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Biology Alevel > Hormonal Communication > Flashcards

Hormonal Communication Flashcards

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1
Q

What are homeostatic mechanisms and what are the 3 key ones?

A

Help organism keep their internal body conditions near constant
3 key mechanisms :
- Thermoregulation - control body temp
- Osmoregulation - control WP of body fluids
Control blood glucose conc

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2
Q

What is a hormone?

A

Chemcial messenger produced by endocrine gland + carried by blood
- transmit info from 1 part of organisms to another /bring about change
Can alter activity of 1/more specific target organs

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3
Q

What functions do hormones control?

A

Functions that don’t need INSTANT responses

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4
Q

What is the endocrine system?

A

All the endocrine glands that produce hormones in animals

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5
Q

How are hormones transported around the body?

A

Endocrine glands have good blood supply so hormones are secreted into BLOODSTREAM
- then transported around body via blood to TARGET CELLS/TISSUES to bring about a response
- hormones bind to complementary receptors on cell surface membranes - GLYCOPROTEINS

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6
Q

What is the 1st/2nd messenger?

A

1st - hormone that brings the ‘info’ from the endocrine gland
- hormones don’t enter cells - they bind to receptors on cell surface membrane

2nd- causes effect inside cell

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7
Q

Structure and function of adrenal glands ?

A

Consist of CENTRAL MEDULLA + OUTER CORTEX
Cortex - Produce steroid hormones :
ALDOSTERONE - regulate salt levels (K and Na) /water balance of blood - impact blood volume/pressure
Cortisol - primary stress hormone , regulates metabolism of glucose,proteins,fats to release usable energy

Medulla: produce adrenaline -
produced at times of stress/excitement - prepare body to respond to emergency situations

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8
Q

Fucntion of pancreas?

A

Functions as ENDOCRINE GLAND and EXOCRINE gland
- endocrine secrete hormones directly into blood , exocrine secrete hormones VIA A DUCT

Exocrine function: produce pancreatic juice (contain digestive enzymes) to the SI to help digestion
Endocrine function : produce GLUCAGON/INSULIN

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9
Q

Which cells in pancreas carry out each function of pancreas?

A

Most cells SECRETE DIGSTIVE ENZYMES - exocrine
Small sections of cells - ISLETS of LANGERHANS- produce hormones - endocrine
Islets of langerhans has 2 cell types:
ALPHA- secrete glucagon
BETA - secrete insulin

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10
Q

What is histology and how can it be studied for the Pancreas?

A

Branch of biology that studies microscopic anatomy of biological tissues
- studied by staining sections of pancreatic tissue + viewing under microscope
- differential staining show exocrine/endocrine tissues in different colours
- can be drawn/labelled

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11
Q

Factors effecting blood glucose conc?

A

3 ways glucose can enter blood:
ABSORPTION in gut after carbs digestion
Hydrolysis of glycogen stores
Non-carbs (lipids,lactate,amino acids) converted to glucose - gluconeogenesis

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12
Q

Why is too high/low blood glucose conc harmful?

A

TOO LOW: not enough glucose for respiration / not able to function normally
TOO HIGH: can disrupt normal function of cells

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13
Q

Response to decrease in blood glucose conc?

A

Detected by alpha/beta cells in pancreas
α cells - secrete glucagon
β cells - stop secretion of insulin
Decrease in blood insulin concentration - reduces use of glucose by liver/muscles cells

Glucagon binds to receptors in the CSM of liver cells
- binding causes conformational change in receptor protein that activates a G protein
- activated G protein activates the enzyme adenylyl cyclase
Active adenylyl cyclase catalyses the conversion of ATP —> cyclic AMP (cAMP) - 2nd messenger
cAMP binds to protein kinase A enzymes, activating them
Active protein kinase A enzymes activate phosphorylase kinase enzymes - adds phosphate groups to them
Active phosphorylase kinase enzymes activate glycogen phosphorylase enzymes
Active glycogen phosphorylase enzymes catalyse the breakdown of glycogen to glucose
KNOWN AS GLYCOGENOLYSIS

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14
Q

How does adrenaline also increase blood glucose concentration?

A

Binds to different receptors on surface of liver cells that activate SAME ENZYME CASCADE + leads to same end result (breakdown of glycogen)
- also stimulate breakdown of glycogen stores in muscle DURING EXERCISE - glucose produced remains in muscles cells for respiration

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15
Q

Response to increase in blood glucose conc?

