Transport Mechanisms, Closed Double circulatory system, Open & closed systems, Main blood vessels, Arteries, Capillaries, Veins, Muscular artery, Elastic artery, Vein, Capillary, Cells of the blood, Monocytes:, Neutrophils, Lymphocytes, Role of water in blood and tissue fluid:Blood tissue fluid and...
TOPIC 8: TRANSPORT IN MAMMALS
THE CIRCULATORY SYSTEM
Closed Double circulatory system:
- All organisms need to exchange materials, circulatory systems are systems
which carry around fluids containing materials needed by the organism, as
well as waste materials that need to be removed.
Open & closed systems
- In a closed circulatory system, blood is pumped around the body and is
always contained within a network of blood vessels. All vertebrates and many
invertebrates have closed circulatory systems.
- In an open circulatory system, blood is not contained within blood vessels but
is pumped directly into body cavities, arthropods and molluscs have open
circulatory systems.
- Humans have a closed double circulatory system; in one complete circuit,
blood passes through the heart twice.
- Right side of the heart pumps blood deoxygenated to the lungs for gas
exchange; the pulmonary circulatory system.
- Blood then returns to the left side of the heart, so oxygenated blood can be
pumped at high pressure around the body; systemic circulatory system.
,Heart: hollow muscular organ located in the chest cavity which pumps blood.
Cardiac muscle tissue is specialised for repeated involuntary contraction without
rest.
Arteries: blood vessels which carry blood away from the heart. The walls of the
arteries contain lots of muscle and elastic tissue and a narrow lumen, to maintain
high blood pressure. 0.2-2.5 cm in diameter.
, Arterioles: small arteries which branch from larger arteries and connect to
capillaries. 30μm in diameter.
Capillaries: tiny blood vessels (5-10μm diameter) which connect arterioles and
venules- Their size means they pass directly through past cells and tissues and
perform gas exchange and exchange of substances such as glucose.
Venules: small veins which join capillaries to larger veins. 7μm-1mm
Veins: blood vessels which carry blood back towards the heart, the walls of veins
are thom in comparison to arteries, having less muscle and elastic tissue but a wider
lumen. Valves help maintain blood flow back towards the heart.
Main blood vessels:
- Pulmonary and systemic circulations are features of a double circulatory
system, where blood passes through the heart twice in one full circuit around
the body.
- Pulmonary circulatory system transports deoxygenated blood to lungs
- Systemic circulatory system transports oxygenated blood to the rest of the
body.
- Diffusion of oxygen is reliant on:
- Concentration gradients that exist between oxygen in the air in the alveoli of
the lungs and oxygen in the blood.
- Concentration gradient that exists between oxygen in red blood cells and the
respiring tissues of the body.
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