BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 2

BIOLOGY FORM 4
CHAPTER 6
NUTRITION
(6.4 – 6.8)
PART 2

Objectives
You will learn to:
• Define and explain the importance of physical and chemical digestion.
• Identify the main part of the human digestive system (mouth, salivary
glands, oesophagus, stomach, small intestine, liver, gall bladder,
pancreas, large intestine, rectum and anus).
• Describe the functions of the mouth, salivary glands, oesophagus and
stomach in relation to ingestion, movement of food along the gut,
physical and chemical digestion.
• Describe peristalsis in terms of rhythmic wave-like contractions of the
circular and longitudinal muscles to mix and propel food along the
alimentary canal.

Digestion is the process by
which
 insoluble food, consisting of large molecules is
broken down into soluble compounds

What are starch, proteins & fats
broken down into?
enzyme
enzyme
enzyme
STARCH
PROTEIN
FAT
Glucose
Amino acids
Fatty acids &
glycerol

Why must food be digested?
Blood Blood
Blood
Food in
intestine
Food in
intestine
Food in
intestine
1
3
2
Wall of
intestine
To be small enough
to be absorbed
through the wall of
intestine.
enzyme

Digestion
starts at the
mouth and
ends at the
……………….anus

Food is broken down by two actions:
1. PHYSICAL
/MECHANICAL
2. CHEMICAL

1. PHYSICAL DIGESTION by:
 teeth
 peristalsis of the alimentary
canal
Chewing (mastication)

Why is it important to break down
food physically?
To increase the surface area for enzyme action.

Question:
Give TWO reasons why food must be masticated
before swallowed. (4)
1. Increased surface area for enzymes to act
quickly.
2. Easier to manipulate by tongue to form a
bolus.

2. CHEMICAL DIGESTION by:
 enzymes
Digestive enzymes are the chemicals that break
large insoluble food molecules into smaller soluble
molecules.

Four stages in feeding & digestion:
1. Ingestion
2. Digestion
3. Absorption into
the bloodstream
4. Egestion

Digested food is absorbed & then
assimilated by the cells
Digestive
system
Circulatory
system
Body
cell
Absorption
Assimilation

Digestive tract is also
called:
 Alimentary canal / tract
 Gut

Mucus is produced
throughout the gut:
 For lubrication
 To protect gut wall
from digestive enzymes

Fig. 1
The human
digestive
system.

The 1st stage of nutrition:
2. Digestion
1. Ingestion
3. Absorption
4. Egestion

 salivary glands produce SALIVA
(pH = 7-8)

Salivation is a reflex action which
is triggered by:
 Sight
 Smell
 Thinking
of food

 mucus
 water
 sodium hydrogen
carbonate
 salivary amylase
(ptyalin [old term])
Saliva contains:

Functions of mucus in saliva:
1. lubricates the food
2. sticks the food particles together
bolus

In swallowing, food is directed into
the gullet / oesophagus

A person cannot breathe while
swallowing. Why?
1. The soft palate closes
the nasal cavity .
2. The epiglottis closes the
trachea.

Peristalsis:
 wave-like motions of the alimentary
canal which move the food forwards
1
2
BolusDigestive tract
Wave of
contraction
Wave of
relaxation
Bolus
moves
2

Peristalsis:
Note:
Peristalsis occurs from the
Oesophagus to the rectum!

Longitudinal
muscle
Circular
muscle
Part of the gut wall

Peristalsis is possible as gut wall is
muscular
 contraction of circular & longitudinal
muscles alternate to push food

Food is pushed when:
What does the
longitudinal muscle
do at the same time?
Circular muscle
above bolus
CONTRACTS
Relaxes

Circular muscle contract,
Longitudinal muscle relax
Wall of the gut constricts –
It becomes narrower and
longer
Push the bolus forward
Circular muscle relax,
Longitudinal muscle
contact
Wall of the gut dilates – It
becomes wider and shorter
Lumen is widen for food to
enter
Mass of food
Antagonistic
action of the
muscles

1. Describe the functions of the stomach, duodenum,
pancreas, gall bladder, liver, ileum, jejunum in relation
to physical digestion, chemical digestion, absorption of
nutrients and water.
2. State the function of proteases pepsin and rennin on
proteins and list the end products of protein digestion
in the stomach.
3. List the digestive enzymes produced by the intestinal
glands and pancreas.
4. Describe the function of bile in the emulsification of
fats.
Objectives

The stomach stores
food for some time &
releases it slowly
 Food stays for 2-6 hours in the
stomach
Chyme:
creamy liquid leaving
the stomach

Food remains inside stomach due to
contraction of two sphincters
Cardiac sphincter
Oesophagus
Duodenum
Pyloric sphincter
Layers of muscle
Churning due to:
Lining of
mucus

Which sphincter is contracted?
Cardiac sphincter:
Pyloric sphincter: contracted
relaxes to let chyme
into the duodenum

Gastric glands
secrete
gastric juice

What happens to food inside the
stomach?

