Lab quiz 1 (Skin, sensation, balance and kinesthetic sense)

Question 1

Why are capillaries so small?

Answer 1

To get RBCs close to the tissue to allow for better diffusion of O2

Question 2

What are the 3 mechanisms to control blood flow?

Answer 2

1. Precapillary sphincter: smooth muscle before a capillary
2. Arterioles: muscular walls
3. Swelling/shrinking of endothelial capillary cells

Question 3

Where are continuous capillaries found?

Answer 3

Areas where you don’t want to allow much leakage of solutes-

Skin, cardiac/skeletal muscle, lungs, adipose tissue

Question 4

Where are fenestrated capillaries found?

Answer 4

Kidneys, intestines

Question 5

Where are discontinous (aka sinusoid) capillaries found?

Answer 5

Liver

Question 6

80-90% of fluids are returned to capillaries, where does the rest go?

Answer 6

Lymphatic system

Question 7

What is a possible cause of vasodilation during excercise?

Answer 7

Rise in CO2 tension, increase in H+ concentration

Question 8

What signal molecule is associated with the local vasodilation associated with inflammation?

Answer 8

Histamine

Question 9

What is edema and what are possible causes of it (4 total)?

Answer 9

Edema is local swelling due to excess interstitial fluid.

1. Low concentration plasma proteins (diet) - osmosis
2. Increased venous pressure - pregnancy
3. Holes or damage to capillary walls - diabetes, physical pressure
4. Obstruction lymphatic system - parasites, chemotherapy, etc.

Question 10

What causes the white line response?

Answer 10

Vasoconstriction of capillaries

Question 11

What causes the red line response (3 lines)?

Answer 11

Vasodilation of capillaries and vasoconstriction on either side

Question 12

What causes the flare response?

Answer 12

Arterioles which are stimulated to dilate due to local reflex arc

Question 13

If pressure on your arm is increased (via a cuff), what happens to the white line?

Answer 13

It dissapears- decreased circulation means unable to vasoconstrict

Question 14

What could be responsible for producing the wheal seen in lab?

Answer 14

Wheal= local edema

Damage to capillary wall which increases permeability and can lead to a local increase in fluid

Question 15

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:

1. Cold/pale
2. Warm/pale
3. Warm/red
4. Cold/red

Answer 15

1. Subcapillary constricted, surface constricted, cold exposure
2. subcapillary dilated, surface constricted, heat stroke or dehydration
3. subcapillary dilated, surface dilated, exercise
4. subcapillary constricted, surface dilated, very cold or frostbite

Question 16

What forces cause interstitial fluid to circulate?

Answer 16

Osmosis and hydrostatic pressure

Question 17

Define a sensory receptor

Answer 17

Cell or group of cells that moniter changes in the environment (internal or external)

Question 18

Somatic senses versus special senses and receptor types

Answer 18

Somatic- body (thermoreceptors, nociceptors, proprioceptors)

Special- sight (photoreceptors), smell (chemoreceptors), hearing (mechanoreceptors?), taste (chemoreceptors?)

Question 19

Define compound sensations

Answer 19

Interpretation of sensations from multiple types of receptors

Question 20

How are Intensity and duration of the stimulus coded for?

Answer 20

Frequency code and population code

Question 21

Sensory Acuity

Answer 21

The ability to identify the type, strength and location of seperate sensations in perception

Question 22

What influences sensory acuity (5)?

Answer 22

1. magnitude stimulus (frequency code)
2. receptive field size (population code)
3. Covergence (receptor field overlap)
4. Amount of sensory cortex devoted to interpretation
5. Lateral inhibition (increases acuity)

Question 23

Projection- definition and how it works

Answer 23

Brain’s ability to localize the source of stimulation

Function of sensory acuity (lateral inhibition) and experience (learning)

Question 24

What is sensory adaptation?

Answer 24

Decrease in receptor activity in response to an unchaning stimulus (reduced action potentials)

Question 25

What are important integrative functions to balance?

Answer 25

Vision, somatic senses, proprioception, vestibular input

Question 26

How is motion interpreted at the vestibular level?

Answer 26

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)