 The human circulatory system is a double circulatory system. It
has two separate circuits and blood passes through the heart
twice
- The Pulmonary Circuit is between the heart and the lungs
- The Systemic Circuit is between the heart and the other
organs
 The Pulmonary Circuit transports blood TO the lungs. The blood
is oxygenated there and then carried back to the heart. Gaseous
exchange happens in the lungs
- Carbon dioxide diffuses from the blood into the air in the
alveoli
- Oxygen diffuses from the air in the alveoli and into the blood,
and is absorbed by haemoglobin in the red blood cells
- Unlike other arteries and veins, the pulmonary artery carries
deoxygenated blood and the pulmonary vein carries
oxygenated blood
 The Systemic Circuit transports blood around the body. It
transports oxygen and nutrients to the body tissues and carries
away deoxygenated blood containing carbon dioxide and other
waste materials
The Heart …..
The heart is a muscular organ. Its function is to pump blood. The right
side pumps blood through the pulmonary circuit. The left side pumps
blood through the systemic circuit
A septum separates the right and left sides. The left side has thicker
walls because it needs to put the blood under higher pressure than
the right side
Arteries carry blood AWAY from the heart and towards organs
Veins carry blood from an organ to the heart
Valves
 Blood flows INTO the heart from a vein (Vena Cava) and goes into
the right atrium
 The heart contains valves to prevent back flowing backwards
- The right side has a tricuspid valve (a valve with three flaps)
- The left side has a bicuspid valve (a valve with two flaps)
- Both side have semi lunar valves (at the entrances to the
pulmonary artery and aorta).
Blood Vessels …..
Arteries
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Carry blood AWAY from the heart
Have thick Muscular walls
Have small passageways for blood (internal lumen)
Contain blood under high pressure
Veins
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Carry blood TO the heart
Have thin walls
Have larger passageways for blood (internal lumen)
Contain blood under low pressure
Have valves to prevent blood flowing backwards
Capillaries
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Found in the muscles and lungs
Microscopic- One cell thick
Very low blood pressure
Where gas exchange takes place
Coronary Heart Disease…..
 The coronary arteries supply blood to the heart muscle. These
may become blocked by a build-up of fatty plaques containing
cholesterol, resulting in Coronary Heart Disease
 If a coronary artery is blocked, the bloody supply to part of the
heart muscle is cut off. That part of the heart can’t continue to
contract, causing a heart attack
 Possible causes of coronary heart disease- Poor diet- eating more saturated fat tends to increase
cholesterol levels
- Stress and smoking- increases blood pressure
- Lack of exercise
- Being overweight
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The trachea branches into two bronchi (one to each lung)
Pleural membranes surround each lung
Cartilage rings in the walls of the trachea help to keep it open
The bronchi split into smaller and smaller tubes called
bronchioles.
 These end in microscopic air sacs called alveoli.
 There is a muscular diaphragm below the lungs
Ventilation…..
The ribs, intercostal muscles and diaphragm all play important roles
in ventilation (breathing)
BREATHING IN
When you inhale….
 The internal intercostal muscles relax and the external
intercostal muscles contract, pulling the ribcage upwards and
outwards
 The diaphragm contracts, pulling downwards
 Lung Volume increases and the air pressure inside decreases
 Air is pushed into the lungs
BREATHING OUT
When you exhale….
 The external intercostal muscles relax and internal intercostal
muscles contract, pulling the ribcage downwards and inwards
 The diaphragm relaxes, moving back and upwards
 Lung Volume decreases and the air pressure inside increases
 Air is pushed out of the lungs
Gas Exchange in the lungs …..
 Happens in the alveoli. The alveoli have –
 Thin Walls
 Large Surface Area
 Moist Surface
 Many blood capillaries
 Blood is a complex liquid tissue. It transports oxygen,
dissolved substances and hear around the body, as well as
being involved in the body’s immune response.
 The blood is composed off
 PLASMA- Transports CO2, digested food, urea, hormones
and heat
 RED BLOOD CELLS – Transports oxygen
 WHITE BLOOD CELLS- Ingests pathogens and produces
antibodies
 PLATELETS- Involved in blood clotting
Red Blood Cells….
