excretion

Question 1

define excretion

Answer 1

the process by which metabolic waste products and toxic substances are removed from the body of an organism

Question 2

define anabolism, catabolism, and metabolism

Answer 2

anabolism:
* metabolic reactions where simple molecules are built up into complex molecules with a net intake of energy

catabolism
* metabolic reactions where complex molecules are broken down to simpler molecules with a net release of energy

metabolism
* sum total of all chemical reactions occuring in the cells of an organism

a = add, c = cut

Question 3

state at least 2 examples of anabolism and catabolism

Answer 3

anabolism:
* photosynthesis
* conversion of excess glucose to glycogen for storage

catabolism
* hydrolysis
* tissue respiration
* deamination of excess amino acids into urea

so urea is deaminated amino acids take note (aka comes from meat)

Question 4

why must metabolic waste products be removed?

Answer 4

these products are harmful if allowed to accumulate in the body

Question 5

define egestion

Answer 5

removal of waste substances, mainly undigested matter, from the alimentary canal

Question 6

contrast excretion and egestion

Answer 6

Egestion: removal of waste substances, mainly undigested matter, which have never been absorbed into cells and hence are not produced as a result of metabolic reactions within cells

Excretion: removal of waste substances that are produced by metabolic reactions that occur within cells

Question 7

contrast excretion in unicellular and multicellular organisms

Answer 7

• Unicellular: excrete metabolic waste products into surrounding water by diffusion
• Multicellular: require special excretory organs to remove metabolic waste products

Question 8

identify 3 excretory organs in humans, and their respective excretory products

Answer 8

1. Lungs: carbon dioxide, water vapour
2. Kidneys: nitrogenous waste, excess mineral salts, excess water
3. Skin: excess mineral salts, excess water, small amount of nitrogenous waste

Question 9

state the 2 main functions of healthy kidneys

Answer 9

1. Removal of toxic metabolic waste
2. Osmoregulation to maintain water potential of blood plasma

(Maintain pH and composition of blood plasma)

Question 10

identify the 6 parts of the urinary system and state their and the liver’s functions

Answer 10

• Hilum (not really a part): depression where renal artery, renal vein and nerves are connected to kidney
• Kidney: remove urea and excess water from the blood as urine and maintains chemical concentrations in the blood
• Ureter: tube that brings urine from each kidney to urinary bladder
• Urinary bladder: elastic muscular bag that stores urine
• Sphincter muscle: controls urine flow into the urethra and out of the body
• Urethra: duct through which urine passes from urinary bladder to outside of body
• Liver: produces urea through deamination of amino acids

Question 11

contrast renal vein and renal arteries

Answer 11

Renal artery vs Renal vein

structural (callback to transport in humans)
* thicker more muscular and elastic walls
* valves absent vs valves present

blood composition
* higher concentration of oxygen vs lower ..
* higher concetration of urea vs lower ..
* lower concentration of carbon dioxide vs higher ..
* higher water potential vs lower ..

direction of blood flow
* from heart to kidney vs away from kidney to heart

Question 12

state how to differentiate the cortex and medulla

Answer 12

• Cortex: outer darker red region
• Medulla: inner, thicker, paler red region

Question 13

fill in the blanks

Answer 13

answer

Question 14

state the substances excreted into urine

Answer 14

• EXCESS water
• EXCESS mineral salts
• nitrogenous waste products (e.g. urea, uric acid, creatinine)

Question 15

state and describe the process that happens in the glomerulus

Answer 15

Ultrafiltration
* mechanical filtration that removes small molecules from the blood
* most of the blood plasma is forced out of glomerular blood capillaries into Bowman’s capsule to form the glomerular filtrate

Question 16

explain how the glomerulus is adapted to allow ultrafiltration

Answer 16

1. afferent arteriole has a larger diameter than efferent arteriole, which creates a high hydrostatic pressure in the glomerulus, which is the main force for ultrafiltration to occur
2. basement membrane around glomerular blood capillaries has very small pores so that it is partially permeable and allows only water and very small molecules to pass through

Question 17

what is filtered off during ultrafiltration?
state 4 substances not filtered off

Answer 17

Filtered
1. water
2. mineral salts
3. glucose
4. amino acids
5. nitrogenous waste products

Not filtered
1. Blood cells
2. Platelets
3. Proteins (too large)
4. Fats (too large)

Question 18

how does selective reabsorption occur (briefly)

Answer 18

useful substances are selectively reabsorbed from the filtrate formed by ultrafiltration through the walls of the tubule into surrounding blood capillaries

Question 19

state the 4 parts of nephron in order and state the processes involved, and which useful substances are reabsorbed

Answer 19

1- proximal convoluted tubule
* active transport & diffusion –> ALL glucose, ALL amino acids, MOST mineral salts
* osmosis –> MOST of water

2- loop of Henle
* osmosis –> SOME water

3- distal convoluted tubule
* active transport & diffusion –> SOME mineral salts

4- collecting duct
* osmosis –> SOME water

Question 20

state at least 3 of 5 causes for kidney failure

Answer 20

1. high blood pressure
2. diabetes
3. alcohol abuse
4. damage to kindey(s) due to accident
5. complications from major surgeries

Question 21

state at least 2 of 3 ways to treat kidney failure

Answer 21

1. kidney transplant
2. hemodialysis
3. peritoneal dialysis

Question 22

state what occurs during hemodialysis

Answer 22

1. blood is channeled from a vein of the patient’s arm into the tubing of dialyser
   -> can dump in features of dialysis machine here if free response or something
2. small molecules such as urea and other metabolic waste products diffuses out of tubing into dialysis fluid through the partially permeable walls of the tubing
3. blood cells, platelets, and large molecules remain in the tubing
4. filtered blood is then returned to the vein of the patients’s arm

Question 23

state features of the dialysis machine and how it aids it in its function

Answer 23

1. tubing is long, narrow and coiled: increase SA:V for more efficient diffusion of substances between blood and dialysis fluid
2. dialysis fluid contains no metabolic waste products (/urea): SETS UP a steep concentration gradient for more efficient diffusion of metabolic waste products (/urea) out of tubing into dialysis fluid
3. dialysis fluid has same concentration of essential nutrients as healthy blood: ensures that there is no diffusion of essential nutrients out of blood into dialysis fluid, and essential nutrients can also diffuse from dialysis fluid into tubing should a patient’s blood lack these.
4. direction of blood flow in tubing is opposite to flow of dialysis fluid: MAINTAINS a steep concentration gradient between patient’s blood and dialysis fluid for higher rate of diffusion of metabolic waste products out of blood

“no metabolic waste products” should be replaced with no urea if question is specific
point 3 should not be written if question asks for removal of substances

Question 24

state features of dialysis fluid

Answer 24

1. maintained at body temperature (to prevent blood from gaining or losing heat)
2. sterile (free from pathogens + contaminants)
3. contains glucose/amino acids at same conc. as healthy blood
4. does not contain any urea

Question 25

# label [the following parts](https://drive.google.com/file/d/1EHhQADzMVsvsRPCUuXOQHgATTDyMHRFg/view?usp=sharing)

Answer 25

[answer](https://drive.google.com/file/d/15a-oJ03gcwPZhcWTeLALg7l5ndiYK2XC/view?usp=sharing)