Session 1: Homeo+cells Flashcards
(52 cards)
Define the term ‘homeostasis’ with respect to water, temperature and pH balance
Homeo= sameness and stasis = standing still
“the ability or tendency of a living organism, cell, or tissue to keep the conditions inside it the same despite any changes in the conditions around it, or maintaining a state of internal balance”
Is in a state of dynamic equilibrium
Explain the concepts behind positive and negative feedback loops
Positive= An initial stimulus produces a response that accelerates or enhances the original change in conditions rather than opposing it
Positive stops when initiator stops
Negative stops when effector ceases
How does the body react differently to internal temperature increase and decrease?
Explain the positive feedback loop when a baby pushes against cervix
Explain positive feedback loop of blood clotting
Explain negative feedback loop of rising blood glucose level stimulus
Explain the importance of acid-base balance for normal human physiology
Importance; maintain within normal limits 7.35-7.45
Why?
To maintain homeostasis
Abnormal pH damage cells and tissues by breaking chemical bonds, changing the shpaes of proteins and altering cellular function
Whats acidosis and its causes, symptoms and treatment?
pH below 7.35
Causes?
Metabolic acidosis and respiratory acidosis
Treatment?
Infusion by bicarbonate solution (increase blood pH) and mechanical ventilation to drive out co2
Whats alkalosis?
pH above 7.45
pH above 7.8 generally causes uncontrollable and sustained skeletal muscle contractions
State the ‘normal range’ for pH in tissues including blood
7.35-7.45
State the ‘normal range’ for core body temperature
Recall the mechanism(s) (in broad terms) that regulate core body temperature
Two temperature sensors: one in skin (external body temp) and in hypothalamus (internal core temp)
Recall the mechanism(s) (in broad terms) that regulate pH
Carbonic acid- bicarbonate buffer: co2 in hemoglobin to bic (carbonic anhydrase), bic (leaves rbc) goes to lungs, converted back to co2 (by carbonic anhydrase) and leaves (low partial pressure of co2)
Recall the percentage of water in a ‘standard’ 70kg male
60%
State the body compartments where fluids accumulate
Compare and contrast water balance in males and females [and in early life and in older populations]
The older and more fat, the less h2o proportionally in body. Women more fat than men.
Outline the differences between dehydration and water toxicity
Water toxicity; Cells in hypotonic solution (environment) therefore cells swell and reach point where theres HIGHER osmotic pressure inside cell compared to outside. Cells swell, enzymes + proteins stop working. Cell keeps swelling until burst.
Dehydration; Osmolality increases (around cells)
Describe the process of oedema
Fluid retention
Hydrostatic Pressure greater than osmotic pressure
Whats Osmolality units?
mOsm/kg
Whats tonicity?
A description of how the solution affects the shape of the cell
(osmotic pressure=osmolarity)
How do we classify and analyse pH imbalances?
Arterial blood gas
Difference between osmolality and osmolarity?
What is the normal pH range for tissue survival?
6.8-7.8 limits of tissue survival.
Whats pyrexia and rigor?
Pyrexia is a fever.
Rigor occurs when “thermostat” in hypothalamus turned up. Hence shivers to warm self up. Increase in temperature helps immune system work optimally.
