Homeostasis Flashcards
1
Q
Define homeostasis
A
Homeostasis is the maintenance of a constant internal environment within tolerable limits
2
Q
Why is there a need for homeostasis in body systems
A
- Achieve a certain degree of independence from external environment
- Internal environment is maintained in optimal condition and a state of maximum efficiency
- Important for optimal functioning of physiological processes
3
Q
What internal environments in mammals are regulated by homeostasis
A
- Body temperature
- pH level of body fluids
- Chemical constituents in blood
- Water potential of blood
3
Q
What must be present for homeostatic control to occur
A
- Norm to be maintained
- Stimulus
- Receptor
- Control centre
- Corrective mechanism
- Negative feedback
4
Q
In a cross-section of skin, what is the thing in a knot
A
Sweat gland
4
Q
In a cross-section of skin, what is the root-like thing near epidermis
A
Thermoreceptor
4
Q
What happens when body temperature decreases below the norm
A
- Thermoreceptors in hypothalamus detect increase in internal body temperature
- Thermoreceptors in skin detect increase in external temperature
- Thermoreceptors send nerve impulses to hypothalamus
- Hypothalamus sends nerve impulses to various effectors to carry out corrective actions
- Arterioles vasoconstrict, allowing less blood to flow to capillaries in skin so less heat is lost by conduction, convection & radiation
- Sweat glands become less active, sweat production decreases, so less latent heat of vaporisation is lost when water in sweat evaporates
- Erector muscles contract, hair shafts become perpendicular to skin to trap air, air is an insulator so prevents heat loss
- Metabolic rate in liver increases to release more heat
- Skeletal muscles undergo spasmodic contractions to release heat
- Negative feedback sent to hypothalamus via receptors once body temperature returns to norm
4
Q
What happens when body temperature increases beyond the norm
A
- Thermoreceptors in hypothalamus detect increase in internal body temperature
- Thermoreceptors in skin detect increase in external temperature
-Thermoreceptors send nerve impulses to hypothalamus - Hypothalamus sends nerve impulses to various effectors for them to carry out corrective functions
- Arterioles vasodilate, allowing more blood to flow to capillaries near skin surface so more heat can be lost to surroundings by conduction, convection & radiation
- Sweat glands become more active, sweat production increases, water in sweat evaporates, removing more latent heat of vaporisation from body
- Erector muscles relax so hair shafts flatten, allowing air to conduct heat away from body
- Metabolic rate in liver decreases so less heat released
- Negative feedback sent to hypothalamus via the receptors to prevent further corrective action once body temperature is back to normal
