Definition of Tissue (basic tissue) – Introduction to fundamental concepts of Biological Science including the organization and common characteristics of living matters, cell structures and functions, food production by photosynthesis, harvesting energy, mechanism of cells reproduction, genetics, evolutions, and Human Biology. Introduction to general chemistry including basic concepts about matter, atomic structure, chemical bonds, gases, liquid, and solids, solutions, chemical reactions, acid, bases, and salt;
organic and biochemistry including hydrocarbons and their derivatives, carbohydrates, lipids, proteins, enzymes, vitamins, and minerals, nucleic acids; principles of physics and applications to nursing including gravity and mechanics, pressure, heat and electricity; nuclear chemistry and nuclear physics, effects of radiation on human beings, and protection and disposal. The aim of the course is to acquire knowledge and skills in general biological science, general chemistry and physics.
Definition of Tissue (basic tissue)
Collection of cells having similar morphological structure & similar function is called tissue.
Or
Tissue may be defined as a collection of cell that has similar morphologic character and similar function.
Types of Tissue:
The basic types of tissue are –
1. Epithelial tissue (Epithelium)
2. Connective tissue
3. Muscular tissue
4. Nervous tissue
Epithelial Tissue :
➤ Features High cellularity, special sensory receptors, forms a barrier, avascular, innervated
➤ Surfaces Basal (hemidesmosomes, basement membrane), apical (lumen, microvilli, cilia, stereocilia), lateral (adhering junctions, tight junctions, desmosomes, gap junctions)
➤ Types squamous, cuboidal, columnar, simple, stratified, pseudostratified, specialized
Connective Tissue :
➤ Structure Cells (structural, immunological, defense, energy reservoirs), extracellular matrix (ground substance, protein fibers)
➤ Types of fibers – Collagen, reticular, elastic
➤ Classification – Proper (dense, loose), embryonic (mesenchyme, mucous), specialized (cartilage, adipose, bone, blood)
Muscle Tissue :
➤ Features – Elastic, extensible, contractile
➤ Types – Skeletal, cardiac (gap junctions, intercalated discs), smooth, striated, nonstriated
Nervous Tissue :
➤ Neurons – Soma, dendrites, axons, ganglia (PNS), nuclei (CNS) Glia astrocytes, oligodendrocytes, Schwann cells, microglia – blood-brain barrier
Figure: Types of Tissue
Definition of Epithelial Tissue
These are collection of closely aggregated cells with very little extra-cellular substance which covers the body surface and lines body cavities.
Or
Epithelial tissue may be defined as a collection of cell, covering both external and internal surface of body.
Characteristics of Epithelial Tissue
1. Structure; Consists of maximum cellular element and little or no extracellular substance.
2. Layer of cell and basement membrane: Cells arranged in single or multiple layers resting on a basement membrane.
3. Size and shape of epithelial cells: Widely varied, ranging from high columnar to simple squamous
4. Vascularity: The epithelium is avascular. Gets nutrition and oxygen via diffusion from underlying capillary of adjacent connective tissue.
5. Nerve supply: Epithelial surface has nerve supply.
6. Regeneration: Most epithelia are continuously renewed and replaced.
7. Lining of surface: Epithelium lines all body surfaces and cavities.
Classification of Epithelial Tissue:
Epithelial tissue can be classified into two ways
1. Covering epithelium
2. Glandular epithelium
A. Covering epithelium:
a) Uni-layered:
➤ Simple:
- Squamaous e.g. Endothelium.
- Cuboidal e.g. Covering of ovary.
- Columner e.g. Stomach.
➤ Pseudostratified e.g. Trachea.
b) Multilayered:
➤ Stratified:
- Squamaous e.g. Epidermis.
- Cuboidal e.g. Sweat gland
- Columnar e.g. Conjunctiva,
➤ Transitional e.g. urinary bladder.
B. Glandular epithelium:
a) Exocrine glands e.g. sweat gland.
b) Endocrine gland e.g. Thyroid gland.
