The Heart and Circulation Essay Plan

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The Heart and Circulation
Cardiac Cycle:
1. Atrial Systole (contraction), Ventricular Diastole (Relaxation)
2. Atrial Diastole, Ventricular Systole
3. Atrial Diastole, Ventricular Diastole
Vessels:
Arteries: Elastic fibres to withstand pressure, recoil to absorb pressure.
Arterioles: Muscley to constrict or dilate, controls blood supply to specific areas.
Capillaries: Thin, permeable, allows rapid diffusion.
Veins: Relatively thin, contains valves, preventing backflow.
Haemoglobin:
A protein found in Red Blood Cells that transports oxygen. Hb+4O2<->HbO8
Regulation of body temperature:
Vasoconstriction- arteriole constricts, shunt vessel dilates, connecting vessel dilates.
Vasodilation- arteriole dilates, shunt vessel constricts, connecting vessel constricts, blood flows
through capillaries.
Hepatic=Liver
Mesentric=Gut
Renal=Kidneys
Heart>Arteries>Arterioles>Capilaries>Venules>Veins>Heart
>Lymph>Veins>Heart
Brain> Parasympathetic nerve (decelerator)>Heart
Brain>Sympathetic nerve (accelerator)>Heart
Exercise:
Increase in muscular activity, more CO2 produces by tissues from increased respiration, blood pH is
lowered. Chemical receptors in the carotid arteries increase frequency of impulses to medulla
oblongata, the centre in the medulla oblongata that speeds up heart rate increases the frequency of
impulses to the Sino-atrial Node via the sympathetic nervous system. The SAN increases heart rate.
Blood Pressure:

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HIGH->Nervous impulse to medulla oblongata->Sympathetic Nervous System->SAN
LOW-> Nervous impulse to medulla oblongata->Parasympathetic Nervous System->SAN…read more

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