B15

Question 1

Homeostasis

Answer 1

Dynamic equilibrium using receptors and effectors.
+ve and -ve FB systems.
Blood, pH, temp. etc.).

Question 2

Thermoregulation

Answer 2

Constant core temp. maintenance. Temp. changes due to physical processes (exothermic chemical reactions, latent heat/evap., radiation, convection).

Question 3

Ectotherm

Answer 3

Warm body with the environment, not regulated due to metabolism.

Question 4

Endotherms

Answer 4

Stable core temp. despite environment. Metabolic rate x5 of ectotherms.

Question 5

Excretion

Answer 5

Remove metabolic waste products from cells and the body e.g. CO2, bile pigments.

Question 6

Liver

Answer 6

5% of body mass. Grow stem cells, rich blood supply.
3 main functions are carbohydrate metabolism, deamination of excess aa, detoxification. Control gluc. levels based off interactions with insulin and glucagon in blood.

Question 7

Hepatic Artery

Answer 7

Carries oxygenated blood from the heart to the liver via the aorta.

Question 8

Hepatic Vein

Answer 8

Carries deoxygenated blood from the liver to the heart. Rejoins vena cava, takes away products of liver metabolism.

Question 9

Hepatic Portal Vein

Answer 9

Carries blood rich in products of digestion from intestines/digestive organs to the liver. Liver absorbs and metabolises the nutrients.

Question 10

Lobule

Answer 10

Make up the liver. Contains hepatocytes, sinusoids, Kupfer cells, bile duct, portal vein, hepatic artery, central vein.

Question 11

Sinusoids

Answer 11

Where blood from hepatic artery and hepatic portal vein is mixed, which supplies hepatocytes with oxygen.

Question 12

Kupfer Cells

Answer 12

Inside sinusoids, act like macrophages, ingesting foreign particles.

Question 13

Canaliculi

Answer 13

Space which hepatocytes secrete bile (from the breakdown of blood) into, which then drains into bile ducts which carry it to the gall bladder.

Question 14

Hepatocytes

Answer 14

Liver cells, have large nuclei and Golgi and lots of mitochondria (metabolically active). Divide and replicate. Next to sinusoids in the lobule.

Question 15

Carbohydrate Metabolism (in hepatocytes).

Answer 15

Gluc. level inc. = insulin level inc. = stim glycogenesis in liver.
Gluc. level dec. = glucagon level inc. = stim glycogenolysis & gluconeogenesis in liver.

Question 16

Glycogenesis

Answer 16

Convert glucose to glycogen, which is stored in liver.

Question 17

Glycogenolysis

Answer 17

Glycogen stored in liver and muscles broken down into glucose which is released into bloodstream.

Question 18

Gluconeogenesis

Answer 18

Production of glucose from non-carb stores e.g. liver can make glucose with glycogen and aa. Glucose released into bloodstream.

Question 19

Deamination of excess aa (in hepatocytes).

Answer 19

Removal of an amine group. Body cannot store aa/proteins, so deaminate so no to waste them.

Question 20

Process of Deamination

Answer 20

1. Remove (deaminate) amine group (H/H/N) as toxic, forms ammonia (NH3) (with multiple amine groups).
2. Ammonia –> Urea (less toxic) via ornithine cycle.
3. Urea excreted by kidneys.
4. Rest if aa for resp. or converted to lipids (store).

Question 21

Ornithine Cycle

Answer 21

NH3 + CO2 –> Citruline + H2O.
Citruline + NH3 –> Arginine + H2O.
Arginine + H2O –> Urea (CO(NH2)2).
= 2NH3 + CO2 –> CO(NH2)2 + H2O.

Question 22

Detoxification (in hepatocytes)

Answer 22

Toxic –> harmless, e.g.
Hydrogen peroxide –> O2 + H2O (catalase).
Ethanol –> ethanal –> ethanoate –> fatty acids (store)/resp.

Question 23

Liver Cirrhosis

Answer 23

Normal liver tissue replaced with fibrous scar tissue.
1. Fatty liver.
2. Alcohol hepatitis.
3. Alcohol cirrhosis (irreversible).