Human tissues

Tissue is collection of similar cells that perform certain function.

Histolgy is microscopic study of tissue (branch of biology).

Classification of tissues according to their structure and function:

1. Epithelial tissue

- covers body and organs surface

- lines the inside walls of body cavities and organs

- form various glands

- nourished from blood cells of connective tissue, there aren't blood vessels

- its cells are closely packed together

- my be one layer or several layers thick

e.g. skin, exocrine glands, sweat glands, salivary glands, sebaceous glands, mammary glands, lining of the respiratory system,

2. connective tissue

- supports or binds other tissues

- provide metabolic need of all body organs

- highly vascular, very well nourished except cartilage

- able to regenerate

- contains more nonliving materials = matrix than cells

- its cells rarely touch one another

Types of connective tissue:

• connective tissue proper

- has a loose, flexible matrix with something (star-shaped cells)

- they produce collagenous, elastic and reticular fibres

e.g. ligaments

• cartilage

- contains chondrocytes, matrix with elastic and collagenous fibres

- provides support and protection - lower flexibility

e.g. hyaline cartilage (example of cartilage in the nose, rib cage, part of respiratory system)

• bone

- the most rigid

- contains matrix with minerals, osteocytes and numerous collagenous fibres

- has a rich blood supply and is metabolically very active

- bone tissue is flexible

• blood (liquid)

- fluid connective tissue plays a votal role in maintaining body homeostasis

- contains elements = red blood cells (erythrocytes), white blood cells (leukocytes), platelets (thrombocytes) + liquid plasma

• muscle tissue

- contracts to produce movement of food, fluids throughout the body, movement of body parts and locomotion

Types of this tissue: - smooth muscle tissue

- cardiac muscle tissue

-skeletal = striated

• nervous tissue

- produces and processes nerve impulses and transmits them from one body part to another

composed of 2 types of cells: nerve cells = neurons - basic structural and functional unit of the nervous system and glial cells = neuroglia - supporting cells, don´t transmit impulses, assist in providing nourishment for neurons