Hormonal Communication

Question 1

The endocrine communication system uses hormones as signalling molecules: what is the process of this system

Answer 1

1. Secretion (production & release) of hormones into the bloodstream
2. Hormones transported by blood
3. Hormone detected by target cells / tissues / organs

Question 2

How do endocrine hormones move vs exocrine ones

Answer 2

Secreted directly into the blood versus secreted via a duct

Question 3

What are the 2 types of hormones

Answer 3

Protein (non steroid) & steroid

Question 4

Protein (non-steroid hormones) Vs Steroid hormones

Answer 4

Question 5

How do hormones work on target cells / tissues

Answer 5

• specific receptor on cell-surface membrane
  (Receptor made of glycoproteins)
  -> complementary to shape of hormone molecule
  -> hormone binds to receptor & changes initiated in the cells

Question 6

1st vs 2nd messenger

Answer 6

Question 7

How is the second messenger activated process

Answer 7

1. 1st non steroid messenger binds to receptor on cell surface membrane
2. G protein activated
3. Adenyl cyclase - effector molecule - activated
4. ATP converted to cAMP (2nd messenger)
5. cAMP acts directly on another protein (e.g, ion channel) or may initiate a cascade of enzyme controlled reactions, which alter cell activity

Question 8

What organ functions as an endocrine and exocrine gland

Answer 8

The pancreas

Question 9

Exocrine function of pancreas

Answer 9

-> secrete pancreatic juices into pancreatic duct (delivered to small intestine)

Pancreas juices made up of
- digestive enzymes (amylase, trypsin, lipase)
- sodium hydrogencarbonate (neutralises contents of digestive system, which has left the acidic stomach)

Question 10

Endocrine function of pancreas

Answer 10

• secrete hormones from the islets of langerhans
  + endocrine tissues are made up of these islets
  -> alpha & beta cells are found in these island

Question 11

Alpha vs beta cells in pancreas

Answer 11

Question 12

Key processes in Pancreas (glycogenolysis, glycogenesis, gluconeogenesis, lipogenesis)

Answer 12

Question 13

What does glucagon do

Answer 13

• stimulate glycogenolysis
• stimulate gluconeogenesis
  # released if blood glucose concentration too low
  -> glucose conc in blood increases, as glucose conc in cell e.g. muscles / hepatocytes increases

Question 14

What does insulin do

Answer 14

• released if blood glucose too high
• stimulates glycogenesis
  -glucose concentration of cells e.g. muscles / hepatocytes decreases therefore in blood decreases

Question 15

What mechanism regulates blood glucose conc (normally 4-6 mol/dm3)

Answer 15

Negative feedback
This is as it’s insulin versus glucagon (antagonistic as they have the opposite effects)

Question 16

What happens in hypoglycaemia & how is it detected (when too low blood glucose conc)

Answer 16

When not enough glucose is delivered to the body tissues & brain
This can lead to seizures, unconsciousness / death

-> detected in alpha cells in the islet of langerhans
Glucagon is secreted into bloodstream
Receptors on the outside of hepatocytes & muscle cells detect glucagon
-> activates gluconeogenesis, glycogenolysis & decreased rate of respiration
-> concentration of glucose in cells increases and so concentration of glucose in blood increases as glucose diffuses into blood from cells

Question 17

What happens in hyperglycaemia& how is it detected (when too high blood glucose conc)

Answer 17

-> detected by beta cells in the islet of langerhans
- insulin secreted into the bloodstream!
- receptors on outside of hepatocytes & muscle cells detect insulin
- activates glycogenesis & increased rate of respiration & lipogenesis

Glucose concentrate decreases in cells & blood as glucose diffuses into cells from blood, down the concentration gradient by facilitated diffusion

Question 18

Mechanism of insulin secretion

Answer 18

Question 19

What ion channels are open & closed @ a normal blood glucose level

Answer 19

• ca2+ closed
• K+ open

Question 20

How is insulin secrete when BGC is high (steps)

