The cardiovascular system Flashcards
What is the conduction system?
consists of specialised cardiac muscle tissue that generates and distributes action potentials
What components make up the conduction system?
-Sinoatrial node (SA) (pacemaker)
-atrioventricular node (AV)
-atrioventricular bundle (AV) (Bundle of his)
-bundle branches
-purkinje fibres
Where is the SAN located and what is its function?
-located in the right atrial wall
-begins cardiac excitation, acting as the natural pacemaker of the heart
Where is the AVN located and what is its function?
-located in the intertatrial septum, just anterior to the opening of the coronary sinus
-here is where the action potential slows down, providing time for the atria to empty their blood into the ventricles
What is the function of intercalated discs?
allows the action potential to be conducted between individual muscle cells
What is a cardiac cycle?
a single cardiac cycle includes all of the events associated with one heartbeat
What does systole mean?
contraction
What does diastole mean?
relaxation
Explain what the 3 main phases that the cardiac cycle consists of are
- diastole- this begins at the end of a cardiac cycle when the ventricles start to relax and all 4 chambers are in diastole
- atrial systole- contraction of the atria
- ventricular systole- contraction of ventricles
Explain the sound of the heart that you would hear through a stethoscope
-the first sound lubb is a ling booming sound from the AV valves closing after ventricular systole begins
-the second sound, dupp is a short sharp sound is from the semilunar valves closing at the end of ventricular systole
What are the 2 types of atrioventricular (AV) valves in the heart?
-right side is tricuspid valve
-left side is bicuspid valve
What are the semilunar valves?
these valves control the flow of blood out of the heart from the ventricles
What is an electrocardiogram?
-A reading which measures electrical activity in the heart
-creates a P wave, QRS complex, and T wave
Describe the flow of blood through both both sides of the heart and around the body
- deoxygenated blood flows into the right atrium via the vena cava from the body cells
- it moves through the tricuspid valve into the right ventricle
- it then flows through the pulmonary artery and to the lungs
- here the deoxygenated blood becomes oxygenated
- oxygenated blood returns to the heart through the pulmonary vein into the left atrium
- moves from the left atrium via the bicuspid valve into the left ventricle
- oxygenated blood leaves the heart via the aorta to go to body cells
What does blood transport around the body?
-oxygen
-carbon dioxide
-nutrients
-hormones
-heat
-waste
What does blood regulate in the body?
-pH
-body temperature
-water content of cells
What does blood provide protection against?
-blood loss through clotting
-against disease
-through phagocytic white blood cells and proteins such as antibodies, interferons and complement
What 2 portions is whole blood composed of?
- Blood plasma (55%)
-a liquid extracellular matrix that contains dissolved substances - Formed elements (45%)
-which are cells (red, white, leukocytes, platelets) and cell fragments
What is hemopoiesis?
the formation of blood cells from pluripotent stem cells, occurs in red bone marrow
What are red blood cells?
-biconcave discs without a nuclei that contains haemoglobin (to transport oxygen)
-have a cell life of 120 days
What is erythropoiesis?
-the formation of red blood cells which occurs in adult red bone marrow.
-it is stimulated by hypoxia, which stimulates release of erythropoietin by the kidneys
-a reticulocyte count is a diagnostic test that indicates the rate of erythropoiesis
How are white blood cells classified?
-either granular leukocytes (neutrophils, eosinophils, basophils)
-or agranular leukocytes (lymphocytes and monocytes)
What is the function of white blood cells?
to combat inflammation and infection
What is the function of neutrophils?
respond first to bacterial invasion and then macrophages do so through phagocytosis
What is the function of eosinophils?
combat inflammation in allergic reactions and are effective against parasitic worms
What is the function of basophils?
involved in inflammatory and allergic reactions and can liberate heparin, histamine, and serotonin
What are the 3 types of lymphocytes that are the major combatants in immune response?
-B cells
-T cells
-natural killer cells
What is found on the surface of red blood cells?
a genetically determined assortment of antigens composed of glycolipids and glycoproteins
What 2 antigens determine the ABO blood group?
antigen A
antigen B
What are anti-A antibodies and anti-B antibodies?
antibodies or agglutinins that are found in the blood plasma and react with the A or B antigens
What is the Rh blood group?
-Rh antigen or Rh factor was first found in the blood of the rhesus monkey
-peoples whose red blood cells have Rh antigens are Rh+ and those who lack it are Rh-
For blood type A, what antigen and antibody is found on the surface of your red blood cells?
-A antigen
-Anti-B antibody
For blood type B, what antigen and antibody is found on the surface of your red blood cells?
-B antigen
-Anti-A antibody
For blood type AB, what antigen and antibody is found on the surface of your red blood cells?
-both A antigens and B antigens
-neither antibody
For blood type O, what antigen and antibody is found on the surface of your red blood cells?
