Week 24 integration of cells and tissue

Question 1

Why are higher eukaryotes able to function efficiently

Answer 1

Due to the existence of organs and tissues with different and specific functions

Question 2

if all cells within an organism contain the same genome, why do different cells have different functions

Answer 2

All cells have the same genome but only express different genes to different extents

Question 3

why do tissues work together in a integrated way

Answer 3

To ensure that needs of each tissue are fulfilled and coordinated to ensure that the organism can grow, metabolise and move and that homeostasis of the organism is maintained

Question 4

what are long protoplasmic fibres also called

Answer 4

Axons

Question 5

How many nuerons does the brain have

Answer 5

33 billion

Question 6

why is 20-25% of basal metabolism devoted to the brain

Answer 6

As the brain has many nuerones, it needs lots of energy to maintain the electrical gradient of the intracellular and extracellular environments via the active transport of ions in out of the the nuerones

Question 7

skeletal muscle can contract and relax because..

Answer 7

it has lots of proteins called actin and myosin organised in filaments which can slide over eachother and combine to form actomyosin. which causes a contraction

Question 8

skeletal is divided into two types of fibres

Answer 8

slow twitch fibres and fast twitch fibres

Question 9

triacylglycerol(triglycerides) is a store of

Answer 9

fatty acids

Question 10

White adipose tissue is

Answer 10

the bodys main store of energy

Question 11

what are lobules

Answer 11

hexagonal function units of the liver, which are made up of hepatocytes(liver cells)

Question 12

What two major vessels supply the liver with blood?

Answer 12

Hepatic portal vein and hepatic artery

Question 13

what does the hepatic artery provide to the liver

Answer 13

oxygenated blood

Question 14

what does the hepatic portal vein supply to the liver

Answer 14

hepatic portal vein provides blood containing nutrients, drugs etc, from the gastrointestinal tract(everything that has just been digestive system and absorbed in the small intestine is then brought to the liver).

Question 15

Give two Liver functions

Answer 15

• Storage of glucose as glycogen

- Synthesis of glucose and ketone bodies

Question 16

what is gluconeogenesis

Answer 16

a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates(gluconeogenic Amino acids)

Question 17

what is the store of glucose

Answer 17

glycogen

Question 18

what are two enzymes which the liver uses for glycogen synthesis and breakdown

Answer 18

it has high concentrations of glycogen metabolizing enzymes (glycogen synthase and glycogen phosphorylase(breakdown)) in near the glycogen pellet of the cell.

Question 19

what is Glucokinase and why does the liver only have it

Answer 19

glucokinase which has a much greater capacity for glucose phosphorylation that hexokinase this allows the liver to quickly deal with increased glucose intake. When Glucose is phosphorylated it cannot diffuse out of cell across its transporter, SO REMAINS IN THE LIVER AND GETS STORED. Glucokinase can increase its activity as glucose intake increases however hexokinase gets saturated and cannot act more

Question 20

What two pathways can fatty acids taken up by the liver enter

Answer 20

1) Esterified in livers cytosol to triacylglycerol and packaged as VLDL for secretion to be transferred and stored in white adipose tissue(fed state)
2) be oxidised in the livers mitochondria in the beta-oxidation pathway

Question 21

How does the liver decide which pathway the fatty acids enter
tip (fatty acids transport mechanism)

Answer 21

it depends on the activity of the mitochondrial fatty acid transport mechanism that involves carnitine acyl transferase I(CAT I)

- In fed state fatty acids aren't required for energy so CAT I in inactive and the majority of fatty acids are esterified into triacylglycerol in the cytosol
- In starved state CA T I is active and the majority of fatty acids are oxidised in the mitochondria