VTEC 1101 AP Epithelial Tissues PDF

Chapter 5- Epithelial Tissues Chapter 5- Epithelial Tissues Tissues are cells of similar type and function clustered together Gross vs microscopic anatomy Gross anatomy is the study of anatomic structures that can be seen with the naked eye Microscopic anatomy (microanatomy) is the study of the m...

Chapter 5- Epithelial Tissues Chapter 5- Epithelial Tissues Tissues are cells of similar type and function clustered together Gross vs microscopic anatomy Gross anatomy is the study of anatomic structures that can be seen with the naked eye Microscopic anatomy (microanatomy) is the study of the microscopic structures of tissues and organs There are 4 basic types of animal tissues: 1. Epithelial -> covers and lines 2. Connective -> provides support 3. Muscle -> enables movement 4. Nervous -> controls work 1. Epithelial Tissue 5 of T functions E.. *➔ Composed of sheets of cells that cover and line other tissues ◆ Protects, covers, and lines ◆ Filters biochemical substances ◆ Absorbs nutrients ◆ Provides sensory input ◆ Secretions and excretions of biochemical substances Glandular epithelia is responsible for the manufacture and release of substances * ➔ Characteristics of epithelia 15 total ◆ Cells are organized into tightly packed groups that form sheets of tissues; sheets can be single or multiple layers of cells Epithelial cells are polar, refers to the fact that these cells have distinct structural and functional differences between their top and bottom surfaces ○ Has an apical surface  ◆ The side of the cell that faces the lumen or body cavity ○ Has a basal surface ◆ The side of the cell that faces the underlying connective tissue Have lateral surfaces that are connected to neighboring cells by junction complexes Cells are avascular meaning they lack blood vessels or capillaries Most epithelial cells are innervated and provide valuable sensory input ➔ Cellular attachments (4 total) ◆ How cells are held together ◆ Plasma membranes join to form specialized attachments called junctional complexes Tight junctions (Belt) ○ Formed by the fusion of the outermost layers of the plasma membranes of adjoining cells ○ Prevents the passage of substances from the luminal end to the basal end of the cell ○ Found in tissues where there can be no leaks ◆ Urinary bladder and digestive tract Desmosomes (Velcro) ○ Is a strong, welded plaque or thickening which connects the plasma membranes of adjacent cells ○ Intermediate filaments called tonofilaments extend from the plaque into the cytoplasm like anchors ○ Most commonly found in tissues that undergo a lot of tensions and stretching; skin, heart, and uterus ○ Hemidesmosomes look like half of a desmosomes and link epithelial cells to the basement membrane Gap junctions  ○ Cells are linked by tubular channel proteins called connexons ◆ These proteins allow the exchange and passage of ions and nutrients ○ Extend from the cytoplasm of one cell to the cytoplasm of the other ○ Exact function in epithelial cells is not fully understood but in cardiac and smooth muscle cells ◆ Have the ability to transport electrical signals quickly between cells Basement membrane (AKA basal lamina) C4pts) ○ The foundation of the epithelial cell ○ A nonliving meshwork of fibers that cements the epithelial cell to the underlying connective tissue ○ Its strength and elasticity help prevent the cell from being torn off ○ Act as a partial barrier between the epithelial cell and the underlying connective tissue # ➔ Surface specialization ◆ Surfaces vary depending on their location and their role in the function of the tissue ◆ The epithelia that line blood vessels; Have smooth surfaces to allow easy passage of blood cells ◆ Other epithelia; Have irregular surfaces covered with microvilli or cilia ○ The surface of a cell covered with microvilli is called the brush border  Generally produce large quantities of mucus ○ May contain goblet cells or multicellular glands ○ Mucus composed of water, electrolytes, and a protein called mucin Some mucosae can also absorb ○ The epithelial layer in the intestine transfers nutrients ◆ Serous membranes (serosae) Line walls and cover organs that fill closed body cavities Continuous sheets doubled over to form 2 layers with narrow space between them ○ Parietal layer (lines cavity wall) ○ Visceral layer (lines surface of organs) A single sheet of simple squamous epithelium bound to underlying layer of loose connective tissue Produces thin, watery serosal fluid ○ Serosal fluid is transudate meaning fluid can squeeze through tissue ○ Contains electrolytes, but no mucin ○ Creates moist and slippery surfaces to reduce fiction between organs and between organs and cavity wall ○ Transudate in thorax = pleural fluid, abdomen = peritoneal fluid, heart = pericardial fluid Normally small amounts found in body cavities ○ Excess fluid production during trauma = effusion ◆ Excess fluid in peritoneal = ascites Can be caused by congestive heart failure nephrosis and peritonitis ○ Low amounts of serosal fluid cause adhesions and may alter functions of organs Visceral layers merge to form mesenteries in the abdominipelvic cavity, they secure organs to