TYPES AND EXAMPLES OF CAPILLARIES
CAPILLARY:(hair like)
It has two meanings:
1-pertaining to hair or resembling a hair.
2-any one of minute vessels that connect the arterioles and venules, forming a network in nearly all parts of the body.
Walls of capillaries:
The walls of the capillary act as semipermeable membranes for interchange of fluids, gases, nutrients, hormones, vitamins, minerals antibodies, etc., between the blood and tissue fluids. Their diameter varies from 7-9 m.
Types of capillaries;
a) Continuous capillaries:
In these capillaries, no pores are seen. They are present at following sites:
*Skin.
*Connective tissue
*Skeletal and smooth muscle.
* Lungs.
*Brain.
b) Fenestrated capillaries:
These are those capillaries, the lining endothelial cells of which show characteristic pore system. They are seen at following sites:
*Renal glomeruli.
* Intestinal villi.
* Endocrine glands.
*Pancreas
Sinusoids of sinusoidal capillaries :
These are dilated capillaries and are lined by reticulo-endothelial cells.
Examples:
*Liver
*Spleen
* Parathyroid glands.
*Hypophysis cerebri.
*Carotid and Coccygeal bodies.
*Pancreas (Endocrine portion).
*Haemolymph nodes.
The sinusoids differ from capillaries in four respects :
>The lining is incomplete, irregular, and is formed by endothelial cells and reticuloendothelial cell
>They are only surrounded by a fine network of reticulin fibres, and are often collapsed when they are empty of blood.
>The sinusoids connect the vessels of same type, i.e., venous vessels whereas a capillary is always a connecting link between arterial and venous vessel
>The sinusoids have a wider lumen (20 μm. or more
Some Interesting Examples of Capillaries~
•Erythrocytic capillaries:
These are the capillaries of bone marrow of early life which seem to produce erythrocyte
•Meigs's capillaries:
These are the capillaries of myocardium of the hear
• Secretory capillaries:
These are extremely thin capillaries present between adjacent gland cell
•Arterial capillaries:
These are minute capillaries, distal to the arterioles and carry oxygenated bloo
•Venous capillaries:
These are minute capillaries proximal to venules which carry venous blood
•Lymphatic or lymph capillaries: These are the capillaries of lymphatic system. Their caliber is slightly greater than the capillaries of blood circulatory system
•Bile capillaries or cholangioles or Bile Canaliculi:
Comments
Post a Comment