Gastric juice contains:
1. HYDROCHLORIC ACID
2. PEPSIN
3. RENNIN
What is the pH in
the stomach?
1-2

Functions of hydrochloric acid:
1. creates the optimum pH for pepsin
Pepsinogen
(inactive form)
Pepsin
(active enzyme)
3. kills bacteria taken in
with the food
2.
HCl

Excessive production of gastric
juice: burning sensation

Gastric juice enters oesophagus:
not enough mucus to protect wall

Remedy for burning sensation in
throat and chest:
1. Drink milk
2. Take antacids

Doctors can see the
stomach lining by using
an:
endoscope
oesophagus

Stomach ulcers due to:
little mucus in stomach

Stomach
(2 enzymes secreted)
Hydrochloric
acid
Pepsinogen Pepsin
(active enzyme)
Prorennin Rennin
(active enzyme)

Why is pepsinogen produced
instead of pepsin?
To prevent pepsin
from digesting the
stomach walls

Pepsin is a protease:
 breaks:
Polypeptides
Proteins

Which conditions are needed for a
piece of meat to be digested?
 Pepsin in acidic conditions

Question:
The following diagram represents the protein found
in egg white. Each circle represents an amino acid.
Complete the diagram below to show how pepsin
breaks down the protein found in egg white.
[Idea is that short chains representing polypeptides are
made.]
(Do NOT accept individual amino acids represented as single
circles or dipeptides represented as a pair of circles)

Question:
List TWO reasons why amylase does not act on
starch in the stomach. (2)
i. pH in stomach is not optimum for amylase
ii. there is no enzyme in the stomach to break
starch

Some substances that are absorbed
by the stomach:
 ethanol
 vitamins
 certain salts and drugs
 some water
 glucose
How did I
get drunk so
quickly?

Rennin
 is an enzyme found in the stomach of young
children
 Function:
Soluble protein
in milk
(caseinogen)
Changes into
insoluble protein
(casein)
Pepsin then acts
on the insoluble
protein

In cheese-making, rennet [contains
rennin] is added to milk

Protein Digestion In Stomach
Proteins Polypeptides
Pepsin
Soluble Insoluble
milk proteins milk proteins
(caseinogen) (casein)
Rennin
Casein Polypeptides
Pepsin

Due to cancer of the stomach, the
entire stomach of Patient A have
being surgically removed.
As the doctor of Patient A, you are to
provide information on the effect on
the lifestyle and digestive function
upon removing the stomach.

• Stomach is the site of initial protein digestion.
Removal of stomach will cause protein digestion
to be greatly affected;
• Patient A can rely only on the small intestine for
protein digestion, rate of protein digestion will be
lowered.
• No HCl, prone to food infection by bacteria.
• Need to reduce protein intake to avoid congesting
the small intestine.

THE INTESTINES:
Small intestine
Large intestine
1.5 m long
7 m long

The small
intestine is
composed of:
duodenum &
jejenum &
ileum

Two functions of the small
intestine:
1. digestion is completed
2. digested food is absorbed
Bloodstream
Products of
digestion

Duodenum
 U-shaped
 first part of small intestine (most digestion
occurs here)
 about 25 cm long

The duodenum receives secretions
from the:
Pancreas
[pancreatic juice via
the pancreatic duct]
Liver
[bile via the
bile duct]

Liver
Pancreas
Gall
bladder
Duodenum
of Small
intestine

Where is bile:
i) made? ii)stored?

Made in
liver
Stored
in gall
bladder
Transported
through the
bile duct

Bile:
 has no enzymes
 consists of:
 water
 sodium chloride
 bile salts
 bile pigments
 pH = 8

Functions of Bile:
 dilutes contents from stomach
 creates optimum pH for pancreatic enzymes
to work in duodenum
 contains bile salts which emulsify fats
Bile salts

Bile salts emulsify fats i.e.:
 break large fat globules into smaller globules
Emulsification
of fats
What is the benefit of emulsification?
The surface area where lipase can act is increased.

