CTR - 9 - Endocrine

Question 1

What is an autocrine? Examples…

Answer 1

Chemicals which expert effects on the same cells which secrete them

Example: growth factors (cytokines, interleukins)

Question 2

What is a paracrine? Examples…

Answer 2

Locally acting chemicals which affect nearby cells.

Example: histamine, prostaglandins, growth factors, blood coagulation factors

Question 3

T or F? Cytokines can be endocrine, paracrine or exocrine.

Answer 3

True!

Question 4

Give an example of a primary lingered, agonist, and antagonist?

Answer 4

At NMJ:

Primary Ligand = acetylcholine
Agonist = nicotine
Antagonist = curare

Question 5

What is a primary ligand?

Answer 5

Chemical which has a physiological response on the receptor - activates a response from the receptor

Question 6

What is an agonist?

Answer 6

A chemical which activates a response from that receptor - but introduced (mimics primary ligand)

Question 7

What is an antagonist

Answer 7

Primary antagonist = physiological role to inhibit receptor

Drug molecule = similar binding entity (mimics primary antagonist)

Question 8

Define a hormone.

Answer 8

Chemical secreted by glands, travels through blood or lymph over long distances and act by binding to specific receptors on/in target cells to produce a response.

Question 9

Give some examples of amino acids based hormones.

Answer 9

Thyroxin, calcitonin, insulin, FSH, LH, TSH, glucagon, epinephrine, ACTH

Question 10

Where are steroid hormones released from? Synthesised from?

Answer 10

Gonads and adrenal cortex. Synthesised from cholesterol

Question 11

What are the three ways hormones can act on target cells

Answer 11

• Alter channel permeability (acts on pre-existing channels)
• Acts through second messenger system (alters pre-existing protein activity)
• Activate specific genes to cause formation of new proteins

Question 12

What are eicosonoids? Examples

Answer 12

Biologically active lipids - local, hormone like activity

Leukotrienes
Prostaglandins

Question 13

What three factors affect the strength of a hormonal response?

Answer 13

1 - blood levels of the hormone (rate of synthesis, release and elimination)

2 - relative number of receptors on target cell

3 - affinity of receptors for hormone

Question 14

How can receptor numbers be changed?

Answer 14

Up-regulation
- target cells form more receptors (when hormone levels are low

Down-regulation
- target cells lose receptors (when hormone levels are high)

Question 15

What are the three types of hormone interaction?

Answer 15

Permissiveness
Synergism
Antagonism

Question 16

What is permissiveness? example

Answer 16

One hormone cannot exert its effects without another hormone being present

Example: thyroid hormone is required for hypothalamic, pituitary and gonadal hormones for sexual development

Question 17

What is synergism? example

Answer 17

More than one hormone produces the same effects on a target cell, but the combined effect is greater than the sum of individual effects

Example: glucagon/adrenaline/cortisol act together to raise blood glucose

Question 18

What is antagonism? example

Answer 18

One or more hormones oppose the action of another hormone.

Example: insulin lowers blood glucose, glucagon raises blood glucose

Question 19

What are the three types of stimuli for hormonal release? What is each? Example.

Answer 19

Humoral stimuli (changing blood levels of ions/nutrients)
Example: low blood calcium stimulates PTH

Neural stimuli (nerve fibres stimulate hormone)
Example: neural stimulation of adrenal medulla releasing catecholamines

Hormonal stimuli (tropic hormones)
Example: hormones from hypothalamus stimulate anterior pituitary

Question 20

How are hormones removed?

Answer 20

Inactivation - via enzymatic activity
Degradation - (especially by liver)
Excretion (via kidneys)

Question 21

Why can urine tests be conducted for hormone levels?

Answer 21

Hormones are excreted by the kidney - into urine

Question 22

What effects can hormones have? (5)

Answer 22

Alter plasma membrane permeability
Stimulate protein synthesis (incl enzymes)
Activate/deactivate enzymes
Induce secretory activities 
Stimulate mitosis

Question 23

ACh binds to ________

Answer 23

cholingergic receptors

Question 24

NE binds to ________

Answer 24

adrenergic receptors

Question 25

What is muscle tone?

Answer 25

slightly constriction of blood vessels

Question 26

NE binding to alpha receptors ______

Answer 26

contracts smooth muscle = vasoconstriction

Question 27

NE binding to beta receptors _______

Answer 27

inhibits smooth muscle contraction = vasodilation (indirectly relaxes muscle)

Question 28

Beta receptors for muscle tone are more often found near __________

Alpha receptors for muscle tone are more often found near __________

Answer 28

Beta = the heart/vital organs. 
Alpha = non-essential tissues/organs