Tissue A tissue is a group of similar

Tissue • A tissue is a group of similar cells, that function together to carry out specialised activities There are four types 1. Epithelial tissue 2. Connective tissue 3. Muscular tissue 4. Nervous tissue 1

Epithelial Tissue • • • Makes up 3% of your body weight They don’t move They don’t send messages Their cells are all touching one another Of all tissues, they are the most widely varied in structure and function 2

Locations of Epithelial Tissues • Covers the body (epidermis) • Found on the inside of hollow organs and the outside of all organs • Found above a connective tissue layer (epi = above) • Lines the cavities, tubes, ducts, and blood vessels inside the body 3

Epithelial Anatomy • Apical surface – upper surface that is free or exposed to the “exterior” • Basal surface – attached surface (below) • Microvilli – small fingerlike extensions that increase the surface area allowing for more work to be done 4

Functions of Epithelial Tissue – Protects from physical & chemical injury – Protects against microbial infection – Contains nerve endings which respond to stimuli – Filters, secretes & reabsorbs materials – Secretes fluids to lubricate joints 5

Types of Epithelial Membranes • Mucous or mucosa– lining of tubes; moistens and protects from enzymes (stomach, trachea, and vagina) • Serous or serosa – outside of organs; lubricates (all thoracic, abdominal and pelvic organs) • Cutaneous or skin – body surface; protection • Synovial – synovial joints; lines and protects synovial cavities (elbow, knee, hip, etc. ) 6

General Features of Epithelial Tissue 1. The cells are arranged in continuous sheets single or continuous layers. 2. Have an apical surface exposed to a body cavity, lining of an internal organ or the exterior of the body; lateral surface facing adjacent cells on either side, basal surface which are the deepest layers of the cell 3. Lack blood vessels get nutrients by diffusion. 4. They have a nerve supply. 5. They have a high capacity for renewal by cell division. 7

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Arrangement of cells in layers Simple epithelium • Is a single layer of cells that functions in diffusion, osmosis, filtration, secretion and absorption. • Secretion is the production and release of mucus, sweat or enzymes. • Absorption is the intake of fluids or other substances such as digested food from the intestinal tract 9

Arrangement of cells in layers Stratified epithelium (stratum = layer) • Consists of two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear 10

Three Basic Shapes • Squamous – like scales, or pancakes (“being squashed like a pancake”) • Cuboidal – looks like cubes • Columnar – longer and look like columns 11

Squamous Epithelium • Simple – one cell thick • Forms solid layer of cells which line blood vessels, body cavities and covers organs in body cavities • Stratified – multiple layers • Forms epidermis 12

Simple Squamous Epithelium • Found in parts of the body where filtration (kidneys) or diffusion (lungs) are priority processes. • Simple squamous epithelium that lines the heart & blood vessels is known as endothelium. 13

Simple Squamous 14

Simple cuboidal epithelium • Found in organs such as the thyroid gland kidneys. • Performs the functions of secretion and absorption. 15

Cuboidal Epithelium Cuboid Cells • Simple – one cell thick Duct • Roughly cube shaped Cuboid Cells • Line ducts in kidneys where re-absorption and secretion activities take place. Duct 16

Simple Cuboidal 17

Columnar Epithelium • Simple – one cell thick • Column shaped (long and narrow) • Lines digestive tract where re-absorption & secretion occurs. 18

Simple columnar epithelium • There are ciliated and non ciliated Non ciliated: • Those with microvilli increase the surface area of the plasma membrane. =increasing the rate of absorption of the cell. • Goblet cells secret mucus • Mucus serves as a lubricant for the lining of the digestive and respiratory tract. • It helps trap dust entering the respiratory tract. • Prevents destruction of the stomach lining by acid secreted by the stomach. 19

Nonciliated Simple Columnar 20

Simple columnar epithelium Ciliated simple columnar epithelium • Contain cells with cilia at their apical surface. • In some parts of the upper respiratory tract mucus secreted by the goblet cells forms a film over the respiratory surface that traps inhaled foreign particles. • The cilia move the foreign particles towards the throat where it can be coughed up swallowed or spit out. 21

