Introduction to CV Flashcards
Why do we need a cardiovascular system?
All living cells are metabolically active so they need a blood supply to get oxygen -even heart.
Why does the heart need a blood supply?
The left ventricle is filled with oxygenated blood. But, the distance of the cells form the source of oxygen and nutrients means that the muscle wall of the left ventricle will be seriously damaged if the vessles supplying it are blocked.
If the heart just got oxygen from diffusion, it would be too slow! It would take half a day for oxygen to diffuse over the heart cell wall. Just 1cm is too thick!
What factors affect the rate of diffusion?
The rate of diffusion is dependant on:
- Area available for exchange
- Diffusion resistance
- Concentration gradient
What does the area available for diffusion depend on?
It depends on the capillary density. The more metabolically active the tissue, the higher the capillary density.
What does the concentration gradient depend on?
The concentration gradient depeds on:
- The rate of use by the tissue
- The rate of blood flow through the capillary bed
The lower the blood flow, the lower the conc. gradient.
What is the perfusion rate?
The rate of blood flow. Increases in metabolism must be met by increases in blood supply. This is because these tissues have a higher demand for oxygen and nutrients.
What organs need a high blood supply?
- Brain - This needs a high, constant flow
- Heart muscle - This needs a high flow that increases during exercise
- Kidneys - This needs a high, constant flow
- Skeletal muscle during exercise
- Gut after a meal
What is the average cardiac output?
5L per minute
How much can blood flow rise during exercise?
In exercise, blood flow can rise to 25L/min. This is 5 times as high as the resting heart rate.
What are the layers of the pericardium?
Fibrous layer
Double layer of serous pericardium:
Parietal (outer) layer and visceral layer (Visceral is known as epicardium)
In between the serous membranes is the pericardial cavity
What arteries can be used to feel a pulse?
Common carotid
Brachial artery
Radial artery
Femoral artery
Poplilteal
Posterior tibial
What is cardiac output equal to?
Cardiac output = heart rate x stroke volume
Cardiac output is equal to about 5L/min
What are the three layers of the heart wall?
Epicardium: Serous membrane; smooth outer surface of the heart
Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting
Endocardium Smooth inner surface of heart chambers.
What are pectinate muscles?
Muscular ridges in auricles and right atrial walls.
What are the trabeculae carnae?
Muscular ridges and columns on inside walls of ventricles.
