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Chapter 6: Transport in humans - Coggle Diagram
Chapter 6: Transport in humans
Plasma
transports
nutrients from the small intestine to other parts of the body
excretory products from organs where they are produced to excretory organs for removal
blood cells around the body
hormones from endocrine glands to target organs
contains
mainly water and substances such as glucose, salts, proteins, amino acids, fats, vitamins, hormones and excretory products such as urea
red and white blood cells
Red Blood Cells
features
no nucleus
contains a red pigment called haemoglobin
circular, biconcave shape
flexible
function: transport oxygen from the lungs to other parts of the body
adaptations
flexible and can change into a bell shaped structure so that they can flow easily through narrow blood capillaries
they have a biconcave shape to increase surface area to volume ratio, increasing the rate of absorption and release of oxygen
they have no nucleus which means there is more space for more hemoglobin to be stored
contains hemoglobin that can combine reversibly with oxygen
when oxygen concentration is high (lungs), hemoglobin binds to oxygen to form oxyhemoglobin
when oxygen concentration is low (tissues), oxyhemoglobin releases its oxygen to the tissue cells
White Blood Cells
Lymphocytes
produce antibodies that
destroy disease causing organisms such as bacteria and viruses
cause bacteria to clump together for easy ingestion by phagocytes
recognise foreign particles
neutralise the toxins produced by bacteria
structure: irregular in shape, have a nucleus
Phagocytes
perform phagocytosis
phagocytosis: a process by which a white blood cell engulfs and destroys foreign particles such as bacteria
Platelets
fragments of cytoplasm that contain a enzyme that catalsyes the conversion of fibrinogen to fibrin threads. these threads form a network that entangles red blood cells to form a clot, preventing excessive blood loss and the entry of harmful organisms into the bloodstream
how does blood clot?
platelets re involved in converting the soluble proteins fibrinogen to insoluble threads of fibrin. fibrin threads entangle blood cells and the whole mass forms a clot or a scab. the clot seals the wound, preventing entry of microorganisms and excessive loss of blood
Blood groups
Blood group B
Antigen B
Antibody A
Blood group AB
Antigen A and B
No Antibodies
Blood group A
Antigen A
Antibody B
Blood group O
No Antigens
Antibodies A and B
Circulatory system
Arterioles
arteries branch to form tiny vessels to form arterioles. they divide and ultimately their branches become very tiny blood vessels called capillaries
Blood capillaries
made up only a single layer of flattened cells
the numerous branches provide a large surface area for the exchange of substances between the blood and the tissue cells
when the arteriole branches into many capillaries, the total cross sectional area of the blood vessels increases. this lowers blood pressure in the capillaries. flow of blood is slowed down, giving more time for the exchange of substances
Arteries
the blood vessels that vary blood
away
from the heart.
arteries have thick, muscular and elastic walls to withstand the high blood pressure in the artery. the elasticity enables the artery wall to stretch and recoil or spring back. this helps to push the blood in spurts along the artery and also gives rise to the pulse
the contraction and relaxation of muscles in the arterial wall bring about constriction and dilation of the artery. when an artery constricts, its lumen becomes narrower and less blood flows through it per unit time. when an artery dilates, its lumen becomes wider and more blood flows through it per unit time
arteries carry oxygenated blood
(except for pulmonary arteries which carry deoxygenated blood from the heart to the lungs)
Venules
before the capillaries leave the organ or tissue, they unite to form small vessels called venules
Heart
when the heart relaxes, it fills up with blood. when it contracts, the blood is squeezed out with great force. the blood then circulates through the blood vessels which direct the blood flow around the body
Veins
venules in turn join to form bigger veins. veins carry blood
back
to the heart
blood flows more slowly and smoothly in the veins hence the walls of the veins do not need to be as thick and muscular as that of the artery.
veins also contain less elastic tissue. most veins have internal valves along their length to prevent backflow of blood
veins carry deoxygenated blood
(except for pulmonary veins which carry oxygenated blood from the lungs to the heart)