The Endocrine System - Hormones (w9)

Question 1

What is neurotransmission and what is there chemical messenger ?

Answer 1

Nerve to nerve transmission
- uses noradrenaline , acetylcholine and others

Question 2

What is neuroendocrine communication and what is its chemical messengers ?

Answer 2

Nerve to target cell transmission
- uses oxytocin and ADH

Question 3

What is endocrine communication and what chemical messenger does it use ?

Answer 3

Secreting cell —> blood vessel —> target cell
- uses insulin, TSH, thyroxine and cortisol

Question 4

What is paracrine communication and what hormones does it use ?

Answer 4

Secreting cell —> target cells
- uses glucagon and somatostatins

Question 5

What is autocrine communication and what’s hormones does it use ?

Answer 5

Secreting cell —> secreting cell (released hormone can act on cell released from)
- uses prostaglandins

Question 6

What is the definition of a hormone ?

Answer 6

Hormones are chemical substances that act like messenger molecules in the body.

Question 7

What happens when a gland secretes a hormone ?

Answer 7

A gland secretes a hormone directly into the blood stream (ductless) this hormone is then carried to the target cells/ tissue (away from the endocrine gland)

Question 8

What is the chemical structure of a peptide hormone and give example of both short and large chains ?

Answer 8

• chemical structure: chain of amino acids
• short chain = TRH contains 3 amino acids
• large chain = LH/FSH contains 80 amino acids

Question 9

Where are peptide hormones secreted from ?

Answer 9

Hypothalamus, pituitary gland, pancreas and GIT (gastrointestinal tract)

Question 10

How are peptide hormones released and do they require a stimulus ?

Answer 10

Released via exocytosis
Require stimulus

Question 11

How are peptide hormones transported, what is a negative of the way they are transported ?

Answer 11

-They are hydrophilic so freely circulate in blood vessels.
-This means no plasma protein binding is required.
- a negative of this is they are easily destroyed due to no binding to proteins this causes them to have a shorter Half life (minutes)

Question 12

What is the chemical structure of a steroid hormone ?
Give examples and where they are secreted from …

Answer 12

Chemical structure = has a cholesterol base
- cortisol and aldosterone - secreted form adrenal cortex
- sex hormones - secreted from gonads

Question 13

How are steroidal hormones synthesized ?

Answer 13

• enzymatic conversion occurs of the precursor (cholesterol base) molecules into the hormones.
• these aren’t stored in cells.

Question 14

How are steroidal hormones transported ?

Answer 14

They are lipophilic so bind with plasma proteins. When they bind to these proteins they become inactive so need to be released to become active again.
- they have a Half lift of hours to days.

Question 15

What is the chemical structure of tyrosine containing hormones ?
Give an example of this hormone and where it is secreted from …

Answer 15

• chemical structure = contains a tyrosine base
• thyroid hormones and catecholamines —> secreted from the adrenal medulla

Question 16

How are tyrosine containing hormones released ?
Is a stimulus required ?

Answer 16

A stimulus is required
Released by simple diffusion across a membrane

Question 17

How are tyrosine containing hormones transported ?

Answer 17

-They are lipophilic
-They bind with the plasma proteins and form weak bonds, this means they are reversible so can easily unbind.
-Have a half life of hours to days

Question 18

What is the chemical structure of eicosanoid hormones ?
Give some examples of these hormones …

Answer 18

• chemical structure = a polyunsaturated fatty acid derivative
• examples = prostaglandins, leukotrienes, prostacyclin, thromboxane

Question 19

How are eicosanoid hormones released ?
Is a stimulus required ?

Answer 19

They are released by poorly diffusing through the cell membranes
They require a stimulus

Question 20

What is negative feedback ?

Answer 20

When the outcome negatively controls a process - maintains the original threshold/ tales levels back to normal or equilibrium.

Question 21

What is a positive feedback mechanism ?

Answer 21

When an outcome amplifies the process (the outcome is increased in comparison to normal levels)

Question 22

What is the correct receptor for a cortisol hormone ?

Answer 22

Glucocorticoid receptors

Question 23

What is the corresponding receptor for the aldosterone hormone ?

Answer 23

Mineralocorticoid receptor

Question 24

What classification of hormones is released form the pituitary gland ?

Answer 24

Peptide hormones

Question 25

What is hyper-secretion ? and give and example of an endocrine disorder caused by this ….

Answer 25

Hyper-secretion = hypothalamus/ glands are secreting too much of a hormone, resulting in there being an excess amount of a hormone.
E.g. ACTH or cortisol
Tumour or immunological factor e.g. Graves’ disease

Question 26

What is hyposecretion ? Give and example of an endocrine disorder caused by this …

Answer 26

Hyposecretion = the glands aren’t secreting enough or sufficient amounts of hormones, not enough hormone produced.
Type 1 diabetes Mellitus , genetic, immunological attack, surgical removal, destruction by disease

Question 27

What is a primary defect ?
Which hormones will you have more of ?

Answer 27

Any defect related to the peripheral endocrine gland
- low CRH and ACTH
- high cortisol

Question 28

What is a secondary defect ?
What hormones will be in excess/ have more of ?

Answer 28

-any defect related to the pituitary gland
- more CRH and cortisol

Question 29

What does ectopic mean ?

Answer 29

The defect is external to the hypothalamus pituitary axis (HPA axis)
- these defects are harder to diagnose