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

13 Excretion in humans Flashcards

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1
Q

[3 MARKS]

Describe how and where in the body urea is formed

A

📌 breakdown of amino acids
📌 removal of nitrogen containing parts
📌 excess amino acids transported to the liver
📌 deamination

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2
Q

ref to book for other mistakes

A
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3
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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4
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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5
Q

What do kidneys excrete?

A

kidneys excrete urea and excess
water and ions

by producing urine

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6
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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7
Q

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

A
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8
Q

Organs involved in excretion

skin & lungs

A

skin excretes water & mineral ions

lungs excrete CO2 & water

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9
Q

liver

A

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

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10
Q

Ureter

A

transports urine from the kidneys to the bladder

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11
Q

urethra

A

facilitates removal of urine from body

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12
Q

bladder

A

collects urine prior to urination

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13
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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14
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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15
Q

Why should urea be excreted?

A

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

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16
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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17
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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18
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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19
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

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20
Q

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

A
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21
Q

Renal vein does?

A

transports filtered blood back to the heart

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22
Q

renal artery

A

transports unfiltered blood from the aorta into the kidney

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23
Q

cortex

A

blood is filtered here by nephrons

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

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24
Q

medulla

A

where water is reabsorbed to maintain water balance

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25
Q

Step 1: Ultrafiltration

Glomerulus?

A

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

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26
Q

-> high blood pressure…

A

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

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27
Q

Exceptions that CANNOT BE forced out

A

proteins, RBCs too large to be filtered

-> This is ULTRAFILTRATION.

28
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)
29
Q

What happens to remaining?

A

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

30
Q

The Nephron – unit of filtration

made up of ;;

A

Glomerulus
Renal capsule
Renal tubule
Capillaries

31
Q

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

/ molecules too large to be filtered

A

Protein

32
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

33
Q

Name substance reabsorbed kidney

A

Glucose

34
Q

Name substance that is a metabolic waste product

A

Urea

35
Q

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

A

Salts

Urea

36
Q

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

A

Ureter

Bladder

Urethra

37
Q

Process of maintaining constant conditions within the body

A

Homeostasis

38
Q

Define excretion

A

Removal from the body

Of toxins

And waste products of metabolism

And substances in excess of requirements

39
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

40
Q

State two waste substances that are removed from the blood by dialysis.

A

urea ;
ammonia ;
water ;

41
Q

Define active transport [2]

A

Movement of ions

Against concentration gradient through a partially permeable membrane

Using energy from respiration

42
Q

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

A

Ions

43
Q

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

[2]

A

water has been reabsorbed ;
by osmosis ;
(in/ by) collecting duct

44
Q

as it passes through the liver

changes in concentration of glucose
and urea in the blood

A

glucose less,
urea more

45
Q

Where is urea formed?

A

liver

46
Q

a function of the kidneys of a healthy person?

A

reabsorb all glucose

47
Q

Where are hormones removed from the blood and broken down in the human body?

A

liver

48
Q

How is urea removed from the body?

A

in solution

49
Q

renal artery - glucose
renal vein - glucose
ureter - salts
bladder - urea

A
50
Q

Explain the function of the renal capsule in the kidney [3]

A

(ultra)filtration ;

high blood pressure assists filtrate to pass through capsule ;

proteins too big to move out of capsule /
glomerulus ;

filtrate small enough to move through ;

51
Q

Explain how a dialysis machine filters blood.

A

dialysis membrane is partially permeable ;

minerals / salts / ions / urea, move by diffusion ;

from high concentration to low concentration / down a
concentration gradient ;

water, moves by osmosis ;

52
Q

Explain how, when the patient is receiving dialysis treatment
(i) the loss of plasma proteins and red blood cells is prevented,

A

too large to go through membrane

53
Q

the normal glucose concentration of the blood is maintained.

A

dialysing solution contains glucose ;

glucose diffuses ;

(until blood is) at, correct / normal, concentration

54
Q

Describe the changes that occur in the urea concentration in the blood over the
period shown in Fig. 2.2.

You will gain credit for using the data in Fig. 2.2 in your
answer. [3]

A

decreases during, dialysis

increases, over next day after dialysis ;

maximum concentration(s) decreases (over time) ;

minimum concentration(s) (after dialysis) decreases (over
time) ;

55
Q

Explain the changes in urea concentration in the blood as shown in Fig. 2.2. [4]

A

(urea) produced in liver ;
deamination ;
amino acids ;

diffuses, out of blood ;
through (dialysis) membrane ;

56
Q

Describe the process of filtration in the kidney. [3]

A

ref to blood pressure ;

due to the heart / AW ;

ref to capillaries ; A glomerulus

small molecules forced out (of blood) ;

two examples ; urea, water

57
Q

Name the processes resulting in the reabsorption of
1. glucose
2. water

A

diffusion ;
active uptake / active transport ; [max 2]

/////
osmosis ;

58
Q

The kidneys remove metabolic waste from the liquid part of the blood.
Name:

(i) the liquid part of the blood;
[1]

(ii) the process that involves removing metabolic waste from the body.

A

plasma;

excretion ;

59
Q

FUNCTIONS

  • glomerulus
A

(ultra)filtration ;

small molecules, from blood or glomerulus;

are forced/ pushed (out)/ under (high) pressure ;

60
Q
  • tubule
A

(selective) reabsorption ;

back into the blood/ capillaries ;

e.g. of any substance that is filtered or reabsorbed like glucose ;

61
Q

is all reabsorbed in the kidney;

A

glucose

62
Q

Dialysis fluid contains sodium ions.
Use the information in Table 1.1 to suggest the concentration of sodium ions that
should be in the fluid and give a reason for your answer.
concentration g per 100cm3
reason

A

0.35 (g per 100cm3) ;
same concentration as the blood

63
Q

State two components of blood that are not in dialysis fluid.

A

urea ;
amino acids ;

64
Q

Use Fig. 3.2 to describe how kidney tubules reabsorb glucose from the filtrate. [2]

A

(glucose is reabsorbed) by active transport (from
filtrate) ;

against concentration gradient ;

using energy ;

65
Q

When plants are grown in a solution that includes a poison that prevents respiration,
the roots continue to absorb water, but do not absorb many ions.
Explain this result [3]

A

active uptake/active transport, of ions against the concentration gradient
(into the root) ;

energy is needed for, active uptake/active transport ;

comes from respiration ;

water is absorbed, by osmosis

66
Q

Describe the changes that occur to the blood as it flows through the dialysis machine
from A to B.

A

urea (concentration) decreases ;
water (content) increases / decreases ;
salt (concentration), decreases

67
Q

Discuss the advantages of kidney transplants compared with dialysis.

A

long term solution / person no longer needs (regular) dialysis ;

an example of a disadvantage of dialysis ;
A pain / tiring / discomfort / takes a long time

increased freedom / better quality of life

Biology (N.A.) (21 decks)

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