Cardiovascular system Flashcards
the composition of the blood
the plasma: liquid part of the blood. contains 90% water, plasma proteins salts, amino acids, glucose, urea and carbon dioxide
red blood cells: Erythrocytes- role to transport oxygen, biconcave disc- large SA: Vol ratio faster diffusion of oxygen, no nucleus, contains Haemoglobin-carry more oxygen
white blood cells- leukocytes-for defence and immunity-detect foreign material and destroy it.
platelets: thrombocytes-promote blood clotting. the three main types of blood vessels are arteries, veins and capillaries
the circulatory system
- closed double circulatory systems- 2 circuits
- the blood passes through the heart twice for each complete circulation of the body
- pulmonary circulation: the deoxygenated blood in the right side of the heart pumped to lungs and then the oxygenated blood returns to left side of the heart.
- systemic circulation: Oxygenated blood in left side of heart pumped to tissues and organs of the body and then the deoxygenated blood returns to the right side.
- this is important for mammals because it prevents mixing of oxygenated and deoxygenated blood so that the blood is pumped to the body is fully saturated with oxygen therefore an efficient delivery of oxygen & glucose for respiration. Blood can be pumped at a high pressure after being lower from lungs- substances taken to and removed from body cells quicker and more efficiently.
what are the coronary arteries
deliver oxygenated blood to cardiac muscle
blood vessels entering & leaving the heart
- Aorta takes oxygenated blood from the heart to the respiring tissues
- Vena cava takes deoxygenated blood from respiring tissues to the heart
pulmonary artery & pulmonary vein
blood vessels entering & leaving the lungs
- Pulmonary artery takes deoxygenated blood from the heart to the lungs
pulmonary vein takes oxygenated blood from the lungs to the heart.
blood vessels entering & leaving the kidneys
Renal arteries take deoxygenated blood to the kidneys
Renal veins take deoxygenated blood to the vena cava from the kidneys
how does the structure of the heart relates to its function
- Atrioventricular valves prevent backflow of blood from ventricles to atria.
- semilunar valves prevent backflow of blood from arteries to ventricles
- left has a thicker muscular wall. this generates higher blood pressure and for oxygenated blood has to travel a greater distance around the body
- right has thinner muscular wall. This generates lower blood pressure and for deoxygenated blood to travel a small distance to the lungs where high pressure would damage alveoli.
how does the structure of arteries, arterioles and veins in relation to their function
- Arteries: carry blood from heart to the rest of the body at high pressure- thick smooth muscle layer, contract pushing blood along, control/maintain blood flow/ pressure
- elastic tissue-stretch as ventricle contracts ( under high pressure) & recoil as ventricle relaxes( when under low pressure)
- Reduces pressure surges/even out blood pressure and maintain high pressure. Thick wall-withstands high pressure & prevents artery bursting.
smooth endothelium- reduces friction
narrow lumen- increases and maintains high blood pressure
Arterioles- division of arteries to smaller vessels which can direct blood to different areas
thicker muscle later than arteries
constrict to reduce blood flow by narrowing lumen
dilates ( relaxes) to increase blood flow by enlarging lumen
thinner elastic later as lower pressure surges
Veins- carry blood back
wider lumen than arteries. Very little elastic & muscle tissue. Valves. Prevent backflow of blood. Contraction of skeletal muscles squeezes veins, maintaining blood flow.
why is the structure of capillaries & importance of capillary beds as exchange surface.
-Capillaries allow the efficient exchange of gases & nutrient between blood and tissue fluid.
- Capillary wall is a thin layer (1 cell thick) of squamous endothelial cells
- Short diffusion pathway—->rapid diffusion
- Increases surface area ( to volume ratio)—-> rapid diffusion
- Narrow lumen
- Reduces flow rate so more time for diffusion/ exchange
- Capillaries permeate tissues ( no cells is far away from capillary)
-short diffusion pathway
- pores in walls between cells
- Allows substances to escape, e.g. white blood cells to deal with infections
Myogenic stimulation of the heart & transmission of a subsequent wave of electrical activity. Roles of the SAN, AVN & Purkyne tissue in the bundle of His
Cardiac muscle is myogenic- can contract/relax without receiving electrical impulses from nerves.
1. Sinoatrial node (SAN) acts as pacemaker, this sends regular waves of electrical activity across atria. Causing atria to contract simultaneously
2. Non-conducting tissue between atria/ventricles prevents impulse passing directly to ventricles. Preventing immediate contraction of ventricles
3. Waves of electrical activity reach atrioventricular node (AVN) which delays impulse. Allowing atria to follow contract & empty before ventricles contract.
4. AVN sends wave of electrical activity down bundle of His, conducting wave between ventricles to apex where Branches into purkyne tissue. Causing ventricles to contract simultaneously from base up.
The roles and locations of chemoreceptors and pressure receptors and the roles of the autonomic nervous system and effectors in control heart rate
•Chemoreceptors and pressure receptors located in aorta and carotid arteries
• Medulla oblongata in brain controls heart rate via autonomic nervous system:
-Sympathetic nerves increase heart rate
- Parasympathetic nerves decrease heart rate
• when you exercise or if your blood pressure is too low:
1. Baroreceptor detect fall in blood pressure and chemoreceptors detect blood rise in blood CO2
2. Send impulses to medulla oblongata
3. Which send more frequent impulses to SAN along sympathetic nervous systems
4. So more frequent waves of depolarisation sent from SAN and AVN
5. So heart rate increases
• When you relax of if your blood pressure is too high
1. Baroreceptors detect rise in blood and chemoreceptors detect blood fall in blood CO2
2.Send impulses to medulla oblongata
3. Which send more frequent impulses to SAN along parasympathetic nervous system
4. So less frequent waves of depolarisation sent from SAN and AVN
5. So heart rate decreases
Coronary heart disease
• Atheroma- fatty deposits within the wall of an artery thrombosis blood clot
• Embolism is the sudden blockage of a blood vessel by an embolu
•Coronary heart disease (CHD) is the narrowing of the small blood vessels that supply blood to the heart
•Myocardial infarction-heart attack
• Risk Factors of CHD- family history, smoking, high blood pressure, high cholesterol, obesity, diabetes, high stress and physical inactivity
•Symptoms of CHD- Chest pain pounding heart beat myocardial infarction
•Stroke- a sudden attack of weakness or paralysis that occurs when blood flow to an area of the brain is interrupted
•Stroke symptoms- Sudden weakness or numbness of the face, arm or leg. Sudden dizziness, loss of distance or coordination or trouble walking. Sudden severe headache
•risk factor of Stroke: high BP, heart disease, smoking, high red blood cell count. Females during pregnancy.
The formation of tissue fluid & its return to the circulatory system
•Tissue fluid is the fluid surrounding cells and tissues
• Provides respiring cells with water/ oxygen/ glucose and amino acids
• Enables( waste) substances to move back into blood, e.g urea, lactic acid, carbon dioxide
Formation of tissue fluid/ nearest arteriole end of capillaries:
• Higher blood/hydrostatic pressure inside capillaries due to contraction of LV than tissue fluid( out ward pressure)
• Forces fluid/ water out of capillaries
•large plasma proteins remain in capillary
The return of tissues fluid to circulatory system/ towards venule end of capillaries:
• Hydrostatic pressure reduces as fluid leaves capillaries
• An increasing concentration of plasma proteins lowers the water potential in the capillary below the water potential of the tissue fluid
• Water re enters the capillaries from the tissue fluid by osmosis down a water potential gradience
•Excess water take up by the lymph system, and is returned to the circulatory system.
