UNIT 14: HOMEOSTASIS
Homeostasis: the maintenance of a constant internal environment (within set
limits)
Cells: change composition of blood as they remove nutrients and O2 and add
wastes and CO2
Heart: keeps blood pressure constant to deliver oxygen and nutrients around
body
Skin: to maintain heat exchange with external environment
Kidneys: regulate water and salt levels and the removal of wastes like urea
Lungs: regulate gas exchange
Intestines: supply soluble nutrients and water to blood.
Liver: regulates blood solutes and removes toxins
Importance of homeostasis
Enzymes do not denature
Maintain constant rate of metabolism and sperm production
Avoid to damage protein, heatstroke/hyperthermia/dehydration…
The skin
Epidermal cells made in the layer of
cells at the base of it, are always
dividing by mitosis
New cells move towards surface,
die, fill up keratin
Conified layer (dead cells): hard
and waterproof to protects the
softer, living cells underneath.
Always being worn away and
replaced by cells underneath
Epidermal cells contain melanin - absorbs the harmful ultraviolet rays in
sunlight, which damage living cells in deep layer of skin
The dermis
Made of connective tissues contains elastic and collagen fibres. Fibres lose
their elasticity as the person gets older so the skin becomes loose and wrinkled
Contains sweat glands that secrete sweat, travels up the sweat ducts and
out onto the surface of the skin through sweat pores which help with
temperature regulation
Contains blood vessels and nerves endings, sensitive to touch, pain, pressure,
temperature to keep you aware of change in the environment
Adipose tissue - large drops oil to insulate body against heat loss and acts as
an energy reserve
The hypothalamus
Homeostasis: the maintenance of a constant internal environment (within set
limits)
Cells: change composition of blood as they remove nutrients and O2 and add
wastes and CO2
Heart: keeps blood pressure constant to deliver oxygen and nutrients around
body
Skin: to maintain heat exchange with external environment
Kidneys: regulate water and salt levels and the removal of wastes like urea
Lungs: regulate gas exchange
Intestines: supply soluble nutrients and water to blood.
Liver: regulates blood solutes and removes toxins
Importance of homeostasis
Enzymes do not denature
Maintain constant rate of metabolism and sperm production
Avoid to damage protein, heatstroke/hyperthermia/dehydration…
The skin
Epidermal cells made in the layer of
cells at the base of it, are always
dividing by mitosis
New cells move towards surface,
die, fill up keratin
Conified layer (dead cells): hard
and waterproof to protects the
softer, living cells underneath.
Always being worn away and
replaced by cells underneath
Epidermal cells contain melanin - absorbs the harmful ultraviolet rays in
sunlight, which damage living cells in deep layer of skin
The dermis
Made of connective tissues contains elastic and collagen fibres. Fibres lose
their elasticity as the person gets older so the skin becomes loose and wrinkled
Contains sweat glands that secrete sweat, travels up the sweat ducts and
out onto the surface of the skin through sweat pores which help with
temperature regulation
Contains blood vessels and nerves endings, sensitive to touch, pain, pressure,
temperature to keep you aware of change in the environment
Adipose tissue - large drops oil to insulate body against heat loss and acts as
an energy reserve
The hypothalamus