-neither A or B antigens
-Both anti-A and anti-B antibodies
Explain what this image is showing
-If someone with blood type A is given Anti-A serum (anti-A antibodies) the blood cells will begin to stick together and clot because they can not receive blood with antigens to their antibodies
-this shows the incompatibility reaction which can have a fatal effect
-(this is the same for all blood types)
For the 4 different blood types, draw a table of what blood type a recipient could receive from a donor, and explain which ones they’d have an incompatible reaction
Blood type A:
-A antigens
-anti-B antibodies
Blood type B:
-B antigens
-anti-A antibodies
Blood type AB:
-both A and B antigens
neither antibodies
Blood type O:
-neither A or B antigens
-both anti-A and anti-B antibodies
Explain the Rhesus factor in terms of a mother and a newborn baby
-if baby is Rh+ and mother is Rh-, if any of baby’s blood enters mother, the mother will develop anti-Rh antibodies to destroy the foreign antibodies
-however if the mother becomes pregnant again and the baby is Rh+, the mothers immune system will begin to destroy the baby’s blood before they’re born
-this was a common cause of infant mortality in the victorian times
-in modern day now a mother can get a vaccine that stops the development of the anti-Rh antibodies so they can’t pass through the placenta to the baby and destroy it
What is haemostasis?
-a sequence of responses that stops bleeding when blood vessels are injured
-it must be quick, localised to the region of damage and carefully controlled
What is the first mechanism that can reduce the loss of blood from blood vessels?
Vascular spasm
What is the second mechanism that can reduce the loss of blood from blood vessels?
Platelet plug formation
-release sticky things
What is the third mechanism that can reduce the loss of blood from blood vessels?
Blood clotting cascade (coagulation)
-3 step process
What is the 3 step process of the third stage, coagulation?
- formation of enzyme prothrombinase
- conversion of prothrombin into thrombin
- thrombin converts soluble fibrinogen into insoluble fibrin
How does a blood clot actually stop blood loss?
it plugs the ruptured area of the blood vessel, stopping the blood loss (clot retraction is the consolidation or tightening of the fibrin clot)
What happens as the blood clot retracts?
it pulls the edges of the damaged vessel closer together, decreasing the risk of further damage, so then permanent repair of the blood vessel can then take place
What is thrombosis?
Clotting in an unbroken blood vessel
What is embolus?
A thrombus that moves from its site of origin
What are anticoagulants?
They prevent clotting
What do B cells develop into and what are their functions?
develop into plasma cells and produce antibodies that help destroy bacteria and other toxins
What is the function of T cells?
they attack viruses, fungi and cancer cells
What is the function of Natural Killer cells?
Attack a wide variety of infectious microbes and tumour cells
What are the five types of blood vessels?
-arteries
-arterioles
-capillaries
-venules
-veins
What is the structure and function of arteries?
-carry blood away from the heart at high pressure
-3 layers of wall
-endothelium
-smooth muscle (middle layer) giving it its elasticity and contractility
-outer layer tough and fibrous
What is vasoconstriction?
a decrease in the diameter of blood vessel lumen= pressure increases
What is vasodilation?
an increase in the diameter of blood vessel lumen= pressure decreases
What is the structure and function of arterioles?
-small arteries that deliver blood to capillaries and tissues
-through constriction and dilation arterioles play a key role in regulating blood flow from arteries into capillaries
What is the structure and function of the capillaries?
-carry blood as close to the individual cells within tissues and organs
-very small diameter so blood cells pass through in a single file, thin single layer of squamous epithelium
What is the structure and function of venules?
-carry blood away from the tissues at low pressure
-have a thin wall of muscle and elastic tissue
What is the structure and function of veins?
-carry blood at very low pressure back to the heart
-have a large lumen, 3 layers of tissue: a smooth thin layer, smooth muscle and elastin in middle layer, tough fibrous outer layer
What is systolic blood pressure?
Blood pressure when the heart contracts (high figure)
What is diastolic blood pressure?
Blood pressure when the heart relaxes (low figure)
Describe the pressure changes of blood from the heart through the 5 blood vessels
-blood at high pressure when it leaves the heart
-each time muscle relaxes the pressure falls momentarily before the ventricle contracts again
-the recoiling of elastic wall of arteries helps increase blood pressure in between contractions
-blood pressure drops rapidly as it passes through the arterioles
-blood pressure very low through the capillaries allowing time for gas exchange
-blood pressure remains low through the venules and veins as it returns to the heart
What is the purpose of valves in veins?
-due to blood being at low pressure as it returns to the heart it is subject to gravitational forces
-the valves ensure that the blood can only go one way towards the heart
-any blood that moves back towards to the capillaries closes the nearest valve preventing any back flow
-valves open when the pressure behind them is greater
What is cardiac output?
the volume of blood ejected per minute from the left ventricle into the aorta
What 2 things is cardiac output determined by?
- stroke volume (SV)= the amount of blood ejected by the left ventricle during each heart beat (contraction)
- heart rate= the number of heart beats per minute
= stroke volume X heart rate
What can increase cardiac output?
exercise
What is peripheral resistance?
-the opposition of blood flow due to friction between blood and the walls of blood vessels
What 3 factors does peripheral resistance depend on?
-size of the blood vessel lumen
-blood viscosity
-total blood vessel length
