Applied Exe Physiology Moda Exam 2

What is temperature homeostasis?

A balance in heat gain and heat loss

What is the normal homeostatic temperature in Celsius?

37

How does our body maintain heat balance?

Continuous metabolic heat production countered by continuous small heat loss

What senses when body is too cold or too hot?

Hypothalamus

How temperature regulation happens in steps

Thermal receptors

Preoptic area

DMH

Homeostatic response

Thermal Receptors

5 receptors that detects temperature higher/lower than 37 degrees Celsius and then sends that info to the PREOPTIC AREA

Preoptic area

Inhibits the DMH from activating homeostatic responses to being cold.

What happens when cold

Preoptic area lets off the “brake” and allows the DMH to cause vasoconstriction, nonshivering thermogenesis, shivering

What happens when hot?

The Preoptic area presses down on break HARD and inhibits the DMH fully.

DMH

What causes cold homeostatic responses

What area of brain is responsible for CONSCIOUS awareness that we are hot or cold?

Cerebral Cortex

Hormones released when cold?

Catecholamines and Thyroxin

What does the catecholamines do in response to drop in blood temp?

Conserve heat through vasoconstriction and produce heat by increase metabolic activity

What does thyroxin do in response to drop in blood temp?

Increases metabolic rate (BMR)

What hormones are released when increase in blood temp?

ACh

What does ACh do when hot?

Dilate vessels, and dilates skin pores, leading to sweating

What are the 5 thermal receptors?

Skin

Peritoneal abdominal cavity

Spinal cord

Hypothalamus

Brain Stem

Which are the peripheral receptors?

Skin

Peritoneal abdominal cavity

Which are the central receptors?

Hypothalamus

Brain stem

Spinal cord

Which receptors detect heat?

ALL OF THEM

Which receptors detect cold? SPS

SKIN

PERITONEAL ABDOMINAL CAVITY

SPINAL CORD

4 processes of heat loss

Conduction

Convection

Radiation

Evaporation

Conduction

gradient between skin and physical object HIGH TO LOW FLOW

Convection

depends on current, gradient between skin and air

Radiation

radiate heat, gradient HIGH TO LOW

Evaporation

gradient between skin and humidity

Processes of heat loss during exercise?

25% evaporation

Lower temperature = higher what?

HIGHER GRADIENT

Higher temperature = lower what?

LOWER GRADIENT

1 lb = how many oz of H2O

16 oz

How to calculate amount of fluid consumed after exercise

(Preweight + fluid intake) - post weight

What can alter cardiac output during exercise?

Cardiovascular dysfunction

Heat can cause serotonin increase which can then do what?

Cause CNS dysfunction (lethargy) and impair the exercise performance

Cardiovascular dysfunction can cause what too?

Accelerated muscle fatigue (glycolysis pathway) which then increases CNS dysfunction and impairs exercise performance

Central and peripheral fatigue occurs

SIMULTANEOUSLY

Muscle contraction and accumulation of metabolites (H+) does what to autonomic and sensorimotor system?

INCREASE FIRING OF GROUP 3 AND 4 AFFERENTS

Cardiovascular drift

Gradual DECREASE in stroke volume (dehydration and reduced plasma volume)

Gradual INCREASE in HR (compensates for the dec in SV)

HR increases 3-5 beats per minute of every ____% loss of body mass

1

Decreased aerobic performance

Decreased Plasma Volume

Decreased SV

Decreased CO

Increased HR

Acclimation

SHORT TERM adjustments produced by exposure to environmental stresses for days to weeks

Acclimatization

LONG TERM adjustments in response to exposure for months to years to natural environment

Capacity to sweat increases with cardiovascular system

expanded plasma volume

reduced HR during exercise

improved blood flow to muscle

How body maintains electrolyte balance when exercising in heat?

Secretion of aldosterone from adrenal gland acts on kidney and the Na+ in kidney will get REABSORBED to BLOOD INSTEAD OF EXCRETED IN URINE

Heat acclimation bodily changes

Capacity to sweat increases (expanded plasma volume, reduced HR during exercise, improved blood flow to muscle)

Heat loss improves (higher sweat rate, faster onset of sweating at lower temps)

Conservation of electrolytes (loss of sodium from urine and sweat decrease due to aldosterone release)

ALL ADAPTATION TAKE ___ DAYS

14

Adaptation lost after ___ days no heat exposure

28

If heat acclimation what happens to heat loss during exercise?

GREATER HEAT LOSS

ACh

dilation

Norepinephrine

Constriction

In response to cold what happens to the peripheral vasoconstriction of cutaneous vessels?

REDUCES SKIN BLOOD FLOW THERE TO PROTECT INTERNAL ORGANS

Primary fuel for shivering?