Bile salts emulsify the fats by
reducing the attractive forces
between the fat molecules
Physically breaks-up the fat
molecules
Bile Salts
Tiny fat
droplets
Increase surface area to
volume ratio – speed up
digestion by lipase.
Bile salts

A person had his gall bladder removed.
Explain why the doctor told him to limit
fats in the diet.
Fats cannot be emulsified;
difficult to digest fats by lipase.

Three enzymes in
pancreatic juice:
Pancreatic amylase
Trypsin
Pancreas
Lipase
Action of
each
enzyme:

lipase +
fat molecule
glycerol fatty
acids
starch molecule
amylase
maltose
proteins &
polypeptides
trypsin
peptides

Secrete Pancreatic Juice:
• Pancreatic amylase,
• Pancreatic lipase
• Trypsinogen
trypsin
(active enzyme)
Pancreas
enterokinase

Question:
Bile and pancreatic juice are involved in
digestion of fats.
a) Describe the role of both secretions in this
process. (4)
b) Explain why bile must be released before
pancreatic juice for the efficient digestion of
fats. (2)

The wall of the ileum has
intestinal glands
that produce
intestinal juice

Secrete Intestinal juice
Maltase Sucrase
Lactase Erepsin
Intestinal
lipase
Intestinal Gland

Enzymes in intestinal juice
SUBSTRATE ENZYME END PRODUCT
Peptides Erepsin Amino acids
Lipids Lipase Fatty acids &
glycerol
Maltose Maltase Glucose + glucose
Sucrose Sucrase Glucose + fructose
Lactose Lactase Glucose + galactose

Remember:
Pepsin
Amino acids
Peptides
Polypeptides
Proteins
Trypsin
Erepsin

Remember: Digestion of starch
Starch
Maltose
Maltose
(in ileum)
Glucose
Pancreatic
Amylase
Salivary Amylase
(In Mouth)
No digestion of starch in
stomach (amylase is
denatured)
Maltase

Starch + water
Summary
6.4 FOOD DIGESTION
1. Digestion in the MOUTH
FOOD
Mouth
Salivary glands
Salivary amylase
bolus
aesophagus
maltose
secrete
chewing
triggers
rolled into
enters
(by peristalsis)# epiglottis

Digestion in Stomach
Gastric glands
Gastric juices
HCl Acid
Pepsin
Rennin
- pH 1.5 – 2.0
- Stops the activity of amylase
- Kill bacteria In food
Protein + water Polypeptides
Caseinogen + water Casein

Digestion in duodenum
Starch + water maltose
Polypeptide + water peptides
Lipid droplets + water glycerol + FA
Pancreatic amylase
trypsin
lipase

Digestion in small intestine
• Intestinal juice
• Digestive enzymes : digestion of peptides & dissaccharides
1) Protein digestion
• Peptides + water amino acids
2) Carbohydrates digestion ( Ma La S )
• Maltose + water glucose
• Sucrose + water glucose + fructose
• Lactose + water glucose + galactose
erepsin
maltase
sucrase
lactase

Region of
Digestion
Source Enzyme Action
MOUTH Salivary glands Salivary amylase Starch Maltose
STOMACH Gastric glands
Pepsin
Rennin
Protein Polypeptide
Soluble Insoluble
milk proteins milk proteins
SMALL
INTESTINE
Pancreas
Intestinal
glands
Pancreatic
Amylase
Trypsinogen
trypsin
Pancreatic Lipase
Maltase
Erepsin
Lipase
Starch Maltose
Protein Polypeptides
Fats Fatty acids+ glycerol
Maltose Glucose
Polypeptides Amino acids
Fats Fatty acids+ glycerol

Digestion is complete in the
ileum. What happens to the
digested food?

Objectives
1) Describe the structure of the inner wall of the small
intestine and explain it’s role in terms of increased
surface area for absorption of nutrients.
2) Explain the role of a lacteal and blood capillaries in the
transport and absorption of nutrients.
3) Describe the functions of the colon, rectum and anus in
relation to absorption of water and mineral salts,
temporary storage and egestion of faeces.