Ciliated Simple Columnar 22

Stratified epithelium Stratified squamous epithelium • Cells in the apical layer are flat. • The basal (deepest) cells continuously undergo cell division. • The cells are pushed upwards towards the surface. • At the apical layer the cells die replaced by cells emerging from the basal cells. 23

Stratified Squamous Epithelium 24

Connective Tissue • Protects and supports the body and its organs together, stores energy reserves as fat & provides immunity Examples: • Cartilage • Bone tissue • Liquid connective tissue (blood tissue) • Adipose tissue 25

Connective Tissue • Binds together, supports and strengthens other body tissues • Protects and insulates internal organs • Compartmentalizes structures such as skeletal muscle • The major transport system within the body • Site of stored energy reserves • Main site of immune responses 26

General Features of Connective Tissue • 2 basic parts: – Cells and Matrix • Matrix – material between widely spaced cells – Consists of protein fibers and ground substance 27

General Features of Connective Tissue • Does not occur on free surfaces • Has a nerve supply (except cartilage) • Highly Vascular (except cartilage and tendons) 28

Connective Tissue 29

Adipose tissue • Has cells called adipocytes. • They are specialised for the storage of triglycerides (fats). • Adipose tissue is a good insulator and can reduce heat loss through the skin. 30

Adipose tissue • It is a major energy source. • It protects various organs. • As the amount of adipose tissue increases with weight gain new blood vessels form. • Thus an obese person has more blood vessels than a lean person. • A situation that can cause high blood pressure since the heart has to work harder. 31

Adipose Tissue 32

Connective Tissue Matrix – Fibers • Strengthens and supports connective tissue – Collagen Fibers • Strong, resist pulling forces, flexible • Made of the protein collagen which is the most abundant protein in your body – Elastic Fibers • Smaller in diameter than collagen fibers, branch to form network • Made of the protein elastin 33

Muscular Tissue • Generates the physical force needed to make body structures move. 34

MUSCLE TISSUE • Abundant, dense tissue – 40 -50% of body weight • High metabolic activity – high energy use/output; – O 2 consumption; – CO 2 production 35

Functions of Muscle Tissue • Produce movement by contracting – Locomotion & manipulation – Movement of blood, food, urine, etc through hollow organs • Maintenance of posture • Stabilize joints – so that other muscles can produce movement or maintain posture • Heat production – Maintenance of body temperature. 36

Three Kinds of Muscle Tissue • Skeletal muscle: – Striated, usu. voluntary, attached to skeleton • Cardiac muscle: – Striated, involuntary, walls of heart • Smooth muscle: – Non-striated, involuntary, wrapping of hollow organs – Stomach, intestines, arteries, bladder, vas deferens, uterus, etc. 37

Muscle Tissue Types · Skeletal muscle · Can be controlled voluntarily · Cells attach to connective tissue · Cells are striated · Cells have more than one nucleus 38

Muscle Tissue Types · Cardiac muscle · Found only in the heart · Function is to pump blood (involuntary) · Cells attached to other cardiac muscle cells at intercalated disks · Cells are striated · One nucleus per cell 39

Muscle Tissue Types · Smooth muscle · Involuntary muscle · Surrounds hollow organs · Attached to other smooth muscle cells · No visible striations · One nucleus per cell 40

Nervous Tissue • Detects changes inside and outside the body and initiates and transmits nerve impulses that coordinate body activities to help maintain homeostasis. 41

Nervous Tissue · Neurons and nerve support cells · Function is to send impulses to other areas of the body · Irritability · Conductivity 42

Tissue Repair · Regeneration · Replacement of destroyed tissue by the same kind of cells · Fibrosis · Repair by dense fibrous connective tissue (scar tissue) 43

Regeneration of Tissues · Tissues that regenerate easily · Epithelial tissue · Fibrous connective tissue and bone · Tissues that regenerate poorly · Skeletal muscle · Tissues that are replaced largely with scar tissue · Cardiac muscle · Nervous tissue within the brain and spinal cord 44