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OCR A level Biology > 5.1.4 - Hormonal Communication > Flashcards

5.1.4 - Hormonal Communication Flashcards

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1
Q

Exocrine gland

A

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

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2
Q

Endocrine gland

A

A ductless gland that secretes hormones directly into the blood

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3
Q

Examples of endocrine glands

A

Pituitary
Adrenal
Pancreas

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4
Q

Examples of exocrine glands

A

Mammary
Gastric
Salivary
Pancreas

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5
Q

Why is the pancreas both endo/exocrine

A

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

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6
Q

What does the pituitary gland secrete

A

TSH
LH
ADH

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7
Q

What does the adrenal gland secrete

A

Adrenaline

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8
Q

Types of hormones

A

Lipid soluble hormones (steroid hormones)

Peptide hormones

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9
Q

What are steroid hormones derived from

A

Cholesterol

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10
Q

Hormones released by cortex of adrenal glands

A

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

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11
Q

What do mineralocorticoids do

A

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

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12
Q

What do glucocorticoids do

A

Help control the metabolism of carbs and proteins

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13
Q

Adrenal Medulla

A

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

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14
Q

Why must hormone target cells have spp receptors on their csm

A

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

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15
Q

First vs. second messengers

A

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

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16
Q

Why are steroid hormones able to enter the cell

A

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

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17
Q

How do hormones act as secondary messengers

A

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

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18
Q

How do hormones act as gene activators

A

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

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19
Q

Endocrine part of the pancreas

A

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

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20
Q

Exocrine part of pancreas

A

Pancreatic acini

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

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21
Q

What does insulin act on

A

Hepatocytes
Muscle cells
Adipose tissue
Brain cells

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22
Q

When is insulin secreted

A

When blood glucose conc is too high

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23
Q

How does insulin work

A

Binds to receptors which activate a second messenger system

24
Q

What does insulin do

A

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

25
Q

What does glucagon work on

A

`Hepatocytes and muscle cells

Has spp receptors

26
Q

When is glucagon secreted

A

When blood glucose is too low

27
Q

What does glucagon do

A

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

28
Q

Normal glucose conc

A

4-6 mmol dm3

29
Q

When blood glucose conc rises

A

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

30
Q

When blood glucose conc falls

A

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

31
Q

Describe how insulin secretion is controlled

A

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

32
Q

Processes that lower blood glucose

A

Glycolysis
Glycogenesis
Lipogenesis

33
Q

Processes that increase blood glucose conc

A

Gluconeogenesis

Glycogenolysis

34
Q

Causes of type 2 diabetes

A 
Obesity 
Poor diet
Insufficient exercise 
Diet high in sugar 
Genetics
35
Q

Insulin resistance

A

Symptom of Type 2 diabetes

When the body doesn’t respond to insulin

36
Q

Hyperglycaemia

A

High blood glucose

37
Q

What can long-term hyperglycaemia lead to

A

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

38
Q

Causes of Type 1 diabetes

A

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

39
Q

Hypoglycaemia

A

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

40
Q

Why are Type 1 diabetics frequently dehydrated

A

Glucose increases osmolarity so more water is lost in urine

41
Q

How does the metabolism of a Type 1 diabetic adapt

A

More glycogenolysis and gluconeogenesis occurs

Body produces ketones and fatty acids for respiration, increases acidity of blood

42
Q

Treatment for diabetes

A

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

43
Q

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

A

Shorter diffusion distance for glucose inthe blood

44
Q

Where is glycogen stored

A

In muscle and liver tissue

45
Q

What is gluconeogenesis a result of

A

Fasting
Starvation
Stress

46
Q

Which hormones stimulate gluconeogenesis

A

Adrenaline and glucocortoids

47
Q

Advantages of using insulin from genetically modified bacteria

A

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

48
Q

Why cant insulin be taken orally

A

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

49
Q

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

A

Increase has to be detected by beta cells

Takes time depolarise beta cells and release insulin

50
Q

How does increased heart rate raise blood pH

A

Removes more CO2 and in turn makes the blood less acidic

Prevents cell damage

51
Q

Where do hormones travel in the blood

A

Blood plasma

52
Q

Tissue that secretes glycogen and insulin

A

Pancreatic

53
Q

In which tissues are glucose removed from in response to insulin

A

Liver

Muscle

54
Q

Acini

A

Groups of cells arranged around a tiny ductule

55
Q

Function of aldosterone

A

Na+ reabsorption in the kidney
Water reabsorption
Control blood pressure

OCR A level Biology (25 decks)

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