Transcript Main processes of mammalian nutrition

Main processes of mammalian
nutrition
Ingestion
Digestion
Absorption
Assimilation
Egestion
Next
Back
Digestion
Absorption
Egestion
Main processes of mammalian
nutrition
Ingestion
Digestion
Absorption
Assimilation
Egestion
Next
Back
Digestion
Absorption
Egestion
Ingestion
is the intake of food into the alimentary canal
relevant organs:
teeth
relevant processes:
swallowing
peristalsis
Next
Back
Ingestion II
is the intake of food into the alimentary canal
relevant organs:
teeth
premolar
incisor
canine
molar
relevant processes:
swallowing
peristalsis
Next
Back
Digestion
is the breaking down of food into molecules
small enough to be absorbed into the body
relevant organs
mouth and teeth
alimentary canal
stomach
duodenum
Next
Back
Absorption
is the movement of digested, soluble and
simple molecules from the gut through the
wall into the body (Cont’d)
relevant processes
diffusion
active transport
relevant structures
Next
Back
Assimilation
is the uptake & utilisation of absorbed food
molecules by all body cells
fate of the absorbed food
glucose energy production
amino acids building up body materials
fats energy reserve
roles of liver in assimilation
Next
Back
Egestion
is the removal of undigested and unwanted
food materials from the alimentary canal
relevant structures
abnormal cases:
diarrhoea
constipation
Next
Back
Egestion II
is the removal of undigested and unwanted
food materials from the alimentary canal
relevant structures
abnormal cases:
diarrhoea
constipation
Next
Back
Teeth
structure of a tooth
enamel
dentine
pulp cavity
Enamel
Crown
Dentine
Neck
Pulp Cavity
Root
Cement
type
dentition
Next
Back
Jaw Bone
Nerve &
blood vessel
Teeth II
structure of a tooth
enamel
dentine
pulp cavity
Enamel
Crown
Dentine
Neck
Pulp Cavity
Root
Cement
type
dentition
Next
Back
Jaw Bone
Nerve &
blood vessel
Enamel
outermost
non-living
hardest layer
made up of
calcium phosphate
calcium fluoride
organic matter
Next
Back
Dentine
middle layer
hard, bone like
(softer than enamel)
Next
Back
Pulp Cavity
innermost layer
living cells, blood vessels and nerve
blood vessels: oxygen and nutrient
nerves: sensitive to stimuli
temperature
pressure
Next
Back
Type of Teeth
Type
Incisor
Canine
Premolar
Molar
Next
Features
 chisel shape
 sharp edge
 sharp & pointed
edge
 large
 board tops with
ridges
 large
Back
Functions
 biting
 cutting
 biting
 cutting
 chewing
 crushing
 grinding
Dentition
dental formula of a human
type of teeth
premolar
incisor
canine
molar
on one side only
upper jaw
lower jaw
milk teeth: 2120
permanent teeth: 2123
20
2120
Next
Back
32
2123
Tooth Decay
caused by the chemical actions of bacteria in
plaque
plaque is a sticky, invisible film on the teeth
surface
bacteria turns sugars into acids
acids dissolve the enamel and dentine
Next
Back
Tooth Decay
caused by the chemical actions of bacteria in
plaque
plaque is a sticky, invisible film on the teeth
surface
bacteria turns sugars into acids
acids dissolve the enamel and dentine
irritation on the nerve, cause toothache
Next
Back
How to prevent tooth decay
good brushing habits
using appropriate cleaning materials
avoiding sugary food
having a balanced diet
having regular dental check-up
Next
Back
Alimentary Canal
a tube from mouth to anus
is modified into different structures
digestive system =
alimentary canal
canal
alimentary
+ associated
associated glands
Next
Back
Alimentary Canal
a tube from mouth to anus
is modified into different structures
digestive system =
alimentary canal
canal
alimentary
+ associated
glands
associated
glands
sequence of the structures
oesophagus
duodenum
appendix
stomach
caecum
rectum
ileum
colon
anus
Next
Back
Intestinal
Pancreas
Salivary
Gastric
Liver
gland
