Cardio System Flashcards
What does the cardiovascular system transport throughout the body?
oxygen to cells nutrients to cells hormones to cells waste products from cells heat around the body
How much blood is in an adult male?
6 litres
how much blood is in an adult female?
5 litres
How much blood is in an 8 year old?
2 litres
How much blood is in an average full term baby?
300mls
How much blood is in an average 30 week pre term baby?
100mls
Describes the structure of the heart?
4 hollow chambers
2 on the right and 2 on the left
2 pumps separated by the septum
The right side of the heart deals with deoxygenated blood
The left side of the heart deals with oxygenated blood
What are the 3 layers that the walls of the heart are made from?
Pericardium
Myocardium
Endocardium
Describe pulmonary circulation.
The right ventricle pumps deoxygenated blood into the pulmonary arteries. These arteries carry the blood to the lungs where it passes through a capillary network close to air filled alveoli. This enables the release of carbon dioxide and the uptake of oxygen from the air. The now oxygenated blood returns to the left atrium in the pulmonary veins.
Describe Systemic circulation.
Oxygenated blood that flows into the left atrium, then flows into the left ventricle. the left ventricle then pumps the blood through the aorta, the major artery which supplies blood to the body.
Describe the Sa node.
Small mass of specialised cells. Near to the opening of the superior vena cava. Electrically unstable means discharge 60-80 times per minute. Followed by recovery. Triggers arterial contraction.
What is the AV node?
transmits electrical signals from the atria into the ventricles
What is the AV bundle?
Divides into left and right branches. Branches then break up into fibres. Transmits electrical impulses from the AV node to the apex of the myocardium.
What controls the heart rate?
Regulated by the autonomic nervous System. Vasomotor centre found in the medulla Oblongata in the brain sends nerve impulses to the sino-atrial system. Influenced by hormones particularly adrenaline.
Describe arteries.
Their major role is to carry away from the heart delivering oxygen rich blood to capillaries. 3 layers: outer, middle muscular and inner smooth epithelial. they expand and contract.
Describe veins.
Their main role is to carry blood to the heart, carrying oxygen depleted blood and carbon dioxide from the capillaries. 3 layers: outer, middle muscular and inner smooth epithelial. They expand and contract.
Describe the capillaries.
Their main role is the exchange of oxygen and carbon dioxide, involved in the release of heat. They are thin and fragile, one epithelial cell in depth.
What way do the arteries flow blood?
away from the heart
Describe the arterioles.
oxygen rich
carbon dioxide poor
describe the venules.
oxygen poor
carbon dioxides rich
What way do the veins flow blood?
to the heart
Describe blood pressure.
The pressure within the arteries created by the force of ventricular contraction.
What is systolic pressure?
highest pressure reached during ventricular contraction
What is diastolic pressure?
lowest pressure reached when the ventricles are relaxed
What is normal systolic pressure?
90 - 140 mmHg
What is normal diastolic pressure?
60 - 90 mmHg
How do you measure blood pressure?
Sphygmomanometer or dinamap
Describe the formation of blood.
Fluid running through arteries and veins. Bright red. Cells are suspended in plasma. 55% plasma and 45% formed elements.
What are the characteristics of blood?
Heavier, more viscous than water. Accounts for 7% of body weight. Temperature 38 degrees centigrade. Oxygenated blood saturation 98-99%
Deoxygenated blood saturation 75%.
The pH is 7.35-7.45
Describe plasma.
Slightly alkaline. yellow in colour. 90% water. 10% dry matter
Organic substances: glucose, lipids, proteins, hormones, amino acids and vitamins
Describe blood cells.
basic structural and functional units. Microscopic. Shaped differently. Special cells (erythrocytes, leucocytes). Includes platelets.
Describe red blood cells.
erythrocyte. Most numerous, biconcave lens shape. Their function is to provide oxygen to tissues and recovers carbon dioxide as waste. carries haemoglobin. They have a life span of 120 days.
Describe white blood cells.
Leucocyte. Their function is defence and immunity. Less numerous. They come in 2 categories, granulocytes have multi lobed nuclei and agranulocytes have a large nucleus.
Describe a platelet.
Thrombocytes. Smaller than erythrocytes. Intense purple colour. Stops loss of blood through promoting blood coagulation.
What are antigens?
The presence or absence of certain antigens determines your blood group. In the ABO system there are 2 possible antigens A and B.
Describe antibodies.
Associated with each blood group are specific antibodies. These antibodies are capable of attacking antigens from other ABO groups.
Describe the rhesus factor.
The immune system is a complex network of specialised cells and chemical signals, which interact providing a defence against infectious organisms. The immune system identifies foreign cells and pathogens (antigens) and produces immunoglobulins (antibodies) to destroy the antigen. The most abundant antibody is IgG (85%). In the last trimester the placental transfer of maternal IgG will include IgG antibodies directed at the fetus’s own antigens. Most do not travel through the placenta to the fetal circulation.
What effect can having the antibodies to the rhesus antigen have?
A mother who is rhesus positive will not make antibodies against the rhesus antigen. A mother who is rhesus negative does not have the rhesus antigen in her own blood, and her immune system has the capability of making rhesus antibodies. These antibodies would then recognise and attack the red blood cells of a rhesus positive fetus.
when does the response to the rhesus happen?
The response come after the birth of the first fetus. Then in subsequent pregnancies maternal antibodies can cross the placenta and damage the fetus. Ant-D gamma-globulin (injection) given to the mother immediately after the first birth will result in the Rh+ cells not being recognised to antibodies are not produced.
What causes changes during pregnancy?
indirectly by hormones and increased load on the system.
How does blood volume change during pregnancy?
Blood volume increases by 30-50%
More in multiple pregnancies and correlates with birth weight.
How is there capacity for the increased blood volume?
Progesterone and oestrogen relax vascular smooth muscle causing vasodilation and decreased peripheral resistance
What are other changes in pregnancy?
The heart is displaced upward and rotated forward. ECG changes.
Increase in size of the heart (70-80 ml)
Dilated and increased contractility
Ventricular hypertrophy
Change in the heart sounds
Increased cardiac output
Women with pre-existing cardiac disease may not be able to cope with the increased demand on the heart in pregnancy.
Describe haemoglobin in pregnancy.
As plasma volume increases haemoglobin concentration falls- reaching its lowest point at 16-22 weeks. Normal adult Hb- 12-15 (g/dl). Pregnancy level is 10.8-14.6
What is cardiac output?
the amount of blood pumped out by the heart (the 2 ventricles) in 1 minute. It is a combination of heart rate and stroke volume. Stroke volume is the amount of blood pumped out by a ventricle with each heartbeat.
What is the average cardiac output?
HR x SV
= 75 (beats per minue) x 70 (mls per beat)
= 5250 mls per minute
What will 90% of pregnant women experience?
breathlessness
palpitations
fainting
oedema
however less than 1% of women have earth disease
