The Cardiovascular system!

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  • Created by: Izzy2807
  • Created on: 28-01-20 13:26
What are the 7 functions of the heart?
Delivering nutrients/O2, removal of waste, transporting hormones/drugs, acid/pH balance, blood clotting, heat distribution and immune response
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What are the 2 divisions of the circulatory vessels?
Systemic circulation (to and from the body, aorta and vena cava). Pulmonary circulation (lungs, pulmonary vein and pulmonary artery)
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What are the 5 types of blood vessel in the body?
Veins, arteries, capillaries, venules and arterioles
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What are the properties of veins?
Veins have a larger lumen (so less peripheral resistance), usually carry deoxygenated blood under low pressure and have lower amounts of smooth muscle
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What are the properties of arteries?
Arteries have a smaller lumen (so higher PR), usually carry oxygenated blood under high pressure and have a larger amount of smooth muscle, long distances!. They are highly elastic to stretch and maintain BP.
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What are the 3 layers in all blood vessels (apart from capillaries)?
Endothelium (Tunica Interna)- made of a single layer of squamous epithelial cells. The tunica media (smooth muscle) and the tunica adventitia (fibrous tissue)
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What are the properties of arterioles?
Highly muscular, regulate blood flow within tissues and arterial blood pressure. They connect arteries to capillaries.
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What are the properties of capillaries?
Are interweaving networks (capillary beds), large cross sectional area (lumen), single layer of endothelial cells, pore for simple diffusion of fluids and solutes. Regulated by sphincters, brought in by arterioles, leaves by venules.
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What is the basic mechanism of tissue fluid perfusion (needed for O2 + nutrient demand)?
Substances move from the capillary into the interstitial fluid at the arterial end due to higher hydrostatic pressure than osmotic pressure. Plasma enters capillaries at venule end due to higher os. pressure than hydrostat. (due to plasma proteins)
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What removes the excess tissue fluid?
The lymphatic system!
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What two hormones help with short-term regulation of BP?
Adrenaline and noradrenaline -- sympathetic ANS
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What are the two types of receptor on the arterioles that control vasodil/cons?
Alpha: vasoconstriction. Beta: vasodilation. VASOFIBRES cause it.
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What are the two main components of blood?
Non-living: Plasma (55%), Living: 45%, erythrocytes, leukocytes, platelets, clotting factors, immunoglobulins, plasma proteins.
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What is the function of blood plasma and erthyrocytes?
Plasma: carries water, salts and enzymes...takes nutrients, proteins and hormones to cells. Erythrocytes: contains Hb, needed for O2 transportation...also carries some CO2 and H+ away from cells!
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What is the function of leukocytes and platelets?
Leukocytes: IMMUNE RESPONSE! Platelets: involved in clotting, forming a plug.
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What is the function of immunoglobulins and plasma proteins?
Immunoglobulins: antibodies, needed for immunity. PP: maintain osmotic gradient, help coagulate blood, can act as antibodies, act as transport molecules for hormones/enzymes/metals
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What is anemia?
Where you lack enough healthy RBCs for sufficient O2 transportation to cells. Can be caused by low iron in diet, blood loss, faulty RBC production (e.g. sickle cell), lack of B12/folate (for RBC formation) or hemolysis
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What is the blood volume in adults and children?
7% of body weight in adults, 8% of body weight in children
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What are the adaptations of erthyrocytes?
Flattened (can get down BVs), biconcave (high surface area for diff.), thin (rapid diff.), no nucleus (store more O2), flexible (squeeze down BVs)
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What is ischaemia and infarction?
Ischaemia: inadequate blood flow (low O2), impairs cell function. Infarction: cell death due to inadequate O2
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What is thombus and embolism?
Thrombus: a stationary blood clot along the wall of a BV, causing vascular obstruction. Embolism: an obstruction due to blood clot/other foreign matter getting stuck as it moves along
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What is atherosclerosis?
A disease of the arteries where cholesterol/other lipids, inflammatory cells and calcium build up within the tunica intima and cause plaques that obstruct bloodflow
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What is an oedema and what can increase the risks of developing it?
Increased build up of fluid in the intercellular environment. Can be caused by excessive salt intake, low protein in the blood, high blood pressure, lymphatic system damage and leaky capillaries!
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Describe how blood flows through the heart! (Vena cava to aorta)
Vena cava (deoxy.) to right atrium, through tricuspid valve to right ventricle, out through pulmonary valve to pulmonary artery (lungs!). Pulmonary vein to left atrium, through mitral valve to left ventricle, through aortic valve to aorta (to body!)
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What are the 3 layers of heart tissue?
Inner: endocardium (endothelial cells), myocardium and pericardium (fibrous lyer and perital/vesceral serous- produce lubricant to reduce friction))
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What are the properties of cardiac muscle (myocardium)?
Uni/bi nucleated, rhythmically regulated by sinoatrial node, involuntary contraction, branched (so coordinated contraction). This muscle controls heart contraction!
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What is venous return?
The flow of blood back to the heart...must be equal to cardiac output.
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What factors prevent venous pooling (accumulation of venous blood)?
Increased flow of lymph, skeletal muscle pump, the respiratory pump, valves of veins!
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Why would a fall in venous return cause a fall in arterial blood pressure?
Venous return is dependent on venous pressure, right atrium pressure and venous resistance. ABP is determined by cardiac output and peripheral resistance, therefore the lower the PR, the lower the ABP
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What is systematic vascular resistance?
The resistance of blood flow by all systematic vasculature, primarily determines by vasoconstriction/dilation but also blood viscosity
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What is diastole and systole?
Diastole: filling with blood. Systole: emptying of blood
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Describe the electrical stimulation of the heart!
Starts with sinoatrial node, AP across atria (atria contract), then atrioventricular node, then bundle of His, then across septum, Purkinjee fibres (contraction of ventricles)
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What are the effects of the sympathetic and parasympathetic NS on the heart?
SYM: noradrenaline attach to beta receptors, increased HR, increased force of contraction. PARASYM: acetylcholine attaches to cholinergic receptors, lower HR and lower force of contraction
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What is the cardiac output and stroke volume?
Cardiac output: volume of blood ejected from RV + LV per min. Stroke volume: volume of blood ejected from LV per cycle
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Why is there a delay in conduction from the SAN to the AVN?
To allow the ventricles to fully fill with blood (atrial distole before ventricle systole)
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Why does the left ventricle have a thicker muscular wall than the right ventricle?
Needs higher force of contraction because it needs to pump blood ALL around the body
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What is the important of blood pressure (pressure blood exerts against wall of vessel/chamber)?
It's a driving force (keeps valves open and pushes blood along), effective tissue perfusion, keep vessels open...critical for brain and kidneys!
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What are the korotkoff sounds?
Systolic: first sound after deflating. Diastole: last found
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Which blood vessels experience the highest/lowest BP?
HIGH: left heart, arteries, arterioles. LOW: sphincters, capillaries, venules, veins. Higher BP at systemic circulation (left) than pulmonary (right)
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What factors effect blood pressure?
INCREASE: anxiety, exercise, kidney disease, pregnancy. DECREASE: hemorrhage, sudden change in posture, severe dehydration
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What is hypertension and hypotension?
Hypertension: greater than 140/90 or 135/85 (ABPM no in clinic). Hypotension: systolic less than 90
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What determines blood pressure? ABP = CO X Peripheral Resistance
CARDIAC OUTPUT: blood volume, venous return, HR and myocardial contractility.
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What factors increase peripheral resistance?
Blood viscosity, size of lumen of arteriole (vasocons. increase PR), ANS (parasymp.), adrenaline and renin
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What are the cardiovascular control centres?
MEDULLA: receive sensory info from receptors (e.g. baro.), influenced by cerebral cortex and hypothalamus. Coordinate parasymp. or symp. effects
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How is blood pressure regulated (short term)?
Baroreceptors located in the aortic arch and carotid bodies (stretch receptors). Baro, sensory signals to medulla, medulla coordinates para (high BP) or symp (low BP)
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What does sympathetic/parasympathetic activity do to the BVs?
Para: vasodilation, decreased PR. Symp: vasoconstriction, increase PR
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How is blood pressure regulated (long term)? ADH also constricts arterioles
Low BV/BP, kidney secretes renin, turns angiotensinogen into angiotension 1. ACE turns AG1 to AG2. AG2 acts on adrenal cortex (releases aldosterone: nephron takes in more water and more Na to lower WP). AG2 stimulates vasocons. of arterioles
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What happens to angiotensin 2 levels in pregnancy?
Too much AG2, severe vasocons, high PR...high BP
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Card 4

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