Chapter 1-b- Tissues-ZD PDF

Introduction to Human Physiology FHSC 203 Chap 1 - The Human Body: the tissues Tissues Tissues are groups of cells with a common structure (form) and function (job). ü There are four main tissues in the body: § Epithelium § Muscle § Connective tissue § N...

Introduction to Human Physiology FHSC 203 Chap 1 - The Human Body: the tissues Tissues Tissues are groups of cells with a common structure (form) and function (job). ü There are four main tissues in the body: § Epithelium § Muscle § Connective tissue § Nervous tissue Tissues a. Epithelial tissue ü Often called epithelium, it is comprised of tightly packed cells, arranged to form layers: § Epithelial cells are constantly renewing and replacing the dead or inactive cells. Tissues ü The two main epithelial tissue types are: § Glandular: found in exocrine and endocrine glands § Lining epithelium: forms the outer layer of the skin and in some internal organs Tissues ü They have distinct inner and outer surfaces: § Outer surfaces = apical ends of the epithelial cells: Upper, free Tissues Ø Lumen of internal cavities: - Microvilli: Increase surface area absorption or secretion - Cilia: Move materials across cell surface Ø Cell connections (cells binding cell communication, permeability) - Desmosomes, tight, gap Tissues Ø Supported by connective tissue underneath the basal lamina - Reticular lamina - BL + RL = basement membrane Ø Avascular Ø Innervated Ø High rate of regeneration Tissues Tissues § Inner surfaces = basal ends of the epithelial cells Tissues ü The number of cell layers & the shape of the cells in the top layer can classify epithelium. i. By shape a) squamous - flat and scale-like b) cuboidal - as tall as they are wide c) columnar - tall, column-shaped Tissues ii. By cell arrangement a)simple epithelium - single layer of cells (usually for absorption and filtration) b)stratified epithelium - stacked up call layers (protection from abrasion (rubbing) - mouth, skin.) Tissues Lining epithelium 1. Epithelial membranes consist of epithelial tissue and the connective tissue to which it is attached: Epithelial membrane Cutaneous Mucous Serous membrane membrane membrane Lining epithelium a. Cutaneous membranes= skin Ø A dry membrane Ø Outermost protective boundary i. Superficial epidermis Ø Keratinized stratified squamous epithelium ii. Underlying dermis Ø Mostly dense connective tissue Lining epithelium b. Mucous membranes i. line the body cavities that open to the outside ii. Often adapted for absorption or secretion Ø The entire digestive tract is lined with mucous membranes Ø Other examples include the respiratory, excretory, and reproductive tracts Lining epithelium c. Serous membranes i. line body cavities that do not open directly to the outside, and they cover the organs located in those cavities ii. are covered by a thin layer of serous fluid that is secreted by the epithelium. Lining epithelium iii. Serous membranes have special names given according to their location Ø Peritoneum: Abdominal cavity Ø Pleura: Around the lungs Ø Pericardium: Around the heart Glandular epithelium ü A gland is one or more cells that makes and secretes an aqueous fluid Glandular epithelium ü Classified by: 1. Site of product release § Endocrine: internally secreting: - Ductless glands - Exocytosis into extracellular space - Secrete hormones that travel through lymph or blood to target organs - Most are multicellular Glandular epithelium § Exocrine: externally secreting - More numerous than endocrine glands - Secretions released onto body surfaces (skin) or into body cavities - Secrete products into ducts - Examples include mucous, sweat, oil, and salivary glands Glandular epithelium 2. Relative number of cells forming the gland § Unicellular: e.g., goblet cells Glandular epithelium § Multicellular: Most have ducts Glandular epithelium secretion mode Glandular epithelium Tissue repair a. Tissue Repair – Step 1: Inflammation § Release of inflammatory chemicals § Dilation of blood vessels § Increase in vessel permeability § Clotting occurs § Debris is phagocytized by macrophages Tissue repair Tissue repair b. Tissue Repair – Step 2: Organization