Unit 3: Chapter 7 - Homeostasis Of Body Temperature And Body Fluids Flashcards
Thermoregulation
The act of endotherms maintaining balance between heat gain and heat loss (otherwise know as heat exchange)
Occurs by controlling heat exchange and metabolic activity
36.8°C
>42°C and <33°C is dangerous
45°C and <32°C is death
Important to maintain cellular reactions, nerve function and protein structure
Metabolic activity (metabolism)
The cellular reactions that help to maintain this high internal temperature
Metabolic rate
X
Thermoreceptors
(Peripheral) and (central)
Provide the hypothalamus, the body’s temperature-regulating centre, with temperature info via the nervous system
Hypothalamus sends out nerve impulses that control activities to either increase or decrease body temp
This works in a negative feedback loop via the autonomic nervous system
Vasoconstriction
Decrease in diameter of blood vessels by sympathetic nerves
Prevents blood flow to skin, stopping heat loss from the skin by conduction, convection, radiation and
Vasodilation
Increase in diameter of blood vessels by sympathetic nerves
Increases blood flow to skin, increasing heat loss by conduction, convection, radiation and evaporation as the surface temperature rises
Metabolism
Energy being released (during cellular respiration) from bonds that hold carbohydrate, protein and lipid molecules together
Most energy is being released as heat
Most heat is produced by thoracic and abdominal organs, the brain (16%) and skeletal muscle (16%) at rest.
During exercise and stress 40x more heat is produced
Shivering
The hypothalamus sends stimuli to the cerebral cortex which initiates oscillating rhythmic muscle tremors (10-20/sec) in the skeletal muscles. Therefore increases heat production.
Sweating
Active secretion of fluid (water, with some salts and other excreted nutrients) by the sweat glands by sympathetic nerves
Heat is removed from skin when liquid sweat changes to vapour (evaporates).
Only effective in DRY environments
Hyperthermia
Occurs when temperature and humidity are too high, resulting in a lack of heat loss. This increases body temp, and regulatory mechanisms lease.
Heat stroke is fatal if brain cells are effected, and can lead to organ failure in other parts of the body
What are the Causes?
Environment (humid)
Fever
Treatment:
Submerge in cool or ice water
Use evaporation methods
Wrap in cooling blanket and apply ice to neck Briton back and armpits
Provide medications to stop shivering
Heat exhaustion
Results from extreme sweating, which reduces water in blood plasma
Results from vasodilation, which reduces resistance to blood flow
Body temp. Is almost normal, but blood pressure reduces and output from the heart decreases, causing collapse and unconsciousness
Treatment:
Rest in a cool pace with legs higher than heart
Drink cool fluids (water or sports drinks)
Have a cool shower or bath
Wear loose clothing
Hypothermia
Occurs when the core body temp drops <33°C. The metabolic rate is so low that heat produced can’t replace heat lost, so it continues to fall
The heart, nervous system, and other organs will stop working normally and eventually fail, causing death
Treatment:
Cover heads and hands in the cold
Avoid overexertion and sweating - stay dry
Wear tightly woven clothing.
Body fluids
Humans are on average 60% water (makes 65%, females 55%)
Intracellular fluid
Inside the cytosol of cells (2/3 of all body water)
Extracellular fluid
X
