Hormone Transport and Kinetics

Question 1

What are the 7 pure endocrine glands?

Answer 1

1. Pineal
2. Hypothalamus
3. Pituitary
4. Adrenals
5. Thyroid
6. Parathyroid
7. Pancreas (endocrine/exocrine)

Question 2

What are the 4 partial endocrine glands (also known as organ-endocrine glands)?
What do they produce?

Answer 2

1. Heart: Atrial natriuretic peptide (ANP) (vasodilator)
2. Intestine: Cholecystokinin (stimulates pancreatic enzymes and bile), gastrin (stimulates HCl release)
3. Kidney: 1,25 dihydroxycholecalciferol (active D3) (regulates Ca2+ metabolism), Erythropoietin “EPO” (stimulates erythropoeisis)
4. Placenta: chorionic gonadotropins (stimulates progestins)

Question 3

What are the 4 characteristics of a classic hormone?

Answer 3

They are chemical agents
Synthesized and secreted by glands
Circulate in the blood to other parts of the body
Stimulate specific tissues (target tissues)

Question 4

What does cortisol bind to in the blood?

Answer 4

globulin

Question 5

What are the characteristics of a neurohormone?

Answer 5

Synthesized within neuroendocrine cells
Secreted from nerve terminals
Diffuse into blood vessels and transported

Question 6

How do local hormones act?

Answer 6

Diffusion of hormone into interstitial fluid
Paracrine function: neighbouring cells (via interstitial fluid not via blood system)
Autocrine function: acts on itself (receptors for hormone produced)

Question 7

Are catecholamines eg. epinephrine lipid or water soluble?

Answer 7

Water soluble

Question 8

How are water soluble hormones transported in the blood?

Answer 8

freely

Question 9

How are lipid soluble hormones transported in the blood?

Answer 9

Bound to transport proteins

Question 10

What is the difference between measuring bound hormone and measuring free hormone?

Answer 10

Measuring bound hormone- measuring amount of hormone produced and measuring free hormone is measuring amount of hormone able to be used

Question 11

Where are transport proteins produced and degraded?

Answer 11

Transport proteins produced and degraded in the liver (consider the consequences of liver failure)

Question 12

What are the functions of transport proteins besides transport?

Answer 12

Serve as a hormone reservoir as bound hormone can’t diffuse into cells

Act as hormone buffers and Short-term peaks in synthesis absorbed

Reduce hormone loss via the kidneys as protein bound hormones won’t be excreted by the kidney

Question 13

Plasma hormone concentrations are the net result of what?

Answer 13

1. Rate of secretion into the blood

2. Rate of removal (elimination) from blood

Question 14

What are the mechanisms of elimination of a hormone?

Answer 14

1. Enzymatic degradation
2. Within target cells after binding receptor
3. Via liver and kidneys

Question 15

How does epinephrine function as an example of a fast hormone?

Answer 15

Rapid release from the adrenal medulla
Immediate action on tissues (heart)
Fast return to normal (few seconds) as water-soluble hormone binds receptors and is enzymatically degraded within cell

Question 16

How does thyroxine (T4) function as an example of a slow hormone?

Answer 16

Circulates as bound (99.7%) or free (0.03%) hormone (lipid-soluble) the bound hormone resistant to degradation

Either converted into T3, which enters cells and alters gene expression or converted into water-soluble compounds by liver and excreted in urine

Question 17

What factors effect hormone responses?

Answer 17

Variation by tissue eg. thyroxine effects the heart and GI more than the spleen and brain

Variation by time, timing of the response may differ between species or with age

Variation by dose- Hormone levels outside physiological range may elicit different responses eg. Prednisolone sodium succinate - Ultra short-acting corticosteroid for shock or Dexamethasone - Long-acting corticosteroid for immuno-suppression

Status of target tissue, overstimulation may cause target tissue to hypertrophy and with understimulation tissues may atrophy

Question 18

A picomol is how many moles per litre?

Answer 18

10(to the -12)/ Litre

Question 19

A nanomol is how many moles to the litres?

Answer 19

10 (to the -9)/L

Question 20

A nanogram is …………… of a gram

Answer 20

1(to the -9) of a gram