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ANATOMY___PHYSIOLOGY_I_histologychp_4[1] - ANATOMY &...

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Unformatted text preview: ANATOMY & PHYSIOLOGY I BIOL 2401 JARED GILMORE M.S., B.S. BIOLOGY PROFESSOR SAN JACINTO COLLEGE HISTOLOGY BACKGROUND HISTOLOGY- microscopic study of tissues Biopsy- the process of removing tissue samples from patients surgically or with a needle for diagnostic purposes. Autopsy- examination of the organs of a dead body to determine the cause of death or to study the changes caused by a disease. EMBRYONIC TISSUE Endoderm- inner layer, forms the lining of the digestive tract and its derivatives. Mesoderm- middle layer, forms tissues such as muscle, bone, and blood vessels. Ectoderm- outer layer, forms the skin, and a portion of the ectoderm, called neuroectoderm, becomes the nervous system. Neural crest cells group of cells that break away from the neuroectoderm during development which give rise to parts of the peripheral nerves, skin pigment, medulla of the adrenal gland, and many tissues of the face. HISTOLOGY BACKGROUND Cells are very organized in terms of their anatomy and functioning. However, a cell rarely works by itself, but will be organized with similar cells to form a tissue. TISSUE: a group of cells that usually have a common embryological origin and function together to carry out a specific function. There will be communication between these cells that allows them to function as a unit. TYPES OF TISSUES 1. Epithelial tissue: covers surfaces, lines inside of organs and body cavities and forms glands. Epithelial cells are found above a BASEMENT MEMBRANE 2. Connective tissue: protects and supports body, binds organs together, provides immunity. 3. Muscle tissue: movement and generation of heat 4. Nervous tissue: initiate and transmits impulses (action potentials) that control and coordinate the functioning of the body. The cells that compose a tissue are not just found near each other. There may be physical connections that allow for communication between them. These points of contact between the plasma membranes of 2 cell are called GAP JUNCTIONS. EPITHELIAL TISSUE 2 general classifications of epithelium. COVERING and LINING EPITHELIUM & GLANDULAR EPITHELIUM. Covering and lining epithelium forms the outside layer of the skin and the outside and inside layer of internal organs and structures. Glandular epithelium makes up the secreting portion of the glands. GENERAL CHARACTERISTICS OF EPITHELIAL TISSUE: 1. ep. cells have an APICAL surface and a BASAL surface. The apical surface is free and the basal surface is connected to a BASEMENT MEMBRANE. 2. ep. cells are arranged close together in the tissue. 3. ep. cells are arranged in sheets that are either single or layered to form the tissue. 4. Many gap junctions occur in ep. tissue. 5. Avascular tissue. No blood vessels found in ep. tissue. The cells rely on diffusion of O2 and nutrients from nearby vessels. 6. ep. tissue has a nerve supply. 7. high rate of mitosis due to location causing wear and tear. 8. FUNCTIONS: protection, filtration, lubrication, secretion, absorption and other functions. EPITHELIAL TISSUE COVERING AND LINING EPITHELIUM 1. arrangement of layers: 2 main possibilities = simple and stratified a. SIMPLE EPITHELIUM: single layer of cells b. STRATIFIED EPITHELIUM 2 or more layers of ep. cells. Mostly found in areas of high wear and tear 2. epithelial cell shapes = 3 possible shapes a.SQUAMOUS EP. CELL: flat cells ( skin) b.CUBOIDAL EP. cube shaped cells ( kidney tubules) c. COLUMNAR EP. shaped like columns. Some have cilia on them ( trachea) GLANDULAR EPITHELIUM: The function of glandular epithelium is secretion which is done by glandular ep. cells usually found deep to other ep. tissue. A GLAND may consist of a cluster of ep. cells or just one ep. cell that is capable of producing a secretion. Exocrine and Endocrine glands a. Endocrine glands: secretions do not go through a duct. These secretions are called HORMONES. ex. pituitary gland, adrenal gland. b.Exocrine glands: glands in which the secretions that are produced flow onto through a tube-like passageway (duct) to get to the surface or the lumen surface of the organ. ex mucus, digestive glands. EPITHELIAL TISSUE (LAB) Kidney slide: The kidneys are responsible for filtering and cleansing blood and producing urine, a metabolic waste product. These