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 areasurface area

The small intestines• What makes the small intestines suitable for Absorption?

1) Elongated ileum, Inner surface of the ileum is folded

These features provide large surface area:vol for absorption

2) Villi and microvilli

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 Mouth & Oesophagus

Gall Bladder &Pancreas

Stomach

Large Intestine & Others Small Intestine

Overview – 4 Stages Ingestion Digestion

AbsorptionAssimilation

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?

A

B

C

D

Carbohydrate metabolism

Hepatic portal vein

transports sugars like glucose from the intestines to the liver

Question!

Receives 5 glucose molecules from the intestines

Requires only 3 glucose molecules for breathing

how many molecules of glucose do you think the liver would transport to the

lungs?

Receives 5 glucose molecules from the intestines

Requires only 3 glucose molecules for breathing

Liver in Glucose metabolism

Hepatic portal vein

In the liver….

1. Some glucose carried in the blood to be distributed to the rest of the body

- Tissue respiration

Carbohydrate metabolism

In the liver….

-Glucose (excess) Glycogen (stored)Hormone : Insulin

- If the glucose level is too low in the bloodGlycogen (stored) GlucoseHormone: Glucagon

Insulin and 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

Fate of amino acids

Amino acid metabolism

•Converted into protoplasm•Used for growth & repair of worn-out parts•Formation of enzymes & hormones

•Excess amino acids cannot be stored : Deamination

Deamination

—N—H

HC—OH

||O

R

|—C— |

H

Amino group Carbon residue

Ammonia (toxic)

Urea (non-toxic)

glucose

glycogen

Intestines lacteal lymphatic vessels blood rest of the body

Fat metabolism

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

(Liver not involved)

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.