Chapter 5 - Tissues Groups of cells that have specialized structural and functional roles

There are 4 types of tissues in the human body.

1.Epithelial – covering, lining 2.Muscle – contracts 3.Connective – bone, adipose (fat), blood, etc. 4.Nerve – sends impulses

Epithelial Tissue Anchored to a basement membrane that is anchored by its underside to connective tissue. The basement membrane is NONLIVING. Always has a free space exposed to the outside or open space internally - lumen

Characteristics of Epithelial Tissues Usually lack blood vessels Readily divide Tightly packed for protection Secretion, absorption, excretion, sensory reception

Organized by layering and cell shape

By layering Simple – extends from basement membrane to lumen – 1 layer Stratified – layered from basement membrane to lumen area Pseudostratified – “seemingly-layered”, but not Nuclei at various levels of cells makes the appearance of layers

By cell shape Squamous – flat cells Cuboidal – cube-shaped Columnar – elongated and thin – like columns

Usually both designations are used to distinguish the type of epithelial tissue!!! ** Denotes that you should know of an example or where these are located in the human body. You will be expected to know this.**

**Simple Squamous Epithelium

What would this be used for or where would we find it? Nuclei are broad and thin Diffusion occurs here Where? –Alveoli –Capillary walls

Simple Cuboidal Epithelium

What would this be used for or where would we find it? Nuclei are spheres Secretion and absorption More protection than previous kind Where? –Lines kidney tubules –Ducts of salivary glands and pancreas

Simple Columnar Epithelium

What would this be used for or where would we find it? Thicker than either previous ones Nuclei near basement membrane Have microvilli and goblet cells Where? –Lines uterus –Lines most organs of digestive tract

**Pseudostratified columnar Epithelium

What would this be used for or where would we find it? Appear layered, but are not (nuclei at various levels) Commonly have cilia and goblet cells Where? –Line respiratory tract

**Stratified Squamous Epithelium

What would this be used for or where would we find it? Many layers thick Division of cells in deep layer push old out Where? –Epidermis of skin – keratin –Mouth lining –Vagina lining –Anal canal

Stratified Cuboidal Epithelium

What would this be used for or where would we find it? More protection than simple 2 or 3 layers of cuboidal cells that form lining of lumen Where? –Lines mammary glands –Sweat glands –pancreas

Stratified Columnar Epitheliem

What would this be used for or where would we find it? Layers Where? –Male urethra and vas deferens –pharynx

**Transitional Epithelium

What would this be used for or where would we find it? Changes in response to an increase in tension Where? –Inner lining of urinary bladder –Lines urethra

**Glandular Epithelium

There are two basic kinds of glands: Exocrine – secrete products into ducts Endocrine – secrete products into tissue fluid or blood

Cells in these glandular tissues secrete fluids a number of ways: Merocrine – release watery, protein-rich fluids by exocytosis Apocrine – lose small portions during secretion Holocrine – entire cell lyses during secretion Kinds of fluids: Serous cells – watery fluids released Mucous cells – thicker mucin released

Section 5.3 – Connective Tissues

Connective tissue serves many purposes in the body: binding supporting protecting forming blood storing fats filling space

There is a matrix of fibers, cells, and ground substance Usually, the cells can divide and have a good blood supply and nourishment.

Major Cell Types: Fibroblasts – large, star-shaped Macrophages – “wandering cells” – are scavengers and defensive cells – phagocytes Mast cells – large and located near blood vessels – release heparin and histamine

Connective Tissue Fibers 1.Collagenous Fibers – thick threads of the protein collagen – form dense, connective tissue – appear white - in ligaments and tendons 2.Elastic Fibers – composed of thinner elastin – allow stretching – appear yellow – in vocal chords 3.Reticular Fibers – thin, collagenous fibers – branched for delicate support

Collagen Fibers

Elastin Fibers

Types of Connective Tissue 1. Loose Connective Tissue (areolar) 2. Adipose Tissue 3. Dense Connective Tissue 4. Cartilage 5. Bone 6. Blood

1. Loose Connective Tissue – (Areolar) Delicate, thin, membranes Contains many fibroblasts located apart that secrete collagen and elastin fibers Fills spaces Binds skin to underlying organs **See transparency

2. Adipose Tissue Fat Forms when connective tissue stores fat in droplets and they enlarge to crowd out other cells

3. Dense Connective Tissue Closely-packed, thick, collagenous fibers Few cells Very strong Ligaments and Tendons See transparency

4. Cartilage Rigid Chondrocytes Perichondrium NO direct blood supply to cartilage

Hyaline Cartilage Most common Ends of bones, soft part of nose, between ribs

Elastic Cartilage Elastic fibers Flexible External ears, larynx

Fibrocartilage Tough tissue with many collagenous fibers Shock absorber Pads between bones

5. Bone Most rigid of connective tissue Mineral salts and collagen Supports, portects, forms blood cells, stores Ca and P Osteonic canals Osteocytes canaliculi

6. Blood RBC’s, WBC’s, platelets, plasma

Section 5.4 – Muscle Tissues – contractile fibers

Skeletal Muscle Attach to bones Voluntary Striations A nerve impulse stimulates contraction

Smooth Muscle No striations Involuntary On walls of internal organs

Cardiac Muscle Only in heart Striations Involutary Branched fibers Intercalated discs

Section 5.5 – Nervous Tissues

Neurons In brain, spinal cord, and peripheral nerves Sense and respond by sending impulses to muscles or glands Coordinate, regulate, and integrate functions **Neuroglial cells