5.1.4 - Hormonal Communication

Question 1

Exocrine gland

Answer 1

A gland that secretes their products into a duct that carries the molecule to where they are used

Question 2

Endocrine gland

Answer 2

A ductless gland that secretes hormones directly into the blood

Question 3

Examples of endocrine glands

Answer 3

Pituitary
Adrenal
Pancreas

Question 4

Examples of exocrine glands

Answer 4

Mammary
Gastric
Salivary
Pancreas

Question 5

Why is the pancreas both endo/exocrine

Answer 5

Releases hormones e.g. insulin and glucagon directly into the blood stream but also releases digestive enzymes e.g. trypsin into ducts

Question 6

What does the pituitary gland secrete

Answer 6

TSH
LH
ADH

Question 7

What does the adrenal gland secrete

Answer 7

Adrenaline

Question 8

Types of hormones

Answer 8

Lipid soluble hormones (steroid hormones)

Peptide hormones

Question 9

What are steroid hormones derived from

Answer 9

Cholesterol

Question 10

Hormones released by cortex of adrenal glands

Answer 10

Mineralocorticoids
Glucocorticoids
Androgens
Vital to life e.g. cortisol and aldosterone

Question 11

What do mineralocorticoids do

Answer 11

Help control the conc. of minerals e.g. aldosterone

Question 12

What do glucocorticoids do

Answer 12

Help control the metabolism of carbs and proteins

Question 13

Adrenal Medulla

Answer 13

Manufacture and release non- essential hormones e.g. dopamine and adrenaline

Question 14

Why must hormone target cells have spp receptors on their csm

Answer 14

So that the correct hormone can bind and no other molecule will be able to bind and have the same effect

Question 15

First vs. second messengers

Answer 15

1st bind to csm and have an effect by activating a 2nd messenger, this is what actually affects the activity of the cell

Question 16

Why are steroid hormones able to enter the cell

Answer 16

Interacts w/ phospholipid bilayer and dissolve as they are lipid soluble

Question 17

How do hormones act as secondary messengers

Answer 17

Hormones bind to spp cell surface receptor
Stimulates production of a messenger molecule e.g. cAMP
cAMP activates or inhibits enzyme pathways

Question 18

How do hormones act as gene activators

Answer 18

Hormone permeates any membrane
Binds to intracellular receptor
Hormone-receptor complex is mobilised toward nucleus
Complex binds to spp regions of DNA
Leads to increase/decrease in translation -> protein synthesis

Question 19

Endocrine part of the pancreas

Answer 19

Islets of Langerhans
alpha cells secrete glucagon
beta cells secrete insulin
INTO bloodstream

Question 20

Exocrine part of pancreas

Answer 20

Pancreatic acini

Secretes digestive enzymes INTO DUCT which drains into the pancreatic duct which empties in duodenum

Question 21

What does insulin act on

Answer 21

Hepatocytes
Muscle cells
Adipose tissue
Brain cells

Question 22

When is insulin secreted

Answer 22

When blood glucose conc is too high

Question 23

How does insulin work

Answer 23

Binds to receptors which activate a second messenger system

Question 24

What does insulin do

Answer 24

Increase glucose uptake into cells by facilitated diffusion
Increase respiration rate (glycolysis)
Glycogen conversion (glycogenesis) in hepatocytes and muscle cells
Lipogenesis

Question 25

What does glucagon work on

Answer 25

`Hepatocytes and muscle cells | Has spp receptors

Question 26

When is glucagon secreted

Answer 26

When blood glucose is too low

Question 27

What does glucagon do

Answer 27

Glycogen breakdown (glycogenolysis) Decrease glucose uptake Converting fatty acids and amino acids to glucose (gluconeogenesis)

Question 28

Normal glucose conc

Answer 28

4-6 mmol dm3

Question 29

When blood glucose conc rises

Answer 29

Detected by beta cells in islets of Langerhans Secretes more insulin Hepatocytes and muscle cells remove glucose from blood and convert to glycogen (glycogenesis) Blood glucose falls -ve feedback

