#5 List 3 Functions of the Lymph Systems.
Lymph systems contribute to Homeostasis
1. Lymphatic capillaries take up excess tissue fluid and return it to the bloodstream.
2. Lacteals receive lipoproteins at the intestinal villi and transport them to the bloodstream.
3. Lymphatic system works with the immune system to help defend the body against diseases.
#11 Relate the structures of arteries and veins to their functions: a. arteries b. veins
a. Arteries are blood vessels that carry blood away from the heart. Arteries have 3 layers.
1. an outer layer of connective tissue that has elastic fibers that give the arteries the characteristic of elasticiness.
2. middle layer of smooth muscle which controls how big or small the arterial lumen (opening) becomes.
3. an inner layer of connective tissue lined with endothelial cells.
b. Veins are blood vessels that carry blood towards the heart. The walls of veins are thinner and the lumen is larger that that of an artery. Veins have the same layers but...
1. The outer layer has fewer elastic fibers.
2. the middle layer of smooth muscle is much thinner, therefore, the vein can much more more easily change the shape when the muscles press against them.
3. Veins also have valves taht close and prevent backflow and continues to send the blood where it needs to go.
#3 Describe capillary-tissue fluid exchange
Capillaries are very thin which allows quick difusion of substances.
Since there are way more capillaries and they cross everywhere, blood flow is slower allowing more time for the process of exchanging.
They are very small which increases friction and resists the flow of blood. This causes blood pressure to drop, opening the passage of materials between the tissues and the blood.
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