Flashcards in 1. CVS intro Deck (17)
What is the main function of the CVS?
Carries oxygen and nutrients to the capillaries to allow diffusion to the tissues.
Which 3 factors affect the rate of diffusion from capillaries to tissues?
1. Area available for exchange
2. Diffusion 'resistance' (nature of molecule, barrier, path length)
3. Concentration gradient
Why will more metabolically active tissues have greater diffusion rates?
Have higher capillary density and so greater area for exchange.
What determines the concentration gradient of substances in the blood? Where is substance concentration greater?
- rate of use by tissue
- rate of blood flow through capillary bed
The lower the blood flow, the lower the capillary concentration - blood flow must be high enough to maintain a sufficient concentration gradient.
Substance used by tissues will have a lower concentration in capillary blood than arterial blood.
What is the perfusion rate, and how does this change in different tissues?
Perfusion rate = rate of blood flow.
Must match the tissues' metabolic demands: higher metabolism rate means greater oxygen and nutrient demand and so greater perfusion rate,
Which tissues require a constant high blood flow?
Brain, heart muscle, kidneys
Which tissues require a higher blood flow during exercise?
Heart muscle, skeletal muscle
What is the cardiac output at rest and to how much can this increase (e.g. during exercise)?
5.0 L/min at rest
Up to 25 L/min in exercise
What is the heart enclosed in?
Name the layers of the pericardium and heart.
Parietal layer (outer serous)
Visceral layer/epicardium (inner serous)
What can be the result of a build up of fluid in the pericardium?
Can compress heart due to inextensible fibrous pericardial layer - leads to cardiac tamponade.
Which procedure must be performed in cardiac tamponade?
Pericardiocentesis - removes fluid from pericardial space using a needle for testing or to relieve compression.
Where is the transverse pericardial sinus?
Passage between the aorta and pulmonary artery anteriorly and the superior vena cava posteriorly.
Where is the oblique pericardial sinus?
Cul-de-sac enclosed between the inverted limbs of the inverted U of the venous mesocardium, behind the left atrium.
Where do the coronary arteries arise from?
First branches of the aorta
Why are coronary arteries end arteries?
Terminal arteries with few anastomoses, vital to supply well oxygenated blood to the myocardium.