Physiology 1

Question 1

what is the endocrine system?

Answer 1

A system that controls organ function by secreting hormones from cells, tissues and glands that are carried in the BLOOD to DISTAL organs.

Question 2

What is a fast hormone-organ response?

Answer 2

The secretion of adrenaline by the adrenal glands - heart rate raises quickly.

Question 3

What is a slow hormone-organ response?

Answer 3

Secretion of the human growth hormone increases protein synthesis over days-weeks.

Question 4

what is a hormone?

Answer 4

A chemical secreted by a cell, tissue or gland that travels through the BLOOD and has a DISTAL site of action.

Question 5

What is the importance of hormone receptors?

Answer 5

Only organs with the specific hormone receptor will respond to the hormone in the blood. If they don’t have the correct receptor, they will ignore the hormone.

Question 6

What is a neurotransmitter?

Answer 6

This is a chemical released by a NERVE - it crosses a SYNAPSE (doesn’t travel through the blood). It has a LOCAL site of action.

Question 7

When do the endocrine and nervous system work together?

Answer 7

To provide long-term phenomena - like growth.

Question 8

What is a neuroendocrine hormone?

Answer 8

A chemical released by NERVOUS TISSUE that travels through the BLOOD. It has a distal site of action.

Question 9

what is an example of a neuroendocrine tissue?

Answer 9

The hypothalamus - it is in the brain (nervous tissue) BUT its secretions travel through the BLOOD to a DISTAL site of action.

Question 10

What effect does insulin have on. skeletal/adipose tissue?

Answer 10

It stimulates glucose uptake.

Question 11

What effect does insulin have on the liver?

Answer 11

It stimulates glycogenesis and inhibits gluconeogenesis.

Question 12

Which glands have purely endocrine function?

Answer 12

Thyroid, adrenal, pituitary, hypothalamus.

Question 13

How do clinicians monitor hormone activity?

Answer 13

Over 24 hours - because its released in short bursts.

Question 14

What concentration of hormones is needed?

Answer 14

10^-9 - 10^-12 Molar.

very small

Question 15

What is the difference between endocrine and exocrine glands?

Answer 15

exocrine glands delivery their secretion into the external environment. Endocrine glands release hormones into the blood - they are always ductless.

Question 16

what is a peptide/protein hormone?

Answer 16

composed of amino acid chains. They are stored in vesicles. They are water soluble and non fat - they travel through the cell using GPRC or tyrosine kinase.

Question 17

What do the GPCR protein hormones produce?

Answer 17

Fast response.

These influence ion channels on the cell surface.

Question 18

What does tyrosine kinase protein receptor produce?

Answer 18

Slower response. Kinase is also an enzyme which phosphorylates proteins - causing a change in cell behaviour.

Question 19

What is C-peptide?

Answer 19

It is an inactive fragment of the amino acid. Produced with insulin. It is still released into the blood and can be measured.

Question 20

How and why is C-peptide measured?

Answer 20

Its measured in the plasma or urine. - to measure pancreatic function.

It is useful to measure because it shows levels of human produced insulin (which will be the same level as the C-peptide) - because insulin can’t be measured as it is given synthetically to type 1 diabetics. - so measuring its levels are not accurate.

Question 21

How are peptide proteins transported into the cell?

Answer 21

They are lipophobic - need to bind to a cell surface receptor. Either G-protein coupled receptor or tyrosine kinase.

Question 22

What are amine hormones?

Answer 22

These are derived from the amino acid tyrosine or tryptophan.

Question 23

What is the only amine hormone produced from tryptophan?

Answer 23

Melatonin. - it regulates the circadian rhythm.

Question 24

What are the two classes of amine hormones?

Answer 24

Catecholamines - similar to peptide hormones (hydrophilic and lipophobic).
Thyroid hormones - similar to steroid hormones - lipophilic and hydrophobic.

Question 25

What is storage like for all amine hormones?

Answer 25

All amine hormones are synthesised and stored before use.

Question 26

What are steroid hormones?

Answer 26

these are derived from cholesterol. These are NOT produced before use. They are hydrophobic and lipophilic. They are transported through the plasma using carrier proteins.

Question 27

What is the most common carrier protein for steroid hormones?

Answer 27

Albumin.

It helps steroids travel through the plasma and it prevents enzyme degradation.

Question 28

What is the half life of steroid hormones?

Answer 28

60-90 minutes.

Question 29

What is the half life of amine hormones?

Answer 29

2 minutes.

Question 30

Why is the half life of steroid hormones longer?

Answer 30

They have a slower onset of action. They are also only synthesised as and when needed. Their half life is protected by carrier proteins.

Question 31

Where are steroid hormones produced?

Answer 31

Gonads - sex steroids.
Placenta - hCG, sex steroids.
Kidney - Vitamin D3.
Adrenal cortex - corticosteroids.

Question 32

where are steroid receptors located?

Answer 32

They are located INSIDE the cell. Because steroids easily cross the plasma membrane.

Question 33

What happens when steroids receptor are activated?

Answer 33

Genomic effect - There is a change in gene expression at the nucleus. This either increases or decreases protein synthesis.

Question 34

How long do steroids take to have an effect?

Answer 34

Hours to days.

Question 35

What is the law of mass action?

Answer 35

As free (unbound) protein leaves the plasma (taken into the cell), more hormone is released from carriers. - there’s always a reservoir.

Question 36

Bound hormone : Unbound hormone ratio.

Answer 36

There is always more hormone bound to carriers than hormones free in the plasma.

Question 37

What is another carrier protein?

Answer 37

Albumin or corticosteroid-binding globulin.