 Transport oxygen for aerobic respiration
 Red blood cells have adaptations that make them suitable for
their role  They contain haemoglobin- a red protein that combines with
oxygen to form oxyhaemoglobin
 They have no nucleus- so they can contain more
haemoglobin
 They are small and flexible so that they can fit through
narrow blood vessels
 They have a biconcave shape (Flattened disc) to maximise
their surface area for oxygen absorption
 About 25% of the white blood cells are LYMPHOCYTES
 They are part of the body’s immune system and produce
soluble proteins called antibodies. Antibodies can
recognise particular types of pathogen
 ANTIBODIES attach to ANTIGENS
 Antigens are substances found on the surface of cells,
including bacteria and pathogens
 Different antibodies attach to different antigens. Meaning
the body’s immune system can’t recognise foreign antigens
(antigens that aren’t normally produced by the body but by
pathogens
 Antibodies can neutralise toxins produced by pathogens.
They can cause the destruction of pathogens by- Causing bacteria to burst open and die
- Labelling the pathogen so that it is recognised more
easily by phagocytes
- Sticking pathogens together so they can be engulfed by
phagocytes more easily
 About 70% of the white blood cells are PHAGOCYTES
 Phagocytes ingest and destroy pathogens such as bacteria
- The phagocyte surrounds the bacterial cell, enclosing it
in a vacuole
- Enzymes are secreted into the vacuole to destroy the
bacterial cell
 The process of ingesting the pathogen is called phagocytosis
 People can be immunised against a pathogen through
vaccination
 Different vaccines are needed for different pathogens
 Vaccination involved putting a small amount of an inactive form
of a pathogen into the body
 Vaccines contain
- Live pathogens treated to make them harmless
- Harmless fragments of the pathogen
- Toxins produced by the pathogen
- Dead Pathogens
 These all contain antigens. When injected into the body they
stimulate lymphocytes to produce antibodies that can recognise
the pathogen
 Some lymphocytes develop into memory cells
 If the vaccinated person later becomes infected with the same
pathogen, the immune system is prepared and the required
lymphocytes are able to reproduce rapidly and destroy it.
Meaning the person is unlikely to become ill
 If the skin is cut the wound must be closed to prevent blood loss
and the entry of pathogens. The formation of a scab does that
 Blood contains tiny fragments of cells called platelets. There
platelets are involved in blood clotting and scab forming
 When the skin is wounded platelets are able to –
- Release chemicals that cause soluble fibrinogen proteins
to form a mesh of insoluble fibrin fibres across the wound
- Stick together to form clumps that get stuck in the fibrin
mesh
 Red Blood cells get stuck in the fibrin mesh forming a clot, which
develops into a scab and protects the wound as it heals
 A hormone is a chemical substance produced by a gland and
carried by the blood which alters the activity of more specific
target organs and then destroyed by the liver
 Like the nervous system, hormone can control the body
 Different hormones affect different organs or cells
Source
Target
(organs)
Kidneys
Role
Effects
Controlling
the water
content of
the blood
Increases
reabsorption
of water by
the collecting
ducts
ADH
Pituitary
Glands
Adrenaline
Adrenal
Glands
Several
Preparation
targets
for fight or
including
flight
the
respiratory
and
circulatory
systems
Insulin
Pancreas
Liver
Controlling
blood
glucose
levels
Increases
breathing
rate, heart
rate, flow of
blood to
muscles,
conversion of
glycogen to
glucose
Increases
conversion of
glucose into
glycogen
The Human Nervous System consists ofTHE CENTRAL NERVOUS SYSTEM (CNS) - The brain and spinal
cord
THE PERIPHERAL NERVOUS SYSTEM - nerve cells that carry
information to or from the CNS
Nerve Cells …..
 Nerve cells are also called neurones. They are adapted to
carry electrical impulses from one place to another
- They have a long fibre (axon) which is insulated by a fatty
sheath
- They have tiny branches (Dendron’s) which branch
further as dendrites at each end
Receptors …..
 Receptors are groups of specialised cells.
 They can detect a change in the environment (Stimulus) and
produce electrical impulses in response
 Sense organs contain groups of receptors that respond to
specific stimuli
Sense Organ
Skin
Tongue
Nose
Eye
Ear
Stimulus
Touch, Temperature
Chemicals (e.g. in food and
drink
Chemicals (e.g. in the air)
Light
Sounds
Effectors…..
Effectors are parts of the body, such as muscles and glands
that produce a response to detected stimulus
Example
1. Muscles containing to move an arm
2. Muscle squeezing saliva from the salivary gland
3. A gland releasing a hormone into the blood
Reflex Actions …..