Question 30

When blood glucose conc falls

Answer 30

Detected by alpha cells in islets of Langerhans Pancreas secretes more glucagon Hepatocytes and muscle cells convert glycogen to glucose and release it in to bloodstream (glycogenolysis) Blood glucose conc rises -ve feedback

Question 31

Describe how insulin secretion is controlled

Answer 31

VG K+ channels in plasma membrane open and K+ diffuses out of beta cell and inside has pd of -70 Blood glucose conc. increases and glucose enters cell Glucose is phosphorylated then metabolised to form ATP Presence of extra ATP causes ligand-gated K+ channels to close K+ cannot diffuse out so membrane potential reduces to only -30 VG Ca2+ open to response in change in membrane potential - Ca move in Ions cause vesicles to release insulin (exocytosis) into bloodstream

Question 32

Processes that lower blood glucose

Answer 32

Glycolysis Glycogenesis Lipogenesis

Question 33

Processes that increase blood glucose conc

Answer 33

Gluconeogenesis | Glycogenolysis

Question 34

Causes of type 2 diabetes

Answer 34

``` Obesity Poor diet Insufficient exercise Diet high in sugar Genetics ```

Question 35

Insulin resistance

Answer 35

Symptom of Type 2 diabetes | When the body doesn't respond to insulin

Question 36

Hyperglycaemia

Answer 36

High blood glucose

Question 37

What can long-term hyperglycaemia lead to

Answer 37

Modification of diff proteins e.g. collagen in blood vessels --> angina and heart failure Also affects peripheral nerves (poor blood circulation)

Question 38

Causes of Type 1 diabetes

Answer 38

Majorly genetically linked but environmental factors such as an infection which causes the immune system to destroy beta cells w/ similar antigens

Question 39

Hypoglycaemia

Answer 39

Excessive, abnormal thirst Frequent urination Tiredness Glucose is excreted in urine instead of being used in body

Question 40

Why are Type 1 diabetics frequently dehydrated

Answer 40

Glucose increases osmolarity so more water is lost in urine

Question 41

How does the metabolism of a Type 1 diabetic adapt

Answer 41

More glycogenolysis and gluconeogenesis occurs | Body produces ketones and fatty acids for respiration, increases acidity of blood

Question 42

Treatment for diabetes

Answer 42

Insulin injection Insulin pump Islets of Langerhans transplant (donors must match ) Exercise --> decreases insulin resistance Drugs when diet therapy fails

Question 43

Why are the islets of Langerhans surrounded in an extensive network of blood vessels

Answer 43

Shorter diffusion distance for glucose inthe blood

Question 44

Where is glycogen stored

Answer 44

In muscle and liver tissue

Question 45

What is gluconeogenesis a result of

Answer 45

Fasting Starvation Stress

Question 46

Which hormones stimulate gluconeogenesis

Answer 46

Adrenaline and glucocortoids

Question 47

Advantages of using insulin from genetically modified bacteria

Answer 47

Exact copy of human insulin, faster and more effective Less chance of develpoing tolerance to insulin Lower chance of rejection Lower risk of infection More ethical

Question 48

Why cant insulin be taken orally

Answer 48

Insulin is a protein and if taken orally cannot be reabsorbed into the bloodstream during ultrafiltration at glomerulus

Question 49

Why is there a delay in the increase of insulin conc following increases in blood glucose conc

Answer 49

Increase has to be detected by beta cells | Takes time depolarise beta cells and release insulin

Question 50

How does increased heart rate raise blood pH

Answer 50

Removes more CO2 and in turn makes the blood less acidic | Prevents cell damage

Question 51

Where do hormones travel in the blood

Answer 51

Blood plasma

Question 52

Tissue that secretes glycogen and insulin

Answer 52

Pancreatic

Question 53

In which tissues are glucose removed from in response to insulin

Answer 53

Liver | Muscle

Question 54

Acini

Answer 54

Groups of cells arranged around a tiny ductule

Question 55

Function of aldosterone

Answer 55

Na+ reabsorption in the kidney Water reabsorption Control blood pressure