Chapter 9: The Excretory System

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68 Terms

1
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What two important factors are influenced by the amount of water reabsorbed from filtrate?

Blood volume (amount of blood) and the concentration of plasma solutes.

2
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Why is blood volume important to blood pressure?

Blood volume influences blood pressure, thus affecting the health of the cardiovascular system.

3
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What happens when we drink too much water regarding the kidneys?

The kidneys allow more water to pass into the urine (clear urine).

4
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What happens when water is scarce regarding the kidneys?

The kidneys increase water reabsorption, resulting in more concentrated urine with less water (darker color).

5
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Why is water absorption important to our overall health?

It prevents dehydration, which can be deadly, and affects the health of the cardiovascular system.

6
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What are osmoreceptors?

Cells that are sensitive to osmotic pressure.

7
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Where are osmoreceptors mostly located?

In the hypothalamus, which regulates thirst, hunger, blood pressure, body temperature, and fluid balance.

8
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Which hormone does the hypothalamus release to help water reabsorption?

Antidiuretic Hormone (ADH), also known as vasopressin.

9
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What happens when blood is too dilute in terms of water reabsorption?

Osmoreceptors stop the release of ADH, the distal tubule and collecting duct become less permeable to water, and more water is excreted in the urine.

10
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What is diabetes insipidus?

A disorder that occurs when ADH secretion is low or not secreted at all, leading to excessive urine production and potential dehydration.

11
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Define diuretics and give examples.

Substances that increase the production of urine. Examples include alcohol (ethanol) and caffeine.

12
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How is salt balance controlled in the body?

By the excretion and reabsorption of ions (Na+ and K+).

13
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What is aldosterone and what does it do?

A hormone that helps stimulate the reabsorption of Na+ ions, leading to increased blood pressure.

14
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What are the three main mechanisms that help regulate blood pH?

Acid-base buffer system in blood, changes in breathing rate, and kidneys excreting excess H+ as needed.

15
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What happens to H+ and HCO3- when blood pH rises (becomes more basic)?

H+ is not excreted, and HCO3- is not absorbed.

16
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What happens to H+ and HCO3- when blood pH falls (becomes more acidic)?

H+ is excreted, and HCO3- is absorbed.

17
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What usually causes a Urinary Tract Infection?

A virus or bacteria (mainly E. coli) causes a bladder or kidney infection.

18
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What are kidney stones made of?

Excess calcium and uric acid.

19
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What are some causes of kidney stones?

Repeated infections, insufficient water consumption, inactivity, and acidic urine.

20
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What can cause damage to the nephrons?

High blood pressure, reduced blood flow, diabetes, or poisoning.

21
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What is dialysis?

The diffusion of dissolved substances through a semipermeable membrane.

22
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What is hemodialysis?

The use of an artificial membrane in an external device, like an artificial kidney, to filter blood.

23
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What is peritoneal dialysis?

The use of the lining of the intestines (the peritoneum) as the dialysis membrane.

24
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When can a kidney transplant be considered?

People with less than 10% kidney function will eventually need a replacement.

25
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What hormones are key in the regulation of water and salt balance?

Water imbalance is controlled by ADH, and salt imbalance is controlled by Aldosterone.

26
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What is the main function of the excretory system?

The excretory system regulates the volume and composition of body fluids by removing wastes and returning needed substances back to the body for reuse.

27
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Why is the regulation of biological waste important?

An accumulation of waste can pose a threat to human health; nitrogenous waste is especially harmful.

28
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What body systems are involved in excretion?

Respiratory system, skin, digestive system, and the excretory (urinary) system

29
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What are the main organs of the excretory system?

Kidneys, ureters, urinary bladder, and urethra

30
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What is the main function of the kidneys?

To filter the blood to form urine for the excretion of waste.

31
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What artery brings unfiltered blood into the kidney?

Renal artery

32
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What vein does filtered blood exit the kidney through?

Renal vein

33
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What are the three major regions of the kidney?

Renal cortex, renal medulla, and renal pelvis

34
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What is the function of the renal cortex?

Site of filtration of wastes from blood using the glomerulus of the nephron.

35
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What is the function of the renal medulla?

Regulates salt and water balance of blood using the renal tubule of the nephron.

36
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What is the function of the renal pelvis?

Funnel urine to the ureter by collecting urine made by nephrons.

37
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What is a nephron?

The functional unit of the kidney that is responsible for filtering the blood that enters the kidneys.

38
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What forces the filtration of blood in the nephron?

High pressure of blood coming into the kidney from the renal artery.

39
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Where does blood plasma and particles get pushed into during filtration in the nephron?

Bowman's capsule.

40
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What is put back into the blood in the renal tubule?

Water, nutrients, and salts.

41
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What two structures form the filter in the nephron?

Glomerulus (capillary network) and Bowman’s Capsule.

42
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What type of molecules cannot pass through the small walls of the glomerulus and Bowman's capsule?

Large molecules, such as proteins and red blood cells (RBCs).

43
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What type of molecules diffuse into the Bowman’s capsule of the nephron?

Small molecules, such as ions, glucose, and urea.

44
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What is the filtrate?

Everything taken out of the blood.

45
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Where does the filtrate eventually lead to?

The renal pelvis and ureter.

46
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What useful materials are reabsorbed back into the blood from the filtrate?

Water, glucose, and ions.

47
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What ions are secreted into the tubule from the blood?

H+ and K+ ions.

48
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What structures are included in the tubule?

Proximal tube, Loop of Henle, and the distal tubule.

49
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What is the function of the collecting duct?

Water conservation.

50
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What is the remaining fluid in the collecting duct called?

Urine.

51
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What is the function of the ureters?

Carry urine from the kidney to the urinary bladder via peristalsis.

52
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How much urine can the bladder hold?

Up to 500-600 mL.

53
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What is the function of the urethra?

Carries urine from the bladder to exit the body via peristalsis.

54
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What substances should not be found in urine?

Glucose and bacteria.

55
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What does the presence of glucose in urine indicate?

Diabetes.

56
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What does the presence of bacteria in urine indicate?

Infection.

57
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What is the average daily urine production for a healthy person?

1-2 L.

58
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What process creates a plasma-like filtrate of the blood?

Glomerular filtration.

59
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What process removes useful substances from the filtrate and returns them to the blood?

Tubular reabsorption.

60
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What process adds wastes from the blood to the filtrate?

Tubular secretion.

61
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What process removes water from the filtrate and returns it to the blood?

Water reabsorption.

62
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What two factors contribute to glomerular filtration?

Permeability and blood pressure.

63
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What is the composition of glomerular filtrate most similar to?

Blood plasma (with the exception of proteins and blood cells).

64
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What is the function of the Loop of Henle?

Reabsorption of water and ions from the glomerular filtrate.

65
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What is the descending limb permeable to?

Water.

66
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What is the descending limb impermeable to?

Salt.

67
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What is the ascending limb impermeable to?

Water.

68
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What is the ascending limb slightly permeable to?

Solutes.