Model of the ileum showing numerous villi
Villus: a finger-like projection

Villi contain blood & lymph vessels
Villi – plural of villus

A villus is adapted for absorption

The ileum is adapted to absorb
digested food
 by providing a LARGE surface area:
 Folded walls
 Has villi
 Has microvilli

Inner wall of small intestine
Why is there a need for numerous folds, villi
and microvilli?
To increase surface area for absorption of digested
food substances – Increasing the absorption rate of
water and digested food products

Ileum is adapted for absorption:
1. Ileum is long:
 more time for digestion
 a greater surface area for absorption
2. Villi:
 increase surface area for absorption
3. Microvilli in epithelium:
 increase surface area for absorption
4. Epithelium is very thin:
 soluble products of digestion pass through quickly
5. Dense capillary network:
 removes the digested food

Glycerol and fatty acids
diffuse into the epithelium –
form fat globules – enter the
lacteals
Lacteal transport fats away
from the small intestine.
Blood
capillaries
Lacteal
Sugars, amino acids, are
absorbed by diffusion into
the blood capillaries
Blood capillaries transport
sugars and amino acids away
from the small intestine.
Epithelium
Villi
One cell
thick
Faster diffusion
of the digested
food products
What is the epithelium
one cell thick?

Would the absorption of
nutrients be affected if
digested food substances
cannot be transported
away by the blood
capillaries?
Explain your answer.
Yes. To a certain extent

The continual transport of
digested food substances
maintains a concentration
gradient for the absorption of
digested food substances by
diffusion
Lower concentration of digested
food substances in the lumen of the
small intestine, glucose and amino
acids are absorbed by active
transport
Mineral salts enter the blood
capillaries by active transport

Absorption of digested food
1) Glucose & Amino acids
- from lumen into the epithelial cells by facilitated
diffusion
- remaining nutrients – by active transport
- from epithelial cells – absorbed into the
bloodstream thru the blood capillaries in the villi
- converge into the hepartic portal vein
- Then transported to all parts of the body
Lumen
(glu & a.a)
facilitated
diffusion
Epithelial
cells
bloodstream
Hepartic portal vein
blood
capillaries
all parts of the body

2) Water
Lumen epithelial cells blood capillaries
3) Water-soluble vitamins
Epithelial cells blood capillaries
3) Fatty acids & glycerol
Epithelial cells (tiny droplets) lacteals lympatic system
Right lymphatic duct
Thoracic duct
Bloodstream
Subclavian
veins

Activity time!
I need a
doctor!

I need a doctor!
You are a doctor that specializes on
the ileum. As the doctor of a
patient who is overweight and has
the intentions to lose weight, what
procedures can be done to help
the patient lose weight? Explain
your answer.

The large intestine is composed of:
1.Caecum
Anus
2. Appendix
4. Colon
3. Rectum

Material in the large intestine
consists of:
 water
 mucus
 dead cells
 undigested matter
Most of the undigested matter is
cellulose. Why is this so?

Function of the:
Colon:
absorbs 90 % water
& mineral salts
Rectum:
stores FAECES before being
expelled through the ANUS

6.6 FORMATION OF
FAECES & DEFAECATION

The 4th stage of feeding &
digestion:
4. Egesting

Contents of Faeces:
1) undigested food
2) dead cells shed from the intestinal lining &
bile pigments & toxic subtances – eliminated
from the body
3) binds to the mucus that secreted by the
colon’s wall and lubricates the movement of
faeces along the colon

Defaecation
• How it works??
- elimination of faeces
- controlled by muscles around the anus, the
opening of the rectum
- When rectum is full, the muscles of the rectal
wall contract to eject the faeces via the anus

Egestion / Defaecation
 the process of removing
faeces
I really have
to go to the
bathroom!

Ingestion
(2 L) Salivary gland secretions
(1 L)
Gastric secretions
(2 L)
Pancreatic secretions
(1.2 L)
1% in
faeces
Small intestine
secretions
(2 L)
Bile
(0.7 L)
Although 8.9 L of
water are ingested
or secreted daily,
the faeces are dry.
Explain.

Ingestion
(2 L) Salivary gland secretions
(1 L)
Gastric secretions
(2 L)
Pancreatic secretions
(1.2 L)
Absorbed in the
small intestine &
colon.
1% in
faeces
Small intestine
secretions
(2 L)
Bile
(0.7 L)

Problems related to food
digestion
Incomplete
digestion
Lack of
digestive
enzymes
Gallstones

Causes:
• when people eat too much or too fast, or certain foods don't agree with them.
• smoke, drink alcohol, are stressed out, or don't get enough sleep.
• certain stomach problems, like gastritis (stomach inflammation) or an ulcer.
Indigestion or dyspepsia or upset stomach.
symptoms:
pain or burning in your upper belly
nausea
bloating
uncontrollable burping
heartburn
Prevention:
Avoid fatty, greasy foods, like fries ,
burgers.
Avoid too much chocolate or citrus fruits
Eat slowly.
Don't smoke.
relax.
Give your body a chance to digest food.

