Lab quiz 1 (Skin, sensation, balance and kinesthetic sense) Flashcards
Why are capillaries so small?
To get RBCs close to the tissue to allow for better diffusion of O2
What are the 3 mechanisms to control blood flow?
- Precapillary sphincter: smooth muscle before a capillary
- Arterioles: muscular walls
- Swelling/shrinking of endothelial capillary cells
Where are continuous capillaries found?
Areas where you don’t want to allow much leakage of solutes-
Skin, cardiac/skeletal muscle, lungs, adipose tissue
Where are fenestrated capillaries found?
Kidneys, intestines
Where are discontinous (aka sinusoid) capillaries found?
Liver
80-90% of fluids are returned to capillaries, where does the rest go?
Lymphatic system
What is a possible cause of vasodilation during excercise?
Rise in CO2 tension, increase in H+ concentration
What signal molecule is associated with the local vasodilation associated with inflammation?
Histamine
What is edema and what are possible causes of it (4 total)?
Edema is local swelling due to excess interstitial fluid.
- Low concentration plasma proteins (diet) - osmosis
- Increased venous pressure - pregnancy
- Holes or damage to capillary walls - diabetes, physical pressure
- Obstruction lymphatic system - parasites, chemotherapy, etc.
What causes the white line response?
Vasoconstriction of capillaries
What causes the red line response (3 lines)?
Vasodilation of capillaries and vasoconstriction on either side
What causes the flare response?
Arterioles which are stimulated to dilate due to local reflex arc
If pressure on your arm is increased (via a cuff), what happens to the white line?
It dissapears- decreased circulation means unable to vasoconstrict
What could be responsible for producing the wheal seen in lab?
Wheal= local edema
Damage to capillary wall which increases permeability and can lead to a local increase in fluid
Match the skin color to the reaction of the subcapillary plexus and surface capillaries (constricted or dilated) as well as naming a possible explanation for each response:
- Cold/pale
- Warm/pale
- Warm/red
- Cold/red
- Subcapillary constricted, surface constricted, cold exposure
- subcapillary dilated, surface constricted, heat stroke or dehydration
- subcapillary dilated, surface dilated, exercise
- subcapillary constricted, surface dilated, very cold or frostbite