Bioenergetics Flashcards
L2-5 (29 cards)
What is membrane potential?
the potential difference between the inside and outside of the cell.
What is the arbitrary when measuring membrane pot?
The outside of the cell is the arbitrary 0
Why are ionic gradients set up?
Ionic gradients allow a difference in potential which allows cells to be electrically excitable.
What is the ionic trend of the following ions:
Na+
K+
Ca2+
Na+ - higher conc extracellular- moves in during depolarisation
K+ - higher conc intracellular- moves out after depol to allow hyperpolarisation of the membrane. Without K+ efflux another AP would bot happen.
Ca2+ - high conc outside the cell
Which way does the membrane potential move to?
Membrane pot. always moves towards the Equil. pot for that ion.
General rule for K+ ionic movement?
Higher [intracellular] –> Moves out down its concentration gradient
–>Moves positive charge out of the cell = Hyperpolarising
starts as a negative resting potential. Hyperpolarisation occurs and shortens duration of the action potential.
General rule for Na+ and Ca+ ?
Higher [extracellular] –>Moves down their concentration gradients
–>Moves positive charge into the cell =Depolarisation
Open Na+ channels cause rapid depolarisation (short lived due to rapid inactivation)
Open Ca2+ channels cause sustained depolarisation
What is the cardiac cycle?
start of one contraction to the start of the next.
Stroke volume?
volume of blood ejected from the heart during each cycle.
eg. If Ventricle contains 100ml of blood after diastole and 40ml after systole, 60ml is the ejected (SV)
Cardiac output?
Equation?
total volume of blood pumped by the ventricle per min.
CO= SV X HR
Location of cardiac muscle?
In the heart
Appearance of cardiac muscle?
Short fibres with lots of branches. intercalated discs between cells which allow rapid depolarisation throughout myocardium.
Activity of cardiac muscle?
Continuous rhythmic contraction.
Stimulation style of cardiac muscle?
involuntary contraction triggered by a pacemaker. Controlled by the nervous system but not dependent on it.
Metabolism of cardiac muscle?
Aerobic metabolism fueled by fatty acids. Can be anaerobic but causes ischemia (lack of blood supply to tissues)
Location of skeletal muscle?
throughout the body, attacked to skeleton and fascia (connective tissue) to allow movement.
Appearance of skeletal muscle?
long cylindrical fibres. Unbranched striated muscle (Z-lines align)
Activity of skeletal muscle?
Voluntary muscle - contracts when required to produce movement - excitation/contraction coupling
Stimulation of skeletal muscle?
voluntary or reflex action of the nervous system
metabolism of skeletal muscle?
Anaerobic for short bursts of activity (type II) , aerobic for longer duration (type I)
What is the difference between Ventricular AP’s in the neurons and heart?
Ventricular AP is much longer in the heart:
Neuron - 2 ms
Cardiac - 300 ms
What is the greatest regulation of BP?
Arterioles, they absorb the greatest pressure drop
Key features of the vascular system ?
blood enters the heart and pressure drops at arterioles
capillaries are only 1 cell thick :. pressure decreases and osmosis occurs
mean arterial pressure?
function of systolic contraction and diastolic pressure.