Gallstones
Gallstones are
hard deposits in
your gallbladder
Gallstones may
consist of
cholesterol, salt,
or bilirubin, which
are discarded red
blood cells.
Causes:
• Too much
cholesterol
• Too much
bilirubin
• Gallbladder
doesn’t empty
properly
Treatment:
• Surgery
• Medication
• Home remedy :

6.5 THE PROCESSES OF
ABSORPTION &
ASSIMILATION

OBJECTIVES
You will learn:
• 1) Define assimilation as the process where the products
of digestion are distributed and use as an energy source or
converted into protoplasm required for growth and repair
of worn-out parts.
• 2) State the role of the hepatic portal vein in transporting
sugars and amino acids to the liver.
• 3) Explain how sugars, amino acids and fats are utilised in
the body.
• 4) State that the hormone insulin is produced by islets of
Langerhans in the pancreas.
• 5) Explain the effect of insulin on glucose.

Assimilation
The distribution and use of
the digested food products
as an energy source or
converted into protoplasm
required for growth and
repair of worn-out parts -
Assimilation
Small
intestine

ASSIMILATION
• Definition
- the conversion of nutrient into the fluid
or solid substance of the body, by the
processes of digestion and absorption
- occurs in the LIVER and the CELLS

Oxygenated
blood from heart
Blood from
digestive system
HEPATIC
PORTAL VEIN
HEPATIC ARTERY
LIVER
HEART
HEPATIC VEIN
to heart
INTESTINES
Blood supply to and away from the liver

Transport of food substances
Hepatic
Portal vein
Small intestine
Liver
Blood capillaries
Gall
bladder
Bile
Duct
Absorbed food
substances (sugars
and amino acids) are
transported via the
hepatic portal vein to
the liver
Note: Fats are
transported through the
lacteal into the lymphatic
system

Assimilation in the LIVER
7 Functions of the LIVER
1) Regulation of blood glucose concentration
2) Production of bile
3) Protein synthesis
4) Iron storage
5) Deamination of amino acids
6) Detoxification
7) Heat production

Assimilation in the LIVER
synthesisconverts
glucose
excess
DEAMINATION
urea
kidney
- excess glucose
- enter heart
through subclavian
veins

Transport and utilization of
Glucose
Small
intestine
Function of glucose:
Glucose is used by all
cells as a source of
energy.
Hepatic vein
Some glucose is transported by the
blood leaving the liver to other parts
of the body
Excess glucose is
converted to glycogen
and stored in the liver.
Hepatic portal vein
Glycogen

Conversion of Glucose
Islets of Langerhan
cells in the pancreas –
secretes a hormone
Insulin
Insulin stimulate the
liver to convert excess
glucose to glycogen
and stored.

Amino acids
Amino acids pass through
the liver before they are
transported to the rest of
the body.
Small
intestine
Hepatic vein
Function of amino acids:
• Make new cells for growth
• Replace worn-out cells
• Make useful substances
such as enzymes and
hormones
Excess amino
acids are
deaminated.
Hepatic
Portal
Vein

Deamination occurs in the liver
AMMONIA
AMINO ACID
is broken into two:
The rest is
used for
energy
Part with
nitrogen forms:
UREA

Question:
Write the correct term for each of the following
processes:
i) the breakdown of excess amino acids
Deamination
ii) rhythmical muscular contractions that push
food along the digestive system
Peristalsis

iii) the elimination of indigestible food from
the body
Egestion / Defaecation
iv) the passage of digested food through the
gut wall in the blood stream.
Absorption

Fats
Fats is transported from
the Lacteal  Lymphatic
vessels  Bloodstream
 Rest of the body and
Liver
Lacteal

Fats
Fate of Fats
• Use to form parts
of the cell such
as cell membrane
• Prevent excessive
heat loss.
Excess fats stored in
adipose tissues
When glucose supply is low,
fats are broken down in the
liver to provide energy

ASSIMILATION OF DIGESTED
FOOD
FOOD USE STORE
Glucose Respiration Glycogen or Fat
Fats Respiration,
to build cell structure,
as a store of energy
Fat
Amino
acids
Build proteins for cell
structures, enzymes
CANNOT BE STORED
– ARE DEAMINATED
& USED IN
RESPIRATION

