Endocrine System 1&2

Question 1

What are examples of local signalling?

Answer 1

Paracrine - bind to neighbour cell

Autocrine - bind to self

Question 2

In the pancreas. there are 2 lobes. What is the structure of the exocrine pancreas?

Answer 2

Cells arranged into acini and ducts, produce digestive enzymes
Across acini are islets of Langerhans

Question 3

What are the 4 types of islets of Langerhans? WHat do they produce?

Answer 3

A - glucagon
B - insulin
Delta - somatostatin
F - pancreatic polypeptides

Question 4

What is the prohormone for insulin? What needs to happen to it before it is active?

Answer 4

Proinsulin

Inactive c protein removed

Question 5

Is insulin water soluble or fat soluble? Which receptor does it bind to?

Answer 5

Water soluble

Tyrosine kinase

Question 6

How do B cells directly detect an increase in blood glucose?

Answer 6

Glucose enters cell via GLUT2
Fuels ATP formation
ATP sensitive K+ channels are blocked
K+ accumulation leads to depolarisation
Opens voltage gated calcium channels
Calcium causes exocytosis of insulin

Question 7

Insulin is controlled by which GI hormones?

Answer 7

GIP & GLP - released before absorption

Question 8

Cellular uptake of glucose is independent of insulin in which parts of the body?

Answer 8

Brain
Mammary tissue
GI
Kidney tubules

Question 9

How does insulin enter a cell?

Answer 9

Second messenger model

Alters proteins, modifies membrane transport

Question 10

Glucose leaves cell by which transporter? (Insulin increase number of these)

Answer 10

GLUT4

Question 11

When fasted, hepatocytes make glucose-and transport it. When fed they also enter cells using which transporter?

Answer 11

GLUT2

Question 12

Insulin stimulates the conversion of glucose to glucose-6-phosphate inside cells. Which enzyme does this? Why is this important?

Answer 12

Hexokinase

Maintains conc gradient - allows more glucose to enter cell

Question 13

What is different about cells in the CNS?

Answer 13

They are not sensitive to insulin

But rely on glucose metabolism - they can’t metabolise fats etc

Question 14

Why can hyperglycaemia be fatal?

Answer 14

XS glucose in CSF
Draws water out of cells
Causes dehyrdation

Question 15

What is glucagon?

Answer 15

Hormone stored in active form

Question 16

How does insulin decrease glucose concentration?

Answer 16

Causes insertion fo GLUT4 into membranes

Question 17

Is glucagon water or lipid soluble? Which protein does it bind to?

Answer 17

Water soluble

Specific G protein receptor

Question 18

WHen is glucagon released?

Answer 18

After meal due to AA increased

Question 19

What is somatostatin? Is it paracrine or autocrine?

Answer 19

Growth inhibiting hormone

Inhibits insulin and glucagon

Question 20

What is type 1 and type 2 diabetes melltius?

Answer 20

Inadequate secretion of insulin

Inadequate response to insulin

Question 21

Why does hyperglycaemia cause weight loss?

Answer 21

Decreased protein synthesis

Muscles are broken down

Question 22

What causes polydypsia? How?

Answer 22

Glucosuria
Causes water to be draw into nephron
Dehydration stimulates osmoreceptors in hypothalamus

Question 23

Where is calcium found in the body? Give %

Answer 23

99% bone

1% ECF/ICF

Question 24

Is calcium mainly intracellular or extracellular? Why?

Answer 24

Extracellular - used in cell excitation

Question 25

What activates vitamin D3? What does this vitamin do?

Answer 25

UV and kidneys | Increase calcium int he blood

Question 26

What does calcitriol do? Which hormone stimulates its production? What solubility is it?

Answer 26

Increases calcium absorption in kidneys Metabolises bone Stimulated by parathyroid hormone Lipid soluble.

Question 27

Why is lots of calcium used in late pregnancy?

Answer 27

Mammary glands - milk production | Mineralisation of foetal skeleton

Question 28

What affect does kidney failure have on calcium and phosphorus?

Answer 28

Retained phosphorus | Decreased vitamin D - decreased calcium

Question 29

What does calcitonin do? Where is it produced? Is it essential?

Answer 29

Decreases calcium - targets osteoclasts/GI secretion Thyroid (parafollicular cells) Not in vertebrates

Question 30

How many glands are there in the parathyroid? Where are they found?

Answer 30

2 | Lobes of thyroid

Question 31

Which cells make parathyroid hormone?

Answer 31

Parathyroid Chief cells

Question 32

How does parathyroid hormone cause calcium increase?

Answer 32

Causes release of calcitriol

Question 33

Parathyroid hormone is produced by some cancers. What does this lead to?

Answer 33

Hypocalcaemia

Question 34

Most phosphorus is found in the bone. What is it bound as?

Answer 34

Hydroxyapatite

Question 35

How is inorganic and organic phosphorus found?

Answer 35

Inorganic - ions | Organic - ATP, phospholipids, nucleotides

Question 36

WHat is milk fever? What are the symptoms and whY?

Answer 36

Parturition hypocalcaemia Recumbency, rumen stasis, bloat, pupil dilation, neck kink Due to poor smooth muscle contractio

Question 37

Why are older cows more prone to milk fever than younger ones?

Answer 37

Younger cows - bone remodelling provides calcium | Older cows - skeleton non mobile

Question 38

What is hypocalcaemia tetany? Which species is it found in?

Answer 38

Lack of calcium causing repeated firing of skeletal muscle - shaking Lactating pigs/bitches