Outgoing Biology Unit 3 (Transporting Substances)

Notes on transporting substances around the body (e.g. blood vessels)

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  • Created on: 23-05-12 08:24
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Transporting Substances around the Body
The Circulatory System
The circulatory system consists of the blood vessels, the heart and the blood.
Humans have a double circulation system, in which the heart acts as a pump, moving blood
around the body. The double circulation system makes our circulation very efficient and quick.
The function of the circulatory system is to carry materials around the body. It carries:
o Digested food and water
o Oxygen from the lungs
o Waste products of respiration
o Hormones from the various glands
o Energy from cell respiration
o White blood cells and antibodies
o Fibrinogen and other dissolved chemicals which form part of the blood plasma
The three main types of blood vessels are the arteries, veins and capillaries.
Blood Vessels Distinctive Features
Artery Carry blood away from the heart to organs.
Bright red oxygenated blood
Stretch as blood is forced through them and go
back into shape afterwards (pulse)
Vein Carry blood to the heart
Low in oxygen (purple)
Do not have a pulse
Have valves to prevent the back-flow of blood
Capillary Between the arteries and the veins is a network
of capillaries.
Narrow, thin walls for easy diffusion

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Transport in the Blood
Blood is the main transport medium in the body. The blood plasma transports dissolved food
molecules, carbon dioxide and urea.
Red blood cells (made in the bone marrow)are adapted to transport oxygen from the lungs
to the organs:
They are biconcave discs, increasing their surface area to volume ratio for diffusion
They are packed with haemoglobin, a special pigment which can carry oxygen
They do not have a nucleus, giving more space to pack in haemoglobin.…read more

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Anaerobic Respiration
In some circumstances, the oxygen supplied to the body is not sufficient to maintain aerobic
respiration, and the muscles switch to anaerobic respiration.
This delivers less energy to drive metabolism, so muscles become fatigued. The glucose is
not broken down completely and lactic acid is produced.
After a period of strenuous exercise, the body is out of breath as the body has an oxygen
debt.…read more

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In the Nephron
o Urea is carried dissolved in the blood plasma; ultrafiltration removes the liquid and
small molecules from the blood
o The walls of the capillaries and the Bowman's capsule act as very fine filters; proteins
and cells remain in the blood
o Water and solutes move into the Bowman's capsule; filtration is brought about by
high blood pressure in the capillaries (the branch of the artery has a wider diameter
than the branch of the vein)
1st Convoluted Tubule
o The…read more

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The Kidney (in short)
Homeostasis is the maintenance of constant internal body conditions; one of the things
needing to be regulated is the amount of toxins present.…read more

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Blood is filtered and then returned to the patient's radial vein.…read more

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Initially costly, cost-effective over time Antigen-antibody reaction when donor
kidney is genetically different to
Patient can live a normal productive life recipient
No dietary restrictions Possibility of rejection by immune
system (Immunosuppressant drugs given
to minimise chances of rejection)
Less resistance to infections because of
Risk associated with invasive operation…read more


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