Write an account of a controlled experiment
you would perform to show the action of the
enzyme amylase on starch. (6)
Two spotting tiles are
prepared with a drop of
iodine solution in each
hole.
An equal volume of starch
is placed into two separate
test tubes, labelled A and B.
1
2

An equal volume of amylase is placed
into two separate test tubes, labelled C
and D.
Test tube C is boiled for 5 minutes to
denature the enzyme and so act as a
control.
All four test tubes are
placed in a water bath at
37C for 5 minutes to
acclimatise.
3
4

Starch in test tube A is
poured into amylase in test
tube D, mixed and the stop
watch is started.
5
After 30 seconds, a drop of the
mixture is taken and added to one
of the drops of iodine solution on
the spotting tile. This is repeated
until a yellow colour appears.
6

Starch in test tube B is poured
into amylase in test tube C,
mixed and the same method is
repeated.
7
8
Contents in test tube:
i) D give a yellow colour with
iodine solution after a few
minutes
ii) C continues to give a blue-
black colour after 30 minutes.

9 The results show that amylase breaks down
starch.
10
If Benedict’s solution is added to
the contents of test tubes C and D
and heated for a few minutes, a
brick red colour is obtained only
in test tube D [unboiled amylase].
This shows that when starch
breaks down, reducing sugars are
formed.
C D

What processes take place in the same part of the
alimentary canal where ingestion of food takes
place?
1. Physical digestion only
2. Chemical digestion only
3. Physical and chemical digestion
4. Digestion and absorption

Which of the following statement(s) about the
Oesophagus is/are true?
I. There is no digestion occuring in the oesophagus
II. Food moves down the oesophagus via peristalsis
III. There is digestion of starch in the oesophagus
IV. The wall of the oesophagus secrete digestive
enzymes
1. II and III only
2. I and II only
3. II and IV only
4. II only

Complete the following equations
Starch _____________
Protein ______________
Fats _______________
amylase
proteases
lipase
Maltose
Amino acids
Fatty acids + glycerol

Why are bile salts not considered
enzymes?
Bile salts does not digest fats,
it only emulsify fats – Increase
surface area for digestion by
lipase.

TRUE / FALSE
Fat digestion will stop if the bile duct is
blocked by gallstones.
False .
Fat digestion will not stop
But will become very slow since
bile is absent to emulsify fats

At which part of the digestive system is
digestion of all food completed.
1. Stomach
2. Colon
3. Oesophagus
4. Ileum

Which of the following listed below is not a
feature of the ileum?
1. The inner surface is folded.
2. It releases gastric juice.
3. It is a very long tube.
4. Its main function is the absorption of
digested food.

The diagram below shows part of the human digestive
system and the associated blood vessels.
Blood vessel X would least likely contain _____________
1. Glycerol 2. Amino acids 3. Water 4. Glucose
X

The diagram below shows the percentage of proteins,
carbohydrates and fats digested as they pass through the
alimentary canal in man.
Which is PART C likely to be?
1. Ileum 2. Duodenum 3. Stomach 4. Oesophagus
Percentageofundigested
foodmolecules

How would the composition of the blood in the
hepatic vein change if there was a high intake
of protein-rich food? Explain.
The composition of the blood
would not change since excess
amino acids caused by the high
intake of protein-rich food will
be deaminated in the liver.

6.4 FOOD DIGESTION
(continuation)

DIGESTION IN
RUMINANTS
&
RODENTS

1.Rumen
2. Reticulum
4. Abomasum
3. Omasum
STOMACH
– 4 Chambers

How it works??
1.RUMEN
- Largest compartment
- Cellulose broken down by
cellulase (bacteria &
protozoa)
2.RETICULUM
- Further hydrolysis
- CUD – its content
- Regurgitated bit by bit
- Soften & break down
cellulose
mouth3.OMASUM
-Reswallowed cud
-Large  small
particles by
peristalsis
-Water is removed
4. ABOMASUM
-True stomach
- gastric juices secreted
– protein digested
Small intestine
Lembu Makan
R – Rumput
R – Redah
O – Onak dan
A – Air Busuk

Rodents
Cellulose digested by
cellulase-producing
bacteria in caecum

Rodent Digestion
-Faeces 1st
batch
- soft & watery
-2nd batch faeces
– drier & harder
• Caecum & appendix =
enlarged to store
cellulase-producing
bacteria
• products pass through
alimentary canal =
TWICE

