Introduction to Animal Tissues

Introduction to Animal Tissues

Animal tissue is one of the primary concepts of Biology. The animal tissues are formed with the groups of animal cells. These tissues differ in their functions, structures as well as origin.

Different types of Animal Tissues are:

1. Epithelial tissue.
2. Muscle tissue.
3. Connective tissue.
4. Neural tissue.

Epithelial Tissues

It is a thin, continuous, protective layer of compactly packed cells with an intercellular matrix that lines the outer surfaces of organs and blood vessels and interior surfaces of cavities in many organs. During embryonic development, these issues were the first to evolve during evolution. It  starts from the ectoderm, mesoderm, and endoderm of the embryo. Diffusion, filtration, secretion, absorption, germination, transcellular transport, and germination are functions of epithelial cells. In addition, compound epithelia serve as protective barriers.

Characteristics of epithelial tissues

Epithelial tissues have the following characteristics:

1. They can be single-layered or multilayered.
2. The tissues can regenerate.
3. Gap junctions, tight junctions, zonula adherens, desmosomes, or interdigitation hold these together.
4. These cells have specialized plasma membranes with flagella, cilia, and microvilli.

Functions of the epithelium:

Epithelium forms boundaries between different environments, so nearly all substances must pass through it. As an interface tissue, epithelium acts in many ways, including:

1. Protection against radiation, desiccation, toxins, and physical trauma.
2. The digestive tract lining absorbs substances in distinct ways.
3. Control and excretion of chemicals between underlying tissues and the body cavity.
4. Glandular epithelium secretes hormones into the bloodstream. Ducts deliver sweat, mucus, enzymes, and other products.
5. The detection of sensation.

Classification of epithelial tissues

The epithelial tissues can be classified as:

1. Sensory epithelium.
2. Glandular epithelium.
3. Pigmented epithelium.
4. Absorptive epithelium.

Connective tissue

Connective tissue is found in the body, including the nervous system, between other tissues. It develops from the mesoderm. Connective tissue comprises fibroblasts, adipocytes, macrophages, mast cells, and leukocytes.

Connective tissue is made up of three main components:

1.  Fibers (elastic and collagen fibers)- connective tissues are composed of collagen fiber, elastic fiber, and reticular fiber.
2.  Ground substance – It is made up of mucopolysaccharide, specifically hyaluronic acid.
3. Cell-membrane – cells include fibroblasts, adipocytes, plasma cells, and mast cells.

The connective tissues perform these functions:

1. The collagen fiber microfibrils and elastin bind bones and other tissues together.
2. The fat they store in their tissues is classified as adipose.
3. They help in repairing tissues.
4. They prevent the organs from being damaged by mechanical shocks.
5. The organs also help in defense.
6. Additionally, they allow organs to resist stretching and tearing forces.

Muscular Tissues

A muscle’s soft tissues are composed of the different types of muscles that make up an animal’s muscles and give muscles the ability to contract. Myogenesis is the process of forming muscle tissue during embryonic development. Muscle tissue is also referred to as my propulsive tissue. Actin and myosin, particular contractile proteins in muscle tissue, contract and relax to cause movement and troponin and tropomyosin, which regulate muscle contraction.

The three types of Muscle Tissue

1. Skeletal or striated muscle tissue – It helps in blood circulation and keeps the heart pumping.
2. Smooth muscle (non-striated) muscle – These help in the body’s peristalsis and other involuntary functions.
3. Cardiac muscle – It helps in blood circulation and keeps the heart pumping.

Muscular tissue performs the following functions:

1. It helps in movement and locomotion.
2. It supports the bones and other structures.
3. It is responsible for peristalsis and parturition.

Nervous Tissues

An important tissue component of the nervous system is nerve tissue, also known as neural tissue. It comprises two parts: the central nervous system (CNS), which consists of the brain and spinal cord, and the peripheral nervous system (PNS), which includes the branching peripheral nerves. There are neurons, also known as nerve cells, which receive and transmit impulses, as well as neuroglia, also known as glial cells or glia, which assist in the propagation of the nerve impulse and provide nutrients to the neurons.

Components of Nervous Tissues:

Neuron: The neuron is the structural and functional unit of the nervous system. It consists of an axon, cell body, and dendrites. Neuroglia: The neurons and fibers in the brain and spinal cord are supported by neuroglia, specially shaped cells. Neurotrophic cells act as endocrine organs, releasing chemicals directly into the bloodstream from the axons.

Functions of Nervous tissue:

1. The transmission of electric signals across the tissue forms the nervous system’s communication network.
2. Gray matter, which contains the synapses, is essential for processing information in the CNS.
3. The white matter in the CNS, composed of myelinated axons, facilitates and connects gray matter areas.
4. The action potential nerve impulses are carried by nerve tissue containing myelinated axon bundles.

Animal Tissue culture

Keeping propagating isolated cells or tissues in an artificial environment in a vitro environment is tissue culture. Under defined conditions, a medium containing nutrients and growth factors can be used to induce many animal cells to grow outside their organ or tissue of origin. The study of the biology of cells from multicellular organisms can be significantly enhanced by tissue culture. It provides an in vitro model of the tissue in a well-defined environment that can be easily manipulated and analyzed. An ideal animal tissue culture medium contains amino acids, vitamins, inorganic salts, glucose, and serum as sources of growth factors, hormones, and attachment factors. The medium also helps maintain pH and osmolality. To replicate viruses, animal cell cultures are used instead of animals to produce vaccines. Cell cultures are also used to detect and isolate viruses and study the growth and development cycles of viruses. They are also used to study the mode of infection. Sterilization involves sterilizing glassware, stainless-steel instruments, plastic containers, distilled water, phosphate-buffered saline, and growth medium in a pressurized autoclave at 121° C for 20 minutes under 15 lb/square inch pressure. Sterilization using an autoclave is called wet heat, followed by dry heat. Animal cell culture techniques play a vital role in the research and development of drugs and help improve the health and quality of life of patients who have cancer and genetic disorders.

History of Animal Culture

Even though the idea of culture in animals has only been around for over half a century, scientists have observed other animals’ social behaviors for centuries. Aristotle was the first to identify social learning in bird songs. Darwin first sought to establish the existence of imitation in other animals to prove that the human mind had evolved from that of lower beings, as he believed that the human mind had become. As a result of his effort to explain the transmission of an adaptive pattern of behavior through a population of bees, Darwin also proposed what is now known as social learning. Almost all cultural anthropological research has been done with non-human primates since they are closest to humans in evolutionary terms. With non-primate animals, research tends to be limited, and thus evidence for culture is weak. However, the topic has become more popular recently, prompting more research into the subject.

Steps to culture animal Tissue:

• Harvest cells
• Isolation of the cells with the use of appropriate enzymes
• In a culture dish with proper growth media, the cells are placed
• The culture dish is now kept in an incubator for the culture of cells
• Cells can be subcultured to resolve the problem or to get pure culture
• Currently, cells are ready to be manipulated or modified for lab procedures

Conclusion

Through the study material on animal tissues, we have explore a variety of animal tissues along with its definition and properties. We have talked about animal tissues class 11, different types of animal tissues, and other related topics in length.