Chapter 11 - Excretion Flashcards Preview

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Flashcards in Chapter 11 - Excretion Deck (61)
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1
Q

Why do larger organisms need excretory organs for excretion?

A

They have impermeable skin and waste products cannot be excreted via diffusion into the surrounding environment.

2
Q

What is in the filtrate of ultrafiltration? (2) (filtered out)

A

1) water

2) small molecules such as glucose, amino acids, mineral salts, urea

3
Q

What is the urethra?

A

It is the duct through which urine discharges from the bladder to outside of the body

4
Q

What is not filtered out (residue) of ultrafiltration?

A

Large molecules such as plasma proteins and red/white blood cells

5
Q

What is the hilus?

A

A concave depression where the renal artery, renal vein and nerves are connected to the kidney.

6
Q

Why is blood pressure indirectly regulated by osmoregulation?

A

Kidneys control water and solute levels in blood plasma by controlling amount of water reabsorbed at nephrons. The amount of water reabsorbed affects blood volume, which affects blood pressure. If the blood volume increases, blood pressure rises.

7
Q

What is the cortex?

A

It is the outer dark red region that is covered and protected by a fibrous capsule.

8
Q

Define osmoregulation.

A

It is the regulation of water and solute concentrations in the blood plasma to maintain a constant water potential in the body.

9
Q

What is the sphincter muscle and what is its function?

A

It is located at the bottom of the bladder where it controls urination.

10
Q

How does dialysis work? (6)

A

1) blood is drawn from a vein in patient’s arm
2) blood is pumped into dialysis machine through tubing
3) the partially permeable tubing is bathed in dialysis fluid
4) small molecules like urea and metabolic waste products diffuse out of tubing
5) larger molecules like platelets and blood cells remain in tubing
6) the filtered blood is returned to a vein in patient’s arm

11
Q

Define excretion.

A

Excretion is the removal of metabolic waste products from the body which when left accumulated in excess will be toxic to the body.

12
Q

What happens during osmoregulation when there is too much water? (7)

A

1) large intake of water causes water potential in blood plasma to increase
2) increase STIMULATES hypothalamus in brain,
3) which causes pituitary gland to secrete less ADH into bloodstream
4) cells in walls of collecting ducts become less permeable to water
5) less water reabsorbed from collecting duct into blood capillaries surrounding kidney tubule
6) larger volume of urine&urine more diluted
7) water potential of blood returns to normal

13
Q

Describe the blood circulation at the kidney tubule. (7)

A

1) blood enters the kidney via the renal artery
2) renal artery branches out into many arterioles
3) arterioles branch into a mass of blood capillaries called the glomerulus.
4) blood leaves the glomerulus and enters blood capillaries surrounding the kidney tubule
5) blood capillaries unite to form venules
6) venules join to form renal veins
7) blood exits kidneys via renal vein.

15
Q

What is the bowman’s capsule?

A

It is a cup-like structure found at the beginning of the kidney tubule.

16
Q

What is reabsorbed at the loop of Henlé?

A

Some water is reabsorbed from the filtrate back into the blood vessels.

17
Q

What is a fistula?

A

It is a direct connection of an artery to a vein.

18
Q

How is carbon dioxide excreted? (1)

A

By lungs as expired air.

19
Q

What are the two conditions required for ultrafiltration?

A

1) high hydrostatic blood pressure at the glomerulus due to afferent arteriole being wider than the efferent arteriole
2) partially permeable basement membrane around glomerular blood capillaries (has very small pores)
NOT BY DIFFUSION OR ACTIVE TRANSPORT

21
Q

What happens if there is a large increase in blood pressure and what can be done to prevent it?

A

A large increase can cause blood vessels in the brain to burst, causing a stroke.
To prevent, diuretics (drug) can be prescribed to reduce production of ADH. Large amount of dilute urine will be produced and volume of water in blood decreases

22
Q

Describe how urea is produced and excreted.

A

During ultrafiltration, urea, being a small molecule, will pass through the basement membrane of the glomeruli in the Bowman’s capsule, as part of the filtrate. It is not reabsorbed in the tubules, thus it passes in solution to the collecting duct. The fluid then passes through ureters into the bladder where it is temporarily stored, then out of the body through the urethra.

