HORMONAL COMMUNICATION

Question 1

What is a hormone

Answer 1

Chemical messenger:

• secreted from endocrine gland directly into bloodstream
• occurs due to changes in concentration of a substance
• travel in blood plasma, carry signal from endocrine gland to specific target
• bind to specific target cells

Question 2

What are endocrine glands

Answer 2

Group of cells, secrete hormones directly into blood capillaries (no ducts)
E.g. pancreas, adrenal glands

Question 3

What are exocrine glands

Answer 3

Secretes molecules (not hormones) into ducts 
E.g. saliva, bile, digestive, enzymes

Question 4

What are examples of non-steroid hormones

Answer 4

POLAR
E.g. adrenaline, insulin, ADH
First messengers

Question 5

Explain what is meant by first messenger

Answer 5

Non-Steroid hormones
Bind to receptor on cell surface membrane, releases second messenger inside the cell
Often act via G protein in the membrane

Question 6

Explain what is meant by a second messenger

Answer 6

Stimulate a change in the activity of the cell
In many cases, enzyme adenylyl cyclase is an effector molecule that converts ATP into cyclic AMP
May activate enzyme controlled reactions

Question 7

Examples of steroid hormones

Answer 7

NON POLAR

E.g. oestrogen, testosterone

Question 8

What are steroid hormones

Answer 8

Hydrophobic- can dissolve in hydrophobic region of phospholipid (simple diffusion)

Question 9

Explain a steroid hormone

Answer 9

Passes directly through cell surface membrane and binds with specific receptor in the cytoplasm
This complex enters nucleus of the cell and acts as transcription factor on DNA
Either promotes or inhibits transcription of gene

Question 10

Where are the adrenal glands located

Answer 10

Just above kidneys

Divided into outer adrenal cortex and inner adrenal medulla

Question 11

How many layers are in the adrenal cortex

Answer 11

3

All secreting steroid hormones

Question 12

What hormone does the first layer of the adrenal cortex secrete and what is its function

Answer 12

Mineralocorticoids
E.g. aldosterone
Controls levels of Na+ and K+ in the blood
Increases absorption of Na+ and decrease for K+
Maintains blood pressure

Question 13

What hormone does the second layer of the adrenal cortex secrete and what is its function

Answer 13

Glucocoticoids
E.g. cortisol
Released in response to stress or low blood glucose levels
Regulates immune response

Question 14

What hormone does the third layer of the adrenal cortex secrete and what is its function

Answer 14

Androgens

E.g. precursors for sex hormones

Question 15

What does the adrenal medulla secrete

Answer 15

Non steroid hormones

Question 16

What hormones are secreted by the adrenal medulla

Answer 16

Adrenaline and noradrenaline (fight or flight)

Question 17

Function of adrenaline

Answer 17

Increases heart rate, increase blood glucose (glycogen broken dow. in liver)

Question 18

Function of noradrenaline

Answer 18

Works with adrenaline in response to stress, producing effects of an increased heart rate, increases blood pressure

Question 19

When are hormones in the medulla secreted

Answer 19

When the sympathetic nervous system is stimulated

In response to stress

Question 20

What is the exocrine function of the pancreas

Answer 20

Location- acinus (cells found in groups surrounding. tubules)
Details- pancreatic juice released from cells and secreted into tubules at centre of group. Join to form interlobular ducts which join to from pancreatic ducts, joins to duodenum

Question 21

Endocrine function of the pancreas

Answer 21

Location- Islets of Langerhan- group of cells in pancreas
Details- alpha cells produce glucagon, beta cells produce insulin
Hormones secreted directly into blood stream

Question 22

What is diabetes

Answer 22

Where someone is unable to metabolise carbohydrates properly, particularly glucose

Question 23

Symptoms of diabetes

Answer 23

Extreme fatigue
Blurry vision
Weight loss

Question 24

Explain hypoglycaemia

Answer 24

Mild- tiredness and irritability
Severe- impairment of brain function and confusion, could lead to seizures, unconsciousness
Decreased blood glucose concentration

Question 25

Details of type 1 diabetes

Answer 25

Unable to produce insulin (B-cells on isle of Langerhan dent produce insulin) Cannot be prevented or cures, treatment available Can arise as result of an autoimmune disease

Question 26

Details of type 2 diabetes

Answer 26

Cannot effectively use insulin and control blood sugar levels Either because: 1. B-cells don't produce enough insulin 2. Cells don't respond properly to insulin Therefore cells lose responsiveness to insulin so cannot take up enough glucose, leaving it in bloodstream Result of obesity and decreased physical activity

Question 27

Treatment for type 1

Answer 27

Regular injections of insulin Regularly test blood glucose levels Increased insulin= increased glucose absorbed by cells

Question 28

Treatment for type 2

Answer 28

Match carbohydrate level to exercise level Over weight people encouraged to lose weight Drugs- stimulate insulin production

Question 29

What is hyperglycaemia

Answer 29

Permanent high glucose concentrations can lead to organ damage

Question 30

Advantages go using GM bacteria to produce insulin

Answer 30

Human insulin produced in pure form |(|decreased chance of causing allergic reaction) Insulin produced in higher quantities Production costs are cheaper

Question 31

Potential use of stem cells in diabetes treatment

Answer 31

``` Totipotent stem cells have potential to grow into any type of body cells Stem cells would be taken from embryos (potential human life) // embryos used would have been destroyed as 'spare' embryos from infertility treatment ]= ```

Question 32

Benefits of stem cells treatment

Answer 32

Small no. of embryos used for lots of Px Px don't need to inject insulin Decreased chance of rejection from transplant

Question 33

Regulation of insulin levels (beta cells)

Answer 33

1. K+ channels on plasma men open, K+ diffuses (facilitated) out, giving resting mem potential of -70mV 2. glucose enters cell through glucose transporter proteins when levels are high 3. glucose phosphorylated by enzyme glucokinase. Metabolised by ATP 4. K+ channels close when ATP levels are too high 5. K+ cannot diffuse out= mem potential= -30mV 6. V-gated Ca2+ channels open in response to mem potential change, Ca2+ enter cell 7. Ca2+ cause vesicles containing insulin move and fuse with mem, release insulin EXOCYTOSIS

Question 34

Similarities between release of insulin from beta cells and transmission of nerve impulse

Answer 34

V-gated calcium channels Vesicles -70mV resting potential Exocytosis

Question 35

Differences between release of insulin from beta cells and transmission of nerve impulse

Answer 35

Different enzymes | Insulin released into bloodstream =, acetylcholinesterase into synapse

Question 36

Response to high glucose levels

Answer 36

Beta cells Insulin secreted Targets all cells Increases glucose transporter proteins on mem Glycogensis- glucose converted to glycogen in liver Glucose converted into fats Glucose for respiration

Question 37

Response to low blood glucose levels

Answer 37

Alpha cells Glucagon sevcreted Targets liver and fat cells Glycogenolysis- glycogen-> glucose in liver + released into bloodstream Gluconeogenesis- amino acids + glycerol converted into glucose in the liver Fatty acids used in respiration

Question 38

What are insulin and glucagon

Answer 38

Antagonistic- have opposite effects on glucose concentrations Inhibit effects of opposing hormone