2.2 Pathology Lecture 2.pptx

Tissue Structure and Function SCI1018-N PATHOLOGY Dr. Ahmad Khundakar Learning outcomes • At the end of the lecture you should be able to: • Outline the levels of cellular organisation • Understand orientation in relation to anatomy • List the main tissue types • Identify the main cellular compone...

Tissue Structure and Function SCI1018-N PATHOLOGY Dr. Ahmad Khundakar Learning outcomes • At the end of the lecture you should be able to: • Outline the levels of cellular organisation • Understand orientation in relation to anatomy • List the main tissue types • Identify the main cellular components of connective, neuronal, muscle and epithelial tissue Levels of Cellular Organisation Cell Tissue Organ Organ System Organism Anatomical orientation Identify the MRI Section Plane! Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Blood • Composed of two main elements • • Plasma Blood cells • Plasma contains proteins, nutrients, metabolic by-products, clotting factors, hormones, water • Blood cells made in thymus and bone marrow • • Red blood cells (RBCs - erythrocytes) ‘Buffy coat’: white blood cells (WBCs) and platelets • Blood volume largely determined by plasma volume • E.g. blood loss, volume increases to maintain blood pressure Blood Cell Production • Haematopoesis – production of blood cells • One of the first systems to form 0–2 months – yolk sac 2–7 months – liver, spleen 5–9 months – bone marrow Infants – bone marrow (practically all bones) • Adults – Vertebrae, ribs, sternum, skull, sacrum and pelvis, proximal ends of femur • • • • Blood Smears • “Peripheral blood smear, blood smear analysis, peripheral blood film, smear, manual differential, manual DIFF” • Type of blood test looking at appearance, number and shape of red and white blood cells and platelets • ‘diff quick’ – modified Giemsa stain • Romanowsky stain commonly used • • Azure (A or B) – cationic (basic) binds to anionic sites in nucleic acids Eosin Y – anionic (acid) binds to cationic sites on proteins in cytoplasm Blood Smears A B C D Look at the following blood smears. Figure A shows a ‘normal’ blood smear. Figures B, C and D show some abnormalities. What do you see? Can you think of any potential causes? Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Areolar Tissue • ‘Mesh-like’ loose connective tissue consisting of collagen, elastic tissue, and reticular fibres • Also contains different types of cells embedded in matrix • Binds skin to muscle tissue beneath, as well as between organs • ‘Loose’ structure allows high degree of movement • E.g. layer below epidermis in skin, lamina propria of digestive and respiratory tracts Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue More in Lecture 12! Adipose Tissue • Loose connective tissue consisting of adipocytes • Main store of fat in body • Energy store • Protects organs • Insulates • Two types of fat tissue – white and brown • White more common in body and associated with obesity (in excess) • Brown common in small mammals and newborns; higher proportion associated with lower body weight Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Dense Connective Tissue • Dense fibrous connective tissue • Fibres composed of collagen (type 1) • Fibroblasts found in between fibres • Forms ‘rope-like’ structures – dense regular connective tissue: • Ligaments and tendons • Lower layers of skin (dermis) – dense irregular connective tissue Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Bone Tissue Composition • Highly specialised connective tissue • Composite material • Organic > collagen > elasticity • Inorganic > hydroxyapatite > hardness/compressive strength Bone Tissue Composition • Highly specialised connective tissue • Composite material • Organic > collagen > elasticity • Inorganic > hydroxyapatite > hardness/compressive strength Bone Tissue Composition • Made up of cells and extracellular matrix • Cells: • Osteoblasts – cells forming new bone • Osteocytes – provide nourishment for bone tissue • Osteoclasts – remodelling cells • Bone matrix: • Collagen (70%) • Glycosaminoglycans • Glycoproteins Bone Tissue I mentioned that bone was made up of 70% of the collagen, the most abundant protein in the body. What are its main properties? Why are these properties important for bone function? Bone Tissue More in Lecture 12! I mentioned that bone was made up of 70% of the collagen, the most abundant protein in the body. What are its main properties? Why are these properties important for bone function? Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue The Nervous System • Two major components • Central nervous system • Peripheral nervous system • Brain: grey matter on outside, white matter on inside • Grey matter = cortex containing cell bodies • White matter = axons (myelin) • Spinal cord: white matter on outside, grey matter on inside The Nervous System • Neuron(e) basic function unit • Glial cells • Astrocytes • Oligodendrocytes (Schwann cells) • Microglia Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Skeletal Muscle • • • • Striated (‘striped’) muscle Responsible for voluntary movement 650 muscles in humans Stretching and contracting in of cells in orderly manner • Adapt to use (or non-use!) • Muscular atrophy in injury • Epimysium (muscle compartment)> perimysium (muscle fascicle)>endomysium (muscle fibre/cells) Skeletal Muscle Structure • Muscle fibre (cell) very long (up to 10cm in length) - though not entire length! • • • Overlapping bundles Force of contraction transmitted through arrangement of tissues Resting length determined by phenotype (e.g. gender, training, age) • Each muscle fibre surrounded by membrane (sarcolemma) and sarcoplasm containing contractile protein (myofilaments), glycogen and mitochondria • Can be viewed under light microscope with H&E staining (+ Gomori’s rapid trichrome for mitochondria) Skeletal Muscle Ultrastructure • Best viewed under electron microscope https ://www.youtube.com/watch?v =Vlchs4omFDM Muscle tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Smooth Muscle • Involuntary • Controlled by autonomic nervous system • Non-striated • Actin and myosin randomly arranged • Thin and dense, flattened nuclei • Found in walls of hollow organs such as the urinary, reproductive, intestinal and respiratory tracts • Single myocytes frequently found in basement membrane of ducts or blood vessels (myoepithelial cells) Muscle tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Cardiac Muscle • Involuntary • Controlled by autonomic nervous system • Striated • Actin and myosin arrangement • Branched cells with central nucleus • Tightly connected by specialised junctions ‘intercalated discs’ • Enables rapid transmission of electrical impulse Types of Tissue • Four main types of tissue • • • • Connective tissue Neural/neuronal tissue Muscle tissue Epithelial tissue Epithelial tissue • Large sheets of tissue covering all surfaces of body • Derive from three embryonic layers • • • Ectoderm: skin, parts of the mouth and nose, anus Endoderm: airways and most of the digestive system Mesoderm: vessels in the lymphatic and cardiovascular system (endoderm) Epithelial tissue • Large sheets of tissue covering all surfaces of body • Derive from three embryonic layers • • • Ectoderm: skin, parts of the mouth and nose, anus Endoderm: airways and most of the digestive system Mesoderm: vessels in the lymphatic and cardiovascular system (endoderm) General epithelial tissue structure • Apical: surface of the cell • Basal: surface close to the underlying body structures • Epithelial cells tightly held together by junctions, adhering junctions and desmosomes • Epithelium attached to basal lamina comprised of mixture of glycoproteins and collagen • Reticular lamina attached to basal lamina, underlying connective tissue forms basement membrane Simple Squamous Epithelium • Single layer of flattened cells, with disc-shaped nuclei and sparse cytoplasm • Allows passage of materials and gases by diffusion or filtration Simple Cuboidal Epithelium • Single layer of cube like cells with large, spherical nuclei • Secretes and absorbs • Found in ducts, kidney tubules and ovary surface Simple Columnar Epithelium • Single layer of cube like cells with large, spherical nuclei • Secretes and absorbs • Found in ducts, kidney tubules and ovary surface • Ciliated in bronchi, uterine wall and uterus, smooth in GI tract Pseudostratified Epithelium • Single layer variable size cells (gives appearance multiple layers) • Found in respiratory tract • Cilia driven by dynein motor • Transport of mucus and material out of lungs Stratified Squamous Epithelium • Epithelial cells arranged in layers upon a basal membrane • Only one layer is in contact with the basement membrane • the other layers adhere to one another to maintain structural integrity • Main function protection • Found in areas undergoing wearand-tear (e.g. skin, mouth, anus, vagina) Skin and hair care products frequently contain the protein keratin. Why do think this is the case? Stratified Cuboidal Epithelium • Superficial layer composed of cuboidal cells • other layers can be cells of other type • Found in glands • e.g. sweat, mammary and salivary glands Stratified Columnar Epithelium • Usually several layers • Basal layer usually cuboidal • Superficial layers elongated and columnar • Protect and secrete • Uncommon in human body • Found in male urethra Transitional Epithelium • Multiple cell layers of varying cell shape hence ‘transitional’ • Main function: distention • Uppermost layers can ‘stretch’ to accommodate fluid etc. • Found in urinary bladder, ureters and urethra, and ducts of the prostrate gland Learning outcomes • You should now be able to: • Outline the levels of cellular organisation • Understand orientation in relation to anatomy • List the main tissue types • Identify the main cellular components of connective, neuronal, muscle and epithelial tissue Quiz Time! KHUNDAKAR Thank you