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
What forces cause interstitial fluid to circulate?
Osmosis and hydrostatic pressure
Define a sensory receptor
Cell or group of cells that moniter changes in the environment (internal or external)
Somatic senses versus special senses and receptor types
Somatic- body (thermoreceptors, nociceptors, proprioceptors)
Special- sight (photoreceptors), smell (chemoreceptors), hearing (mechanoreceptors?), taste (chemoreceptors?)
Define compound sensations
Interpretation of sensations from multiple types of receptors
How are Intensity and duration of the stimulus coded for?
Frequency code and population code
Sensory Acuity
The ability to identify the type, strength and location of seperate sensations in perception
What influences sensory acuity (5)?
- magnitude stimulus (frequency code)
- receptive field size (population code)
- Covergence (receptor field overlap)
- Amount of sensory cortex devoted to interpretation
- Lateral inhibition (increases acuity)
Projection- definition and how it works
Brain’s ability to localize the source of stimulation
Function of sensory acuity (lateral inhibition) and experience (learning)
What is sensory adaptation?
Decrease in receptor activity in response to an unchaning stimulus (reduced action potentials)
What are important integrative functions to balance?
Vision, somatic senses, proprioception, vestibular input
How is motion interpreted at the vestibular level?
Difference between right and left inputs
Semicircular canals holds fluid (endolymph), utricle and saccule. Otoliths (little crystals) within the maculae open or close K+ channels on the hairs of receptor hair cells (K+ greater on outside of cell)
