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