Endocrine System and Cell Signalling

Question 1

What are the main functions of paracrine signalling?

Answer 1

• plays an important role in fetal development

- regulates gastrointestinal secretions and motility

Question 2

What are hormones?

Answer 2

chemical messengers that are carried in the blood to reach target organs

Question 3

Properties of hormones

Answer 3

• hormones act to enhance or inhibit cellular reactions
• hormones are present at low conc in blood
• hormones are specific

Question 4

4 main functions of hormones

Answer 4

1) regulate internal environments
2) control growth and development
3) help establish circadian rhythm
4) regulate operation of reproductive system

Question 5

3 structural classes of hormones and examples of them

Answer 5

1) amine - catecholamine, dopamine, thyroid
2) peptides and proteins - most hormones (eg insulin)
3) steroids - testosterone, aldosterone, estrogen`

Question 6

What are the major organs which metabolize hormones

Answer 6

kidney, liver

Question 7

What is the responsiveness of a target cell to a hormone dependent on? (3)

Answer 7

1) concentration of hormone in blood
2) the number of receptors available
3) the influence of other hormones

Question 8

What is a permissive effect between hormones

Answer 8

• action of one hormone requires action from another hormone

Question 9

What is the synergistic effect in hormones?

Answer 9

hormones have an accumulative effect on one another

Question 10

what is the antagonistic effect of hormones

Answer 10

effect of one hormone opposes the effect of another q

Question 11

What are the 3 main inputs which control hormone secretion?

Answer 11

• plasma concentration of ions or nutrients
• neural input to endocrine cells from the autonomic system
• other hormones (some hormones stimulate the secretion of another hormone )

Question 12

What is a tropic hormone?

Answer 12

a hormone which stimulates the secretion of another hormone

Question 13

in non-stressful situations, what is the role of cortisol? (3)

Answer 13

• regulate [hormones] involved in metabolic homeostasis
• change responsiveness of smooth muscle cells to epinephrine and norepinephrine
• has inhibition effects on inflammation and immune responses

Question 14

In stressful situations, what does cortisol do?

Answer 14

• inhibit inflammation, immune responses and non-essential functions
• improves cardiovascular performance
• increase ventilation
• triggers the breakdown (catabolism) of substances

Question 15

what substances are broken down during stressful situations

Answer 15

• protein is catabolised in liver, bones, lymph and others
• amino acids are broken down -> glucose @ liver (maintain plasma [glucose])
• lipids in adipose tissue -> fatty acid + glycerol

Question 16

What is the function of IGF-1 in the liver?

Answer 16

• stimulates glycogenesis and glucaneogenesis
• glycogen -> glucose
• increases [glucose] in liver cells
• gluc is then secreted into blood and plasma [glucose] increases

Question 17

What is the function of IGF-1 in adipose tissues?

Answer 17

• stimulates break down of lipids (triglyceride) -> fatty acids and glycerol
• provide a different energy source to cells

Question 18

What is the function of IGF-1 in the skeletal muscles?

Answer 18

• stimulates glycogenesis and lypolysis in muscles

- provide energy for muscle metabolism

Question 19

Describe Pathway of Thryroid Hormones

Answer 19

hypothalamus -> TSH
TRH -> anterior pituitary (portal vessel)
APG -> TSH -> thyroid glands
thyroxine + triiodothyronine produced
thyroxine (inactive )-> triiodothyronine (active)

Question 20

Function of thyroid hormones

Answer 20

• normal development of brain
• work with GH to stimulate growth in children
• stimulate glycogenesis and gluconeogenesis
• stimulate lipolysis and fatty acid oxidation
• increase heart rate and cardiac contractability (allow for a greater cardiac output and blood flow to tissues)
• increase metabolic rate -> increase body temperature
• high levels -> anxiety and nervousness

Question 21

Describe Pathway of cortisol

Answer 21

hypothalamus -> corticotropin releasing hormones (CRH)
CRH -> anterior pituitary (portal vessel)
APG -> adrenocorticotropin hormones -> adrenal cortex
cortisol is produced

Question 22

What is the pathway of cortisol

Question 23

what is the pathway of growth hormones

Question 24

what is the pathway of prolactin

Question 25

what is the pathway of female sex hormones

Question 26

what is the pathway of male sex hormones

Question 27

what is the pathway of vasopressin

Question 28

what is the pathway of oxytocin