Homeostatic Mechanisms Flashcards
Definition of homeostatic mechanisms
The process of maintaining a constant internal environment despite external changes.
Why is homeostatic mechanism important
it is essential for optimal functioning of cells and organs
What is the internal environment
this includes blood, tissue, fluid, body cell contents and metabolic processes
What variables are regulated by homeostatic mechanism
temperature
pH levels
blood glucose concentration
fluid balance
What is negative feedback
a regulatory mechanism where a change in a variable results in a response that counteracts the initial change
Key components of negative feedback
receptors - detect the change in the internal environment
control centre - processes info and directs the response to right place
Effectors - muscles or glands that carry out the response to restore balance
EXAMPLE - regulation of blood glucose levels
What is the hypothalmus
A region in the brain that acts as the body;s thermostat
It regulates temperature, hunger, thirst and other autonomic functions
It processes signals from receptors and activates effectors via the autonomic nervous system
What is the skins role in negative feedback
acts as a barrier and regulatory organ
contains sweat glands, blood vessels and hair follicles
What is the skins function is thermoregulation
sweating - evaporation cools the body
vasodilation - widening of blood vessels to increase heat loss
vasoconstriction - narrowing of blood vessels reduces heat loss
hair erection - traps air for insulation (goosebumps)
Name 4 types of heat loss
Conduction - transfer of heat to objects in direct contact
Convection - transfer of heat to surrounding air or water
Radiation - emission of heat to cooler surroundings
Evaporation - heat loss through the conversion of sweat to vapour
Name 2 types of heat production
metabolic processes - chemical reactions in the cells produce heat. The liver is a major source due to its metabolic activity
muscle activity - shivering generates heat through muscle contractions. Exercise increases heat productions
What are implications of surface area to volume ratio
Smaller bodies have a larger surface area to volume (e.g. small children) - they lose heat more quickly and are at greater risk of hypothermia
Larger bodies retain heat more efficiently but can be at risk of overheating
What is hypothermia
Where body temperature falls below 35 degrees
Causes are: prolonged exposure to cold, inability to generate heat
Symptoms: shivering, confusion, drowsiness, low pulse rate
It can progress and lead to a coma or death in serious cases
During hypothermia the brain slows down so the person might not feel cold or be able to act to protect themselves
What is HYPERthermia
Where body temperature rises above normal
Causes are: high external temperatures, inability to lose heat
Symptoms: sweating, rapid heart rate, dehydration
What is water balance
Input must roughly equal output to maintain homeostatis
What is dehydration
it occurs when fluid loss exceeds intake
Symptoms include thirst, dry mouth, decreased urine output
Severe cases can be life threatening and require prompt fluid replacement
What is the role of the pancreas
Produce insulin and glucagon
What do insulin and glucagon do?
Insulin lowers blood glucose by promoting uptake into cells and storage as glycogen in the liver and muscles
Glucagon raises blood sugar by stimulating glycogen breakdown in the liver
How do insulin and glucagon relate to negative feedback?
They work antagonistically to maintain glucose levels within a narrow range
What pre-existing conditions can impact older people getting HYPOthermia
Hypothyroidism - slowed metabolssm in older people
Dementia - impaired cognitive function
Arthritis - reduced mobility
What can causes & symptoms of dehydration?
CAUSES:
Environmental conditions (hot weather)
Fever, excessive vomiting / diarrhoea
Increased urine production (e.g. diabetes)
Excessive sweating (loss of salts and water)
SYMPTOMS:
Thirst
Dry lips and mouth
Small amounts of dark urine
In severe cases, drowsiness, coma and death can occur
How do you treat dehydration?
Rehydrate with oral or I-V fluids
In hot climates, salts may also need to be replenished
