Excretion

Question 1

Define Excretion

Answer 1

The removal of metabolic waste from the body

Question 2

Define deamination

Answer 2

The removal of the amine group from an aminoacid to produce ammonia

Question 3

Define Egestion

Answer 3

Things that leave the body, and are unchanged by metabolic processes

Question 4

Why is CO2 excreted?

Answer 4

As too much causes the carrying capacity of oxygen by the haemoglobin to decrease
To avoid carbonic acid being formed

Question 5

What is respiratory acidosis?

Answer 5

When carbonic acid causes the blood pH to drop below 7.35,causing the breathing rate to increase to expell CO2.
Headaches, restlessness and HR all increase too

Question 6

What can keto acids be used for?

Answer 6

Respiration

Question 7

What does the Hepatic portal vein link?

Answer 7

The digestive system to the liver

Question 8

Define Sinusoids

Answer 8

Channels that empty into the heptic vein

Question 9

Define Hepatocytes

Answer 9

Liver cells that manafacture bile, proteins, and store carbohydrates

Question 10

What are the functions of the liver?

Answer 10

Control of blood glucose, amino acid, and lipid levels
Detoxification of drugs and alcohol
Vitamin storage
Synthesis of bile, plasma proteins, and cholesterol

Question 11

The ormithin cycle does what?

Answer 11

Converts ammonia to urea (by adding CO2)

Question 12

Why does ammonia need to be converted to urea?

Answer 12

As ammonia is very soluble (so excretion would dehydrate too much)
And it is much more toxic

Question 13

What is the pathway of the breakdown of alcohol?

And what is the product used for?

Answer 13

Ethanol&raquo_space; Ethanal&raquo_space; Ethanoic acid&raquo_space; Acetyl CoA

Used in respiration (kreb cycle)

Question 14

What causes Cirrhosis?

Answer 14

When too much alcohol is taken then there is not enough NAD for respiring fatty acids
So the fatty acids are converted to lipid, which accumulate in the livers hepatocytes

Question 15

What is the Ureter of the kidney?

Answer 15

The tube connecting the kidney to the bladder (transports urine)

Question 16

How does Ultrafiltration occur in the bowmans capsule?

Answer 16

Different diameters of afferant and efferant arterioles generate a high hydrostatic blood pressure in the glomerulus
Some small molecules pass through the basement membrane, between the podocytes in the epithelium cells of the bowmans capsule
This forms the glomerular filtrate in the lumen of the bowmans capsule

Question 17

Explain how the pct works to selectively reabsorb certain molecules

Answer 17

Na+ ions activley transported out of the pct (via Na/K Pumps + ATP)
Glucose + amino acids + Na+ are diffused (by co-transporter proteins) into the pct from the filtrate
The increase of moleucles in the pct causes its WP to drop, so water moves into the pct via osmosis
These molecules then diffuse out of the pct and into the blood
The WP of the pct is high, so the water moves into the blood via osmosis
Large molecules can be reabsorbed by endocytosis

Question 18

What type of cells are used to increase the surface area of the pct?

Answer 18

Microvilli

Question 19

Explain how the loop of henle (L of H) reabsobs water

Answer 19

Na+ and Cl- diffuse into the descending limb
Water leaves the descending limb by osmosis and into the medulla
The ions then diffuse out of the base of the ascending limb and into the medulla
The ions are actively transported out of the ascending limb to form a high WP
The ascending limb is impermeable so water cant leave
Water moves via osmosis into the medulla at the collecting duct

Question 20

What is the type of current that is present in the loop of henle to increase the efficiency of water reabsorption?

Answer 20

Hairpin Counter Current Multiplier

Question 21

What job does the Dct do?

Answer 21

Uses active transport to adjust the concentration of salt in the urine

Question 22

How is ADH released, and what affect does it have?

Answer 22

Osmoreceptors in the hypothalamus detect the WP of the blood
When the blood WP is low the osmoreceptor cells lose water and shrink
This shrinkage stimulates neurosecreatory cells
These cells release ADH into the posterious pituitury gland, and they are then released
ADH binds to the receptors on the cells of the collecting duct
Enzyme controlled reactions occur to cause vesicles containing aquaporins to be inserted into the plasma membrane
So the WP of the blood returns back to normal

Question 23

What is the half life of ADH?

Answer 23

20 minutes

Question 24

What is added to the blood in Haemodialysis to prevent clotting?

Answer 24

Heparin

Question 25

Describe Peritonel dialysis

Answer 25

A permanent tube is surgically insterted into the abdomen
Dialysis fluid added to the tube to fill the space between the abdominal wall and the organs
The fluid is in for several hours at a time, and happens many times a day
Patient is free to do what they please during treatment (they are ‘free’)

Question 26

What is the membrance of the tube in peritoneal dialysis made of?

Answer 26

Peritoneum

Question 27

How do you test for pregancy?

Answer 27

Test stick contains monoclonal antibodies that bind to HCG
The antibodies are attatched to a blue beed
The HCG/antibody complex attatches to a strip of immobilized antibodies so that a blue line is formed

Question 28

What are anabolic steroids?

Answer 28

Increase protein synthesis in cells

Remain in the blood for many days