Swallowing
tongue raises pushing the bolus to the back
bolus pushes the soft palate upwards
epiglottis lowers and covers the trachea
bolus enters the oesophagus
Next
Back
Peristalsis
food is moved along the canal by
rhythmic contraction and
relaxation of two muscles
circular muscle
longitudinal muscle
demonstration
Next
Back
Peristalsis
Oesophagus
Digestion II
only small molecules can pass through the
wall of intestine
food are usually composed of large molecules
food should be digested before absorption
physical methods
chemical methods
Next
Back
Physical Digestion
Teeth
Stomach
Bile salt
Next
by churning
by emulsifying
action in duodenum
 by grinding
chewing
tearing
cutting
biting
Back
Chemical Digestion
involved the change of the chemical structures
of food
amylase
maltose maltose
e.g. Starch
maltose
maltose
this involves digestive enzymes
no digestion on: water, glucose, simple sugars,
minerals, vitamins
Next
Back
Mouth
saliva is a digestive juice consisting of
amylase
mucus
water
it is slightly alkaline
Next
Back
Stomach
cardiac sphincter
action of proteases
protease
action of hydrochloric acid
provide acidic medium for
proteases
pyloric sphincter
Next
Back
Duodenum
pancreatic juice
amylase, proteases, lipases
bile
colour, composition, no enzymatic property
intestinal juice
carbohydrases, proteases
Next
Back
Caecum,Colon & Rectum
no enzyme secretion in omnivores and
carnivores
specific function in herbivores
micro-organisms
cellulase
weakness
Next
Back
Absorption II
take place in ileum
starts at stomach / duodenum
villus
Next
Back
Villus
finger like projections
increase S.A./V
one cell thick
many blood vessels
central lacteal
Next
Back
villus
Blood vessels
lacteal
epithelium
Transport of absorbed food
Water
Fat soluble
solublefood
food
lumen
lumen
epithelium
epithelium blood capillaries
lacteal
hepatic vein
liver
vena cava
hepatic portal
veinvessel
Lymph
vena
cava
heart (general circulation)
heart
(general circulation)
Next
Back
Assimilation II
fate of absorbed food substances
glucose
amino acids
fats
roles of liver
Next
Back
Fate of glucose
for releasing energy
excess glucose will be stored as
glycogen
fats
storage site
liver
muscle
Next
Back
Fate of amino acids
for making new cells and tissues
excess amino acids will be deaminated
product: urea
site of excretion:
kidney
Next
Back
Fate of fats
for formation of cell membranes
excess fats will be stored
fats
storage site
adipose tissue
Next
Back
Roles of liver
regulating blood glucose level
storing glycogen
storing iron and vitamins
breaking down excess amino acids
Next
Back
Diarrhoea
Causes:
(1) bacterial infection
(2) eating poisonous substances
Consequences:
(1) quick movement of intestine
(2) food passes along the canal quickly
(3) less water absorbed
(4) watery faeces produced
Next
Back
Constipation
Causes:
eating too less dietary fibres
eating too less fresh fruit
Consequences:
(1) slow movement of intestine
(2) food passes along the canal slowly
(3) much water absorbed
(4) hard, dried faeces produced
Next
Back
End of the Chapter
By Nicholas Lai
(PLKWCC)
Glossary
 Active transport: movement of molecules against
concentration gradient with the utilizing of energy.
 Amylase: an enzyme that convert starch to maltose.
 Carbohydrases: enzymes digest carbohydrates into simpler
molecules.
 Carnivores: organisms feed on animals only
 Diffusion: movement of molecules from a region of high
concentration to a region of low concentration
 Herbivores: organisms feed on plants only
 Lipases: enzymes digest fat/oil into simpler molecules
Glossary
 Mucus: a sticky substance secreted by epithelial cells of the
gut
 Omnivores: organisms feed on animals and plants
 Proteases: enzymes digest protein into simpler molecules