Physiology Flashcards
What is facilitated diffusion?
Diffusion that uses a carrier protein to facilitate passive diffusion
What is active transport?
Requires energy to pump molecules against their concentration gradient
What is primary active transport and what is an example?
When energy is used directly to move substance against the concentration gradient
Sodium potassium pump
What is secondary active transport?
Solute moves against its concentration gradient facilitated by the passive movement of an ion down a concentration gradient
What is a symport?
Solute and ion move in the same direction
What is an antiport?
Solute and ion move in opposite directions
What is the process of the sodium potassium pump?
- 3 Na from inside cell bind
- ATP hydrolysed to ADP and Pi, providing energy to change conformation
- 3 Na released outside of cell, 2 K bind
- Pi released from pump, which reverts back to original cell, 2 K released into cell
What is the membrane potential?
-70mV
What is the process of an action potential?
- Resting membrane potential - voltage-gated Na channels in resting state and voltage-gated K channels closed
- Stimulus causes opening of Na channels - depolarisation of cells
- Once threshold reached more Na channels open
- Na channels close and K channels open - repolarisation
- Hyperpolarisation - more K channels open, Na channels in resting state - refractory period
Which factors affect rate of diffusion?
Surface area Membrane thickness Concentration gradient Lipid solubility Molecular weight
What is endocytosis?
‘Pinching off’ and engulfing to take molecule into cell
What is exocytosis?
Vesicle bind to plasma membrane then release its contents into extracellular fluid
What is pinocytosis?
Engulfing with fluid around the area
What is osmolarity?
The concentration of osmotically active particles in a solution
What is tonicity?
The effect a solution has on cell volume
What are the ways fo heat loss?
Radiation
Convection
Conduction
Evaporation
What is the process of returning the body to homeostasis in response to decrease in temperature?
- Thermoreceptor detects temperature change
- Posterior hypothalamus is stimulated, and causes vasoconstriction, contraction or erector muscles, decreased sweating, shivering
What is the process of returning the body to homeostasis in response to increase in temperature?
- Thermoreceptor detects temperature change
2. Anterior hypothalamus is stimulated, and causes vasodilation, increased sweating and water retention
What is defined as hyper and hypothermia?
Hyperthermia - >40
Hypothermia - <35
What is the body’s response to inflammation (fever)?
As part of inflammatory response, macrophages release chemicals that act as pyrogens
These stimulate release of prostaglandins
These change the temperature set point in the hypothalamus to higher temp
The body initiates cold response mechanism to increase body temperature to new set point - fever
When the body fights the cause or antipyretics are given, the body induces the hot response to reduce the body temperature
What is the main homeostatic response?
Negative feedback
What is normal pulse pressure?
30-50mmHg
What are the equations for MAP?
[(2 x diastole) + systole]/3
MAP = SV x HR x SVR
MAP = CO x SVR
What is the purpose of the baroreceptor reflex?
Short term control of MAP
What is the process of the baroreceptor reflex?
Baroreceptors sense change in MAP
Cardiovascular control centre in medulla receives afferent signals
Sends instructions to the effectors - heart and blood vessels
Causes vasodilation and reduced HR to reduce blood pressure
What are the main resistance vessels?
Arterioles
What is the vasomotor tone?
Keeps the vessels partially constricted at rest