Answer 20

1. Glucose molecules move into the beta cells by a glucose transported
2. Glucose metabolised in mitochondria via glucokinase to form ATP
3. Extra ATP binds to K+ channels & causes their closure
4. K+ can’t diffuse out of cell / builds up / inside less negative / P.D reduced / depolarised membrane
5. Voltage gated Ca2+ ion channels open
6. Ca2+ enter cells
7. Secretion of insulin (vesicles contains it move towards & fuse with the cell surface membrane)
8. Insulin released by Exocytosis

Question 21

Insulin action in hepatocytes

Answer 21

Question 22

Glucagon action to do with hepatocytes

Answer 22

Question 23

Type 1 diabetes (insulin dependent) cause
& typical onset

Answer 23

• in childhood
  Cause = autoimmune response or viral infection, in which the immune system destroys beta cells OR physical trauma

Question 24

Type 1 diabetes symptoms

Answer 24

Weight loss (less glucose converted into glygogen, lipids etc & stored - lost in urine instead)
More urine produced (less water reabsorbed in the collecting duct, due to high glucose conc

Question 25

Effects of type 1 diabetes on the body

Answer 25

- insulin can no longer be synthesised by beta cells in the pancreas to control blood glucose concentration - excess glucose can’t be stored as glycogen - excess glucose not removed quickly: prolonged periods of high b.g.c. especially after meals -> no store of glycogen, which can be used to release glucose -> blood g.c. falls too low

Question 26

Type 1 diabetes: typical treatment vs in severe cases vs potential treatments

Answer 26

Question 27

Type 2 diabetes (non-insulin dependent) onset & causes?

Answer 27

Over 40, but many children getting it now Beta cells still produce insulin, but it’s ineffective -> specific receptors on cell surface membrane of liver & muscle cells = less responsive to it - cells lose ability to respond to insulin in blood

Question 28

Risk factors for type 2 diabetes

Answer 28

- obesity - lack of regular exercise - high blood pressure & cholesterol - ethnicity (Asian & Afro-Caribbean) - family history

Question 29

Type 2 diabetes: typical vs severe treatment

Answer 29

Question 30

Alternate insulin sources & evaluation of them?

Answer 30

1. Pig Insulin ( 🐷 pancreas = matches human close, but some = ethical or religious objections) 2. Genetically modified bacteria producing insulin

Question 31

Adrenal glands structure

Answer 31

Question 32

What does the adrenal cortex secrete

Answer 32

Mineralcorticoids like aldosterone Glucocorticoids like cortisol - precursor androgen molecules, which are used to make sex hormones like testosterone & oestrogen

Question 33

What does aldosterone regulate

Answer 33

Levels of sodium & potassium & water balance in blood, which impacts blood volume & pressure by targeting the collecting duct

Question 34

What does cortisol, the primary stress hormone regulate

Answer 34

Released in response to stress & low B.G.C -> regulates metabolism of glucose, fats & proteins -> releasing usable energy -> stimulates production of glucose from stored compounds: glycogen, fats & proteins in the lvier

Question 35

What do sex hormones do

Answer 35

Help development of secondary sexual characteristics & regulate production of gametes

Question 36

What does the adrenal medulla secrete

Answer 36

- adrenaline & noradrenaline

Question 37

Effects of adrenaline

Answer 37

Increases breathing rate not heart rate

Question 38

Effects of noradrenaline

Answer 38

- works with adrenaline in response to stress Increases heart rate Widens pupils Widens air passages in lungs Narrow blood vessels in non-essential organs (so higher blood pressure)

Question 39

When is adrenaline produced & how does it work

Answer 39

Produced @ times of stress of excitement: prepares the body for activity & to respond to emergency situations (fight/flight) -> binds to specialised adrenaline receptors on cell-surface membrane of target cells (many cells & tissues have adrenaline receptors)