Download Transport in humans

Transport in humans
Circulatory system
Syllabus
• understand why simple, unicellular organisms can rely on
diffusion for movement of substances in and out of the cell
• understand the need for a transport system in multicellular
organisms
Humans
• recall the composition of the blood: red blood cells, white
blood cells, platelets and plasma
• understand the role of plasma in the transport of carbon
dioxide, digested food, urea, hormones and heat energy
• describe the adaptations of red blood cells for the transport
of oxygen, including shape, structure and the presence of
haemoglobin
• describe how the immune system responds to disease
using white blood cells, illustrated by phagocytes ingesting
pathogens and lymphocytes releasing antibodies specific to
the pathogen
Syllabus
• describe the structure of the heart and how it
functions
• understand that the heart rate changes
during exercise and under the influence of
adrenaline
• describe the structure of arteries, veins and
capillaries and understand their roles
• recall the general plan of the circulation
system to include the blood vessels to and
from the heart, the lungs, the liver and the
kidneys.
Heart
• Made up of cardiac muscle
• Structure
– 2 pumps
– 4 chambers
• 2 atria
• 2 ventricles
– Heart labeled according to how it sits
in the body.
Heart
• Function
– Pump blood around the body
– Supplies cells with oxygen & nutrients,
removes carbon dioxide and other
waste products
• Double circulatory system
– Blood travels through the heart twice
– Advantages
• Blood pressure maintained
• Oxygenated blood kept separate from
deoxygenated blood
• Enables lower pressure in pulmonary
circulation
• Other facts on the heart
Vena cava
Tricuspid
(left AV)
Aorta
Right atrium
Left atrium
Bicuspid/mitral
(right AV)
Left ventricle
Aortic
semilunar
Pulmonary
Semilunar
Right
ventricle
Pulmonary
vein
To the lungs
Pulmonary
artery
To the body
Arteries, veins & capillaries
• Arteries
– Structure
• Thick walls (blood pressure
high)
• Narrow central tube (lumen)
• Thick muscular layer (avoid
over stretching when blood
is pumped out)
– Function
• Carry blood away from the
heart
Arteries, veins & capillaries
• Veins
– Structure
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Thin walls (blood pressure low)
Valves present to prevent backflow
Wide central tube
Bigger than arteries
– Function
• Carry blood to heart
• Valves prevent blood flowing
backwards
• Muscles contracting help move
blood through veins
Arteries, veins & capillaries
• Capillaries
– Structure
• Thin walls (one cell thick)
• Large surface area
• Walls ‘leak’
– Function
• Slows down the blood so materials
can be exchanged
• Reduces blood pressure
• Allows plasma to pass through the
walls
Blood
• An adult weighing 70 kg has 5-6 litres of blood
• Functions of blood
– Transport various substances
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Oxygen
Carbon dioxide
Hormones
Glucose, amino acid
Urea
– Distribution of heat
– Defence against disease
– Message-transfer using hormones
Blood
• Structure
– Plasma
• Makes up 55% of blood
• 90% is water
• Pale yellow in colour
– 45% consists of cells
• Red Blood cells (RBC)
– Carry oxygen
• White blood cells (WBC)
– Help against infections
• Platelets
– Used for clotting
Plasma
• 90% water
• 10% includes:
– Dissolved food from digestion
• Glucose
• Amino acids
– Salts
• Help keep the blood at the right concentration and the cells working
properly
• Na+, Cl-, Ca2+
– Proteins
• Help the blood clot and help to protect the body against invaders
– Hormones
• Control the way the body responds
– Waste materials
• Carbon dioxide
• urea
Red Blood Cells
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Biconcave in shape
Made in the bone marrow
No nucleus
Contain the protein haemoglobin which carries
oxygen
• Live for 120 days
• Travel once around circulatory system every 75
seconds
• Shortage of haemoglobin = anaemia
– Symptoms = tiredness
White blood cells
• Two types identified by the shape of their
nucleus.
– Phagocytes
– Lymphocytes
• Protect the body against diseases
• Can be destroyed by cancer = leukaemia and
by HIV.
