HOMEOSTASIS Flashcards
What is homeostasis?
Maintenance of a constant internal environment and is the control of internal conditions within set limits achieved by negative feedback
Give examples of internal conditions
Temperature
blood pressure
water concentration
glucose concentration
When does negative feedback happen?
When conditions change from the ideal point and returns conditions to this set point
What are negative feedback mechanisms usually?
A continuous cycle of bringing levels down and then bringing them back up so that overall they stay withing a narrow range of what is considered normal
What is the ideal body temperature for enzymes?
37 C
What is hyperthermia?
When heat gain exceeds heat loss and the temperature rises
What is hypothermia?
When heat loss exceeds heat gain and the temperature falls.
Where is regulation controlled?
In the hypothalamus which contains receptors sensitive to the temperature of the blood.
Where are there temperature receptors?
The skin and sends impulses via sensory neurones
What is the top layer of the skin called?
Epidermis
What is the lower layer of the skin called?
Dermis
What is the dermis made of?
Connective tissue
What does the connective tissue contain?
Elastic fibres and collagen fibres
What happens as a person gets older?
Fibers lose their elasticity so the skin becomes loose and wrinkled
What does the dermis contain?
Sweat glands
What do the sweat glands do?
They secrete a liquid called sweat which is mostly water with small amounts of salts and urea dissolved in it
How does sweat travel?
It travels up the sweat ducts and onto the surface of the skin through the sweat pores
What happens when it is too warm?
Hair erector muscle relaxes lowering the hair
a thin insulating layer of air is trapped above the skin
more heat is lost to the environment by evaporation convection and radiation
What happens when it is too cold?
The hair erector muscle contracts raising the hair
the hairs trap a thicker layer of air above the skin
The air insulates the skin
What is underneath the dermis?
A layer of fat called adipose tissue
What does the adipose tissue do?
Helps insulate the body against heat loss and acts as an energy reserve
What is shivering?
When muscles in some parts of the body contract and relax very quickly
How does shivering help?
Heat is generated in the muscles and warms the blood as it flows through them
What does the dermis contain?
Blood vessels and nerve endings
What do the nerve endings do?
They are sensitive to touch, pain, pressure and temperature
What happens to our arterioles when we are cold?
They become narrower
What is it called when our arterioles contract?
Vasoconstriction
How does Vasoconstriction help?
Reduces the amount of heat loss from blood by radiation as less blood flows through the surface of the skin
What happens when our arterioles when we are hot?
They dilate
What is it called when our arterioles dilate?
Vasodilation
How does Vasodilation help?
there is more blood and bc there is a lot of blood near the surface of the skin heat is readily lost from the blood into the air by radiation.
What is an effector?
An effector is a part of the body that creates a response such as muscles
What happens when the body temperature raises?
Temperature receptors in the skin detect an increase
Nervous impulse sent to the hypothalamus and it coordinates a response
sweat is released and blood vessels dilate
What is produced when blood glucose rises?
Insulin
What happens when blood glucose rises?
Insulin produced
stimulates the liver
muscle cells to convert excess glucose into glycogen
How are blood glucose levels controlled?
Negative feedback mechanism involving glucagon and insulin
Where are insulin and glucagon produced?
Pancreas
Why do cells need glucose?
To respire to release energy
Why is too much glucose not good for cells?
water moves out of the cells and into the blood by osmosis
What is type 1 diabetes?
A condition where the blood glucose levels are not able to be regulated as the insulin secreting cells in the pancreas are not able to produce insulin
What happens if you have Type 1 diabetes?
the blood glucose levels are too high
How can you treat type 1 diabetes?
Injecting insulin
What can having high or low blood glucose concentrations cause?
Damage to numerous body organs
What is hyperglycaemia?
When the blood glucose concentration goes up and stays up
What is hypoglycaemia?
When the blood glucose drops very low
What can hypoglycaemia cause a person to feel?
very tires
confusion
irrational behaviour
How can people monitor type 1 diabetes?
Levels of physical activity
their diet affects the amount of insulin needed
