Tissues Groups of cells similar in structure and function The four types of tissues –Epithelial...
Transcript of Tissues Groups of cells similar in structure and function The four types of tissues –Epithelial...
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
Figure 4.2b
• 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
Epithelia: Simple Columnar
Figure 4.2c
Epithelia: Pseudostratified Columnar
Figure 4.2d
• 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)
Epithelia: Stratified Squamous
Figure 4.2e
• 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)
Epithelia: Transitional
Figure 4.2f
• 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
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
Figure 4.8h
• Similar to hyaline cartilage but with more elastic fibers
• Maintains shape and structure while allowing flexibility
• Supports external ear (pinna) and the epiglottis
Connective Tissue: Fibrocartilage Cartilage
Figure 4.8i
• 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
Connective Tissue: Bone
Figure 4.8j
Connective Tissue: Blood
Figure 4.8k
Nervous Tissue
Figure 4.10
Muscle Tissue: Skeletal
Figure 4.11a
• Long, cylindrical, multinucleate cells with obvious striations
• Initiates and controls voluntary movement
• Found in skeletal muscles that attach to bones or skin
Muscle Tissue: Cardiac
Figure 4.11b
• Branching, striated, uninucleate cells interdigitating at intercalated discs
• Propels blood into the circulation
• Found in the walls of the heart
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