CVS Flashcards
What is the main function of the CVS?
Transport
What are the transport functions the CVS carries out?
1) External to internal environment- oxygen from the respiratory system and nutrients and water from the GIT.
2) Cell to cell- waste products are taken to the liver, immune cells and antibodies are taken to other cells in need of them, hormones are taken to their target cells.
3) Materials leaving the body- metabolic waste to the kidneys, heat and thermoregulation done by circulation to the skin, CO2 is got rid of by perfusion of the lungs.
What is the arrangement of the CVS?
Left heart, arterial system, systemic circulation, venous system, right heart.
What is the relationship between the right and left sides of the heart?
They are in series with eachother. Output of RV into pulmonary circulation = output of LV into systemic circulation.
What is the relationship between the vascular beds?
They are in parallel. All beds get blood with the same level of oxygenation, prevents changes in blood flow in in one organ affecting flow in other organs.
What is systole?
Phase of ventricular contraction and ejection
What is diastole?
Phase of ventricular relaxation and filling
What is the formula for CO?
SV x HR
What is cardiac output and what is a typical value?
Volume of blood pumped per minute. 5Lmin-1
What is CO determined by and what are the typical values for these
Heart rate- 70bpm and stroke volume- 70ml
True or False, left CO = right CO
True
What is the formula for pulse pressure?
SP-DP
What does a strong pulse indicate?
A high pulse pressure
What percentage of the cardiac cycle is diastole?
60%
What is the formula for mean ABP?
Mean ABP= (SP-DP)/3 + DP
What happens to pressure through the system?
Pressure drops because there is resistance to flow
What determines pressure in the arterial system?
1) Resistance to blood flow
2) Blood volume in the arterial system
ABP= CO x TPR
How do arterioles control blood flow to organs?
Vasoconstriction or vasodilation changes resistance and controls flow. Vasodilation increases flow and vasoconstriction decreases it.
What are the functions of veins and how are these achieved?
Carry blood at v low pressure Thin walls Muscle control by ANS Wide lumen to accommodate large volumes Reservoirs used to adjust ventricular filling
What are the functions of arteries and how are these achieved?
Carry blood at high pressure Thick muscular walls Elastic layers Narrow lumen High pressure conduits
What are the functions of arterioles and how are these achieved?
Carry blood at modest pressure
Thick, muscular walls
Muscle under influence of local factors and ANS
Function to control flow to tissues
What are the functions of capillaries and how are these achieved?
Carry blood at low pressure
Single endothelial cell wall
Maximise exchange between blood and tissue
What are the functions of venules and how are these achieved?
Low pressure
Resemble capillaries
Low pressure conduits
How is ABP maintained?
Negative feedback control. ABP= CO x TPR
= (SV x HR) x TPR
ANS causes cardiac stimulation, vascular constriction (if ABP decreases) Kidneys change blood volume.