Animal Tissues

Animal Tissues

1. Epithelial: Occurring in sheets of tightly packed cells. Covers the outside of the body,and lines organs and cavities of the body. In most cases the cells are held together by tight junctions. The cells are attached to a basal membrane.

a. Simple epithelium consists of a single layer of cells.

b. Stratified epithelium consists of multiple layers of cells. Psuedostratified: single layer of cells of different lengths, giving the appearance of a multi layer structure.

 

2.Connective: Functions mainly to bind and support other tissues. They contain a sparse population of cells surrounded by a nonliving matrix. This matrix can be fibrous, liquid or jellylike.

a. Loose Connective Tissue: bind epithelia to underlying tissue and as a packing material to hold organs in place. This type of tissue gets its name from the fibers it contains: collagenous, elastic, and reticular.  

1. Collagenous: made of collagen, the most abundant protein in the animal kingdom. A collagen fiber is a mass of fibers each a rope like coil of 3 collagen molecules. They have great tensile strength.

2. Elastic: Made of protein called elastin. These fibers are very resilient and as rubber snap the structure back after it has been moved.

3.Reticular: are branched and form tightly woven fabric fabric that joins connective tissue to adjacent tissue. Cells found in this type of tissue are: Fibroblasts, which the protein ingredient in extracellular fluid. Macrophages: are ameoboid cells that roam the body looking for bacteria and other unwanted foreign material to engulf.

4.Adiopse Tissue: Loose connective tissue that stores fat. These cells form when we are babies and fill and empty as we go through life. They also pad certain organs in the body.

 

b.Fibrous Connective Tissue: Dense tissue owing to the large amounts of collagenous tissue. Tendons and ligaments are the two types of structures containg this tissue. Tendons hold muscle to bone. Ligaments hold bone to bone.

1.Cartilage: Collagenous fibers embedded in a rubbery ground-substance called Chondrin, which is a protein-carbohydrate complex. The chondron is secreted by chondrocytes.

 

 


Cartilage

2.Bone: mineralized connective tissue. Cells called osteocytes deposit a matrix of collagen and calcium-phosphate which harden to form crystals of a substance called hydroxyapatite. Mammalian bone is constructed from repeated units called Haversian Units. The process of making new bone is called ossification.

 


Bone Tissue

3.Muscle Tissue: Composed of long contractile cells. The cells are composed of long microfilaments made of the proteins actin and myosin. There are 3 types of muscle tissue: Striated or skeletal, cardiac, and visceral or smooth.

 

 


 Cardiac muscle

 


Smooth Muscle

 


Striated Muscle

4.Nervous Tissue: Senses stimuli and sends signals from one part of the body to another. The cells are called neurons. The neuron consists of a cyton (cell body), dendrites (many branches that carry impulses to the cyton), and an axon (long filament that carries impulses away from the cell). 

 


Neuron