Flashcards in Cutaneous & Splanchnic Circulation Deck (49):
How is skin blood flow regulated? (it is unlike the other systems for this reason)
Sympathetics, not metabolic control
What is the MAIN purpose of cutaneous circulation? (blood flow to the skin)
-maintain constant temp via vasodilation/constriction
The cutaneous circulation is more efficient at preventing heat loss rather than promoting heat loss.
True or False?
Better at promoting heat loss via vasodilation of cutaneous vessels
- we acclimatize better to heat than cold
What do the following colors signify in circulation or oxygen content of blood?
4. Bright Pink
1. LOW BLOOD FLOW
2. Desaturated Hemoglobin (low O2)
3. Saturated Hb w/ O2
4.CO poisoning (carbon monoxide)
Why does the skin appear red in cold climates, even though blood flow is LOW due to vasoconstriction?
Low temp = skin DECREASES O2 dissociation!
- less O2 unloaded from Hb
= more saturated with O2
What color does Oxyhemoglobin give the skin?
What are the 2 types of resistance vessels in the skin? What type of mechanism controls their resistance?
1. Arterioles -
b) Local regulatory
2. Arteriovenous Anastomoses (AV)
- bypasses capillary beds
a) SYMPATHETIC CONTROL ONLY
- no basal (non-neural tone)
- no reactive hyperemia
- no autoregulation
What parts of the body contain Apical Skin?
Name the 2 most important qualities of Apical skin:
Ears, nose, lips, fingertips, hands, feet,
1. Large surfave-tovolume ratio to favor HEAT LOSS
2. AV Anastomoses called GLOMUS bodies
What is the function of glomus bodies?
What are 2 features present in Non-Apical Skin that areNOT found in Apical skin?
1. No AV Anastomoses (almost)
2. Sympathetic CHOLINERGIC
Why does the skin appear paper white during hypovolemic shock?
Due to VASOCONSTRICTION of the skin
- shunting blood to brain,lungs, heart
What innervation does Apical Skin receive? Non-Apical?
1. Sympathetic adrenergic
- at rest = vasoconstriction
(withdraw sympathetics = passive vasodilation)
2. Sympathetic CHOLINERGIC - vasodilate via Bradykinin
& Adrenergic via NE (vasoconstrict)
The release of BRADYKININ is dependent on what?
Where is this released (which type of skin)?
Does this cause vasoconstriction or dilation?
1. SWEAT -DEPENDENT
2. Non-APical (not ears,nose, lips, fingertips, hands, or feet)
There are glomus bodies & AV anastomoses in Non-Apical skin. True or False?
What provides temperature regulation of the skin?
What happens to sympathetic control with increases in temp?
WITHDRAW sympathetic activity
- passive vasodilation
Do cutaneous vessels contribute a large amount to total peripheral resistance & BP?
- flow in skin is only 5-10% of CO
What were to happen if you were shot in Iraq, or another hot temperature climate? (decrease in BP)
Baroreceptor VASOCONSTRICTION would have little affect on BP due to the reflexive VASODILATION caused by warmer temps
-BP is not well maintained in warm temps
When is LOW blood flow not well maintained? How does this compare to HIGH BP?
At HIGHER temps
- High BP causes withdrawal of sympathetics (little affect on skin blood flow since apical vessels already dilated)
What freezes first?
1. Smaller or larger vasculature
2. Venous or Arterial System
2. Venous (low flow rates)
If you exercise & are dehydrated, what happens to body temp?
- cannot dissipate more heat
(occurs quickly if you are dehydrated since less sweat produced)
What is the primary regulator of the cutaneous system?
SYMPATHETIC nervous system via the hypothalamus
What happens to cutaneous flow with exercise?
1. Sympathetic stimulation vasoconstrictor to shunt blood to skeletal muscle
- Internal metabolic HEAT PRODUCTION causes cutaneous vasodilation!
What wins out with cutaneous exercise? Sympathetic Vasoconstriction or Vasodilation?
Does flow continuously increase in skin with increased exercise?
- flow only increases to a LIMIT
- only small increases in flow w/ increasing internal temp
What artery provides blood to the stomach, spleen, and pancreas?
TO the intestines? (2)
What is the function of arterial & venous blood in SPLANCHNIC circulation?
Arterial = brings O2 & metabolic substrates
Venous = picks up O2 and NUTRIENTS absorbed from intestine
What happens if the venous system backs up into the abdominal region? (due to increased hydrostatic pressure)
What is a distinguishing factor in the organization of the arterioles, capillaries, and venules in the intestinal lumen?
How does this affect Arteriole Osmolarity?
What is this phenomenon called?
THINK DUCK FEET!
1. Arterioles come up the villi and branch into capillaries which then converge into venues that carry blood back to the base of the villus
- arterioles & venules run PARALLEL to each other so that solutes like Na can diffuse from:
- high Arteriole Osmolarity INCREASES FLOW!
2. COUNTER CURRENT!
Portal vein is located between 2 _______ ____.
Which vessels collect blood from the liver and empty into the Vena Cava?
What vessel collects blood from capillary beds of intestine, stomach, pancreas, and spleen?
What are 2 ways that Portal Hypertension can develop?
1. Increased pressure in Vena Cava (CHF)
2. Increase RESISTANCE in Hepatic Veins
(cirrosis, hepatitis B, C)
What can portal Hypertension lead to? (3)
1. Abdominal Edema
3. Esophogeal, Umbilical, & Rectal Varices
What does an increase in arteriole osmolarity result in?
INCREASED FLOW & nutrient absorption
Why is it possible to "bleed out" during hemorrhoids brought on by liver failure?
Lower amount of clotting factors due to liver damage
- less ALBUMIN
High after load on the RIGHT ventricle is a result of what pathological condition? If this progresses into Liver Cirrhosis, what is a second pathological condition that arises?
- can lead to PORTAL HYPERTENSION
& Ascites & Varices
Which vessels regulate Hydrostatic Pressure?
- less resistance (no auto regulation)
What is cirrhosis?
Anything that damages the liver
What are 3 ways that intestinal blood flow is regulated?
1. Local Factors (mechanical & metabolic)
What is the affect of an increase in metabolism on the following:
Does this cause vasodilation or vasoconstriction?
1. O2 decreases
2. metabolites increase
During intestinal contractions, what happens to blood flow?
DECREASES due to compression of vessels (like in the heart)
Intestine does not exhibit auto regulation. True or False
Moderate Autoregulation from METABOLITES
(adenosine, CO2, H+, K+)
What are 2 HORMONES that are important in digestion? DO they cause vasoconstriction or vasodilation?
- increase flow via VASODILATION
What is the major NEURAL control in the splanchnic circulation? What is the only exception?
Post-Ganglionic SYmpathetic VASOCONSTRICTION
- except the capillaries
What INDIRECTLY stimulates intestinal blood flow by stimulating intestinal motility and glandular secretions, increasing metabolism?
= indirect affect
What is Postprandial Hyperemia?
Increased flow after eating
(food ingestion increases intestinal flow through 1. Metabolic/mechanic 2. Neural 3. Hormonal influences)
What intestinal lumen contents increase the magnitude of blood flow?
FATS & Carbs!
- induce hyperemia
What is the affect of peristalsis?
Increase metabolic activity and thus FLOW in the gut