the body wall ○ Mesentery in stomach = omentum ○ Mesentery in uterus = broad ligament ◆ Cutaneous membranes (integument or skin) Always exposed to outside environment Composed of an outer keratinized stratified squamous epithelium aka epidermis Epidermis is attached to an underlying layer of dense irregular connective tissue called dermis ◆ Synovial membranes Line the cavities of joints Have no epithelium, only connective tissue ○ Loose connective tissue and adipose tissue covered by a layer of collagen fibers and fibroblasts Manufacture synovial fluid that fills joint spaces Muscle Tissue Muscle Tissue ➔ Muscle cells or muscle fibers are designed for contraction ◆ Fibers are composed of proteins called actin and myosin ◆ When microfilaments slide over each other = contractions ➔ 3 types of muscle tissues: ◆ Skeletal (voluntary striated muscle) Contains many large cells, so there are lots of nuclei and mitochondria Controlled through conscious effort = voluntary muscle Are striated (striped) Collagen fibers surrounding cells merge with collagen fibers in tendons to attach muscle to bone ◆ Smooth (nonstriated involuntary muscle) Composed of small, spindle shaped cells, nonstriated Contractions no consciously controlled = involuntary Found in walls of hollow organs ○ Blood vessels, urinary bladder, uterus, intestines, stomach, exocrine glands Responsible for peristalsis (wave like movement of muscle) in the GI tract ◆ Cardiac (involuntary striated tissue) Only found in the heart Cells are small and branched, only 1 nucleus Muscle cells are striated and connected via intercalated disks Nervous Tissue Nervous Tissue ➔ Designed to receive and transmit electrical signals throughout the body ➔ Found in: brain, spinal cord, peripheral nerves ➔ 2 general cell types: ◆ Neurons Longest cells in the body Composed of 3 parts ○ Perikaryon (cell body) ○ Dendrites ○ Axon ◆ Neuroglial cells Neural tissues have more neuroglial cells than neurons Functions: ○ Do not transmit impulses but serve to support the neurons ○ Isolate conductive membranes ○ Provide supportive framework ○ Supply nutrients ○ Phagocytize (ingest) or digest debris Tissue healing and repair ➔ The body response to injuries is inflammation: a series of events that develop quickly to limit further damage and eliminate harmful agents ➔ Repair occurs more slowly and involves the organization of granulation tissue and the regeneration of lost tissue 1. Inflammation a. Begins with a 5-10min period of vasoconstriction and later vasodilation b. Fluid from plasma pour into affected area, causing edema c. Clot formation begins, which slows bleeding  d. WBC squeeze through dilated capillaries to remove debris and microinvaders, these phagocytic cells are short lived, function for only a few hours before dying e. With increased blood flow, histamine and heparin are dispersed, the decrease in these molecules causes the return of normal capillary size and permeability 2. Organization a. Wound repair begins soon after injury i. Phogacytosis occurs and granulation tissue forms beneath the overlying blood clot or scab ii. If granulation tissue becomes too thick and stands out above the epithelial layer = proud flesh 1. Has to be cut down surgically 3. Regeneration or fibrosis a. While organization is happening, a new layer of epithelial tissue forms over the granulation tissue, this is called epithelialization b. Scab is pushed off c. The granulation tissue is slowly replaced by fibrous scar tissue i. Often results in the formation of fibrous adhesions Classifications of wound healing ➔ Wound repair may be classified as first or second intention ◆ First intention Edges of wound are held in close apposition ○ Superficial scratches or sutured wounds No granulation tissue formation or scarring ◆ Second intention Edges of wound are separated from each other Granulation tissue forms and results in scarring Chapter 6- Axial The skeletal system: Axial Types of skeletons: 1. Axial skeleton a. Located along central axis of body b. Bones of the head and trunk i. Skull, hyoid bone, spinal column, ribs, sternum 2. Appendicular skeleton a. Bones of thhe limbs 3. Visceral skeleton a. Bones formed in soft organs (viscera) i. Os penis Bone characteristics Second hardest natural substance in body Composed of cells embedded in a matrix ○ Osteocytes = osteoblasts and osteoclasts Osteoblasts harden the matrix through a process called ossification ○ When areas of bone are created, osteoblasts are trapped in lacunae ○ Once surrounded by bone, osteoblasts become osteocytes or bone cells Osteocytes only contact with each other through canaliculi Functions of bones: ○ Support, protection, leverage, storge, blood cell formation (hematopoiesis) Bone structure Cancellous bone (spongy bone) ○ Light and spongy ○ Consists of tiny spicules of bone that appear randomly arranged Spaces between the spicules are occupied by bone marrow ○ Trabecular bone Compact bone ○ Very heavy, dense, and strong ○ Composed of tiny, tightly compacted cylinders of bone called Haversian systems(osteon) that run lengthwise with the bone Composed of a concentric layers of ossified bone matrix arranged around a central Haversian