Liver Functions Part II

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.

Guess what is the organ shown! From which animal? Some animal samples Guess what is the organ shown! From which animal?

Adaptation of the small intestine for absorption

Structure of small intestine Blood vessels (capillaries) combine to form a large blood vessel which carries food to the liver.

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: After absorption, Diffusion Active transport After absorption, Glycerol and fatty acids enter the lacteals Glucose and amino acids enter the blood capilliaries

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 Mouth & Oesophagus Stomach Large Intestine & Others Gall Bladder &Pancreas Small Intestine

Overview – 4 Stages Ingestion Digestion Assimilation 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

Assimilation 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…. Some glucose carried in the blood to be distributed to the rest of the body Tissue respiration

-Glucose (excess)  Glycogen (stored) 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 worn-out parts Formation of enzymes & hormones Excess amino acids cannot be stored : Deamination

Deamination H O | H || —C— C—OH —N— R Amino group Carbon residue Ammonia (toxic) glucose Urea (non-toxic) glycogen

Fat metabolism Fate of Fats (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.