A

DETECTED BY β cells in the pancreas
- glucose molecules enter β cells by FACILITATED DIFFUSION
- cells respire the glucose + produce ATP
- high conc of ATP causes K+ channels in β cells to close - CHANGE IN MEMBRANE POTENTIAL
- this change in potential causes VOLTAGE GATED Ca2+ channels to OPEN
- response to influx of Ca2+ ions - INSULIN SECRETED by β cells (insulin containing vesicles move towards/fuse with CSM to release insulin to capillaries - EXOCYTOSIS)
- stimulates UPTAKE OF GLUCOSE by muscles cells,fat cells and liver

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16
Q

How does insulin increase glucose uptake through facilitated diffusion?

A
  • glucose transporter proteins on target cells are insulin-sensitive
    Insulin binds to specific receptors on the membranes of target cells
    This stimulates them to activate/add more glucose transporter proteins to their cell surface membrane - increases permeability to glucose
  • so rate of FACILITATED DIFFUSION INCREASES
17
Q

Which cells have glucose transporter proteins in their CSM and what is the rate of glucose uptake dependant on?

A

Muscle/fat storage cells, adipose tissue, liver cells - the target cells of insulin
The proteins allow uptake of glucose molecules via facilitated diffusion
- rate of glucose uptake depends on *no. glucose transporter proteins

18
Q

How does insulin increase uptake of glucose in liver by glycogenesis?

A

Glucose enters liver cell - enzyme converts it to glucose PHOSPHATE
- enzymes convert glucose phosphate —> glycogen
- Lower glucose concentration in liver cells
STEEP DIFFUSION GRAD MAINTAINED between blood and liver cells

19
Q

How is the regulation of blood glucose concentration an example of negative feedback?

A

In negative feedback :
Receptors detect if a specific level is too low or too high
This info is communicated through hormonal or nervous system to effectors
Effectors counteract the change - bring level back to normal

α and β cells = receptors
- release glucagon/insulin
Liver cells = effectors in response to GLUCAGON
Liver, muscle and fat cells = effectors in response to INSULIN

20
Q

What is gluconeogenesis?

A

Synthesis of glucose molecules from NON CARBOHYDRATE MOLECULES
- glucagon tiggers this by activating enzymes in liver
- enzyme converts molecules (fatty acid/amino acids) —> glucose molecules - released into blood
INCREASE BLOOD GLUCOSE CONC

21
Q

What is gluconeogenesis?

A

Synthesis of glucose molecules from NON CARBOHYDRATE MOLECULES
- glucagon tiggers this by activating enzymes in liver
- enzyme converts molecules (fatty acid/amino acids) —> glucose molecules - released into blood
INCREASE BLOOD GLUCOSE CONC

22
Q

What is type 1 diabetes? Most common cause?

A

Conditions where pancreas fails to produce sufficient insulin/ shortage of Beta cells to control blood glucose levels - glucose will build up in bloodstream instead of go into cells

  • Normally due to AUTOIMMUNE RESPONSE where immune system (T cells) attacks β cells of islets of Langerhans
  • β cells detect high blood glucose / synthesis insulin
23
Q

Treatment for type 1diabetes?

A

Regular blood tests
Insulin injections - insulin can be fast/slow acting
Specific diet

24
Q

Why does type 1 diabetes cause FATIGUE and organ damage?

A

FATIGUE : lack of insulin can affect glycogen stores
Organ damage : too high blood glucose concentration leads to organ damage

25
Q

What is type 2 diabetes ?

A

Pancreas still produced insulin but receptors have reduced in number or liver cells no longer respond to insulin
- reduced sensitivity to insulin occurs in liver/fat storage tissues
- so HIGH BLOOD GLUCOSE , due to reduced glucose uptake
- can cause β cells to produce larger amounts of insulin which then damages the cells

26
Q

Treatment for type 2 diabetes?

A

Sugar/fat controlled diet - food that is digested into sugar will cause sudden spike in blood glucose
Exercise regime

27
Q

Risk factors for type 2 diabetes?

A

Obsesity
Physical inactivity
High BP
High blood cholesterol
Genetics
Certain ethnic groups

28
Q

Why does diabetes lead to high blood pressure?

A

High blood glucose conc lower WP of blood
- causes water to move from tissues —> blood vessels by osmosis
So larger vol of blood in circulatory system - increase BP

29
Q

How can stem cells be a potential treatment for diabetes?

A

Stem cells can differentiate into pancreatic β cells
- new β cells can be transplanted into pancreas of diabetic individual , replacing damaged cells + can produce insulin

30
Q

Why must protein insulin be administered intravenously rather than orally?

A

Insulin is a protein so if taken orally , would be digested by enzyme protease before entering bloodstream

31
Q

Role of aldosterone?

A

Na+/K+ re absorption in kidney
Water reabsorption
Control blood pressure

Biology Alevel (26 decks)

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