canal The canal contains blood vessels, lymph vessels, nerves  ○ Canaliculi allow osteocytes to contact each other and exchange nutrients and wastes ○ Other than articular and joint surfaces, outer surfaces of bones are covered by a membrane called periossteum Outer layer is composed of fibrous tissue Inner layer contains osteoblasts ○ Another membrane, the endosteum, lines the hollow interior surfaces of bones Bone cells There are 3 types of cells that make up bone ○ Osteoblasts (b=build) Cells that form bone ○ Osteocytes Are osteoblasts surrounded by bone ○ Osteoclasts (c=chip) Remodel and remove bone NF-> Blood supply to bone Volkmann’s canals ○ Where blood vessels pass through in the bone matrix ○ Right angles to the Haversian canals ○ Blood vessels in Volkmann’s canals join with the blood vesselss in the Haversian canals to bring nutrition to osteocytes in the HS Large blood vessels enter large bones through channels called nutrient foramina ○ Carry blood into and out of the bone marrow ○ In xray, a NF looks like a fracture of bone cortex Bone formation joint in between Processes(projections): ○ lumps, bumps, and other projections on a bone ○ Are where tendons attach ○ Names depend on location Scapula - spine, acromion Humerus - tubercle Ulna - olecranon, anconeal Tibia - crest Femur - trochanter Atlas - wings Ilium - wings Ischium - tuberosity Tarsus - calcaneus  Foramen (foramina): ○ holes in bone ○ Usually nerve or blood vessel passes through ○ Hole in bones just to make them lighter Fossa/fovea: ○ depressed area -> allow muscles to move around ○ Usually occupied by muscles or tendons Bone marrow Fills the spaces within bones 2 basic types ○ Red bone marrow Is Hematopoietic tissue Forms blood cells Most common type in younger animals ○ Yellow bone marrow Primarily adipose connective tissue (fat) Most common type in adult animals Does not produce blood cells but can revert to red marrow if needed Skull 37-38 separate bones Most skull bones are united by jagged, immovable, fibrous joints called sutures Only mandible or lower jaw is connected to the rest of the skull by a freely moveable synovial joint We group the skull bones into regions: ○ The bones of the cranium Consist of external and internal ○ The bones of the ear (ossicles) 3 tiny bones hidden in middle ear ○ The bones of the face external=landmark bones internal=hidden bones External bones of the cranium Visible on the surface of an intact skull *Occipital 1 ○ Single bone form base of the skull ○ A large hole, the foramen magnum, is in the center *It is where the spinal cord exits the skull ○ There are 2 occipital condyles on either side of foramen magnum *It is the skull bone that forms a joint with neck Interparietal bones 2 ○ Are 2 small bones located on dorsal mindline between occipital and parietal bones ○ May fuse into 1 bone in older animals *Parietal bones 2 ○ The 2 parietal bones form the dorsolateral walls of the cranium ○ Large and well developed in dogs, cats, and humans ○ Relatively small in horses and cattle *Temporal bones 2 ○ The 2 temporal bones are located below the parietal bones ○ Why important? Form lateral walls of cranium Contain middle and inner ear structures Form TMJ (temporomandibular joint) with mandible ○ The only visible ear structure is external acoustic meatus ○ Tympanic bulla houses tempanic cavity *Frontal bones 2 ○ Form the forehead region of the skull and oart of the socket that holds the eye ○ Horn core develops here for horned breeds of cattle ○ Paranasal (frontal) sinus contained within frontal bone Internal bones of the cranium The 2 hidden bones are ○ Sphenoid bone Single bone resembles flying bat and forms bottom of cranium Contains the pituitary fossa that houses the pituitary gland Sphenoid bone contains a paranasal sinus called sphenoidal sinus ○ Ethmoid bone A single bone rostral to sphenoid bone Contains cribriform plate for olfactory nerves to pass through Bones of the ear = ossicles 3 pairs of ear bones ○ Malleus/hammer ○ Incus/anvil ○ Stapes/stirrup Function: to transmit vibrations ○ From tympanic membrane across middle ear cavity to an inner ear structure called cochlea The bones of the face Landmark bones Hidden bones External ○ *Incisive bones 2 House the upper incisor teeth Ruminants have a dental pad instead of upper incisors ○ Nasal bones 2 Dolichocephalic (long faced breed) Brachycephalic (short faced breed) ○ *Maxillary bones 2 Makes up the upper jaw and house upper canine teeth, all upper cheek teeth, and the maxillary sinuses Form the hard plate which separate mouth and nasal cavity ○ Lacrimal bones 2 Contains lacrimal sac for tear drainage  ○ *Zygomatic bones 2 Joins with process of temporal bone to form the zygomatic arch ○ *Mandible (1 or 2) Is the lower jaw, houses all lower teeth The only movable skull bone Forms temporomandibular joint (TMJ) with the temporal bone Two sides of the mandible are separate bones unit by a cartilaginous joint, the mandibular symphysis Internal ○ Palatine bones 2 ○ Pterygoid bones 2 ○ Vomer bone 1 ○ Turbinates 4 Why coiled? Increase SA, we get more cilia for capturing things, mucosa membrane, etc Hyoid bone/ hyoid apparatus A single u shaped bone