Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

71 Cards in this Set

  • Front
  • Back
For the body, what acts as a
-Radiator system
-Insulator system
Radiator = the circulation

Insulator = clothes and fat
What is the anatomy of cutaneous (skin) circulation like?
A very dense system of capillary loops
What is the structure of subpapillary venous plexi like?
-Large volume
-In close proximity to body surface
What is the bloodflow through subpapillary venous plexi like?
Slow - low flow velocity
Function of Arteriovenous anastomoses:
Allows fast shunting of hot blood from arteries to veins
Are arteriovenous anastomoses always open?
No; in cold they are shut.
How does blood get shunted more quickly by arteriovenous anastomoses?
It doesn't have to go through capillaries first.
What is the prominent controller of skin circulation?
Sympathetic outflow
What type of receptors are on cutaneous arteries?
Predominantly alpha adrenergic receptors (few beta)
How does sympathetic stimulation alter arteries?
It causes vasoconstriction
What is the normal resting state of cutaneous arteries at normal body core and skin temp?
Vasoconstricted due to tonic sympathetic outflow.
What allows vasodilation of cutaneous arteries?
Decreased sympathetic outflow, as well as some innervation by Cholinergic fibers.
What is the structure of cutaneous veins like? Why?
Highly compliant - allows them to act as a large reservoir of blood - like a floodwater plain to allow evaporation, lets blood release from skin surface when filled.
What type of nerve receptors are on Cutaneous veins?
Alpha adrenergic - like the arteries.
What does sympathetic outflow do to cutaneous veins?
Causes constriction
What is the system that controls vasoconstriction and dilation?
The Hypothalamic Thermoregulatory Reflex Control
How is Core temp different from Skin temp?
Core temp varies much LESS than skin temp; remains constant in spite of fluctuations of atmospheric temp
What are the 2 components involved in physiological control of temperature?
1. Hypothalamus
2. Peripheral temp sensors (in the skin and deep body tissues)
How do peripheral sensors affect temperature control?
They alter the setpoint in the hypothalamus, above/below which sweating and shivering will occur.
What is the normal body temp range?
97 to 99.5
What can cause a body temp range of 99.5 - 101?
-Hard work
-A few normal adults
-Many active children
What can cause a body temp range of 95.5 to 96.5?
-Early morning
-Cold weather
At what range of atmospheric temps does body temp remain constant? Stipulation?
50 - 130 -> that is if the air is dry!
What happens to arteries in cold? In hot?
Cold = vasoconstrict
Hot = vasodilate
Why do vessels constrict in cold?
-To reduce loss of body heat
-To maximize flow to deep organs like the brain and heart.
What happens if you are adapted to wisconsin weather (Avg T=0) and go to the tropics (T=100)?
-Initially period of hypotension due to intense sweating
-Symptoms resulting from shunt of bloodflow from deep body organs to the skin
How does increasing environmental temp affect heat conductance through skin? How?
It increases because the arteries go from a fully constricted state (up to 75) to fully dilated state (at 100).
What is the main mechanism of heat production in the body?
The metabolic rate
What is the main mechanism of heat loss in the body?
Heat transfer from deep organs to the skin by bloodflow.
What are the 2 determinants of heat loss?
1. Speed of conduction from deep organs to the skin
2. Speed of transfer from skin to environment.
7 mechanisms for heat GAIN by body:
1. Metabolic heat production
2. Exercise
3. Shivering
4. Thyroxine
5. Sympathetic stimulation
6. Radiation
7. Conduction
8. Convection
What are 4 mechanisms for heat LOSS by the body?
1. Radiation
2. Evaporation (of sweat)
3. Convection
4. Conduction
How is heat lost by radiation?
How much?
By the emission of infrared heat rays - dependent on the relative temp of body to atmosphere.
How is heat lost by conduction?
How much?
Mainly by contact with air - 15%; (very small amt is directly through touching OBJECTS - 3%).
How is heat lost by convection?
How much?
Air currents/wind has a major cooling effect; think about it as you sweat and air hits you get cold. This is the conduction to air - 15%
How is heat lost by evaporation?
How much?
By loss of sweat from sweat glands; 22%
3 main mechanisms for heat loss:
1. Vasodilation
2. Sweating
3. Decrease in heat production
How is vasodilation achieved?
By inhibiting sympathetic output -> decreases tonic vasoconstriction.
How much increase in heat loss can be achieved by inhibition of sympathetic vasoconstriction?
Up to 8x
How is Sweating achieved?
By stimulation of sweat glands when the core temp rises above the set point.
How does the body decrease Heat Production?
By inhibiting shivering and chemical thermogenesis.
What is the composition of sweat like?
Protein free plasma - mainly sodium and chloride.
How is sweat produced?
By epithelial cells of sweat glands; produce a precursor secretion.
What happens to the precursor solution secreted by glandular epithelial cells?
It is modified as it flows through sweat ducts - remove more solutes and water.
What is the final product of sweat gland ducts like?
High in Lactate, Urea, and body waste.
How does sweating help to reduce body temperature?
By removing heat via evaporative cooling.
What does excessive sweating do?
Causes increased Aldosterone secretion from adrenal cortex - to reabsorb more sodium from sweat.
When does excessive sweating occur?
When an unacclimatized person moves to a climate that is much warmer.
What is the response of an unacclimitized person in a warm climate?
-Initial hypotension due to excess loss of H2O/Na in sweat
-Then adaptation and less sweat production due to Aldosterone
What types of nerves innervate sweat glands?
Cholinergic sympathetic nerves
What controls the formation and release of sweat?
The preoptic area of the anterior hypothalamus.
What stimulates sweat release?
-Cholinergic nerves
-Circulating Epi and NE during heavy exercise
What is Behavioral thermoregulation?
An extremely important mechanism for controlling heat production in extremely cold environmental temps
Can behavioral thermoregulation play a role in losing excess heat in extremely warm environmental temps?
No; the only way to lose heat is via sweating and evaporation.
What are 3 main mechanisms for increasing body temperature?
1. Cutaneous vasoconstriction
2. Piloerection
3. Increased heat production
How is cutaneous vasoconstriction achieved?
Via stimulation of posterior hypothalamic sympathetic centers.
What are 3 ways of increasing heat production?
1. Shivering
2. Chemical thermogenesis
3. Thyroxine secretion
What type of neural control is shivering under?
Autonomic - cannot voluntarily cause shivering to stop.
Where is shivering initiated?
In the primary motor cortex
How is shivering caused?
By activation of motor neurons causing muscle spindle oscillations.
What is nonshivering thermogenesis?
Chemical thermogenesis
2 types of chemical thermogenesis:
-Sympathetic nervous system
-Brown fat
What causes increased Thyroxine output and what is its effect?
-Caused by cooling of the preoptic region in hypothalamus;
-Result is TRH release, Thyroxine release, and increased metabolism generating heat.
2 types of insulator systems:
-Fat/subcutaneous tissue/skin
What is the most important type of insulator? Why?
Fat - because it conducts heat only about 1/3 as well as other tissues.
How does fat insulation affect core and skin temp?
-Insulates core because it is SUBcutaneous
-Lets skin temp approximate environmental temp
How does clothing act as an insulator?
By trapping air and decreasing convective loss of heat.
What are 2 causes of fever?
1. Pyrogens
2. Brain lesions
What are 3 pyrogens?
-Bacterial toxins
What brain lesions can alter body temp?
-Surgery in area of hypothalamus
-Brain tumors
What causes heat stroke? Why?
Exercise - because the heat generated cannot be dissipated adequetely.