6.2 The Blood System Flashcards
What are the three main types of blood vessels?
- Arteries
- Veins
- Capillaries
What is the transport system for in our body?
- supply oxygen and nutrients to cells. The oxygen is needed to produce ATP (Energy) for Cell Respiration
- Carry away waste products
- Maintain blood pressure
What do arteries do?
- Arteries convey blood at high pressure from the ventricles to the tissues of the body.
- Arteries have muscle cells and elastic fibres in their walls.
- The muscle and elastic fibres assist in maintaining blood pressure between pump cycles.
Carry oxygenated blood under high pressure
How are artery walls composed?
•Arteries have muscle and elastic fibres in their walls
The wall of artery is composed of several layers:
oTunica externa – a tough outer layer pf connective tissue
oTunica media - a thicker layer containing smooth muscle and elastic fibres made of the protein elastin
oTunica intima – a smooth endothelium forming the lining of the artery
Explain the arterial blood pressure
•The muscle and elastic fibres assist in maintaining blood pressure between pump cycles
Blood transported away from the heart in an artery is at high pressure.
It pushes the artery wall outwards and stretching elastic fibres in the wall to widen the lumen and store potential energy. After each heartbeat the pressure in arteries falls for the stretched elastic fibres to squeeze the blood in the lumen.
When circular muscles in the artery walls contract, the lumen is narrowed: Vasoconstriction increases blood pressure in arteries which can restrict blood flow. (Vasodilation is the opposite and increases blood flow)
Compare the composition of the blood in the renal artery and renal vein.
- blood in renal artery more oxygenated than the blood in the renal vein / oxygenated versus deoxygenated
- blood in renal artery contains more urea than the blood in the renal vein / urea versus no urea / nitrogenous waste products
- blood in renal artery contains more glucose than the blood in the renal vein
- variable water / salt content in renal artery but constant / correct / regulated content in vein
What do capillaries do?
•Blood flows through tissues in capillaries with permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary.
- narrowest blood vessels.
- walls consists of one layer of very thin endothelium cells, coated by a filter-like protein gel, with pores between the cells.
- Thin walls minimize the distance that nutrients and oxygen has to diffuse to reach body tissues
What do the capillary walls allow?
•The wall is permeable and allows part of the plasma to leak out and form tissue fluid.
Capillaries deliver oxygen and nutrients to body tissues and remove waste products (such as urea and CO2
What do veins do?
•Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
- From body/lungs to heart, has low pressure
- carry deoxygenated blood
- have thin tunica media (thin walls) and contains far fewer muscle and elastic fibres.
- hold more blood because they can dilate
Hepatic portal vein is unusual because it does not carry blood back to the heart. It is regarded as a portal vein nonetheless because the blood it carries is at low pressure.
How does blood not backflow in veins?
•Valves in veins and the heart ensure circulation of blood by preventing backflow.
- Their veins contain pocket valves to maintain circulation.
- If blood starts to flow backwards, it gets caught in the flaps of the pocket valves, that blocks the lumen in the vein.
- When blood flows towards the heart, it pushes the flaps to the side so that blood can flow freely.
- They allow blood to flow in one direction only.
Draw/Describe double circulation
remember:
- Blood always flows out of ventricles (bottom of the heart) and back in to atria (top of the heart)
- Arteries carry blood from the heart, veins back to the heart
- Oxygenated (O2) blood is in the left side of the heart (your right side if you are looking straight at the diagram)
The pulmonary circulation, to and from lungs
The systemic circulation, to and from body
- From the kidney (or the body)… into vena cava
- Right atrium
- Through the atrio-ventricular valve
- Right ventricle
- Through the semi-lunar valve
- Through the pulmonary artery
- To the lungs… picks up oxygen/ loses CO2
- Through the pulmonary vein
- Left atrium
- Through the atrio-ventricular valve
- Left ventricle
- Through the semi-lunar valve
- Through the aorta
- To somewhere in the body
- Later the blood will end up in the vena cava
Draw and label the structure of a heart.
- right and left ventricles - not connected shown larger than atria
- right and left atrium - not connected, thinner walls than ventricles
- right ventricle has thinner walls than left ventricle
- atrioventricular vales/tricuspid and bicuspid vales shown between atria and ventricles
- aorta and pulmonary artery - shown leaving the appropriate ventricle with semilunar valves shown
- pulmonary vein and vena cava - shown entering appropriate atrium
What are factors that affect occurence of coronary thrombosis (blood clotting in ateries)?
- hypertension / high blood pressure;
- having parents who have experienced heart attacks indicates a genetic precondition;
- old age leads to less flexible blood vessels;
- risk in females increases post-menopause because of fall in estrogen level;
- being male (more risk than being female) because of less estrogen;
- smoking raises blood pressure because nicotine causes vasoconstriction;
- obesity strains heart;
- eating too much saturated fat and cholesterol promotes plaque formation /atherosclerosis;
- sedentary life style / lack of exercise;
- but excessive exercise can be dangerous;
- high salt diet / excessive amounts of alcohol / stress can also affect coronary heartdisease;
Outline the condition atherosclerosis and how it may cause coronary thrombosis. [4]
Conditions:
- atherosclerosis – progressive degeneration of artery walls;
- atheroma / lipids / cholesterol deposited on endothelium / wall;
- fibrous tissue may also be laid down;
Causes:
- blood flow is impeded causing platelets to stick;
- clotting factors may then be released;
- a clot or thrombus may form;
- if in coronary artery / arteriole flow of blood to part of heart muscle is reduced / stopped;
- myocardial infarction / heart attack / cardiac arrest / heart failure;
What is atherosclerosis?
- hardening and narrowing of the arteries, due to the deposition of material commonly known as plaque (atheroma)
- included the development of fatty tissue called atheroma in the artery wall adjacent to the endothelium
Explain events of the cardiac cycle
- SA (sino atrial) node/pacemaker receives signal to fire;
- when ventricle 70 %/almost full;
- AV (atrio ventricular) valve opens and blood fills ventricle (to maximum) / atrial systole;
- pressure increase in ventricle closes AV valve / ventricular systole;
- AV node fires;
- Purkinje fibres carry impulses to all areas of ventricles for simultaneous firing;
- pressure increase causes semilunar valve to open;
- blood pumped from ventricle to aorta/systole sound / ventricular diastole;
- pressure lowers in ventricle closing semilunar valve / diastole sound;
- pressure in ventricle lower than atria so AV valve opens;
- increases blood ventricular volume;
- both atria and ventricles are relaxed / diastole;
- atria receives blood from veins;
- cycle repeats; [6 max]