Comparison of cellulose digestion
process in human, ruminant & rodent
Similarities
1)
2)
Differences
Aspect Human Ruminant Rodent
Stomach chambers
Cellulase producing bacteria
Food passes through
alimentary canal
Gastric juice is produced in
Size of caecum
Undigested cellulose

Caecum & Appendix are
 Large in herbivores Vestigial in humans:
[small & no function]
Caecum
Appendix

Question:
Humans are omnivores.
Do not depend only upon vegetation for
nutrients.
A large caecum is found in herbivores and is full
of bacteria that produce cellulase to digest
cellulose.
Explain why the caecum /
appendix in humans is small
and non-functional. (4)
Human Rabbit

Animal Nutrition
Oral Cavity
Carbohydrate
Digestion
Physical
Digestion
Salivary
Amylase
Starch
Maltose
Teeth Tongue
Food
Smaller
Pieces
Mix
Food
Bolus
Oesophagus
Peristalsis
Antagonistic
Muscles
Circular Longitudinal
Stomach
Protein
Digestion
Gastric
Juice
Enzymes
HCl
Acidic
MediumPepsin Rennin
Protein
Polypeptides
Soluble
Milk Proteins
Insoluble
Caesin
Small
Intestine
Carbohydrate
Digestion
Protein
Digestion
Fat
Digestion
Pancreatic
Amylase
Intestinal
Maltase
Pancreatic
Trypsin
Intestinal
Peptidase
BilePancreatic
Lipase
Intestinal
Lipase
Fats
Smaller
Globules
Polypeptides
Amino acids
Starch
Maltose Fatty
Acids
Glycerol
Liver
Large
Intestine
Colon Rectum
Faeces
Anus
DetoxificationDeamination Glycogen storage
involves
involved in
by
hydrolyses
into
involves
break
down
into into
helps
involved in
involves
that are
involved in
by
contains
provides
for
consist of
hydrolyses
into
into
coagulates
hydrolyses
hydrolyse
hydrolyse
into into
into
involved in
Consists of
involves
involves
involves
emulsifies
into
is involved in is for storing
is egested
via
Eventually lead to
has functions like
Blood glucose level
Breakdown of fatty acids
to regulate
EnergyAmino Acids
to provide
Breakdown of
haemoglobin
Recycle iron
of
Heat production
Body temperature
to regulate
hydrolyses
Maltose
Monosaccharides
Transported by
into
Blood capillaries
Transported by
Lacteals
to
Absorption of
H2O and
Mineral salts

6.7 EVALUATING GOOD
EATING HABITS

Problems related to food
digestion
Gastritis Obesity
Anorexia
nervosa
Bulimia

What is gastritis?
(
Gastritis is basically the condition where the mucosa
(which is the stomach lining) becomes inflamed.

• Causes:
• excessive alcohol consumption
• prolonged use of nonsteroidal
anti-inflammatory drugs.
• Sometimes after major surgery,
traumatic injury or burns

What happens to a person’s weight when:
Weight remains constant

Weight increases
Obese person

Weight decreases

• We can say that obesity is an increase in
bodyweight (>20% over BMI) because of
excess body fat.
What is obesity?

What is obesity?
• Obesity is a disease!
Obesity is a chronic disease caused by excess
weight.

• Affects men and women of all ages
• Predominates in
developed countries.
What is obesity?

• The World Health Organization considered
this disease as an epidemic of the 21st
century.
What is obesity?

Causes
Sedentary life
 Don’t do physical exercise;
 See a lot of television;…

Extreme consumption
Incorrect alimentary habits
 Eat fast food; poor foods…
Causes

Causes
Genetic cause (rare)

Consequences
Arteries
disease
Cancer
Obesity
Problems in
the biliary
vesicle
Renal
disease
Alterations in
the bones
Heart disease
&
Hypertension
Diabetes
Lung
diseases

Consequences
Arteries
disease
Cancer
Obesity
Problems in
the biliary vesicle
Renal
disease
Alterations in
the bones
Heart disease
&
Hypertension
Diabetes
Lung
diseases
It can cause death !

Consequences
And…
• Social isolation;
• Depression and loss of auto-esteem.

Consequences
And…
• Social and educative discrimination;

What to do to avoid?
• Eat healthy food;

 Physical exercice;

• Medical help when obesity starts to be
serious.

Look in the mirror. What do you see? Is it the real
you or just another "me"?

What is an Eating Disorder?
• mental illnesses
• cause serious disturbances in a
person’s everyday diet.
• eating extremely small amounts
of food or severely overeating.