essential organs are actually million of tubes made up of SIMPLE CUBOIDAL EPITHELIUM with LUMENS in the middle. Note the numerous BASEMENT MEMBRANES and the outside SEROSA. Many organs are constructed in layers. Always find the lumen first, then the epithelium that surrounds that lumen. Note the other layers on the walls. Tongue slide: The tongue is an essential structure, important in speech and digestion. There is STRATIFIED SQUAMOUS EPITHELIUM around the outside, next to the lumen. A BASEMENT MEMBRANE is found under the epithelium. Under the basement membrane there is a LAMINA PROPRIA (connective tissue under epithelium) and SKELETAL MUSCLE under this. Small Intestine Slide: The ileum is a section of the small intestine and is involved in digestion. The layering begins, next to the lumen, with SIMPLE COLUMNAR EPITHELIUM covering the fingerlike projections, the VILLI (villus = singular). There are GOBLET CELLS that are interspersed within the epithelium that will secrete mucus. A BASEMENT MEMBRANE is under the epithelium, followed by a LAMINA PROPRIA. There is an area referred to as the SUBMUCOSA, consisting of connective tissue under the lamina propria, then 2 layers of SMOOTH MUSCLE (circular and longitudinal) follows and then a SEROSA surrounds the outside of the organ. Trachea slide: The trachea is the airway that attaches the nasal region to the lungs. The lumen will be lined by PSEUDOSTRATIFIED COLUMNAR EPITHELIUM - a type of tissue that will appear to be layered because the nuclei of the cells will be found on different levels. However, all of these epithelial cells touch the BASEMENT MEMBRANE and therefore is not really stratified. Note the hair-like structures on the apical surfaces of the epithelial cells, CILIA which providing protection. Under this is LAMINA PROPRIA. The incomplete rings are made of HYALINE CARTILAGE, the most abundant type of cartilage in the body. Note the CHONDROCYTES inside of the LACUNAE and surrounding MATRIX. Urinary Bladder slide: The function of the urinary bladder is to store urine until micturition can occur. The lumen of this organ is surrounded by STRATIFIED TRANSITIONAL EPITHELIUM, a BASEMENT MEMBRANE, layered SMOOTH MUSCLE and a SEROSA. EPITHELIAL TISSUE (LAB) Pigmented and Non-pigmented Thin Skin: There are 2 sections of tissue on each of these slides – one is pigmented and the other is not. In both sections, there are 2 regions, the epidermis and the dermis. The EPIDERMIS is composed of KERITANIZED STRATIFIED SQUAMOUS EPITHELIUM. If the skin is PIGMENTED, you will be able to see the MELANIN (brown pigment) which exists within melanocytes near the BASEMENT MEMBRANE. If you are observing the NONPIGMENTED skin, there will be no melanin within the epidermis. The DERMIS is deep to the epidermis. It is CONNECTIVE TISSUE that is composed primarily of COLLAGENOUS FIBERS. There are protrusions of dermis that rise up into the epidermis – these are DERMAL PAPILLAE that cause the unique ridges on the surface of the fingers used in fingerprinting. Human scalp slide: Note the EPIDERMIS and DERMIS regions on this slide. Within the dermis, there are a number of structures that are visible. The HAIR FOLLICLES are tilted structures – some contain hair and continue into the epidermis – others do not. Closely associated with the follicles are the SEBACEOUS GLANDS that secrete oil onto the hair. A bit deeper, there are also SUDORIFEROUS GLANDS that secrete sweat onto the surface of the skin. The dermis is filled with COLLAGENOUS FIBERS. Thick skin slide: Thick skin exists only in two areas of the human body – the soles of the feet and the palms of the hands. Compared to thin skin, the dermis is thicker but maintains the same structure, containing DERMAL PAPILLAE and COLLAGENOUS FIBERS. There is a deeper region visible on the slides – the HYPODERMIS,(subcutaneous layer) that is composed primarily of adipose tissue. It is within the EPIDERMIS where the anatomy is different. All epidermis is made up of KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM and all epidermal regions will have at least 4 strata of cells. However, thick skin has an extra layer, the clear stratum lucidum. LUMEN Stratum corneum s. lucidum, s.granuolosum, s. spinosum, s. basale (deepest). BASEMENT MEMBRANE CONNECTIVE TISSUE Most abundant type of tissue in the body. There are a variety of different tissues in this group. examples = bone, cartilage, blood, adipose. Cells