SKIN
XYZ
STRUCTURE OF SKIN
sensory
receptor
Photomicrograph of skin
Functions of skin
Provides protection against pathogens.
Prevents the body from drying up.
Excreatory organ (e.g. sweat)
Sense organ (e.g pressure, temprature)
Thermoregulation
Negative feedback response
A mechanism that detects a move away from the set point, and
brings about actions that take the value back towards the set point.
Homeostasis
Maintaining blood glucose level
Homeostasis
The maintenance of a constant internal environment.
conditions inside the body
e.g. blood plasma
Temprature
High temp = denatured enzymes
Low temp = Inactive enzymes
Glucose
Water
High water potential = cells burst
Low water potential = cell shrink
pH level
Over-Cooling
Hair
Hair erector
muscle will cotract
and hair will
‘stand’.
Sweat gland
Arterioles
Sweat glands will
Shivering
Vasoconstriction
Muscles in the
wil cause the
body will
arterioles to
involentarily
stop producing
sweat.
constrict which will
reduce blood flow.
this will reduce the
loss of heat.
contact which will
produce heat.
Over-Heating
Hair
Sweat gland
Arterioles
Breathing rate
Hair erector
Sweat glands will
vasodilation will take
Breathing rate will
muscle will relax
start producing
place which will increase
increase which will lead
and hair will lie flat.
sweat, which will
the blood flow through
to more evaporation
evaporate and
arterioles. this will allow
from the moist surface
create a cooling
heat to escape.
of alvioli.
effect.
Controlling the blood glucose level
Vitamins
vitamins are organic molecules that are only required in minute amounts. They
do not provide energy.
Vitamin C
help in the absorbtion of iron
makes stretchy protiens
(collagen)
pervents Scurvy
Vitamin D
Helps in the absorbtion of
calcium and phosphorus.
Helps in the deposition of
calcium and phosphorus in
bones and teeth.
prevents Rickets
Diseases caused by vitamin deficienties
Scurvy
Rickets
symptoms: Pain in joints
Swollen gums
poor wound healing
Bleeding gums
Symptoms: soft bones
bowed legs
knocked knees
Sources of vitamin C
Sources of vitamin D
DNA
DNA is a molecule that carries the genetic code which instructs the cell about which
amino acids to link together.
Nucleotide
Phosphate group
Sugar
Nitrogen containing base
Complimentry base pairing
The two chains of nucleotides are held together by bonds that
form between the bases of opposite strands.
A bonds with T
C bond with G