Figure: Types of Epithelial Tissue
Functions of Epithelial Tissue:
- Covering and living the surfaces e.g. skin.
- Protection e.g. Epidermis, conjunctiva.
- Absorption e.g. Intestine.
- Reabsorption e.g. renal tubule
- Prevents reabsorption e.g. transitional epithelium
- Secretion e.g. the epithelial cells of the glands.
- Sensory function e.g. Neuroepithelium.
- Contractile function e.g. Myoepithelial cells.
- Prevents water loss. e.g. Skin.
- Trans-cellular transport of molecules across the epithelial layer.
Connective Tissue
Definition of Tissue:
These are a group of tissues structurally composed of cell, fibres & ground substance which is responsible for maintaining a functionally integrated body.
Characteristics of Connective Tissue:
1. Cellular component is minimum, whereas intercellular substance is maximum.
2. Cells, fibers and ground substance are present.
3. Both blood and nerve supplies are present.
Functions of Connective Tissue:
1. Connect & bind the cells and organs and thus give support to the body
2. Provide a tight covering for deeper structures, especially in the limbs.
3. Hold bone ends together at joints & provide attachment of many muscles.
4. Provide planes along which blood vessels, nerves & lymphatic’s travel to their destination.
5. Helps in tissue healing or repair.
6. Defense- Macrophages & plasma cells destroy invading foreign particles
7. Storage- In the form of adipose tissue, it acts as store of nutritive substance.
Classification of Connective Tissue:
1. Connective tissue proper
A. Loose Connective Tissue
a) Areolar
b) Adipose
c) Reticular
B. Dense Connective Tissue
a) Dense regular
b) Dense irregular
c) Elastic
2. Cartilage
A. Hyaline
B. Elastic
C. Fibrocartilage
3. Bone (osseous tissue)
4. Blood
Figure: Types of Connective Tissue
Difference between Epithelial Tissue & Connective Tissue:
| Basis for Comparison | Epithelial tissue | Connective tissue |
| Made up of | Cells and small amount of intercellular matrix. | Cells and a huge amount of intercellular matrix |
| Develops from | It develops from the endoderm or mesoderm or ectoderm from the embryological germ layer. | Develops from mesoderm (embryonic mesodermal origin). |
| Arrangement | These cells are arranged in layers which can be either single or multi- layer. | Here cells are present in scattered form in the matrix and does not show any arrangement. |
| Surrounded by | Does not surrounded by blood capillaries. | These cells are surrounded by blood capillaries. |
| Location | These tissues lie above the basement membrane. | These tissues lie below basement membrane, called lamina propia. |
| Bounded by | Special proteins, desmosomes and hemidesomes. | Blood capillaries and materials like elastic or collagen fibres |
| Can be found | Lungs, kidneys, skin, mucous membranes | Bones, nerves, ligaments, tendons, blood. |
Muscular Tissue
Definition of Muscular Tissue:
Muscle is a specialized type of tissue containing contractile proteins which can perform the function of movement by the process of contraction & relaxation.
Types of Muscle:
1. Skeletal muscle – Voluntary, striated, attached to skeleton
2. Cardiac muscle – Involuntary, striated, present in heart.
3. Smooth muscle – Involuntary, non-striated, present in intestine, blood vessels etc.
Difference between Skeletal, Cardiac and Smooth Muscle
| Skeletal Muscle | Smooth Muscle | Cardiac Muscle |
| Striated | Not striated | Striated |
| Voluntarily controlled | Involuntarily controlled | Involuntarily controlled |
| Cells have many nuclei that are peripheral to their fibers | Cells have only one nucleus at the center | Cells have only one nucleus at the center |
| Attached to bones | Found on hollow internal organs such as stomach and blood vessels | Found on the heart’s wall |
| Responsible for movement of the skeleton and muscles | Responsible for the movement of substances such as food and blood | Responsible for moving blood in the heart |
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