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Biology (N.A.) > 13 Excretion in humans > Flashcards

13 Excretion in humans Flashcards

1
Q

How is carbon dioxide excreted

A

carbon dioxide is excreted through the lungs [during exhalation]

  • WASTE PRODUCT of aerobic respiration
  • must be excreted as it dissolves in water easily to form an acidic solution which can lower the pH of cells
  • can reduce the activity of enzymes in the body which are essential for controlling the rate of metabolic reactions
  • too much carbon dioxide in the body is toxic
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2
Q

Define excretion

A

removal of toxic materials, the waste products of metabolism, and substances in excess of requirements

e.g., urea, CO2, salts/ions

NOT defacating - this is NOT excretion, but egestion

metabolism: chemical reactions in the cell including respiration

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3
Q

What do kidneys excrete?

A

kidneys excrete urea and excess
water and ions

by producing urine

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4
Q

Why are kidneys important?

[excretory system, filters - “clean” blood]

A

important for maintaining the water & ion balance in the body; ADJUSTMENT OF IONS (SALTS) IN THE BLOOD + ADJUSTMENT OF WATER IN THE BLOOD

also filter urea out of blood and excrete it; REMOVAL OF UREA FROM BLOOD

waste products transferred to bladder

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5
Q

Identify in diagrams and images the kidneys,
ureters, bladder and urethra

A
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6
Q

Organs involved in excretion

skin & lungs

A

skin excretes water & mineral ions

lungs excrete CO2 & water

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7
Q

liver

A

liver: PRODUCES urea from amino acids [breakdown of them; process: deamination]

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8
Q

Ureter

A

transports urine from the kidneys to the bladder

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9
Q

urethra

A

facilitates removal of urine from body

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10
Q

bladder

A

collects urine prior to urination

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11
Q
  1. Removal of Urea

Why are excess amino acids broken down by liver?

A

Bc - proteins CANNOT be stored by the body

so excess amino acids broken down by liver -> deamination

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12
Q

What is the waste product?

A

Urea

[nitrogen-containing part of amino acids. Diffused into blood to be]

filtered out by the kidneys

[also excreted partly in sweat]

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13
Q

Why should urea be excreted?

A

toxic waste product so must be excreted before it reaches high concentrations

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14
Q
  1. Adjustment of ion content

Ions e.g.?
Taken in how? Removed by?

A

Ions such as sodium are

taken into the body in food.

Excess ions are removed by the KIDNEYS.

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15
Q
  1. Adjustment of water content

Too little water in blood?

A

Hypothalamus detects blood is too highly concentrated ->

Pituitary gland releases ADH ->

More ADH enters kidneys - more water is reabsorbed ->

So less & more concentrated urine produced

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16
Q

Too much water in blood

A

Hypothalamus detects blood is not concentrated enough ->

Pituitary gland releases LESS ADH ->

Less ADH enters kidney - less water is reabsorbed ->

More urine that’s less concentrated is produced

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17
Q

The hypothalamus in the brain _______ to ___________ into the _____

EXAMPLE of homeostasis

A

monitors the water content of the blood and instructs the pituitary gland,

TO: release the hormone ADH (Anti-diuretic hormone)

INTO: into the blood

18
Q

Kidney structure: pelvis, cortex, renal vein (above), renal artery, medulla (look like shells), ureter (coming out of it at the bottom)

A
19
Q

Renal vein does?

A

transports filtered blood back to the heart

20
Q

renal artery

A

transports unfiltered blood from the aorta into the kidney

21
Q

cortex

A

blood is filtered here by nephrons

[pelvis - urine collects here before passing into the ureter]

22
Q

medulla

A

where water is reabsorbed to maintain water balance

23
Q

Step 1: Ultrafiltration

Glomerulus?

A

The glomerulus is a knot of blood vessels surrounded by the renal capsule

24
Q

-> high blood pressure…

A

High blood pressure in the glomerulus forces water, ions, urea, & glucose out of the blood

25
Q

Exceptions that CANNOT BE forced out

A

proteins, RBCs too large to be filtered

-> This is ULTRAFILTRATION.

26
Q

Step 2: Selective Reabsorption

  • In the renal tubule:

USING ACTIVE TRANSPORT (for filtering blood)

A
  • ALL glucose is reabsorbed
  • sufficient ions/salts are reabsorbed using active transport as for glucose & water
  • sufficient water is also reabsorbed here (depending on effects of ADH)
27
Q

What happens to remaining?

A

The remaining urea, water & salts are passed on to the bladder as urine

28
Q

The Nephron – unit of filtration

made up of ;;

A

Glomerulus
Renal capsule
Renal tubule
Capillaries

29
Q

Name substance that has molecules too large to pass through walls of capillaries

/ molecules too large to be filtered

A

Protein

30
Q

Name substance reabsorbed in kidney /

Has molecules which are small enough to be filtered but is completely reabsorbed from fluid in the kidney tubule

A

Glucose

31
Q

Name substance reabsorbed kidney

A

Glucose

32
Q

Name substance that is a metabolic waste product

A

Urea

33
Q

Name substance that increases in concentration as fluid moves along the kidney tubule

A

Salts

Urea

34
Q

State 3 structures thru which fluid from region 4 passes as it leaves the body (NO GLUCOSE NO PROTEIN)

A

Ureter

Bladder

Urethra

35
Q

Process of maintaining constant conditions within the body

A

Homeostasis

36
Q

Define excretion

A

Removal from the body

Of toxins

And waste products of metabolism

And substances in excess of requirements

37
Q

Define excretion

A

Removal from the body

Of toxins

And waste products of metabolism

And substances in excess of requirements

38
Q

Outline role of liver in excretion [3]

A

Deamination

Removal of nitrogen containing part of amino acids

To produce urea

Urea passes into blood

39
Q

Define active transport [2]

A

Movement of ions

Against concentration gradient through a partially permeable membrane

Using energy from respiration

40
Q

1 e.g. other than glucose of substance reabsorbed into blood from renal tubule

A

Ions

41
Q

Explain why the concentrations of sodium ions and urea are greater at Z (urine) than Y (fluid)

A

Water has been reabsorbed

By osmosis (in tubule)

By collecting duct

By z there is no change in sodium ions but volume of water is less

42
Q

as it passes through the liver

changes in concentration of glucose
and urea in the blood

A

glucose less,
urea more

Biology (N.A.) (13 decks)

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