Transcript Thermoregulation2Glucose1

For 1QQs
Last name, First name
Question #
a
b
c
d
e
Announcements
• Turn in Personal Information (place on
Piano.)
• Reading and Chapter Questions
– Will finish Thermoregulation Today and
– Glucose Homeostasis on Monday
– By Monday,complete all Glucose
Homeostasis Questions
1QQ Sample Questions
Name on top edge, back side of paper
Answer on blank side of paper.
Answer one of the following:
1. The San people of Botswana were
clothing made of tanned animal skins. A)
What would be the preferred type of
clothing for their hot desert environment,
b) why would it be preferred (think heat
exchange mechanisms) and c) why do
you suppose they don’t wear what would
be preferred?
2. What is the difference between a reflex
and a negative feedback loop?
1QQ # 2 for 8:30
Name on top edge, back side of paper
Answer on blank side of paper.
1. For the negative feedback loop for thermoregulation
a) The hypothalmus is an afferent pathway
b) Somatic nerves are the efferent pathway to sweat
glands
c) Skeletal muscle tone would be increased as a
response to a drop in core body temperature
d) Peripheral nerves are the afferent pathway that
convey skin temperature information
e) Cutaneous arterioles would dilate in response to a
drop in core body temperature.
1QQ # 2 for 9:30
Name on top edge, back side of paper
Answer on blank side of paper.
1. For the negative feedback loop for thermoregulation
a) The hypothalmus is an efferent pathway
b) Somatic nerves are the efferent pathway to
skeletal muscles
c) Skeletal muscle tone would be decreased as a
response to a drop in core body temperature
d) Peripheral nerves are the afferent pathway that
convey skin temperature information
e) Sympathetic nerves would lead to constriction of
cutaneous arterioles in response to a drop in core
body temperature.
Add covers
Conductive heat loss
Skin temp And Core body temp
or clothing
Radiative heat loss
or enter
Convective heat loss
Central
sleeping
thermoreceptors
bag
Detected by thermoreceptors in skin
Cerebral cortex
Activity in sensory nerves
Somatic nerves
Hypothalamus
Sympathetic nerves
Relax smooth muscle in
cutaneous arterioles
Blood flow to skin
Somatic nerves
Sweat Glands
Voluntary behaviors
Muscle tone
Heat production
Sweat production
Skeletal
Muscles
Heat loss
Evaporative heat loss
Heat loss by conduction & radiation
Remove covers
Turn on fan, etc via
Core temp.
o
~37 C
Be able to explain the physiology in each of these situations
with a detailed diagram of negative feedback responses and
the modes of heat exchange involved.
Which roofers are most appropriately dressed for the job?
Red shirts
No shirts
• 1st day onbegin
the jobeven before core temperature increases!
Responses
Increase
body temp…..
Delayed
via negative feedback
Not –just
negative
feedback,
thissweating
is Feedforward
(requires
• 10th day on the
experience).
FF job
is evidence of Acclimitization.
– Sweating precedes changes in core body temperature
Advantage
of feedforward:
– and sweating
is increased anticipates disruption
– And salt
loss in sweatfrom
is minimized
minimizes
fluctuation
the set point.
and
Acclimatization & Feedforward
• Deviations from set point are minimized
• Learned (by experience)
• Anticipates changes of a physiological
parameter
• Response begins before there is a change
in the physiological variable
• Minimizes fluctuations
Heat Stroke
Massive Cutaneous Vasodilation
Increase
cell
Excessive Sweating
metabolism
Failure of
1. Brain function &
2. Heat loss mechanisms
Blood volume
Blood Pressure
Increase
Body Temp.
Blood Flow to brain
Cutaneous vasodilation
Disrupted function
of neurons
Sympathetic outflow
Treating Heat Stroke
Sweating
Positive feedback
• Inherently unstable
• Examples of Positive Feedback in Physiology
– Heat stroke
– formation of blood clot
– menstrual cycling of female sex hormone
concentrations at ovulation
– generation of action potentials in nerve fibers
– uterine contractions during childbirth
• Each of these examples terminate naturally (self
limiting)
Homeostasis is achieved by negative feedback loops: the integrator
detects deviations from set point and orchestrates responses produced
by effectors that return the parameter toward the set point.
If setpoint is suddenly reset
to a higher temperature,
then actual temperature is
LESS THAN the new set
•point,
Explain
“chills”
at
so one
feels “cold”
onset
a fevercurls up,
and
addsof
clothing,
shivers.“sweat”
These are
•and
Explain
“Chills.”
a isfever
If when
setpoint
reset to a
“breaks”
lower
temperature or back
normal,
then actual
•toHow
does
temperature is GREATER
Tylenol reduce a
THAN the new lower set
fever?
point,
so one feels “hot” and
removes clothing, fans, and
sweats. These are “the
sweats” when a fever
breaks.
p. 579 Fig 16-18
Central &
Peripheral
Thermoreceptors
Tylenol and other nonsteroidal antiinflammatory drugs
(NSAIDS) suppress the
production of
eicosanoids (IL-1, IL-6,
etc) so effect of these
on the set point in
hypothalamus
is new,
To reach
minimized. Higher set point
Plasma Glucose Homeostasis
•
•
•
•
Glucose metabolism
Hormonal Control
Disruptions of glucose homeostasis
A Case Study
Homeostasis of Plasma
Glucose Concentration
•
•
•
•
Normal physiological range: 65-100 mg/dl
What is the set point?
Why is too much plasma glucose harmful?
Plasma glucose concentration = glucose entering the
plasma – glucose leaving the plasma
• What are the mechanisms that regulate plasma
glucose concentration?
• What are the components of the negative feedback
loop:
–
–
–
–
–
Glucose receptors?
Afferent pathway?
Integrator?
Efferent pathway(s)?
Effector organ(s)?
Phases:
absorptive,
post-absorptive, and
fasting
Graph your daily caloric intake
over a 48 hour period
Plasma
Glucose
Calories
consumed
?
?
6am
Noon
6pm
MN
6am
Noon
6pm
MN
6am
Noon
Overlay absorptive and post-absorptive phases on the graph
Absorptive
Phase
Fig. 16.01
Lipoprotein Lipase
=sink
Hepatic Portal System
Once inside, glucose is
converted to something else,
thereby maintaining a
concentration gradient
for facilitated diffusion of
glucose into cells.