Lecture 9 Temp

Question 0

The continuous venous plexus in the subcutaneous tissue is supplied by what?

Answer 0

inflow of blood from capillaries from dermis

Question 1

what kind of tissue especially acts as heat insulators?

Answer 1

Skin and subcutaneous tissue

Question 2

how great can the rate of inflow be?

Answer 2

30% of CO

Question 3

how big of an increases in conductance is there between vasoconstricted to vasodilated?

Answer 3

8x

Question 4

vasoconstriction is controlled by what?

Answer 4

sympathetic system in response to core and environmental temps

Question 5

what are the 3 mechanisms of heat loss from the skin?

Answer 5

radiation, convection, conduction

Question 6

what is convection

Answer 6

heat loss from body bc of air currents

Question 7

what is conduction?

Answer 7

KE of the skin transferred to air IF air is colder than body

Question 8

what is radiation?

Answer 8

loss in the form of infared heat rays (most common, 60%)

radiated by all objects NOT at ABSOLUTE ZERO

Question 9

True or False:

Water has a specific heat several thousand times less than air.

Answer 9

False, greater than air, same with heat loss

Question 10

what rate does insensible perspiration occur at per day and how many Cals per day?

Answer 10

600-700 ml/day

16-19 Cal/day

Question 11

what part of the brain does the stimulation for sweating occur?

Answer 11

anterior hypothalamus pre-optic area

Question 12

what type of nerve fibers and what hormones stimulate it?

Answer 12

cholinergic

Epi and NE

Question 13

what is the precursor secretion similar in composition to?

Answer 13

plasma w/o proteins

Question 14

What ions are present in precursor secretion and in what concentration?

Answer 14

Na+: 142
Cl-: 104

Duh, sweat is salt

Question 15

In strong stimulation of sweat glands what is reabsorbed?

Answer 15

little water

ducts reabsorb only half NaCl

Question 16

True or False
An acclimated person normally produces 1 liter sweat per hour while a person unacclimated to hot weather produces 2-3 liters sweat per hour?

Answer 16

False, reverse

if you are acclimated, you will sweat more because your body knows how to get rid of heat

Question 17

what is the heat removal factor? what is acclimation due changes in?

Answer 17

10x

internal sweat glands

Question 18

what are the 2 areas of the brain that affect body temp?

Answer 18

anterior hypothalamic pre-optic

pre-optic

Question 19

which area of the brain contains both cold and heat-sensitive neurons?

Answer 19

anterior hypothalamic pre-optic

Question 20

what happens when the pre-optic area is heated?

Answer 20

immediate dilation of blood vessels, profuse sweating, inhibition of excess heat production

Question 21

how do you reduce body heat?

Answer 21

vasodilation, sweating, inhibition of thermogenesis

Question 22

how do you increase body heat?

Answer 22

vasoconstriction, piloerection, increase thermogenesis

Question 23

what is thermogenesis?

Answer 23

shivering, metabolic pathways, thyroxine secretion

Question 24

where is the primary motor area for shivering located?

Answer 24

dorsomedial portion of posterior hypothalamus

Question 25

what activates shivering?

Answer 25

cold signals from skin and spinal cord

Question 26

how does the dorsomedial portion of the post. hypothalamus initiate shivering?

Answer 26

transmits signals into lateral column of spinal cord
signals increase muscle tone, shivering starts when it goes above a certain level
may involve muscle spindle stretch reflex

Question 27

what is chemical thermogenesis?

Answer 27

increase cellular metabolism due to sympathetic stim (NE in blood)

Question 28

what does Epi/NE do?

Answer 28

uncouples ox phos

Question 29

what is the relationship between thermogenesis and brown fat?

Answer 29

direct

Question 30

what effect does inc. thyroxine output have on cell metabolism?

Answer 30

increases the rate of cellular metabolism throughout the body (chemical thermogenesis

Question 31

what is the critical body core temp?

Answer 31

37.1 C, 98.8 F

Question 32

The level at which sweating begins or shivering begins in order to return to critical core body temp is called what?

Answer 32

set-point

Question 33

what is the feedback gain of the temp control system?

“ “ baroreceptors in arterial pressure?

Answer 33

27 –> (28/1) - 1

less than 2

Question 34

skin temp changes are primarily responsible for what?

Answer 34

physiological mechs that alter the critical set point

Question 35

what are pyrogens and give some examples

Answer 35

pyrogens induce an abnormal rise in body temperature, set-point to rise

ex. pathogens and bacteria

Question 36

how does IL-1, prostaglandins effect fever?

Answer 36

induce fever (Inc. temp)

Question 37

How does aspirin and arachidonic acid effect fever?

Answer 37

Reduce fever

Question 38

what are some febrile conditions

Answer 38

chills - set point higher than normal

crisis/flush - set point lower than normal

Question 39

when is heat stroke likely to occur?

Answer 39

at 105-108 degrees F

Question 40

what are the symptoms of heat stroke? how is related to circulatory shock?

Answer 40

dizziness, vommiting, loss of consciousness

loss of electrolytes and fluid

Question 41

what temp point does the hypothalamus lose its ability to regulate temp?

Answer 41

85 degrees F