Describe the major animal tissues (epithelial, connective, muscular, and nervous) in terms of their cell specificities, locations, and functions?
Difficulty: Hard
Animal Tissues:
In the bodies of animals, there are four major categories of tissues: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
- Epithelial tissue:
Epithelial tissue covers the outside of the body and lines organs and cavities. The cells in this type of tissue are very closely packed together and joined with little space between them.
The function of Epithelial tissue:
Epithelial tissue helps to protect organisms from microorganisms, injury, and fluid loss. These tissues are commonly classified on the base of the shape of the cells as well as the number of cell layers.
Types of Epithelial tissue and their function:
Some types include:
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Simple Squamous Epithelium |
· A single layer of tightly packed, flattened cells. Squamous. · Found in the lining of air sacs of the lungs, heart, and blood Epithelium ves, seals, etc. · Allows diffusion and filtration. |
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Simple Cuboidal Epithelium |
· Consists of single layer of tightly packed, cube-shaped cells. · Found in kidney tubules, ducts, and small glands. · Makes secretions and absorbs materials. |
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Simple Columnar Epithelium |
· Consists of a single layer of elongated cells. · Found in the lining of the digestive tract and gallbladder etc. · Makes enzyme secretions. |
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Ciliated Columnar Epithelium |
· A tuft of cilia is present at the top of each columnar cell. · Found in the lining of the trachea and bronchi. · Propels mucous by ciliary action. |
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Stratified Squamous Epithelium |
· Consists of many layers of flattened cells. · Found in the inner lining of the esophagus, mouth, and at the surface of the skin. · Protects underlying tissues from abrasion. |
- Connective Tissue
As the name implies, connective tissue serves a "connecting" function. It supports and binds other tissues. Unlike epithelial tissue, connective tissue typically has cells scattered throughout an extracellular matrix.
Types of Connective Tissue:
There are many types of this tissue.
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Loose Connective Tissue |
a. The most common type, matrix contains loosely arranged collagen (a protein) fibers. b. Widely distributed under the epithelial tissues. c. Holds organs in place and attaches epithelial tissue to other underlying tissues. |
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Fibrous Connective Tissue: |
a. The matrix contains tightly packed collagen fibers. b. Found in tendons, which attach muscles and bones, and ligaments, which join two bones. c. Provides structural strength. |
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Adipose Tissue |
a. Swollen cells due to the presence of a large number of fat droplets. b. Found around kidneys, under the skin, in the abdomen, etc. c. Provides energy when fat is oxidized, insulates against heat loss, and protects and supports organs. |
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Cartilage |
a. The matrix contains bundles of collagen fibers embedded in a rubbery substance. b. Found around the ends of bones, in the external ear, in the nose, trachea, in discs between vertebrae (bones of the vertebral column), like a skeleton in many fishes. c. Provides support while allowing flexibility.
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Bone |
a. The matrix contains collagen fibers embedded in calcium salts b. Found in the skeleton. c. Supports protects, provides a lever system for movements, stores calcium, and forms blood cells. |
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Blood |
a. Matrix is not solid but in the form of a fluid (plasma) Red and white blood cells are suspended in plasma. b. Found in blood vessels. c. Transports substances from one part of the body to the other, and is responsible for immunity. |
- Muscle Tissue:
Muscle tissue consists of bundles of long cells called muscle fibers. It is the most abundant tissue in a typical animal. The cells of this tissue can the contract
Voluntary Action Muscle Tissue:
The skeletal muscles are voluntary in action i.e. their contraction is under the control of our will.
Involuntary Action Muscle Tissue:
The smooth and cardiac muscles are involuntary in action i.e. their contraction is not under the control of our will.
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SkeleMusclesles |
a. Composed of striated (striped) cells that are long and cylindrical and contain many nuclei b. Found attached to bones e.g. bicep muscle. c. Responsible for voluntary movements and locomotion |
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Smooth Muscles |
a. Composed of non-striated (smooth) cells that are spindle-shaped and each contains a single nucleus. b. Found in the walls of the digestive tract, urinary bladder er, and blood vessels. c. Moves substances (foodstuff, urine) along internal passageways. |
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Cardiac Muscles |
a. Composed of striated cells that are branched and each contains a single nucleus. b. Found in the walls of the heart c. Produce a heartbeat that propels blood into the circulation |
- Nervous Tissue:
Animal's survival depends on its ability to respond appropriately to stimuli from its environment. This ability requires the transmission of information from one part of the body to another. Nervous tissue forms a communication system and performs this task.
Specification of nervous tissue:
This tissue is mainly composed of nerve cells, or neurons, which are specialized to conduct messages in the form of nerve impulses.
Location of nervous tissue:
Nervous tissue is found in the brain, spinal cord, and nerves.
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