 A reflex action is a way for the body to automatically
and rapidly respond to a stimulus to minimise any
further damage to the body
 It follows this general sequence and does not involve
the brain
 The nerve pathway followed by a reflex action is called
a reflex arc, e.g. a simple reflex arc happens if we
accidentally touch something hot
1. Receptor in the skin detects a stimulus (the change in temperature)
2. Sensory Neurone sends impulses to relay neurone
3. Motor neurone sends impulses to effector
4. Effector produces a response (muscles contracts to move hand
away)
Antagonistic pairs …..
 Muscles work in antagonistic pairs
 This ensures when a part of the body is moved, it can
move back to its original position, e.g
- The biceps and triceps in the arm
- The quadriceps and hamstrings in the leg
The Synapse …..
- Where two neurones meet there is a tiny gap called a
synapse
- Information crosses this gap using neurotransmitters
- One neuron releases neurotransmitters into the synapse
- These neurotransmitters diffuse across the gap and
make the other neurone transmit an electrical impulse
The Eye …..
 is a sense organ that responds to light
-
Cornea- Refracts light (bends it as it enters the eye)
Iris- Controls how much light enters the pupil
Lens- Focuses light onto the retina
Retina- Contains the light receptors
Optic nerve- Carries impulses between the eye and the
brain
The Retina …..
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Light passes through the eyeball to the retina
There are two main types of light receptors- Rods and Cones
Rods are more sensitive to light than cones
There are three different types of cone cells which produce
colour vision
The Pupil Reflex …..
 The amount of light entering the eye is controlled by a reflex
action
 The size of the pupil changes in response to bright of dim light
 This is controlled by the muscles in the iris
 The ability of the lens to change shape to focus near and distant
objects is called accommodation
 A stent is a small mesh tube that's used to treat narrow or weak
arteries.
 A stent is placed in an artery as part of a procedure called
percutaneous coronary intervention (PCI), also known as
coronary angioplasty
 Stents help keep coronary arteries open and reduce the chance
of a heart attack
 A stent is inserted into the clogged artery with a balloon catheter
 The balloon is inflated and the stent expands and locks into
place. This holds the artery open and allows blood to flow more
freely
Cholesterol…..
 Is a substance found in the blood
 It is made in the liver and is needed for healthy cell membranes
 However too much cholesterol in the blood increases the risk of
heart disease and of diseased arteries
 The bloodstream transports cholesterol around the body
attached to proteins. The combination of cholesterol and protein
is called lipoprotein. There are two types of lipoprotein
- Low Density Lipoproteins- LDLs- Carry Cholesterol from the
liver to the cells
- High Density Lipoproteins- HDL’s- Carry excess cholesterol
back to the liver
 LDLs are often called bad cholesterol because they lead to fat
building up on artery walls, which causes heart disease
 HDLs are often called good cholesterol because they help stop
fat building up in the arteries
 Statins are a drug sometimes used to help people with high
cholesterol lower their cholesterol. They work by blocking a step
in the body’s production of cholesterol
 A pacemaker is a small device that is placed in the chest or
abdomen to help control abnormal heart rhythms
 This device uses low energy electrical pulses to prompt the heart
heat at a normal rate
 Pacemakers are used to treat arrhythmias (problems with the
rate or rhythm of the heart
Effects of Smoking …..
 Smoking can cause lung disease, heart disease and certain
cancers
 Nicotine is the addictive substance in tobacco. It reaches the
brain and creates a dependency so that smokers become
addictive
 Sticky mucus in the lungs traps pathogens. The mucus is
normally swept out the lungs by cilia on the epithelial cells lining
the trachea, bronchi and bronchioles
 Cigarette smoke contains harmful chemicals that damage these
cells, leading to a build-up of mucus and a smokers cough
 Smoke irritates the bronchi, causing bronchitis’s
 Smoking damages the walls of the alveoli. The alveoli walls break
down and join together forming larger air spaces than normal.
This reduces the efficiency of gas exchange, so people with the
lung disease emphysema carry less oxygen in their blood and
find even mild exercise difficult
 Carbon Monoxide combines with haemoglobin in red blood cells.
This reduces the ability of the blood to carry oxygen, putting a
strain on the circulatory system and increasing the risk of
Coronary heart disease and strokes
 Carcinogens are substances that cause cancer. Tobacco smoke
contains many carcinogens, including tar. Smoking increase the
risk of lung cancer and cancer of the mouth throat and
oesophagus