Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOLOGY > Topic 6 - Homeostasis > Flashcards

Topic 6 - Homeostasis Flashcards

1
Q

What is homeostasis?

A

The state of a stable internal environment in the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the islets of langerhan?

A

Endocrine tissue that contains cells which make different hormones.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which hormone do alpha cells produce?

A

Glucagon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which hormone do beta cells produce?

A

Insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What will cause blood glucose concentration to fall?

A

Not eating in a while or a decrease in activity level.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the receptors for a fall in blood glucose concentration?

A

Alpha cells in the islets of Langerhans.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do alpha cells respond to a fall in blood glucose concentration?

A

They secrete glucagon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does glucagon increase blood glucose concentration?

A

Glucagon activates enzymes inside cells that convert glycogen into glucose in glycogenolysis.
Glucose then diffuses into the blood, increasing blood glucose concentration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is glycogenolysis?

A

The conversion of glycogen into glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is gluconeogenesis?

A

When glycogen supplies begin to run out glucose is made from non-carbohydrate sources (pyruvate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens when blood glucose concentration rises?

A

Beta cells detect the rise and respond by secreting insulin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does insulin decrease blood glucose concentration?

A

Insulin increases the rate at which liver cells, muscle cells and fat cells absorb glucose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is glucose uptake increased by facilitated diffusion?

A

Glucose uptake is increased by facilitated diffusion as Glucose can only pass into cells through specific Glucose carrier proteins.
the more proteins there are, the faster Glucose leaves the blood and enters cells.
cells with insulin receptors in their Membrane also have vesicles that contain extra Glucose transport proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does insulin decrease blood glucose concentration?

A

1) Insulin molecule binds to specific receptors on the cell membranes of target cells.

2) This binding causes vesicles containing glucose channel proteins to join the cell surface membrane and increasing the rate of facilitated diffusion into the cells by increasing the number of glucose carrier proteins.

3) The rate of glucose movement into the cells increases as more carrier proteins are added to the membrane, decreasing the blood glucose concentration.

3) insulin also activates enzymes in the liver to convert glucose into glycogen (glycogenesis). In some cells insulin also activates the enzymes that synthesise triglycerides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What secretes adrenaline?

A

The adrenal gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does adrenaline stimulate?

A

Stimulates glycogenolysis in liver cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does adrenaline/glucagon stimulate glyogenolysis?

A

1) Adrenaline/glucagon bind to receptor proteins on the cell surface membrane of their target cells.
2) This changes the shape of the protein that spans the membrane
3) This shape change activates adenylate cyclase.
4) Adenylate cycle as converts ATP into cyclic AMP (cAMP), second messenger it carries the message of the hormone inside the cell.
5) cAMP activates protein Kinase A which activates the enzymes which hydrolyse glycogen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why must adrenaline and glucagon enter by second messenger?

A

Adrenaline and glucagon are only water soluble so they cannot cross the cell membrane whereas cAMP is lipid soluble meaning it can cross the cell membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why does T1 occur?

A

The islets of Langerhans fail to produce insulin

20
Q

Why does T2 diabetes occur?

A

When the body produces insulin but the cells fail to respond to it.

21
Q

What is low blood glucose caused and what are the symptoms?

A

Hypoglycaemia

Sweating, hunger, blurring vision

22
Q

What is high blood glucose called and what are the symptoms?

A

Hyperglycaemia

Sick, drowsiness, stomach pain

23
Q

What is osmoregulation?

A

The control of water potential and bodily fluids.

24
Q

What are the three functions of the kidneys?

A
  1. Excretion - the removal of metabolic waste from the body
  2. Control of blood volume
  3. Control of blood water potential
25
Q

How do substances enter and leave the kidney?

A

Enter = renal artery
Exit = renal vein and ureter

26
Q

What are the two processes that the kidneys carry out?

A

Ultrafiltration and selective re-absorption

27
Q

What is the renal medulla?

A

The inner region of the kidney containing the loop of Henle, collecting duct and blood vessels.

