physiology Flashcards
What does EPO do?
Controls RBC production and increases circulating reticulocyte count as well as maturation of committed HSC
How are RBCs destroyed?
Old cells are removed by a filtration system in the reticulo-endothelial system (spleen, liver and bone marrow)
They are phagocytosed by macrophages
How are cells chose to be removed?
Reduced flexibility
Altered membrane surface
Rupture
What percentage of plasma is water?
90%
What percentage of plasma is protein?
7%
What does albumin bind to?
Just about everything from cations, FFA, to bilirubin and hormones
What do chylomicrons do?
Produced in gut and distribute dietary lipids to rest of the body
They are taken up by the liver as CMRs (chylomicron remnants)
What are LDLs?
Low density lipoproteins produced in the liver, loaded with liver lipids, distribute lipids to the rest of the body.
What are HDLs?
Produced in the liver but are empty and pick up cholesterol from the rest of the body
How are LipoProteins unloaded?
2 ways:
- Unload lipids from lipoprotein (enzyme-catalysed removal of lipids, TGs require lipoprotein lipase enzyme (LPL), chol only from HDLs via SRB1)
- Remove entire lipoprotein via endocytosis after LPR receptor binding. (this is seen in the liver mostly)
What does lipoprotein lipase enzyme do?
Found in muscle , adipose tissue, heart, mammary glands and liberates FFAs from TGs FFAs are then removed from LPs
What are apolopoproteins?
Ligands for cell surface receptors.
apoB is required for cellular uptake of CMs and LDLs
Which apoprotein is found on ChyloMicrons?
apoB48
Which apoproteins are found on LDL?
apoB100
What happens to apoprotein cofactors?
They are recycled between circulating LPs (they are swapped)
What does LDL contain?
Lots of cholesterol
What does HDL do?
Picks up excess cholesterol from tissue and brings it to the liver
How is CO2 transported in blood?
It dissolves in plasma well but it is also loaded onto RBCs through carbonic anhydrase:
CO2 + H2O H2CO3 H+ +HCO3
Hb in RBCs bind CO2 forming carbamino compounds
How is CO2 transport distributed?
Dissolved = 10%
Carbamino = 20% (attached to terminal amino groups of proteins in Hb)
Bicarbonate = 70%
What is acidosis?
Reduction in arterial pH <7.35
What is alkalosis?
Increase in arterial pH >7.45
Why is pH so important to maintain?
Every step of metabolism is pH dependent. Deviations of pH reduce reaction efficiency.
The reason for this is enzymes
How does pH affect neuromuscular system?
Acidosis is inhibitory
Alkalosis is excitatory (
Why is acidosis inhibitory for the neuromuscular system?
More free calcium in blood due to Ca2+ binding to albumin being pH dependent
Ca2+ blocks vNa+ channels raising AP threshold
Acidosis increases K+ in serum
What are the consequences of acidosis?
Headaches, confusion, lethargy, tremors, sleepiness
Cerebral dysfunction -> coma
Hyperventillation
What are the consequences of alkalosis?
Muscular weakness, pain, cramps, spasms -> tetany
Hypoventilation
Where does acid come from in the body?
Most acid comes from CHO/fat metabolism (CO2 production)
How do the kidneys regulate BP?
They control the concentration of HCO3 and H+ in the blood.
How does the kidney control pH?
Kidneys constantly remove HCO3 from the blood. For reabsorbtion H+ must be secreted into tubule. This stage of the process is regulated
What is time-intensity relationship?
Both severity and length of exposure are factors.
What kind of concept is response to injury in cells?
A time-intensity relationship
What causes cell injury?
Oxygen deprivation
Physical agents such as trauma, heat, cold, pressure, radiation, electric shock
Chemical agents such as drugs and toxins
Infectious agents
Immunological reactions
Genetic derangements
Nutritional imbalances
What is necroptosis?
Necroptosis is a programmed form of necrosis, or inflammatory cell death.
What is pyroptosis?
Pyroptosis is a highly inflammatory form of programmed cell death that occurs most frequently upon infection with intracellular pathogens and is likely to form part of the antimicrobial response.
What nuclear changes occur during necrosis?
Pyknosis
Karyorrhexis
Karyolysis
What is pyknosis?
Pyknosis, or karyopyknosis, is the irreversible condensation of chromatin in the nucleus of a cell undergoing necrosis or apoptosis. It is followed by karyorrhexis, or fragmentation of the nucleus.
What is the difference between coagulative and liquefactive necrosis?
Coagulative: Affected cells retain their shape but lose their nuclei, defined area usually due to loss of blood supply, scaffolding is still present meaning healing is done by scar formation.
Liquefactive necrosis occurs if damage to tissue is cleared resulting in cavity formation instead of a scar.
What are the types of necrosis that can occur?
Coagulative
Liquefactive
Caseous (mixture of coagulative and liquefactive)
Fat necrosis (foamy macrophages and calcification and accumulation of lipids)
Fibrinoid necrosis (looks like fibrin in walls of blood vessels)
Gangrene (coagulative necrosis where tissue turns black)
What are the 2 pathways of apoptosis?
Intrinsic: Loss of survival signals, DNA damage, and accumulation of misfolded proteins (ER stress)
Extrinsic: Death receptor activation (TNF receptor)
How are apoptosis byproducts cleared?
Macrophages can clear the stuff without inflammation
What family of proteins are anti-apoptotic?
BcL