• Individuals have a distorted body image that causes them to
perceive themselves as overweight even when they are
emaciated
• They often lose large amounts of weight because they refuse to
eat, exercise compulsively, or refuse to eat in front of others
• Females experience loss of menstrual cycles
• Males become impotent (erectile dysfunction)

Anorexia Nervosa: Warning Signs
 Dramatic weight loss
 Refusal to eat certain foods or food categories.
 Consistent excuses to avoid situations involving food
 Excessive and rigid exercise routine
 Withdrawal from usual friends/relatives

Health Risks with Anorexia
Heart failure
Kidney failure
Low protein stores
Digestive problems
Menstrual cycle
stops

Bulimia Nervosa
An eating disorder in
which one starts to
consume large amounts of
food at once and then is
followed by purging, using
laxatives, or
overexercising to rid
themselves of the food
they ate.

Bulimia Nervosa: Warning Signs
 Wrappers/containers indicating consumption of large
amounts of food
 Frequent trips to bathroom after meals
 Signs of vomiting e.g. staining of teeth, calluses on hands
 Excessive and rigid exercise routine
 Withdrawal from usual friends/relatives

Health Risks with Bulimia
• Dental problems
• Stomach rupture
• Menstruation
irregularities

deaths were caused
by eating disorders in the U.S.
in eating disorder deaths.
In 2009
The U.S. is ranked

• Low Self-esteem
• Feelings of inadequacy or
failure
• Feelings of being out of
control
• Response to change
(puberty)
• Response to stress (sports
or dance)
• Personal illness

• Troubled family and
personal relationships
• Difficult expressing
emotions and feelings
• History of being teased
or ridiculed based on
size or weight
• History of physical or
sexual abuse

• Cultural pressures that glorify thinness and
place value on obtaining the perfect body
• Narrow definitions of beauty that include
women and men of specific body weights and
shapes
• Cultural norms
that value
people on the
basis of physical
appearance and
not on inner
qualities and
strengths

• Seven feet tall
• 38 inch chest
• 21 inch waist
• 36 inch hips
• Virtually unattainable for an adult woman

http://www.youtube.com/watch?v=J_ax0h9F
Nag&feature=endscreen

WHAT IS THE THREATMENT FOR AN AND BN?

• Psychotherapy
• Support or self-help
groups
• Medical treatment
• Nutritional treatment
• Medication
• Hospitalization

6.8 IMPORTANCE OF A
HEALTHY DIGESTIVE
SYSTEM

TO PREVENT
DISEASES OF THE STOMACH
• Gastritis, Gastric Ulcer, Stomach Cancer,
Hemorrhage from the Stomach, Hyperacidity,
Dyspepsia
OTHER DIGESTIVE DISEASES
• Hepatitis, Diarrhea, Cirrhosis, Lactose
Intolerance, Short Bowel Syndrome,
Appendicitis, Constipation, Gallstones,
Flatulence and Abdominal Adhesions

nuts, beans,
grain, wheat,
rice,
vegetables
and fruits
1. Eat foods rich in fiber
 it helps the body eliminate waste, lowers cholesterol, feeds healthy bacteria
and reduces risks of irritable bowel syndrome and colon cancer

2. Eat good amounts of fish
 Fish contain omega-3 fatty acids which can improve certain digestive
problems because of their special anti-inflammatory properties.

3. AVOID PROCESSED FOODS!
 processed foods may contain ingredients which irritate the stomach

Avoid Junk food
- empty calories, minimum nutrients
- Artificial colourings, flavourings

Avoid food with high sugar /fat content
- Prevent diabetes, obesity, cardiovascular
disease

4. Take Good Bacteria –
THE GOOD BACTERIA

FOOD RICH IN PROBIOTICS
Probiotics are good bacteria that live in the gastrointestinal system. They maintain its health by
keeping bad bacteria at bay and creating a good harmony in your digestion's ecosystem. They
have been known to help ease conditions like gastroenteritis, irritable bowel syndrome and
inflammatory bowel disease.

DO DON’T
5. Develop good eating habits

6. Exercise regularly
 Exercise is great for boosting your body's natural functions and can improve
the natural rhythm of your digestive system, too. It is also great for helping
your food move through the digestive tract.

DO DON’T
7. Choose healthy hydration

BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 2

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

En vedette

En vedette (11)

Similaire à BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 2

Similaire à BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 2 (20)

Plus de Nirmala Josephine

Plus de Nirmala Josephine (20)

Dernier

Dernier (20)

BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 2