4/ Low metabolic rate so release of TRH.
  2. Carried by hypophyseal portal veins to anterior pituitary which stimulates release of TSH.
  3. TSH released into blood stimulates thyroid follicular cells.
  4. T3 and T4 release into blood by follicular cells.
  5. Elevated T3 levels inhibits release of TRH and TSH.
38
Q

If there is excess T3 and T4 what happens to the body?

A

Negative effects- Increased heart rate, muscle wasting and bone loss.
Positive effects- Reduce bad cholesterol and fat loss.

39
Q

What are the 2 cells make up the parathyroid gland?

A

Chief Cells & Oxyphilic Cells

40
Q

Which cells in the parathyroid produce parathyroid hormone?

A

Chief Cells.

41
Q

What does congenital hyperthyoidism cause? What is the name for this condition in adults? How does the condition differ to children?

A

Causes mental retardation/ stunted growth.

Myxedema. No mental retardation as brain has already developed.

42
Q

What is Graves Disease?

A

Auto immune disease and is the most common form of hyperthyoidism. Thyroid glands produce too much thyroid hormones.

43
Q

Name the 3 parts of the adrenal cortex and the type of hormones each releases.

A
  1. Zona Reticularis- Androgens.
  2. Zona Fasiculata- Glucotoricorids.
  3. Zona Glomerulosa- Mineralcorticoids.
44
Q

What do Androgens do in females?

A

Promote sex drive and only form of estrogen after menopause.

45
Q

What types of hormones are there in the Adrenal Cortex and the Adrenal Medulla?

A

Adrenal Cortex- Steroid Hormones.

Adrenal Medulla- Peptide Hormones.

46
Q

What is the Adrenal Medulla?

A

Modified sympathetic ganglion of ANS.

47
Q

What is the Adrenal Medulla made up of? Where do they lack and where are they located?

A

Chromaffin Cells.

Lack axons and cluster around blood vessels.

48
Q

What is Crushing Syndrome?

A

Hypersecretion of cortisol. Metabolic implications- hyperglycaemia.

49
Q

What is Addison’s disease?

A

Hyposecretion of glucocorticoids and Aldestone- hypoglycaemia.

50
Q

What are gonads?

A

Organs that produce gametes.

51
Q

What are the problems with limited testosterone production?

A
  1. Acne
  2. Increased BP.
  3. Gynecomastic (Boobs).
  4. Elevated volume of red blood cells.
52
Q

In the Ovaries what does FSH, LH, Progesterone and estrogen do?

A

Regulated menstraul cycle.
Maintains pregnancy.
Prepare mammary glands.

53
Q

What does the pineal gland consist of?

A

Neuroglia and secretory cells (pinealocytes).

54
Q

What does the pineal gland secrete? What does this do?

A

Secretes melatonin helps set body’s clock.

Is also a potent anti-oxidant that may provide protection from free radicals.

55
Q

What is the body’s response to stress? What part of the body controls it?

A

Fight or flight (ANS)- immediate fast response
Slower resistance reaction (CRH, GHRH, TRH)- long term response
Exhaustion (mainly cortisol) causes wasting of muscle, supressed immunity, ulceration, failure of pancreatic beta cells.
HYPOTHALAMUS.

Semester 2 Biology Revision (5 decks)

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