Introduction to Body Tissues and Organs 2024 AF.pdf

Introduction to Body Tissues, Organs & Organ Systems Dr Allison Fulford Lecture learning outcomes Identify the location of organs in the human and animal body Distinguish between the terms tissue and organ Define the term organ system List the major organ systems of the body and outline their functi...

Introduction to Body Tissues, Organs & Organ Systems Dr Allison Fulford Lecture learning outcomes Identify the location of organs in the human and animal body Distinguish between the terms tissue and organ Define the term organ system List the major organ systems of the body and outline their functions. Levels of Body Organisation Tissue: a collection of cells & their products in which one type of cell predominates Organ: a distinct collection of tissues forming a structure within an animal which is adapted to perform a specific purpose System: a collection of organs and tissues which are related by function Body composition of tissues There are three basic elements: 1. cells- one type forms the majority of the cells and gives the tissue type its name eg. muscle tissue consists of mainly muscle cells (myocytes) 2. intercellular substances- these are produced by the cells and lie in the spaces between them 3. body fluids- interstitial fluid flows through specialised channels running through the tissue ALL ADULT TISSUES DEVELOP FROM 3 LAYERS IN THE EMBRYO: three cellular layers (ectoderm, endoderm, mesoderm) In the adult, only 4 primary tissues are present Tissues of the Body Make up the entire body. Histology: microscopic study of tissues In vertebrates, there are FOUR PRIMARY types of tissue: 1. Epithelial Cells adjacent with little matrix eg. skin (epidermis), lining of hollow organs & tubes, glandular epithelium 2. Connective (support) Abundant extracellular matrix, strong eg. bone, cartilage, tendon, loose connective tissue 3. Muscle Highly contractile cells create movement eg, striated, cardiac, smooth 4. Nervous Conduct electrical signals (action potentials) along cell membranes eg. brain & spinal cord, cranial nerves, peripheral nerves, ganglia Some tissue examples Bone is a connective tissue containing various cell types, although osteocytes/osteoblasts/osteoclasts predominate BONE formation requires a community of cells Cortical (compact) bone Hyaline cartilage Trabecular (spongy) bone Fig: end of a growing long bone Osteocytes Mature cells lying within the bone itself ‘entrapped’ by osteoblasts, sense ‘stress’ Dense connective tissue Densely packed collagen bundles with few fibroblasts & other cells in between Fibres arranged in two formations 1) Dense regular: fibres in 1 main direction. Fibrous connective tissue eg. tendons (strong bands of fibrous tissue linking muscles to bone; and ligaments, which link bone to bone), vocal cords 2) Dense irregular: fibres in random mesh. Seen in the dermis of the skin and capsules of joints, as well as organ capsules like of testis and lymph nodes. Layers of most fascias, serous membranes and aponeuroses Tendons Aponeurosis Connect muscle to bone Optimise muscle position and length attaches muscle to bone or other muscle wide flat sheet rather than round tendon Ligaments Connect bone to bone Stabilise joints EPITHELIUM Lining sheets of cells with little matrix. Basal surface anchored Separates organs & protects the body Covers the body surface & organs, cavities & tubes within it Forms the lining of most organs; may be secretory (eg.sweat, wax, mucus, saliva etc) and absorbent (water, metabolites, debris, waste) eg: Skin (superficial layer= epidermis), lining of GIT & respiratory tract, glands e p i d e r m i s e p i d e r m i s EXAMPLE ORGAN= SKIN/INTEGUMENT: Continuous covering of entire body Comprised of three tissue layers: eg. Epidermis, Dermis & Hypodermis & hair, fur, nails,claws, horns & sweat/oil glands Example: ORGAN SYSTEM of the Body Smallest Level Largest Level 5 QUESTIONS ADJECTIVE: GASTRIC CARDIAC RENAL GONADAL HEPATIC PULMONARY VESICAL CHOLECYSTIC MATCH ORGAN TO IT’S DESCRIPTOR A C B D ovary E F G H NAME THE ORGAN SYSTEM FOR ORGAN A-G ON THE LAST SLIDE A B C D E F G H DOG HUMAN SKELETAL SYSTEM Body cavities Body is divided into separate areas called body cavities (thoracic; abdominal; pelvic cavities) Are ‘potential’ spaces as they are filled with visceral ORGANS and fluid. Only a very small amount of free space. Body cavities are lined with a continuous layer of serous membrane (mesothelium) that produces thin serous fluid (lubrication) Contents of the body cavities 1. Thoracic cavity: heart, lungs & associated structures within the bony thoracic cage (ribs, thoracic spine & sternum). 2. Abdominal cavity: abdominal viscera- GI tract, glands & urogenital system, associated nerves and vessels. 3. Pelvic cavity: urinary bladder, rectum & reproductive organs. NB: Body cavities are lined with a continuous layer of serous membrane (mesothelium) that produces thin serous fluid (lubrication) Summary Overview of Tissues Concept of Organs & Organ Systems The named organ systems Position of major organs in the body Introduction to Body cavities This week and by the end of week 14 make sure you read Chapter 4 of Seeley’s ‘TISSUES’. This includes the summary section. Always refer to the Unit Intended Learning Outcomes (ILOS listed in Unit Handbook)