and restored blood supply § The blood clot is replaced with granulation tissue § Epithelium begins to regenerate § Fibroblasts produce collagen fibers to bridge the gap § Blood clot is phagocytized Tissue repair Tissue repair c. Tissue Repair – Step 3: Regeneration and fibrosis § The scab detaches § Fibrous tissue matures; epithelium thickens and begins to resemble adjacent tissue § Results in a fully-regenerated epithelium with underlying scar tissue Tissue repair Tissues b. Connective tissue ü Connective tissue is made up of cells and protein fibers and provides support for other body tissues. ü The main proteins in connective tissue are: § collagen § elastin Tissues ü There are five types of connective tissue: § Loose connective tissue- Including adipose tissue (Insulation); fibers & many cell types in gelatinous matrix, found in skin, & surrounding blood vessels, nerves, and organs § Dense connective tissue- Bundles of parallel collagen fibers& fibroblasts, found in tendons& ligaments (binding) Tissues § Blood (Transportation) § Bone- Provides rigid, structural (support) (Protection) § Cartilage- Occurs in the human body in the ears, tip of the nose, and at joints such as the knee and between bones of the spinal column (Protection) Tissues Tissues Tissues Tissues ü Characteristics of the Connective tissue § Originate from the mesenchyme Ø Embryonic connective tissue Ø Mesenchymal/undifferentiated connective tissue Ø Gel-like ground substance with fibers and star-shaped mesenchymal cells Ø Gives rise to all other connective tissues Tissues § Varying degrees of vascularity Ø E.g Cartilage is avascular § Cells separated by non-living extracellular matrix Ø Major part of CT Ø Ground substance Ø Fibers Tissues Tissues 1. Ground Substances ü Medium through which solutes (e.g. nutrients) diffuse between blood capillaries and cells ü Components: § Interstitial fluid Tissues § Adhesion proteins (“glue”) Ø Fibronectin and laminin Ø Allow cells to attach to the matrix § Proteoglycans Ø Protein core + large polysaccharides (chrondroitin sulfate and hyaluronic acid) Ø Trap water in varying amounts → affects the viscosity of the ground substance Tissues 2. Fibers ü Three types of fibers that provide support a) Collagen (white fibers) Ø Collagen → fibrous Ø Strongest and most abundant type Ø Provides high tensile strength Ø Resist longitudinal stress Tissues b) Elastic (yellow fibers) Ø Elastin → rubber-like Ø Networks of long, thin, elastin fibers that allow for stretch c) Reticular Ø Form networks (reticul = network) Ø Short, fine, highly branched collagenous fibers Tissues 3. Cells ü Mitotically active and secretory cells = “blasts” § Secret ground substance and fibers ü Mature cells = “cytes” § Less active § Maintain health of matrix Tissues i. Fibroblasts in connective tissue proper ii. Chondroblasts and chondrocytes in cartilage iii. Osteoblasts and osteocytes in bone iv. Hematopoietic stem cells in bone marrow v. Fat cells, white blood cells, mast cells, and macrophages Tissues Tissues Tissues Tissues Tissues Tissues Tissues Tissues Tissues Tissues Tissues 1. Cartilage § Avascular § Lacks nerve fibers § 80% water § Ability to rebound after being compressed ü Three types of cartilage: § Hyaline cartilage § Elastic cartilage § Fibrocartilage Tissues Tissues Tissues Tissues Tissues Introduction ü Physical Characteristics and Volume § Blood is a sticky, opaque fluid with a metallic taste § Color varies from scarlet to dark red § The pH of blood is 7.35–7.45 § Temperature is 38°C § Blood accounts for approximately 8% of body weight § Average volume: 5–6 L for males, and 4–5 L for females Introduction ü Functions of Blood: § Substance distribution § Regulation of blood levels of particular substances § Body protection Introduction 1. Distribution ü Blood transports: § Oxygen from the lungs and nutrients from the digestive tract § Metabolic wastes from cells to the lungs and kidneys for elimination § Hormones from endocrine glands to target organs Introduction 2. Regulation ü Blood maintains: § Appropriate body temperature by absorbing and distributing heat § Normal pH in body tissues using buffer systems § Adequate