28
Q

What is the renal artery?

A

Kidneys receive oxygenated blood through the renal artery

29
Q

What is the renal vein?

A

Returns the filtered blood to the heart via the vena cava.

30
Q

What is the renal pelvis?

A

Collects urine into the ureters.

31
Q

What is the renal cortex?

A

Contains the bowman’s capsule, convoluted tubules and blood vessels.

32
Q

What is the function of the Bowman’s capsule in the nephron?

A

It surrounds the glomerulus, where the blood is filtered to produce filtrate.

33
Q

What is the function of the PCT in the nephron?

A

Reabsorbs useful substances including water, glucose and salts into surrounding capillaries.

34
Q

What is the function of the loop of Henle in the nephron?

A

Creates a high solute concentration in the medulla, helping with reabsorption.

35
Q

What is the function of the DCT in the nephron?

A

Fine tunes the water balance by reabsorbing water into surrounding capillaries. Substances are reabsorbed or excreted according to the needs of the body.

36
Q

What is the function of the collecting duct in the nephron?

A

The final part of the nephron that reabsorbs water.

37
Q

What is the function of the afferent arteriole?

A

Supplies the glomerulus with blood.

38
Q

What is the function of the efferent arteriole?

A

Carries blood away from the glomerulus.

39
Q

How is filtrate formed in the bowman’s capsule?

A

The bowman’s capsule is a region of ultrafiltration. There is a high hydrostatic pressure which forces blood against a fitter consisting of: the capillary endothelium, podocyte cells and the basement membrane.

40
Q

What is the function of the proximal convoluted tubule?

A

To allow glucose, amino acids and most ions to be reabsorbed into the blood and water follows by osmosis.

41
Q

Describe the process of reabsorption in the proximal convoluted tubule.

A
  1. Na+ are actively transported into blood, reducing [Na+] in epithelial cells lining PCT.
  2. Na+ moves from the PCT lumen into the epithelial cells down its concentration gradient.
  3. Na+ is cotransported with substances such as glucose and amino acids into the epithelial cells.
  4. These reabsorbed molecules can then diffuse into the blood capillaries.
42
Q

What is the role of the loop of henle?

A

Takes filtrate deep into the medulla and then returns it to the cortex.
the loop creates a region of high salt concentration in the medulla, through which the collecting duct must pass.
Consists of an ascending and descending limb.

43
Q

What happens in the descending limb of the loop of henle?

A

Water leaves by osmosis due to a low Water potential in the medulla, causing the Water potential of the filtrate to decrease.
lons cannot differs out due to the descending limb being impermeable to water.
Volume of the filtrate decreases.

44
Q

What happens in the ascending limb of the loop of henle?

A

Na+ diffuses by facilitated diffusion out as there is a higher concentration in the filtrate.
water potential increases as ions move out but water can’t as ascending limb is impermeable.
The last few ions are actively transported out of the filtrate.

45
Q

How is osmoregulation achieved in the body?

A
  1. Specialist sensory neurones (osmoreceptors) found in the hypothalamus monitor the water potential of the blood.
  2. If the osmoreceptors detect a decrease in the water potential of the blood, nerve impulses are sent along these sensory neurones to the posterior pituitary gland.
  3. These nerve impulses stimulate the posterior pituitary gland to release ADH.
  4. ADH molecules enter the blood and travel throughout the body.
  5. ADH causes the kidneys to reabsorb more water.
  6. This reduces the loss of water in the urine.
46
Q

How does ADH increase the reabsorption of water?

A
  1. ADH binds to receptor proteins in the cell surface membranes besides of the correcting duct cells
  2. Aquaporins are phosphorylated
  3. Vesicles (with aquaporin containing membranes) more towards luminal membranes of collecting duct cells.
  4. Vesicles fuse with luminal membranes
  5. Water moves through aquaporins down the water potential gradient into the concentratedtissue fluid and blood plasma in the medulla of the kidney.

BIOLOGY (41 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions