Cardiovascular System Flashcards
Valves
The right av valve is also called the tricuspid valve because it has three leaflets
The left AV valve has only two leaflets and is also known as bicuspid or mitral valve
Each ventricle protected by semilunar valve with with three cusps. Right semilunar valve called pulmonic valve now because it sits between the right ventricle and pulmonary arteries. The left semi lunar valves is called the aortic valve because it separates the left ventricle from the aorta
Semi lunar valves prevent backflows from the pulmonary arteries and aorta into the Ventricles during ventricular (diastole) where as the AV valves prevent back flow from ventricle into Atria during contraction (systole)
Anatomy
- in the left atrium with oxygenated blood then we can follow the blood as it moves to the left ventricle and then into the aorta,the largest artery in the body
- The coronary, common carotid and renal arteries divide the blood flow from the aorta toward different peripheral tissues. Arteries branch into arteriolar and these ultimately lead to capillaries which perfuse the tissues
- The venules join into vein which carry the deoxygenated blood
- deoxygenated blood travels through the veins into the inferior and superior vena cava, the largest vein in the body, which carry the blood to the right atrium
- The blood travels from: left atrium to left ventricle to aorta to arteries to arterioles to capillaries to venules to veins to IVC and SVC to right atrium to right ventricle to pulmonary arteries to lungs to pulmonary veins to left atrium
- The heart lies between the lungs, behind in a little to the left of the sternum, and it is tilted so that the exterior wall of the right ventricle forms the base of the heart
- The right heart pumps the blood at lower pressures because there’s little resistance to bloodflow through the pulmonary circulation
- The left heart must be more muscular since it has have to generate higher pressures to pump the blood over greater distances
Phases of contraction
During systole (high pressure) ventricular contraction and closure of the AV valves occur, blood is pumped out of the ventricles. During diastole heart is relaxed semi lunar valves are closed and blood from the atria is filling the ventricles
Large arteries have elasticity which stretched out to receive volume of blood from the heart, allows the vessels to maintain sufficient pressure while ventricular muscles are relaxed
Cardiac output
Total blood volume pumped by the ventricle in a minute
Two ventricles pump the same cardiac output
The product of a heart rate (beats per minute) and stroke volume (volume of blood pumped per beat)
5L/min
Mech and control of contraction
Neural signals can modulate the rate at which the heartbeat but the heart will continue to function even without input from the nervous system
Pathway of contraction: SA NODE, the atrioventricular node, the bundle of His and its branches and the Purkinje fibers. Impulse initiation occurs at SA node which generate 60 to 100 signals per minute without any neural imput
The autonomic division which consent of parasympathetic and sympathetic branches controls the heart. Parasympathetic neurotransmitter slow the heart via the vagus nerve whereas sympathetic neurotransmitter speed it up
Blood vessels arteries
Most arteries containing oxygenated blood. Only the pulmonary artery and Fetal (umbilical) arteries carry deoxygenated blood
Highly elastic
Arteries offer high resistance the flow of blood which is why the left ventricles generate higher pressures. After they are filled with blood the elastic recoil from their walls maintains a high pressure and force his blood forward
Veins
Veins are thin-walled inelastic vessels that transport blood to the heart
Vein can carry large amounts of blood because their inelastic walls stretch out easily and do not recoil so almost of our blood volume maybe in venous circulation at any time
Larger veins have one-way valves to prevent backflow. Blood flowing forward pushes the valve open but if blood moves backward the valves are pushed shut. Failure of the Venus valves result in the formation of varicose veins which are distended where the blood has pooled
Most large veins are surrounded by skeletal muscle which squeezes the veins as muscle contract forcing Blood up against gravity
Capillaries
Capillaries are vessels with a single endothelial cell layer which allows for exchange of nutrients and gases
Blood pressure is expressed as a ratio of systolic to diastolic pressures; pressure gradually drop from the arterial to venous circulation with the largest drop across the arterioles
Blood composition
Plasma is the liquid portion of blood, an aqueous mixture of nutrients salts respiratory gases hormone and blood proteins
Erythrocyte is a specialized cell designed oxygen transport. Red blood cells are like couriers travel up and down elevators all day delivering good and picking up packages
Each erythrocytes contains about 250 million molecules of hemoglobin proteins, and each hemoglobin can find bind 4 moleculesof oxygen
Red blood cells form and mature in the bone marrow before they are released into the circulation. The loss of membrane bound organelles is a dramatic modification, when this happened it allows the cell area maximum amount of hemoglobin for gas exchange- red blood cells must rely on fermentation for ATP production
Blood comp white blood cells
Leukocyte comprise less than 1% of total blood volume and they form in the bone marrow
White blood cells are our defenders against pathogens foreign cells and other materials not recognize as self
Granular white blood cells ( neutrophils, eosinophils, basophils) are named because Cytoplasmic granules are visible under microscopy
Agranulocyte which do not have granules consists of lymphocytes and monocyte. Lymphocytes are important in the specific immune response, the body’s targeted fight against particular pathogens such as viruses and bacteria
Lymphocytes that mature in the spleen and lymph nodes are referred to as B cells and those that mature in the thymus are called T cells; B cells are responsible for antibody generation were as T cells kill virally infected cells and activate other immune cells
Monocytes phagocytize foreign matter such as bacteria; renamed it microphages once they leave the marrow, traveled through the bloodstream, and moved into tissue outside the vascular system. In the brain they are called microglia
Platelets ourselves brakeman to ride from the break up of cells known as megakaryocytes in the marrow; platelets function is to clot the blood
Blood antigens - abo antigens
Aand B alleles are codominant
If you have B allele it will be expressed if you have to A allele it will be expressed
O recessive to both a and b. People with type O blood don’t express either variant of this protein
The naming system of blood types based on the presence or absence of these protein variants doesn’t referred to be allele themselves but the proteins and four blood type that are a, B, a B, & O
Foreign antigens recognized by antibodies - a person with type a blood will recognize the type a protein Variant as self but the type B Protein as foreign and will make antibodies to type B
Type O blood cells express neither antigen variant they will not initiate any immunoresponse regardless of the recipient actual blood type. However a recipient who is type O and the immune system does not recognize either protein variant as self will produce both and antiA and anti B antibodies
Type AB blood universal recipient can receive from all blood types. No blood antigen is foreign AB blood. People with type O blood can donate to all groups as their blood cells have no ABO antigen on the surface
Rh factor blood antigen
Rh+ individuals express Rh protein on the red blood cells and Rh- individuals do not
Rh is a dominant condition
Can become an issue in pregnancy because if a woman is the RH negative sign and her fetus is RH positive sign, she will become sensitized the Rh factor and her immune system will begin making antibodies against it. This is not a problem during first pregnancies however any subsequence pregnancy when the fetus is the Rh+ is problem maternal anti Rh+ antibodies can cross the placenta and attack the fetal blood cells resulting in hemolysis of the frtal cells. This is known as erythroblastosis fetalis which can be fatal to the fetus
Transport of gasses
Oxygen is primarily carried by hemoglobin in the blood. The protein is made up of four separate but interconnecting chains, each of which has a prosthetic heme group to bind oxygen molecule
As the first oxygen binds to heme group,it Induces the confirmational shit in the shape of hemoglobin from taut to relax. This shit result in an increase in hemoglobins affinity for oxygen making it easier for subsequent molecules of oxygen to bind to the other on occupied heme groups
Once hemoglobin is full, the removal of one molecule of oxygen also result in a confirmational shift. This shift result in a decrease in hemoglobins affinity for oxygen making it easier for the other molecules the oxygen to leave the heme groups. this phenomenon is referred to as cooperative binding and result in the classic S shape hemoglobin binding curve
A right shift releases oxygen whereas a left shift latches onto oxygen; a right shit occurs when there is an increased amount of carbon dioxide, a decrease in the PH, or an increase in body temperature (increased metabolic rate)
Carbon dioxide can be directly carried by hemoglobin has a much lower affinity for carbon dioxide then for oxygen. Only a small percentage of the total carbon dioxide being transported in the blood to the lungs is dissolved in the plasma. The vast majority of carbon dioxide exists in the blood in a disguised form known as the bicarbonate ion
Increased proton concentration (lowered pH) shift the curve to the right this is known as the Bohr effect. A right shift will occur when we have high energy demand which require an increased rate of cellular respiration (higher rate of cellular metabolism, accumulation of lactic acid) and a concomitant increase in oxygen supply
The presence of the weak acid conjugate base pair in solution helps to minimize dramatic shift and pH (a buffer)
In response to changing blood pH, the respiratory rate may rise or fall to increase or decrease the amount of carbon dioxide gas excreted.
Transport of nutrients and wastes
Carbohydrate and amino acids: absorbed in the small intestine capillaries, enter systemic circulation via hepatic portal system
Bats: absorbed into lacteals in the small intestine. Enter systemic circulation via thoracic duct. Once in bloodstream, packaged into lipoprotein’s which are water-soluble
Waste: carbon dioxide, ammonia, urea, enter bloodstream throughout the body as they travel down their concentration gradient from the tissues into the capillaries. Blood eventually passes through the excretory organs where these waste products are filtered or secreted for removal from the body
Gradients of bloodstream
- at arteriole and of the capillary hydrostatic pressure is high. Hydrostatic pressure is the force for unit area the blood exerts against the vessel walls
- at the venue will end of the capillary bed, hydrostatic pressure has dropped below the oncotic pressure which is the osmotic pressure generated by the concentration of particles in the plasma compartment. Plasma osmotic pressure determinant is the concentration of plasmic proteins so it is also known as the oncotic pressure
- Oncotic pressure exerted thinking workforce and draws fluid, nutrients, and waste out of the tissues into the bloodstream
- the lymph returns to the central circulatory system by way of a channel called the thoracic duct -> some interstitial fluid is also taking up by the lymphatic system
