Lecture One- Homeostasis

Question 1

Homeostasis and examples

Answer 1

regular range despite changes in the external environment

Examples: body temp, blood pressure,

Question 2

Steady state

Answer 2

a condition that does not change with time

Question 3

Is energy required to maintain equilibrium?

Answer 3

No

Question 4

Is equilibrium a type of steady state?

Answer 4

Yes

Question 5

Difference between equilibrium and steady state

Answer 5

When input is equal to output it is steady state…. requires some energy

In equilibrium there is NO net movement-two equal and opposite forces

Question 6

Energy requirement for Equilibrium

Answer 6

None- NO ATP is required, no net flow

Question 7

______ systems are needed to maintain equilibrium

Answer 7

Control systems

Question 8

Sensor

Answer 8

Measuring variable trying to control-think a thermostat

Question 9

Integrating center

Answer 9

compares info from sensor with a set point, generally the brain or spinal cord

Question 10

effector (as a component of a control system)

Answer 10

way to cause a change i.e. glands, smooth muscle (it is the heater itself in the heating example)

Question 11

Negative feedback

Answer 11

when the effector opposes the change

Question 12

When room gets too cold, the heat turns on and opposes the change, this is what?

Answer 12

Negative feedback

Question 13

Positive feedback

Answer 13

the effector increases the change given a defined ENDPOINT when the system resets

Question 14

When smooth muscle of the urinary bladder reflex to tell smooth muscle to contract and causing bladder to empty-this is an example of what

Answer 14

Positive feedback

Question 15

When glucose is too high, insulin converts to glycogen stores, this is an example of what process

Answer 15

Negative Feedback

Question 16

why is temperature regulation necessary?

Answer 16

For optimal enzymatic and chemical reactions

Question 17

Excessive heat (what is the temp and results)

Answer 17

43C/109F-Fatal as rate if reaction slows, cardiovascular collapse and CNS effects… Cells will die via apoptosis and denaturation of proteins

Question 18

Excessive cold (what is the temp and results)

Answer 18

25 C/77F… Fatal as rate of rxn slows, cardiovascular collapse and CNS effects

Question 19

Define the bodies core and the temperature it should be at

Answer 19

brain, thoracic/abdominal cavities should be around 37C

Question 20

Define Fever and what happens regarding temp changes

Answer 20

increase in set point, when body temp goes below that you shiver

Question 21

In fever, infection, trauma will cause what (stimulates what and what is the result)

Answer 21

macrophages–> increase in pyrogens (ex:IL-1) –> increase in prostaglandins (PGE2) in hypothalamus –>
increase set point

Question 22

Why do inhibitory drugs work for fever reduction

Answer 22

they block prostaglandins

Question 23

Hyperexia is defined as what

Answer 23

Fever which is > 41.5C

*HE did say would not ask temps on hypothermia.. so not sure

Question 24

Hypothermia defined as (what temp is fatal?)

Answer 24

less than 25C is fatal

Question 25

What are the effects of hypothermia (2)

Answer 25

CNS effects: apathy, confusion, unconsciousness

Cardiac arrhythmias can be fatal

Question 26

Progression of heat exhaustion

Answer 26

profuse sweating –> fluid loss –> decrease blood volume –> decreased blood pressure –> faintaing

Question 27

Is heat exhaustion life threatening

Answer 27

No- but needs to be treated

Question 28

Signs/Symptoms of heat exhaustion:

Answer 28

cramps, nauseated, headache

Question 29

Can skeletal muscle produce heat?

Answer 29

yes, via shivering and nermogenesis??? Moving skeletal muscle is not efficient so it produces heat (less than 50% efficient)

Question 30

Heat stroke progression

Answer 30

GI Vasoconstriction –> ischemia –> endotoxins from intestines released into blood which will change the set point so high that body does not know to sweat

Question 31

Why is drinking alcohol when cold bad?

Answer 31

Increases vasodilation of skin allowing heat to be lost

Question 32

Is heat stroke life threatening?

Answer 32

Yes-mechanism unknown

Question 33

Signs of heat stroke

Answer 33

increased body temp, no sweating, delirium, coma, seizure

Question 34

Peripheral thermorecetors (what and location)

Answer 34

on the skin to monitor shell temp and to tell the temp of the environment

Question 35

Where are central core receptors found

Answer 35

in the hypothalamus and abdominal cavity

Question 36

Brown adipose tissue

Answer 36

Brown fat common in babies, found in some adults, more dense and good at generating heat-has lots of mitochondria in it

Question 37

The integrating center of the control center is located where and how does it work

Answer 37

hypothalamus: it compares ambient temp to core to maintain set point

Question 38

Proteins in brown adipose important for heat production

Answer 38

Uncoupling Proteins (UPC) which allows protons to flow down their gradient (against proton gradient) without producing energy and therefore produces lots of heat rather than energy

Question 39

Effectors of the control system include what… (3)

Answer 39

Vascular smooth m.

Sweat glands

Skeletal muscle

Question 40

When you have vasodilation you do what

Answer 40

release heat to environment to cool down-NOT when temp is too hot of course

Question 41

most important method of heat dissipation

Answer 41

sweating

Question 42

Vascular smooth muscle as an effector (where and what)

Answer 42

in arterioles

Can dilate or contract to direct blood flow to skin

Question 43

Sweat glands as an effector (where and what)

Answer 43

dissipate heat

Question 44

what a fever does to bodies set point

Answer 44

increases it-this is why you can feel cold even with a 100 degree F

Question 45

Pyrogen

Answer 45

Fever causing hormone or agent

Question 46

Sweat glands as an effector (where and what)

Answer 46

dissipate heat through evaporative loss-secrete sweat –> cooling effect

Question 47

Skeletal muscle as an effector

Answer 47

shiver-works to regain heat

Metabolic uncoupling-burns energy (not making ATP, just dissipating energy as heat in mitochondria)

Question 48

Why adults with brown fat may be skinnier

Answer 48

this fat does not store fat well

Question 49

How you can die with heat stroke

Answer 49

When dehydrated you stop sweating and cannot regulate body temp-GI tract when heated up the bacterial pyrogens can circulate (this is just a theory)

Question 50

Blood flow when cold?

Answer 50

decreased blood flow to skin

Question 51

Nervous system activity in cold and what the result of this is

Answer 51

increased sympathetic NS activity –> skin vasoconstriction –> decreased blood flow –> decreased heat loss

Question 52

How shivering is activated

Answer 52

The hypothalamus stimulates rythmic motor neuron activation which causes skeletal muscle contraction to generate heat

Question 53

Response to cold

Answer 53

Behavioral adjustment: drink warm drinks, put on sweater ii. Decreased blood flow to skin: increase sympathetic NS activity à skin
vasoconstriction à decreased blood flow à decreased heat loss iii. Shivering: hypothalamus à rhythmic motor neuron activation à
skeletal muscle contraction to generate heat iv. Increase metabolic rate: increase epinephrine and thyroid hormone
release OR increase fat breakdown OR brown fat
1. Controlled by adrenal gland, increases metabolic uncoupling