BLG 251 Lecture Notes - Cardiac Output, Stroke Volume, Cardiac Muscle
Document Summary
Decline in functional effectiveness of cells and organ systems: deterioration in cells / slower responds to stimuli / slows homeostatic mechanism. Ageing is controlled by genes but can be slowed down by: regular (and adequate) sleep, (well balanced) meals, exercise, refrain from smoking and alcohol, keep body mass close to desirable mass for your height. Cardiac output = stroke volume x heart rate: cardiac output decreases even though heart rate does not decline, due to cardiac muscle fibres weaken (mainly left ventricle, decreases stroke volume of ventricles/volume of blood pumped per beat/cycle. Nerve conduction velocity: cells in peripheral nervous system and brain get less. Neurones (nerve cells) are lost and cannot divide. Effect of cell loss depends on cells location. Increased width of synapses: longer needed for diffusion/movement/greater distance to receptors/further to stimulate post- synaptic membrane/further diffusion distance of transmitter (across synapse: slower synaptic transmission: presynaptic neurones produce less neurotransmitter.