Cardiovascular System Flashcards
What are the 3 major blood vessels?
- Arteries
- Capillaries
- Veins
What happens in the capillary bed?
The exchange of gases takes place
What are the 3 layers of arteries and veins?
- Tunica Adventitia (outermost)
- Tunica Media (middle)
- Tunica intima/endothelium (innermost)
What is the role of the tunica adventitia?
Is made of connective tissue fibres which reinforce the walls of the vessels allowing it to withstand high pressure
What is the role of the tunica media?
Is made up of smooth muscle cells and is thicker in the arteries then in the veins
What is the role of the tunica intima or endothelium?
Is a single layer of cells which lines the entire cardiovascular system
What are the features of arteries?
- Always take blood away from the heart
- Thick muscle layer
- Under autonomic nervous control
- Stretches under force of blood pressure then elastic recoil maintains pressure wave
- Larger arteries have their own little arteries
What are the features of arterioles?
- Smaller than arteries
- Basic structure is the same
- Arteriolar network is important for the maintenance of pressure and temperature control
What are the features of capillaries?
- Walls are composed of a single layer of cells to allow for quick exchange of glucose, O2 and waste
- The layer is so thin so that molecules such as oxygen, water and lipids can diffuse through them and enter the tissue
What is the capillary bed?
It is the network of capillaries supplying an organ. the more metabolically active the cells, the more capillaries it will require to supply nutrients
What are venules?
- Small veins collecting blood from capillary network
- Very little muscle therefore dependent on external muscle activity to return blood towards the heart
- Contains valves to prevent back flow
What are veins?
- Thinner layer of muscle then in arteries therefore external muscle activity needed to help retire blood to the heart
- Valves to prevent back flow
What is the pulmonary circuit?
Carries blood to the lungs to be oxygenated and then back to the heart. In the lungs CO2 is removed from the blood and oxygen taken up by the haemoglobin in the red blood cells
What is the systemic circuit?
Carries blood around the body to deliver the oxygen and returns the de-oxygenated blood to the heart
What is the hepatic portal circulation?
The veins of the gastrointestinal tract carry blood to the liver through the hepatic portal vein. The liver removes toxins, stores sugars and processes the products of digestion before they reach the other body tissues. Blood from the liver then returns to the heart through the inferior vena cava
What is foetal circulation?
Specialised blood vessels carry the foetal blood to the placenta where exchange occurs and then returns it to the foetal body. 2 umbilical arteries and 1 umbilical vein accomplish this purpose
What are the 4 chambers of the heart?
- Left and right atria
- Left and right ventricle
What are the 4 valves of the heart?
- Tricuspid and bicuspid
- Aortic and pulmonary valves
What are the 3 layers of the heart?
- Pericardium
- Myocardium
- Endocardium
What is the role of the 2 atria?
Thin walled chambers that receive blood form the veins
What is the role of the 2 ventricles?
Thick walled chambers that forcefully pump blood out of the heart
What are the valves between the atria and ventricles called?
Atrioventricular valves
What are the valves at the bases of the aorta and pulmonary artery called?
Semilunar valves
What are the left and right AV valves called?
- Bicuspid valve = left
- Tricuspid valve = right
What are the actions of papillary muscles and the chordae tendinae?
Open the valves and keep the valve flaps in place as the chambers contract
What is the first ‘Lub’ sound caused by?
The closure of the AV valves as the ventricles contract
What is the ‘dub’ sound caused by?
The closure of the semilunar valves when the ventricles undergo diastole or relaxation
What is systole?
Contraction phase
What is atrial systole?
Atria contract, forces remaining blood into the ventricles, ventricles remain relaxed
What is ventricular systole?
Ventricles contract a the same time, blood pressure increases, AV valves forced shut (so no back flow), semi lunar valves forced open, blood pushed into aorta and pulmonary artery
What is diastole?
Relaxation phase
What happen in diastole?
Atria fill with blood, pressure rises, atrioventricular valves open, blood passes by gravity into ventricles, semi lunar valves closed
What is the sinoatrical (SA) node?
Pacemaker
What is the atrioventricular (AV) node?
Here the impulse is delayed briefly so that the contracting atria have enough to pump all the blood into the ventricles
What is the AV bundle?
Passes impulses down into the ventricles
What are the bundle branches?
Ensure all areas of the heart receive the impulses
What is the purkinje fiber?
Pass impulse into the muscle cells
What is an electrocardiogram (ECG)?
A graphic record of the heart electrical activity
