CVS 1 (Basics) Flashcards
(75 cards)
Which side of the heart (left/right) pumps blood from the body to the lungs?
Right heart
The left heart pumps blood from where to where?
Lungs to body
Why does the heart wall require its own blood supply?
Heart wall is thick, and diffusion from chambers would take too long
Describe the capillary wall:
Single endothelial cell thick, surrounded by basal lamina
What is required for diffusion of gases to occur?
Concentration gradient
Rate of diffusion depend on:
- Surface area available for diffusion
- Diffusion resistance (nature of molecule/barrier, and path length)
- Concentration gradient
How does capillary density differ between tissues?
A more metabolically active tissue will have higher capillary density than a less metabolically active tissue
In the body, what maintains the concentration gradient of substances used by tissues?
Blood flow
Define perfusion rate:
Rate of blood flow to capillary bed
What are the units given to describe blood flow in the body to tissues?
ml/min/g
What is the blood flow required by the brain?
0.5 ml/min/g
What is the blood flow required by the heart at rest?
0.9 ml/min/g
What is the blood flow required by the kidneys?
3.5 ml/min/g
What is the minimum total blood flow around a typical 70kg man in L/min?
5 L/min
What is the maximum total blood flow around a typical 70kg man in L/min?
25 L/min
What are the 2 main ways of controlling flow through the CVS?
1) Arterioles
2) Pre-capillary sphincters
Why is the brain one of the hardest-to-perfuse areas of the body?
Gravity
What part of the CVS acts as a variable reservoir of blood, allowing the total flow in the system to change?
Veins
What characteristics of veins allow them to act as variable reservoirs of blood?
Thin elastic walls that can easily distend or collapse
Approximately what percentage of the bodies blood is in the venous system at any time?
~ 67%
Approximately what percentage of the bodies blood is in the artery/arteriole system at any time?
~ 11%
Approximately what percentage of the bodies blood is in the capillary system at any time?
~ 5%
Approximately what percentage of the bodies blood is in the heart/lungs at any time?
~ 17%
Describe the layers of the pericardial sac:
3 layers:
- Outer fibrous layer
- Parietal serous layer, connected to fibrous layer
- Visceral serous layer, connected to myocardium