Download Liver Functions Part II

Liver Functions Part II
3E1
From where we left off…
In the small intestines
• Complete digestion occurs in the small
intestines
• End products (glucose, amino acids, fatty
acids, glycerol) diffuse into the blood vessels
lining the small intestines.
• This process is called Absorption.
Some animal samples
• Guess what is the organ
shown!
• From which animal?
Adaptation of the
small intestine for
absorption
Structure of small intestine
What do you see in the intestinal walls?
How do the folds and villi help
in absorption?
• The presence of folds and villi
in the intestinal wall increase
surface area
More adaptations from the small
intestine
• the epithelial cell of the intestinal wall
• One-celled thick epithelial wall and microvilli
further increases surface area
The small intestines
• What makes the small intestines suitable for Absorption?
2) Villi and
microvilli
1) Elongated ileum, Inner
surface of the ileum is folded
These features provide large surface area:vol for absorption
The small intestines
• What makes the small intestines suitable for Absorption?
3) Many blood
vessels lining the
small intestines
Absorption
• Absorption occurs by:
– Diffusion
– Active transport
• After absorption,
Glucose and
amino acids enter
the blood
capilliaries
Glycerol and
fatty acids
enter the
lacteals
How does absorption takes
place in the intestines
Absorption of fatty acids and glycerol
• Glycerol and fatty acids diffuse into the
epithelium where they combined to form
minute fat globules and enters the lacteals
• Fat globules mix with lymph in the lacteals to
form chyle
• Liver is not involved *
Assimilation
and
function of the liver
Overview
Role of Digestion
Large Intestine & Others
Mouth & Oesophagus
Gall Bladder &Pancreas
Stomach
Small Intestine
Overview – 4 Stages
Ingestion
Assimilation
Digestion
Absorption
Lesson objectives:
•
•
Describe the fate of glucose, amino acids and fats in
the blood that leaves the intestines, after a meal.
Describe the 5 major roles that the liver plays in the
human body
–
–
–
–
–
Regulation of blood glucose concentration
Deamination of amino acids
Production of bile
Detoxication
Iron storage
Fate of
glucose and
amino acids
Transport and utilization of absorbed foods
In the Liver!
Types of absorbed food products
 Glucose
 Amino acids
 Fats
From the small intestines to the
liver! How??
Connected by a
vein called Hepatic
Portal Vein!
Guess which part the vein connects
to the intestine?
B
C
D
A
Carbohydrate metabolism
Hepatic portal vein
transports sugars like glucose from
the intestines to the liver
Question!
Requires only 3
glucose molecules for
breathing
Receives 5 glucose
molecules from the
intestines
how many molecules of glucose do you
think the liver would transport to the
lungs?
Requires only 3
glucose molecules for
breathing
Receives 5 glucose
molecules from the
intestines
Liver in Glucose metabolism
Hepatic portal vein
Carbohydrate metabolism
In the liver….
1. Some glucose carried in the blood to be
distributed to the rest of the body
- Tissue respiration
Insulin and glucagon
In the liver….
-Glucose (excess)  Glycogen (stored)
Hormone : Insulin
- If the glucose level is too low in the blood
Glycogen (stored)  Glucose
Hormone: Glucagon
What about the amino acids
absorbed by the small intestines?
Similar route as sugars:
Intestines  hepatic portal vein
 liver  general blood
circulation
Liver in Protein metabolism
Hepatic portal vein
Amino acid metabolism
Fate of amino acids
•Converted into
protoplasm
•Used for growth
& repair of wornout parts
•Formation of
enzymes &
hormones
•Excess amino
acids cannot be
stored :
Deamination
Deamination
H
O
H
|
||
—N— —C— C—OH
|
H
R
Amino group
Carbon residue
Ammonia (toxic)
glucose
Urea (non-toxic)
glycogen
Fat metabolism
(Liver not involved)
Intestines  lacteal  lymphatic vessels  blood  rest
of the body
Fate of Fats
• maintenance of cell
membranes
•Production of
hormones
• Excess fats stored in
adipose tissues
When glucose supply is low,
fats will be oxidised in the liver
to provide energy
Summary:
5 major roles that the liver plays
– Regulation of blood glucose
concentration
– Deamination of amino acids
– Iron storage
– Production of bile
– Detoxication
True/False
• Liver is part of the alimentary canal
True/False
• Carbohydrates are digested in the liver
True/False
• Excess amino acids are deaminated
True/False
• Fats are absorbed in the liver and
transport to other parts of the body for
usage.