23
Q

How are glucose, amino acids and salts reabsorbed?

A

Glucose, amino acids and salts diffuse into the CELLS lining the proximal convoluted tubule. They are then actively transported into the interstitial fluid, where they enter the blood capillaries via diffusion.

24
Q

What is the function of a fistula?

A

Blood pressure in artery is higher than in the vein. Since blood can flow from artery to vein, more blood at higher pressure flows into the vein. The vein becomes larger and stronger over time, allowing a greater amount of blood to pass through the dialysis machine. It increases the pace of filtration, allowing all the blood to be filtered in a shorter period of time.

25
Q

What is the renal corpuscle/malpighian corpuscle?

A

The glomerulus and the Bowman’s capsule

27
Q

Is egestion part of excretion?

A

No. Egestion is the removal of undigested material from the alimentary canal. Undigested material is not formed from substances within the cell and has never been absorbed to into the cells. Hence, egested material is not a product of metabolic processes.

28
Q

What happens at the collecting duct?(2)

A

1) some water is reabsorbed back into the blood vessel
2) excess water, excess salts and excess urea such as creatinine, urea and uric acid pass out of the collecting duct into the renal pelvis to form urine.

30
Q

How can kidney failure be treated?(2)

A

1) kidney transplant

2) dialysis

31
Q

Why must the water potential if blood plasma be kept relatively constant? What are 2 problems caused?

A

If large fluctuations in water potential occur,

1) blood plasma too concentrated: water moves out of the cells by osmosis, cells dehydrate and undergo crenation. They are unable to carry out metabolic functions which might be fatal
2) blood plasma too diluted: water enters cell by osmosis, cells absorb water, expand and burst

32
Q

What are 6 common causes of kidney failure?

A

1) high blood pressure
2) diabetes
3) alcohol abuse (constant heavy drinking)
4) severe incidents that physically damage kidney
5) complications from undergoing major surgery
6) drug overdose

33
Q

What is ultrafiltration?

A

The mechanical filtration that occurs at the renal corpuscle

34
Q

What is the function of kidneys?

A

Produce urine

35
Q

Define metabolism.

A

Metabolism is the sum of all chemical reactions within the body of an organism.
Catabolism + anabolism = metabolism

37
Q

What is the function of selective reabsorption?

A

It allows useful substances to be reabsorbed, preventing our body from losing too much water and other useful substances.

38
Q

What are 4 features of a dialysis machine?

A

1) dialysis fluid contains the same concentration of essential substances in healthy blood, to ensure essential substances like glucose and amino acid do not diffuse into dialysis fluid. If the blood lacks these substances, they can diffuse into the blood
2) dialysis fluid does not contain nitrogenous waste such as urea and creatinine, to set up a concentration gradient for faster diffusion of nitrogenous waste out of the blood into the dialysis fluid.
3) the tubing in the machine is narrow, long and coiled to increase surface area for faster diffusion of metabolic waste and essential substances in and out of the blood.
4) the direction of blood flow is opposite to dialysis fluid to maintain concentration gradient to remove nitrogenous waste products.

39
Q

What is the distal convoluted tubule?

A

As the tubule re-enters the cortex, it coils again to form the distal convoluted tubule.

40
Q

What is the proximal convoluted tubule?

A

It is a short, coiled tubule that straightens out as it enters the medulla

41
Q

What are the two main regions of the human kidney?

A

1) cortex

2) medulla that contains renal pyramids that contains nephrons.

41
Q

What is the loop of Henlé?

A

It is the U-shaped portion of the tubule in the medulla.

43
Q

What is reabsorbed at the distal convoluted tubule?

A

Some minerals salts and water are reabsorbed back into the blood vessel.

44
Q

Define kidney failure.

A

It is the inability of kidney to function properly, causing the accumulation of excretory products in the blood

45
Q

What are kidney tubules/nephrons?

A

They are narrow tubules in the medulla pyramids that are richly supplied with blood vessels. Urine is formed in the kidney tubules.

46
Q

What is the function of a dialysis machine?

A

It mimics the functions of a kidney by helping to clean the patient’s blood from metabolic waste products and toxins.