White blood cells
• Phagocytes
– Made in bone marrow
– Contain a nucleus that has several
lobes
– Used to defend us against disease
by killing germs which enter the
body
– Kill by engulfing (‘eating’) germs
– Dead phagocytes often contain
dead bacteria = ‘pus’
– Dispose of old red blood cells
White blood cells
• Lymphocytes
–Produce chemicals called
antibodies to destroy germs and
react with poisons to make them
harmless.
–Nucleus is large and circular in
shape
–Mature in lymph tissue
Platelets
• Made in the bone
marrow
• Fragments of cells
• No nucleus
• Used for blood
clotting
Clotting
• Stops:
– pathogens entering through cuts
– Person from losing too much blood.
• Procedure
– Platelets bump into the rough edges of a cut
– A chemical is then released, the damaged
tissues also release chemicals.
– Blood plasma contains a soluble protein
(fibrinogen) that is changed into fibrin
(insoluble), when the chemicals (from the
platelets & damaged tissues) are released.
Clotting
• Procedure
– Fibrin forms fibres which form a mesh across
the wound.
– RBC and platelets get trapped in these fibres
= BLOOD CLOT
– When blood clot is exposed to air = scab
– Animation of clotting process
Exercise
• Cells need to respire to produce the energy
needed by the body to perform various
metabolic processes
– Oxygen and glucose are needed for this.
– Muscles cells have many mitochondria so that they
can have enough energy
• More exercise = more cellular respiration = more
CO2 = blood must be pumped more to rid body
of waste and to deliver more O2 & glucose.
• Therefore heart and breathing rate increases.
• If sudden the exercise can cause stress for the
heart
– It is not able to pump enough blood
How healthy is your heart?
Measuring your heart rate can be used to
monitor fitness. The fitter you are, the sooner
your pulse rate returns to normal after exercise.
Adrenaline
• ‘Fight or flight’ hormone
• Is released in times of stress
• Increases heart rate and the amount of
blood pushed out of the heart, when the
ventricles contract, (stroke volume)
How lifestyle affects the heart
Heart problems are made worse by an unhealthy
lifestyle.
• Smoking causes high blood pressure.
• Eating too much makes you overweight so your
heart has to work harder to supply your body.
• Stress makes your blood pressure higher.
Preventative measures
• exercise
• healthy diet
• Reduce stress
Heart problems
• Coronary heart disease
– Occurs when the coronary arteries (arteries that
supply the heart muscles with blood) become blocked
= heart stops beating = heart attack.
• Angina
– Symptom of coronary heart disease
– occurs when your heart muscle does not get enough
blood.
– may feel like pressure or a squeezing pain in your
chest.
• Diabetes (mellitus)
– is a condition in which the amount of glucose (sugar)
in the blood is too high because the body cannot use
it properly.
Reference
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http://library.thinkquest.org/C0115080/?c=circ_sys
http://www.emints.org/ethemes/resources/S00001019.shtml
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
http://owensboro.kctcs.edu/gcaplan/anat2/notes/Notes7%20Nonspepecific%20Defenses.htm
http://www.surgeryencyclopedia.com/A-Ce/Bone-Marrow-Transplantation.html
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http://www.medicinenet.com/heart_attack/article.htm
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http://www.nhlbi.nih.gov/health/dci/Diseases/Angina/Angina_WhatIs.html
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http://www.diabetes.org.uk/Guide-to-diabetes/What_is_diabetes/What_is_diabetes/, cited 8th Oct 2006
http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0029864.html
http://www.niaid.nih.gov/publications/immune/the_immune_system.pdf#search=%22immune%20system%22
• http://www.biology.arizona.edu/IMMUNOLOGY/tutorials/antibody/str
ucture.html
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http://www.eicsd.k12.ny.us/staffweb/jDipzins/Curriculum/7th%20Grade/Diseases/Immune%20System.jpg
• Jones, M (1994) Biology for IGCSE, Heinemann, Oxford.
• Jones, M & Jones, G (2002) Biology, Cambridge University Press,
Cambridge.
• http://library.thinkquest.org/C0115080/images/bl
oodgroupss.gif