of connective tissue are directly involved with the matix of the tissue. Those that have the suffix “blast” will produce the matrix. Those cells with “cyte” at the end of the word will maintain the matrix and those ending in “clast” will break the matrix down. Examples of this terminology is: osteoblasts, osteocytes and osteoclasts. General Characteristics: a. cells are usually scattered. Substance in between the cells is the MATRIX. b. Connective tissue is not located on surfaces. c. Most conn. tissue has a nerve supply ( exception: cartilage) d. Conn. tissue is highly vascularized (exceptions: cartilage and tendons) e. The matrix may be solid, fluid, semifluid depending upon which tissue it is. Example: Blood has a fluid matrix and bone has a solid matrix. All connective tissue is derived from embryonic conn. tissue called MESENCHYME CONNECTIVE TISSUE (LAB) a. ADIPOSE: Adipose or fat tissue is found throughout the body. It functions in energy storage, protection and insulation. The cytoplasm and nucleus is found on the periphery of the cell and the LIPID DROPLET is found in the center. b. BONE: Bone tissue composes most of the skeleton of the human body. Its purposes include support, storage (calcium, phosphorus) and hemopoiesis (production of blood). Bone tissue contains units of organization called OSTEONS. The center of each osteon has a HAVERSIAN CANAL that contains blood vessels and nerves in life. Indentations referred to as LACUNAE form concentric circles around the Haversian canal and within each lacuna is an OSTEOCYTE. The MATRIX (area in between cells of connective tissue) is hard in bone and contains small canallike structures called CANALICULI. VOLKMAN’CANALS are occasionally seen connecting two Volkmann’s canals. c. BLOOD : Blood is another example of a connective tissue. Although it appears to be a red fluid, blood is actually a light straw colored fluid referred to as PLASMA. This plasma is the Matrix of blood. Suspended in the plasma are FORMED ELEMENTS – RED BLOOD CELLS (RBC’S), the most numerous of the cells gives the blood its red color and carries oxygen to the tissues. Notice the RBC’s of humans have no nucleus when they are circulating within the blood. There are also WHITE BLOOD CELLS (WBC’s) that stain a purple color, involved in protection of the body as well as fragments of cells important in blood clotting called PLATELETS. NERVOUS TISSUE Although the nervous system is very complex, there are only 2 general types of cells: neuroglia cells (glial cells) and neurons. Neurons carry the impulses that control and coordinate the body. Neuroglial cells do not carry impulses but support the neurons in different ways. NERVOUS TISSUE (LAB) NEURON: The type of cell that carries impulses from one place to another, offering coordination to the body. The major portion of the neuron is the area that contains the nucleus and is referred to as the CELL BODY. There are projections (processes) that come from this cell body referred to as DENDRITES or AXONS. Usually, there are more than one dendrite per neuron but only one axon. NEUROGLIAL CELLS: These cells are more abundant than the neurons and don’t carry impulses. There are different types of glial cells, depending on what part of the body is being studied. They perform a variety of functions including support of the neurons. MUSCLE TISSUE The purposes of muscle are movement, maintaining posture and thermogenesis. There are 3 different types of muscle tissue: skeletal muscle, smooth muscle and cardiac muscle. MUSCLE TISSUE (LAB) a. CARDIAC MUSCLE: This type of muscle is found only in the walls of the heart. It is involuntary and functions in the flow of blood through the heart chambers. It contains areas where the membranes of 2 cardiac cells overlap each other, called INTERCALATED DISCS. These appear as dark perpendicular lines. Lying parallel to the discs are lighter lines called the STRIATIONS. These cells are UNINUCLEAR – 1 nucleus per cell. b. SMOOTH MUSCLE: This is involuntary muscle found in the walls of the viscera. The cells do not have any striations in the cytoplasm (hence the label “smooth”), are uninuclear and are spindle shape. They tend to exist in sheets. c. SKELETAL MUSCLE: This is the large muscle mass that are associated with the skeleton. This tissue is under voluntary control, containing MULTINUCLEATED CELLS that have STRIATIONS in the cytoplasm. MEMBRANES A