The cardiovascular system is a network that distributes blood containing oxygen and nutrients and collects wastes. It comprises the heart, arteries, blood and veins.
Every second the body requires a fresh supply of oxygen and food that the tissues require on a regular basis. This is provided by the blood. Blood flows constantly around the body to the extremities delivering nutrients and oxygen to the cells and back to the heart. It is a full round trip. This is termed (circulation) and all parts related to circulation come under the heading Cardiovascular system. Cardio meaning = heart and vascular meaning = blood vessels. This system provides oxygen and nutrients to all parts of the body and extracts carbon dioxide and waste products.
It includes the following parts – Blood, heart, blood vessels (arteries, capillaries and veins)
complex fluid circulated by the pumping action of the heart. It feeds every cell of the body.
An average sized person contains around 5 litres of bood.
Transports oxygen and nutrients to all bodies tissues and removes carbon dioxide and wastes.
Protection of the body via the immune system and blood clotting to prevent blood loss.
Regulation of the body’s temp and fluid content of the bodies tissues. Blood is part liquid, 55% is called plasma and a solid part is made up of red blood cells and white blood cells 45%.
Plasma contains proteins, nutrients, hormones, mineral salts and wastes are all dissolved inside the plasma. Plasma is responsible for nourishing tissues for their survival and without blood tissues would die.
Much of carbon dioxide and some oxygen are also kept in plasma.
Due to the high amount of water that is maintained in plasma frequent hydration is required so that the blood maintains it’s viscosity. When there is a lack of water in plasma the blood volume drops and dehydration occurs.
Red blood cells
Red blood cells are formed in bone marrow. (think back to the inside structure of bone)
They have a major role in the delivery of oxygen and carbon dioxide around the body. They are the postmen of the body.
They are made up of hemoglobin. This teams up with oxygen to be carried from the lungs to the cells of the body.
Red Blood cells really outnumber the white blood cells by nearly 700 to 1. Why???? This is a an easy one?
They are killed and remade almost every second (except in some people) and the ones that survive have a really long life of four months.
Women carry less hemoglobin in the blood therefore can not carry as much oxygen.
What are the implications of this????
White blood cells
! White blood cells are made in bone marrow and also in lymph nodes.
These great little things provide our weaponry against all sorts of bacteria and infections and disease.
These are great little swimmers because they can swim against blood fow to get to an infected area to start working.
There are two types of white blood cells:
Phagocytes = they engulf foreign material
Lymphocytes = They produce antibodies to fight disease
An example of a enemy that can get past white blood cells is HIV/AIDS = It manages to suppress the action of white blood cells. Hence death
These are the materials that stop blood from continually flowing from our body!
Blood clotting is performed by platelets getting in the way of blood. E.G if we have no platelets we would bleed to death from any cut or hole in our body.
So it makes sense when you are doing first aid that you should perform the same function of platelets with compression.
They are made up of bone marrow sections.
Structure and function of the heart
A heart is a pumping machine and if it could dance it would be on “So you think you can dance” due to it’s ability to keep rhythm.
Without a heart blood would not move and therefore we would never get any oxygen around the body and tissues of the body would die. The pump is very similar to a water pump. Pressure creates movement and movement is maintained with a rhythm continuously being pumped.
The heart is provided protection by what section of the skeletal system???
The heart beats around seventy beats per minute at rest and obviously increases with work!
The heart is the strongest machine in the world, and if you consider that in one day it will pump 100000 times and only really breaks down due to human lifestyle and nutrition you should have a rough understanding of it’s importance in keeping you in my class.
Put on the heart monitors and see your resting heart rate! See if you are normal?
The heart is made up of two major sections divided by a muscle. Each side the left and the right has two chambers.
Atria = Is the receiver of blood coming back to the heart in the upper chamber
Ventricles = lower section and is responsible for the pumping of blood away from the heart.
A system of four one way valves allow blood to flow in only one direction. E.G From the atria to ventricle.
Action of the heart
The heart receives blood from the veins and pumps it to the lungs through the rhythm mentioned before and relaxation. This is termed cardiac cycle: This contains two parts
=Diastole (relaxation or filling of the blood from areas of the body especially from the lungs? why) It fills the atria ready to go on another journey around the body. Why has it visited the lungs???
= Systole (contraction or pumping) Firstly the atria contracts to fully fill the ventricles then the blood is pumped under pressure to the lungs and all parts of the body. The rising pressure closes all atrio ventricular valves and opens the artery valves so blood can be spread to the rest of the body.
The heart beats or contracts by small electrical impulses. This moves the muscle of the heart.
The first low thud heard when listening to a heart beat is the atria ventricular valves closing and the second larger deeper thud is the pressure of the blood being pushed out of the ventricular section of the heart at the end of the systole phase.
At the end of the systole phase the blood is pushed through the arteries and this contracts and expands the artery walls. This is called a pulse! Yes that thing people feel is the contracting and expanding of artery walls. It represents blood being pushed along the artery walls so therefore the heart working, eg why it is used in first aid.
Pulse can be felt at any point in the body where an artery is located close to the skin. E.G neck. (What artery is this????)
Tricky question; Why should you not use your thumb to measure a pulse????
Blood supply to the heart
Coronary circulation = The actual heart is like any other muscle or tissue in the body in the way it actually requires blood to continually beat.
Blood vessels are located all over the (myocardium) = heart wall to feed the muscle of the heart blood and nutrients.
The heart has an extreme need for blood and will attract 75% of oxygen as it passes through especially during exercise.
Resting Heart Rates
Effects of Exercise on the Heart
Measuring Blood Pressure
Structure and function of the respiratory system
The exchange of gases
Immediate effect of exercise on respiration
Now read the summary and complete the following questions!