Experiment 7

Topic : Examining slides of liver and kidney

Purpose :

1) To understand the structures of the liver and kidney as well as understanding

the functions of the two organs in homeostasis.

2) To understand the important structures in the liver and kidney which function

in homeostasis.

Theory :

The liver has many functions. Two main ones are :

1) It secretes bile into the bile duct down which it flows via a gall bladder to the

duodenum.

2) It regulates the amounts of blood sugar, lipids and amino acids by removing

them from the blood stream or adding them to it as appropriate.

It receives blood from two sources; oxygenated blood is taken to it via hepatic artery,

blood rich in food substances via the hepatic portal vein. Blood is removed from the

liver via the hepatic vein.

The diagram provided as a guidance to examine the slides.

Figure I shows the microscopic structure of liver

The kidney extracts unwanted substances from the blood, adjusting the blood’s

composition so that it has the right osmotic and ionic concentration. The basic

functional unit of the kidney is the nephron.

The diagram provided as a guidance to examine the slides.

Figure 2 : Mammalian kidney sectioned to show the position of the nephrons and

their blood supply. For clarity the nephron and blood vessels are shown separately;

in reality they are intimately associated. A Bowman’s capsule and its associated

glomerulus together constitute a Malphigian body. Note how the nephron and its

blood supply are oriented relative to the kidney as a whole, and also which parts of

the nephron are in the cortex and which ones in the medulla.

Figure 3 : A Malpighian body as it may appear in a microscope section of the kidney.

This drawing is idealised ; rarely would a section pass through the afferent and

efferent vessels and the proximal tubule.

Figure 4 : Tubules, collecting duct and capillaries as they appear in a microscopic

section of the cortex of the kidney. Plasma membranes are not usually visible

between adjacent cells in the walls of the tubules, hence their absence in this

drawing. Red blood cells are sometimes present in the blood capillaries.

Figure 5 : the loop of Henle, collecting duct and capillaries as they appear in a

microscopic section of the medulla of the kidney. The thin limb is the top two-thirds of

the descending limb of the loop of Henle; the thick limb is the descending limb plus

the whole of the ascending limb. Plasma membranes are not usually visible between

adjacent cells in the walls of the loop of Henle, hence their absence in this drawing.

Apparatus : Microscope, knife, dropper

Materials : Chicken’s liver and kidney

Procedure :

1) A thin slice of chicken’s liver is cut and placed on a slide.

2) Water is dropped on the slide containing the liver.

3) A glass cover slip is placed slowly onto the at an angle. The cover slip should

be handled carefully as it is very fragile and break easily.

4) Then, the slide is placed on the microscope. The slides should be observed

under a low power microscope to determine the plan of general tissue

distribution. The detailed structures are examined under high power

microscope by observing the form of the cells and other features.

5) The liver structures that examined are drawn and labelled. The name of

organ, type of section and magnification of the prepared slide are stated too.

6) Step 1 to 5 are repeated by replacing the kidney to be observed under a

microscope.

Conclusion :