membrane is a thin sheet of tissue that covers a structure or lines a cavity. Most membranes are composed from EPITHELIUM and CONNECTIVE tissue under it. The SKIN is the EXTERNAL MEMBRANE of the body. In addition, there are 3 major catagories of INTERNAL MEMBRANES; MUCOUS MEMBRANES, SEROUS MEMBRANES and SYNOVIAL MEMBRANES. MUCOUS MEMBRANE: consists of a epithelial cells, their basemetn membrane and the lamina propria (connective tissue found under the epithelium of mucous membranes) underneath. Mucous membranes line cavities and canals that open to the outside of the body (digestive system, reproductive system, excretory system and respiratory system). Many of these mucous membranes contain GOBLET CELLS ot MUCOUS GLANDS that produce MUCUS. SEROUS MEMBRANE: membranes consist of SQUAMOUS EPITHELIUM which is referred to as MESOTHELIUM, the basement membrane and connective tissue. Serous membranes line cavities such as those found lining the chest wall and the abdominal wall. They do not open to the exterior of the body. The cells of the membrane produce a SEROUS FLUID that decreases friction. 3. SYNOVIAL MEMBRANE: Most of these type of cells form connective tissue. Synoval membranes line the capsule of freely movable joints(shoulder, thigh). They produce a fluid that decrease friction. INFLAMMATION The function of the inflammatory response is to isolate injurious agents from the rest of the body and to attack and destroy the injurious agent. The inflammatory response produces five symptoms: redness, heat, swelling, pain, and disturbance of function. Inflammatory, Repair, and Remodel Stage 1: Inflammatory phase The acute phase - the first 72 hours (peaks at day 4 and continues at least until day 10 of postinjury) Bleeding and swelling make the area red, hot and painful. Various cells, including white blood cells and scavenger cells, are attracted to the region to begin the process of cleaning up debris. These cells also release chemicals which encourage fibroblasts to multiply - fibroblasts are the cells which produce the proteins of repair, especially collagen. Stage 2: Proliferation (repair) phase (may last from 48 hours up to 6 weeks and is characterized by the synthesis and deposition Repair and regeneration depend on three major factors: elimination of debris, the regeneration of endothelial cells, and the production of fibroblasts, which compose connective tissue throughout the body and form the basis of scar tissue.Typically in a traumatic event injured blood vessels become deprived of oxygen and die. Before repair and regeneration can occur, debris must be removed.Stimulated by a lack of oxygen, capillary buds begin to form in the walls of the intact vessels. From these buds grow immature vessels that form connections with other vessels. As these vessels become mature, more oxygenated blood is brought to the injured area. Fibroblasts migrate to the injury and form collagen substances, often within a few days. New protein fibres are laid down in a haphazard manner. Once laid down, the scar tissue begins to contract.Also during this stage, two types of healing occur. Primary healing: healing by first intention takes place in an injury that has even and closely opposed edges, such as a cut or incision. With this type of injury if the edges are held in very close approximation, a minimum of granulation tissue is produced. Secondary healing: healing by secondary intention, results when there is a gaping lesion and large tissue loss, leading to replacement by scar tissue. External wounds such as lacerations commonly heal by secondary intention. Stage 3: Maturation (remodeling ) phase 9 (MAY LAST FROM 3 WEEKS TO 12 MONTHS OR MORE) This phase can last from 6 weeks to several months. The protein fibres of the scar orient themselves in the direction in which pressure is applied. The protein matures and the number of cells in the tissue decreases. It may take several months for the scar to fully mature and achieve its full strength. TISSUE REPAIR Tissue repair is the substitution of viable cells for dead ones. Tissue repair occurs by regeneration or replacement. Labile cells divide throughout life and can undergo regeneration. Stable cells do not ordinarily divide after growth is complete but can regenerate if necessary. Permanent cells cannot replicate. If killed, permanent tissue is repaired by replacement. ...
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