Download THE CIRCULATORY SYSTEM THE BLOOD Commonly described

THE CIRCULATORY SYSTEM
THE BLOOD
Commonly described as a connective tissue, approx 8% of body weight is blood, the flow
of blood around the body is such that a fairly stable environment is maintained.
Composition of Blood; 55% PLASMA 45% CELLULAR CONTENT
PLASMA contains;
• Water
• Plasma proteins
• Mineral salts
• Nutrients
• Organic wastes
• Hormones
• Enzymes
• Gases
• Antibodies & Antitoxins
CELLULAR CONTENT
• Red cells
• White cells
• Platelets
The primary function of Red Blood Cells is to carry oxygen around the body using
Haemoglobin. The primary function of White Blood Cells is in fighting infection. And
the Platelets are used in the Blood Clotting mechanism.
FUNCTIONS OF THE BLOOD
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Transports oxygen from the lungs to other body cells and carbon dioxide from
cells to lungs.
Transports nutrients from digestive system to cells
Transports wastes, urea to appropriate organ foe excretion
Transports Hormones and Enzymes to target tissues
Aids in the defence of the body by utilizing the white blood cells
Prevents the loss of body fluids by the mechanism of blood clotting
Helps to maintain Body Temperature...
CLOTTING MECHANISM
Refer to Class Handout
BLOOD VESSELS
ARTERIES, VEINS & CAPILLARIES
The wall of the artery is thicker than the vein: thicker connective tissue
layer, thicker mixed layer of muscle and elastic tissue. The lumen of the artery is much narrower. Arteries
do not have valves along their length, veins do. Valves in the veins prevent the backflow of blood so the
flow is in one correct direction towards the heart. Blood flows away from the heart in arteries; blood flows
towards the heart in veins. The real work of the blood, exchange with tissue cells is carried out at the
capillaries, Capillaries are the microscopic links between arteries and veins. The capillary wall is one cell
thick and somewhat porous — ideal to allow materials to pass in and out.
CIRCULATION OF BLOOD
Pulmonary Circuit: deoxygenated blood flows from the heart to
the lungs, oxygen is taken on and carbon dioxide is excreted,
oxygenated blood flows from the lungs back to the heart.
Systemic Circuit: oxygenated blood flows from the heart to the
organ systems of the body, oxygen is delivered and carbon
dioxide is taken on, deoxygenated blood flow from the organs
systems back to the heart.
THE HEART
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The heart is located in the thoracic cavity between the lungs protected by the rib cage. The heart is
a double pump.
The right side collects deoxygenated blood from all parts.
The right side pumps deoxygenated to the lungs for oxygenation and excretion of CO2.
The left side collects oxygenated blood from the lungs and pumps it to all parts.
The right and left side fill and empty in unison.
Each side pumps the same volume of blood.
The wall of the left ventricle is about three times thicker than that of the right ventricle. The left
ventricle needs more cardiac muscle to give the blood a much stronger push, because oxygenated
blood has to be driven a far greater distance.
CARDIAC CYCLE
DIASTOLE
ATRIAL SYSTOLE
VENTRICULAR SYSTOLE
BLOOD PRESSURE
This is a measure of the force of the blood against the blood vessel walls. Reference BP is
measured in a large artery in the upper arm. The pressure needed to stop flow in this
artery is measured at systole and diastole, normal 120/80 mm Hg
FACTORS AFFECTING HEART RATE
INCREASE; exercise, increased body temp, stress, infection and red light
DECREASE; increased physical fitness, sleep low salt levels and blue light.
STRUCTURE OF THE HEART & BLOODFLOW