Week 24 integration of cells and tissue Flashcards
Why are higher eukaryotes able to function efficiently
Due to the existence of organs and tissues with different and specific functions
if all cells within an organism contain the same genome, why do different cells have different functions
All cells have the same genome but only express different genes to different extents
why do tissues work together in a integrated way
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
what are long protoplasmic fibres also called
Axons
How many nuerons does the brain have
33 billion
why is 20-25% of basal metabolism devoted to the brain
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
skeletal muscle can contract and relax because..
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
skeletal is divided into two types of fibres
slow twitch fibres and fast twitch fibres
triacylglycerol(triglycerides) is a store of
fatty acids
White adipose tissue is
the bodys main store of energy
what are lobules
hexagonal function units of the liver, which are made up of hepatocytes(liver cells)
What two major vessels supply the liver with blood?
Hepatic portal vein and hepatic artery
what does the hepatic artery provide to the liver
oxygenated blood
what does the hepatic portal vein supply to the liver
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).
Give two Liver functions
- Storage of glucose as glycogen
- Synthesis of glucose and ketone bodies
what is gluconeogenesis
a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates(gluconeogenic Amino acids)
what is the store of glucose
glycogen
what are two enzymes which the liver uses for glycogen synthesis and breakdown
it has high concentrations of glycogen metabolizing enzymes (glycogen synthase and glycogen phosphorylase(breakdown)) in near the glycogen pellet of the cell.
what is Glucokinase and why does the liver only have it
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
What two pathways can fatty acids taken up by the liver enter
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
How does the liver decide which pathway the fatty acids enter
tip (fatty acids transport mechanism)
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