Fats

Epinephrine causes what for shivering?

Breakdown of fuel sources to use for shivering

During cold there is reduced neural transmission

reduction in nerve conduction velocity/ rate neural impulses travel to muscle fibers

Exercise in cold water causes ___ heat loss

GREATER

Exercise in cold air _____ decreases muscular force production

RARELY

Nonshivering thermogenesis caused by what?

Thyroxine

Which of the following is a thermal receptor sensitive to a rise in temperature, but not a decrease in temperature?

Hypothalamus

Thermoreceptors sending information to the preoptic area that core temperature is rising will cause...

increased preoptic area activity

Order the events that occur when core body temperature decreases below its homeostatic setpoint.

Thermal receptors stimulated

Dec in preoptic area activity

Inc in DMH activity

Shivering

T/F The area in the brain that is responsible for temperature regulation in humans is the thalamus.

FALSE its the hypothalamus

Thermoreceptors are located in the brain, they can be found in the hypothalamus and in the __________.

BRAIN STEM

Giving an athlete fluid to drink as they exercise outdoors in the heat promotes heat loss through what mechanism?

Evaporation

With profuse sweating during exercise there is a decrease in _____ that requires ____ to increase in order to maintain blood flow sent out to the body

STROKE VOLUME

HR

In order to lose heat through convection, the ____ must be warmer than the _____

skin

air

If the room temperature remains constant during exercise, but the intensity of exercise increases every minute during exercise then our reliance on convection will ......

Decrease more about evaporation

Part of brain aware of the warm or cold blood temp and can have voluntary response

Cerebral cortex

What part of blood contains water?

Plasma

Partial pressure of oxygen at sea level?

159 mmHg or 20% of atmospheric pressure

Atmospheric pressure at sea level?

760 mmHg

What kind of relationship does barometric pressure and altitude have?

INVERSE RELATIONSHIP

Lower PO2 results in ____ aerobic performance

POOR

dependent on oxygen delivery to muscle

What in the FICK equation is affected by altitude?

LITTLE A!!!! VO2 = CO x [(a - v) O2 diff/100]

Increased altitude causes decrease in VO2 max due to

LOWER O2 EXTRACTION

Less atmospheric PO2 —> Less alveolar PO2 —> _____

Less arterial PO2

Whats in the lungs determines what is in the _____

arteries

Larger gradients = better

TRANSFER

AT EXTREME ELEVATIONS fall in VO2 max is partially due to fall in maximum _____

Cardiac output

• dec max HR at altitude to slow HR due to less oxygen available for heart to use to contract, PROTECTS HEART FROM BECOMING ISCHEMIC

There are fewer oxygen molecules per liter in the air while exercising in high altitude so to consume same amount of oxygen we need to do what?

MORE BREATHS TO COMPENSATE

Declines for performance are thought to be around

400 meters or 1300 feet above sea level

What can be fatigued at higher altitude?

Diaphragm

Integrative system

Chemoreceptors would be triggered by elevated H+ production to stim the respiratory center to INC ventilation

What is the Bicarbonate pathway for buffering?

H+ + HCO3 —> H2CO3 —> H2O + CO2

HIF

hypoxia inducible factor (activates genes associated with EPO)

Less oxygen environment = ___ HIF factors in blood = ___ EPO = activates __ ___ ___ = ____ blood oxygen

more

more

red bone marrow

increase

Longer in less oxygen environment =

better HIF factors and EPO

Short term (3-6 weeks) in low oxygen environment increases

pulmonary ventilation

releases of EPO for RBC production

Hb and HCt

Plasma volume

Long term (less than 3 months) increase

STRUCTURAL

Mitochondrial and capillary density

Pulmonary diffusing capacity

Mitochondrial enzymes

Respiratory chain enzymes

Maximal cardiac output

LIVE ____ TRAIN ___

HIGH (benefits from living in hypoxia)

LOW (better quality workout)

When does little v gain adaptations from high altitudes?

3 month mark due to more mitochondria

More Co2 you push out to the alveoli the more ______ gradient is made

pressure

Hyperventilation you turn H+ into H2O and increase ___

PH (basic/alkaline)

More basic the PH lets you store more ______ in the blood

oxygen

Particulate matter

consist of solid particles or liquid droplets

small particles enter the circulation

promotes inflammation and oxidative stress

Carbon monoxide

Binds to hemoglobin instead of oxygen

What can I do to help prevent air pollution for myself

REDUCE EXPOSURE TIME

Peak force production during a fast contractions could be impaired in the cold if there is a reduction in nerve conduction velocity

Atmospheric pressure _____ as a person travels higher above sea level

decreases

Thyroxine

elevates metabolism

Norepinephrine

cutaneous constriction

Aldosterone

reabsorption of Na into blood