fluid volume in the circulatory system Introduction 3. Protection ü Blood prevents blood loss by: § Activating plasma proteins and platelets § Initiating clot formation when a vessel is broken ü Blood prevents infection by: § Synthesizing and utilizing antibodies § Activating complement proteins § Activating WBCs to defend the body against foreign invaders Introduction ü Blood is a highly specialized tissue composed of many different kinds of components. ü Blood has two distinct parts to it: § Plasma § Cellular elements ü All humans produce these blood components: there are no populational or regional differences. Introduction Introduction 1. Plasma ü Plasma is the relatively clear liquid water, sugar, fat, protein and salt solution which carries the red cells, white cells, platelets, and some other chemicals. ü Normally, 55% of our blood's volume is made up of plasma. ü About 95% of it consists of water. 1. Plasma ü As the heart pumps blood to cells throughout the body, plasma brings nourishment to them and removes the waste products of metabolism. ü Blood plasma contains over 100 solutes, including: § Proteins – albumin, globulins, clotting proteins, and others § Lactic acid, urea, creatinine § Organic nutrients – glucose, carbohydrates, amino acids § Electrolytes – sodium, potassium, calcium, chloride, bicarbonate § Respiratory gases – oxygen and carbon dioxide 2. Cellular elements White blood   cells Platelet Red blood   cells 2. Cellular elements A. Red blood cells: RBCs ü Normal RBCs are biconcave discs having a mean diameter of approximately 7.5µm. 2. Cellular elements ü The shape of RBCs can change as the cells pass through capillaries. ü Actually the RBC is a “bag” that can be deformed into almost any shape because they contain the plasma membrane protein spectrin and other proteins. 2. Cellular elements ü The concentration of RBCs in the blood: 5,200,000 (± 300,000) /mm3 4,700,000 (± 300,000) /mm3 ü It is mainly affected by the altitude at which the person lives. 2. Cellular elements Areas of the body that produces RBCs Period Organ Early embryonic life Yolk sac Middle trimester gestation Liver (major) Spleen, Lymph node Latter part of the gestation Exclusive bone marrow and after birth! 2. Cellular elements ü The major function of RBCs, also known as erythrocytes, is: 1. To transport hemoglobin (Hb), which in turn carries oxygen from the lungs to the tissues 2. Cellular elements ü Hb is composed of the protein globin, made up of: § two alpha chains § two beta chains § each bound to a heme group 2. Cellular elements ü Hematopoiesis: blood cell formation § Occurs in red bone marrow of axial skeleton, girdles and proximal epiphyses of humerus and femur § Hemocytoblasts (hematopoietic stem cells) Ø Give rise to all formed elements Ø Hormones and growth factors push the cell toward a specific pathway of blood cell development § New blood cells enter blood sinusoids Ø A small blood vessel similar to a capillary but has pores 2. Cellular elements 2. Cellular elements ü Erythropoiesis: red blood cell production A hemocytoblast →transform into a proerythroblast → develop into early erythroblasts → transform into anucleated reticulocytes → become mature erythrocytes 2. Cellular elements Tissues c. Muscle tissue ü Muscle tissue provides stability to the skeleton and internal organs and allows body movement. ü Muscle tissue makes up approximately 60% of the body’s mass and there are three types of muscle tissue. Tissues ü These are: § Cardiac: found in the heart § Skeletal: usually attached to bone § Smooth: found in walls of blood vessels in digestive system, respiratory system and the eye Tissues Tissues d. Nervous tissue ü The nervous system is made up of the: § Central Nervous System (CNS) § Peripheral Nervous System (PNS) ü Comprised of neural and nervous tissue, the CNS and PNS transmit signals from the brain to the body parts (muscles, glands, sense organs) to activate a response. Tissues ü Consists of only two cell types in the central nervous system (CNS) & peripheral nervous system (PNS): § Neurons - Cells that convert stimuli into electrical impulses to the brain § Neuroglia – supportive cells