1. Body Tissues
Anatomy & Physiology

2. Body Tissues
Tissues are groups of cells that are similar in structure and function
Four primary types of tissue:
Epithelium - Covering
Connective - Support
Muscular - Movement
Nervous - Control

3. Epithelium Tissue
Epithelium tissue is the lining, covering, and glandular tissue of the body.
Glandular epithelium forms various glands in the body.
Lining and covering epithelium cover all free body surfaces and contain versatile cells with specific functions.

4. Function of Epithelium Tissue
The function of epithelium tissue is to protect, absorb, filter and secrete.
Examples
Skin protects against bacterial and chemical damage.
Lining of digestive system absorbs food into the body.
Kidney lining absorbs and filters.
Glands secrete substances such as perspiration, oil and mucus.

5. Excrete vs Secrete
“Secretion” &“excretion” are the same in nature since both are involved in passage or movement of materials.
“Excretion” is the removal of material from a living thing while “secretion” is the movement of material from one point to another.
Excretion is mostly body wastes while secretion is important materials that can be metabolized and used by our bodies (enzymes, hormones, saliva, mucous) Read more: Difference Between Excretion and Secretion | Difference Between | Excretion vs Secretion 

6. Characteristics of Epithelial Tissue
Fit closely together to form sheets
Always have one free surface or edge
Lower surface rests on basement membrane (structure-less material secreted by cells)
Avascular (they have no blood supply)
Regenerate easily

7. Classification of Epithelial Tissue
Epithelial tissue is classified into two main categories: simple and stratified
Simple epithelial has a single layer of cells.
Stratified epithelial has multiple layers of cells
Tissue is further classified by cell shape into three more categories:
squamous (flat),
cuboidal (cube-shaped)
columnar (column-shaped) cells.

8. Simple Epithelium
Simple epithelium cells mostly absorb, secrete and filter.
Simple squamous cells usually filter
Found in air sacs of lungs and capillaries
Simple cuboidal cells secrete and act as lining
Common in glands
Simple columnar cells produce mucous
Goblet cells in digestive tract
Pseudostratified columnar absorb and secrete
Lining of respiratory tract

9. Stratified Epithelium Tissue
Stratified epithelium’s main function is to protect.
Stratified squamous cells protect areas with high friction such as mouth and esophagus
Stratified cuboidal and columnar are found mainly in large glands
Transitional epithelium are highly modified stratified squamous cells and are found in the lining of organs like the bladder.

10. Glandular Tissue
A gland consists of one or more cells that secrete a particular product.
Two major types of glands:
Endocrine – they secrete hormones directly into blood vessels Ex. Thyroid, adrenals and pituitary
Exocrine – Secrete products like sweat and oil through ducts

11. Connective Tissue Common Characteristics of connective tissue are:
Protect, support and bind together body tissues
Well-vascularized (good blood flow)
Extracellullar matrix containing ground substance

12. Types of Connective Tissue
The five different types of connective tissue are:
Bone
Cartilage
Dense connective tissue
Loose connective tissue
Blood

13. Bone
Bone or osseous tissue forms the framework of the body and consists of two types of supporting tissues: cartilage and bone
Bones are composed of cartilage at birth and are slowly replaced by calcium and phosphorous salts as the body grows and matures.

14. Cartilage
Cartilage works along with bone as the support system for the body, provides cushioning & elastic support.
There are three types of cartilage:
Hyaline
Elastic
Fibrocartilage
Cartilage is composed of a nonliving material called the matrix.

15. Hyaline Cartilage
Hyaline cartilage is the most common cartilage in the body.
Hyaline is composed of collagen fibers and a rubbery matrix
A fetal skeleton is entirely composed of hyaline cartilage which is then converted to bone tissue over time.

16. Elastic Cartilage
Elastic cartilage is denser than hyaline cartilage and provides elasticity to the body structure.
Elastic cartilage is present in the external ear and nose.

17. Fibrocartilage
Fibrocartilage is more highly compressible than the other types of cartilage and thus is used to cushion body structures.
Fibrocartilage makes up the discs between the vertebrae of the spine.

18. Dense Connective Tissue
Dense connective tissue forms strong rope-like structures.
The main matrix element is collagen.
Cells that make up the tissue are called fibroblasts.
Example
Tendons
Ligaments

19. Loose Connective Tissue
Loose connective tissue makes up the soft, pliable structures of the body.
It has more cells and fewer fibers than other connective tissues
Includes: areolar tissue, adipose tissue, and reticular connective tissue

20. Areolar Tissue
Areolar tissue is the most widely distributed tissue in the body.
The soft, pliable tissue contains all of the fiber types.
Is found beneath epithelial tissues, attaching them to underlying tissues & allows for diffusion of nutrients to epithelium; also soaks up excess fluid.

21. Adipose Tissue
Adipose tissue is commonly called fat because the cells contains large, fat deposits.
It forms the subcutaneous tissue beneath the skin.
Adipose tissue works to insulate the body and protect organs from injury by providing a protective layer.

22. Reticular Connective Tissue
Reticular connective tissue is made up of a delicate network of fibers and reticular cells.
It forms the stroma or internal framework in organs like the spleen, lymph nodes, and bone marrow to support blood cells.

23. Blood
Blood is considered a connective tissue because the blood cells are suspended in a nonliving, fluid matrix called blood plasma.
The fibers of blood are the proteins that become visible during clotting.
Blood is the transport vehicle for oxygen, carbon dioxide, nutrients, antibodies, WBC & platelets throughout the cardiovascular system.

24. Muscle Tissue
Muscle tissues are specialized to contract and shorten, & are attached to bones to produce movement.
Three types of muscle tissue:
Skeletal
Cardiac
Smooth

25. Skeletal Muscle Tissue
Skeletal muscle has long cylindrical multinucleated cells with obvious striations or stripes.
Skeletal muscle can be controlled voluntarily and forms the flesh of the body.
When the skeletal muscles contract, they pull on bones and tissues to cause movements.

26. Cardiac Muscle Cardiac muscle is found only in the heart.
As it contracts, the heart acts as a pump and propels blood through the blood vessels.
Cardiac cells are also striated, but they are uninucleated with relatively short, branching cells that fit together at intercalated disks where the electrical impulse pass quickly between cells.
Cardiac muscle is under involuntary control.

27. Smooth Muscle Smooth or visceral muscle has no visible striations.
The cells have a single nucleus and are spindle-shaped (pointed at each end).
Smooth muscle is found in the walls of hollow organs like the stomach, bladder uterus and blood vessels.
Smooth muscle contracts much slower than the other two types and is involuntary.

28. Nervous Tissue Nervous tissue is made up of cells called neurons.
All neurons receive &conduct electrochemical impulses from one part of the body to another.
Structure of neurons is unique with their cytoplasm drawn out into long processes which allow a single neuron to conduct signals over long distances.
Neurons have a special group of supporting cells that insulate and protect them.