Circulatory System 2 Flashcards
What are Capillary Systems?
Minute low pressure porous vessels allowing exchange of substances with tissue cells
What are Venous Systems?
- Low pressure:large diameter vessels
- Pooling of blood for return to the heart
- Unidirectional flow maintained by valves
What are the three main factors important for blood pressure?
Cardiac Output
-Heart rate (rate of contractions)
Stroke volume (volume ejected from heart with each contraction)
Vascular Resistance
Blood viscosity
Number of capillaries perfused
Gravity
Blood Volume
Exchange of substances with tissues
Explain how the Capillary exchanges substances with tissues\
Capillaries are made of thin cells, meaning that some parts of the blood can easily leave the capillary, bathing the cells in a fluid known as tissue fluid.
Useful substances within the tissue fluid - including glucose, oxygen and amino acids - can then diffuse into the cells down a concentration gradient. The concentration gradient is always maintained as the useful substances are constantly being used up by the cell.
Waste substances generated by the cell diffuse out of the cell, and back into the tissue fluid. Most of the tissue fluid is then reabsorbed back into the blood, and with it the waste substances – such as carbon dioxide and urea – which are taken away to be excreted.
A concentration gradient is always maintained as the cell constantly generates more waste substances, and the blood constantly takes them away.
What is the lymphatic system?
The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections.
It is made up of a complex network of lymphoid organs, lymph nodes, lymph ducts, lymph tissues, lymph capillaries and a network of lymphatic vessels that carry lymph and other substances throughout the body.
What is the job of the lymphatic system?
The removal of excess fluids from body tissues. This process is crucial because water, proteins, and other substances are continuously leaking out of tiny blood capillaries into the surrounding body tissues. If the lymphatic system didn’t drain the excess fluid from the tissues, the lymph fluid would build up in the body’s tissues, and they would swell.