47
Q

How are bile pigments(from breakdown of haemoglobin) excreted? (1)

A

By liver as constituent of faeces

48
Q

Why are kidneys called osmoregulators?

A

They help regulate water and solute concentrations in blood. It is a type of homeostasis.

49
Q

What is reabsorbed during selective reabsorption and how?

A

Glucose, amino acids and mineral salts(sodium ions) are reabsorbed through walls of the tubule into surrounding blood capillaries, via diffusion and active transport, while water is reabsorbed via osmosis following the glucose and salt.

50
Q

How are excess mineral salts and nitrogenous waste products such as urea, uric acid and creatinine excreted? (2)

A

1) By kidneys as constituents of urine

2) by skin as constituent of sweat (only small quantities of nitrogenous waste products)

51
Q

What are the 4 main parts of the nephron?

A

1) bowman’s capsule
2) proximal convoluted tubule
3) loop of Henlé
4) distal convoluted tubule

52
Q

What is the urinary bladder?

A

It is an elastic muscular bag in front of the rectum that stores urine.

53
Q

What is the function of anti-diuretic hormones?

A

It increases reabsorption of water into blood capillaries surrounding kidney tubules.

54
Q

Why must metabolic waste products be removed?

A

Metabolic reactions produce metabolic waste products that are toxic to the body if they accumulate.

54
Q

What are 4 example reasons that might cause water potential fluctuations in blood plasma?

A

1) excess water intake/dehydration
2) excess salt intake (lowers water potential)
3) excessive blood loss
4) excessive sweating

55
Q

What happens during osmoregulation when there is too little water? (7)

A

1) loss of water decreases water potential in blood plasma
2) decrease STIMULATES hypothalamus in brain
3) which causes pituitary gland to secrete more ADH into bloodstream
4) cells in walls of collecting ducts become more permeable to water
5) More water reabsorbed from the collecting ducts into blood capillaries surrounding kidney tubules
6) smaller volume of urine produced&concentrated urine
7) water potential of blood returns to normal

56
Q

What are medulla/renal pyramids?

A

They are conical structures located in the medulla. They contain large number of kidney tubules/nephrons.

57
Q

What is the renal pelvis?

A

It is the enlarged portion of the ureter inside the kidney. the renal pyramids project into this funnel-like space.

57
Q

What is the collecting duct?

A

The duct where the tubule is open to, which passes through the medulla and opens to the renal pelvis.

57
Q

How is urine formed in the kidney tubule/nephron? (2)

A

1) ultrafiltration (at renal corpuscle)

2) selective reabsorption (mostly at proximal convoluted tubule)

57
Q

What is the anti-diuretic hormone (ADH)? Where is it released and produced?

A

It controls the amount of water and mineral salts (which affects water potential) in the blood plasma.
Produced: hypothalamus
Released: pituitary gland

58
Q

What is the medulla?

A

It is the inner pale red region that contains 12-16 medulla pyramids.

59
Q

How does the sphincter muscle control urination?

A

When the bladder is full, sensory neurones send nerve impulses to the brain. To urinate, the brain sends nerve impulses to the sphincter muscle to cause it to relax. Urine is then able to flow into the urethra and out of the body.

60
Q

How is excess water excreted? (3)

A

1) by kidneys as main constituent of urine
2) by skin as main constituent of sweat
3) by lungs as water vapor in expired air

60
Q

What is the function of ureters?

A

Connect kidneys to urinary bladder. Urine passes through the ureter to the bladder.

61
Q

How is dialysis different from kidney? (6)

A

1) dialysis involves diffusion only while kidney involves diffusion and active transport
2) dialysis does not involve ultrafiltration and selective reabsorption while kidney does.
3) in dialysis, pressure is provided by dialysis machine while in kidney, pressure is provided by narrower lumen of efferent arteriole as compared to afferent arteriole
4) dialysis does not involve hormones while kidney does
5) dialysis fluid is needed for dialysis while kidney does not; it only involves glomerular filtrate
6) dialysis cannot produce more concentrated/dilated urine while kidney can.
7) dialysis involves diffusion down concentration gradient while kidney uses hydrostatic pressure during ultrafiltration to force out the filtrate