Tissues Groups of cells similar in structure and function The four types of tissues Epithelial Covers and lines body cavities both inside and outside of the body. Connective Protects and insulates vital organs and fills body cavity spaces. Connects different type of tissues to each other. Muscle Functions in locomotion, digestive and cardiovascular functions. Nerve Communicate electrical impulses which facilitates the action of both muscles and glands.

Epithelial Tissue Covers the entire surface of the body Skin and reproductive tracts Barriers between what is in and out of the body. Lining of the lung, digestive and urinary tracts controls what substances enter/exit the body and what substances stay in/out of the body Specialized type types of epithelial tissue include: exocrine glands secrete substances outside of the body (sweat, salivary) endocrine glands secrete substances (hormones) into the blood (insulin, growth hormone)

Epithelial Membranes Serous – moist membranes that line internal organs.

Epithelial Membranes

Classification of Epithelial Tissues Epithelial tissue is classified based on 2 criteria: Shape and number of layers Cell shape squamous (flattened cells) cell width is larger than cell height cuboidal (cube-like cells) cell width is equal to cell height columnar (column-like cells) cell height is larger than cell width

Classification of Epithelial Tissues Number of layers of epithelial cells Simple Thin layer allows for exchange of substances into or out of the body Stratified Multiple layers protects act as a natural barrier to prevent abrasion, puncture.

Epithelia: Simple Squamous Figure 4.2a

Epithelia: Simple Cuboidal Single layer of cubelike cells with large, spherical central nuclei Function in secretion and absorption Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface Figure 4.2b

Epithelia: Simple Columnar Figure 4.2c

Epithelia: Pseudostratified Columnar Single layer of cells with different heights; some do not reach the free surface Nuclei are seen at different layers Function in secretion and propulsion of mucus Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated) Figure 4.2d

Epithelia: Stratified Squamous Thick membrane composed of several layers of cells Function in protection of underlying areas subjected to abrasion Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells) Figure 4.2e

Epithelia: Transitional Several cell layers, basal cells are cuboidal, surface cells are dome shaped Stretches to permit the distension of the urinary bladder Lines the urinary bladder, ureters, and part of the urethra Figure 4.2f

Connective Tissue Widely spaced cells separated by fibers and ground substance. Most abundant and variable tissue type Connective tissue proper Dense Regular and Irregular Loose Areolar, Adipose, Reticular. Cartilage Hyaline, Elastic, Fibrocartilage Bone Spongy, Compact Blood Fluid connective tissue (plasma ) red blood cells, white blood cells, platelets Functions connects organs gives support and protection (physical and immune) stores energy and produces heat movement and transport of materials

Connective Tissue Figure 4.5

Structural Elements of Connective Tissue

Cells of Connective Tissue Fibroblasts produce fibers and ground substance Adipocytes store triglycerides Chondroblasts – produce cartilage Osteoblasts – build bone Hematopoietic stem cells – blood White blood cells, plasma cells, macrophages, and mast cells

Fibers of Connective Tissue Collagen fibers (white fibers) tough, stretch resistant, yet flexible tendons, ligaments and deep layer of the skin Reticular fibers thin, collagen fibers coated with glycoprotein framework in spleen and lymph nodes Elastic fibers (yellow fibers) thin branching fibers of elastin protein stretch and recoil like rubberband (elasticity) skin, lungs and arteries stretch and recoil

Connective Tissue Ground Substance Gelatinous material between cells absorbs compressive forces attract sodium and hold water

Ground Substance: Proteoglycan Structure Figure 4.6b

Fibrous Connective Tissue Types Loose connective tissue gel-like ground substance between cells types areolar reticular adipose Dense connective tissue fibers fill spaces between cells types vary in fiber orientation dense regular connective tissue dense irregular connective tissue

Loose Connective Tissue Proper: Areolar

Areolar Connective Tissue Figure 4.8b

Connective Tissue: Embryonic Figure 4.8a

Adipose Connective Tissue

Reticular Connective Tissue Figure 4.8d

Connective Tissue: Dense Regular Figure 4.8e

Connective Tissue : Dense Irregular Figure 4.8f

Connective Tissue: Hyaline Cartilage Figure 4.8g

Connective Tissue: Elastic Cartilage Similar to hyaline cartilage but with more elastic fibers Maintains shape and structure while allowing flexibility Supports external ear (pinna) and the epiglottis Figure 4.8h

Connective Tissue: Fibrocartilage Cartilage Matrix similar to hyaline cartilage but less firm with thick collagen fibers Provides tensile strength and absorbs compression shock Found in intervertebral discs, the pubic symphysis, and in discs of the knee joint Figure 4.8i

Connective Tissue: Bone Figure 4.8j

Connective Tissue: Blood Figure 4.8k

Nervous Tissue Figure 4.10

Muscle Tissue: Skeletal Long, cylindrical, multinucleate cells with obvious striations Initiates and controls voluntary movement Found in skeletal muscles that attach to bones or skin Figure 4.11a

Muscle Tissue: Cardiac Branching, striated, uninucleate cells interdigitating at intercalated discs Propels blood into the circulation Found in the walls of the heart Figure 4.11b

Muscle Tissue: Smooth Figure 4.11c

Tissue Shrinkage and Death Atrophy = loss of cell size or number disuse atrophy from lack of use (leg in a cast) Necrosis = pathological death of tissue gangrene - insufficient blood supply Diabetic complications. infarction - death of tissue from lack of blood Heart attack or cerebral vascular accident ( stroke) decubitus ulcer - bed sore or pressure sore Pressure cuts off blood supply to a specific part of body.

Diabetic Ulcer Bedsores