Cardiovascular System Flashcards
What are the 3 functions of blood?
- Transportation:
- oxygen, carbon dioxide, nutrients, hormones, heat and wastes - Regulation:
- body temperature, pH, water content of cells - Protection
- against blood loss through clotting and against disease through phagocytic white blood cells and proteins such as antibodies, interferons and complement
What are the components of the whole blood?
- Blood Plasma
- a liquid extracellular matrix that contains dissolved substances - Formed elements
- cells (red blood cells or erythrocytes, white blood cells or leukocytes, and platelets) and cell fragments
What is Hemopoiesis?
The formation of blood and occurs in red bone marrow.
What is hemostasis?
- hemostasis is a sequence of responses that stops bleeding when blood vessels are injured
- hemostatic response must be quick, localised to the region of damage, and carefully controlled.
3 mechanisms can reduce loss of blood from blood vessels are:
1. vascular spasm
2. platelet plug formation
3. blood clotting (coagulation)
What are the 5 types of blood vessels?
- arteries
- arterioles
- capillaries
- venules
- veins
What is the function and structure of arteries?
Function:
- carry blood away from the heart to body tissue
Structure:
- walls consist of 3 layers
1. endothelium
2. smooth muscle (middle layer)
- gives arteries elasticity and contractility
3. outer layer
What is vasoconstriction?
A decrease in the diameter of the blood vessel lumen.
Vasodilation is an increase.
What are arterioles?
- small arteries that deliver blood to capillaries
- through constriction and dilation
- play a key role in regulating blood flow from arteries to capillaries
What is the pericardium?
- the membrane that surrounds and protects the heart and holds it in place
What are the layers of the heart wall and their structures/functions?
Epicardium (external layer)
- known as the visceral layer or serous pericardium
- is thin and transparent
Myocardium (middle layer)
- consists of cardiac muscle tissue
- constitutes the bulk of the heart
Endocardium (inner layer)
- thin layer of simple squamous epithelium and lines the inside of the myocardium and covers the valves of the heart and the tendons attached to the valves
- it is continuous with the epithelial lining of the large blood vessels
What are the four chambers of the heart?
The 2 upper chambers are the atria (entry halls/chambers)
The 2 lower chambers are the ventricles (little bellies)
Where is the interatrial septum? What is its main feature?
A thin partition between the right atrium and left atrium.
Has an oval depression called the fossa ovalis. The foramen ovale normally closes soon after birth.
It separates the right ventricle from the left ventricle.
Where does the right atrium receive blood from?
- superior vena cava (brings blood mainly from parts of the body above the heart)
- inferior vena cava (brings blood mostly from parts of the body below the heart)
- coronary sinus (drains blood from most of the vessels supplying the wall of the heart)
where does the left atrium receive blood from?
- oxygenated blood enters the left atrium via 4 pulmonary veins
- blood passes to the left ventricle which then pumps the blood into the ascending aorta
functions and structure of the atrioventricular valve
- lies between the atria and ventricles
- av valve in between the right atrium and ventricle is the tricuspid valve (has three cusps)
- av valve in between left atrium and ventricle is the bicuspid (mitral) valve (has 2 cusps)
function and structure of semilunar valves
- near the pulmonary trunk and aorta are the SLV
- they are called the pulmonary valve and the aortic valve
- they prevent back-flow into the heart.
- pulmonary valve lies in the opening where the pulmonary trunk leaves the right ventricle
- aortic valve is situated at the opening between the left ventricle and the aorta
- each valve has 3 semilunar cusps
- semilunar valves permit blood flow in one direction only
how is the movement of blood through the heart controlled?
- by opening and closing of the valves and the contraction and relaxation of the myocardium
- blood flows through the heart from areas of higher pressure to lower pressure
sequence of blood flow 1-10
- deoxygenated blood enters right atrium
- moves into the right ventricle via the tricuspid valve
- moves into the pulmonary trunk and arteries via the pulmonary valve
- moves to the lungs where in pulmonary capillaries, blood loses carbon dioxide and gains oxygen
- oxygenated blood flows into the pulmonary veins
- blood moves into the left atrium
- moves into the left ventricle via the bicuspid valve
- moves into the aorta and systemic arteries via the aortic valve and travels to the rest of the body
- in systemic capillaries blood loses oxygen and gains carbon dioxide
- blood moves back into the heart via the superior/inferior vena cava’s and the coronary sinus
what are the components of the conduction system?
- consists of specialised cardiac muscle tissue that generates and distributes action potentials
- sinoatrial SA node (pacemaker)
- atrioventricular AV node
- atrioventricular AV bundle (bundle of his)
- bundle branches
- purkinje fibers
function/structure of SA node
- located in the right atrial wall
- begins cardiac excitation
- natural pacemaker
function/structure of AV node
- located in the interatrial septum
- at the AV node the action potential slows
- provides time for the atria to empty their blood into the ventricles
function/structure of AV bundle
- from AV node, the action potential enters the AV bundle in the inter-ventricular septum
- is the only site where action potentials can conduct from the atria to the ventricles
function/structure of bundle branches
- action potential enters both right & left bundle branches
- these course through the inter-ventricular septum toward the apex of the heart
function/structure of purkinje fibers
- rapidly conduct the action potential
- first to the apex of the ventricles and then upward to the remainder of the ventricular myocardium
