Homeostasis Ch. 19 The Human Body – An Orientation • Anatomy – study of the structure and shape of the body and its parts • Physiology – study of how the body and its parts work or function Levels of Structural Organization Anatomy – Levels of Study • Gross Anatomy – Large structures – Easily observable • Microscopic Anatomy – Very small structures – Can only be viewed with a microscope Survival Needs • Nutrients – Chemicals for energy and cell building – Carbs, proteins, lipids, vit. & minerals • Oxygen - required for chemical reactions • Water – Provides for metabolic reaction – Stabilizing body temperature Homeostasis • Internal Equilibrium (or balance) • Maintenance of a stable internal environment = a dynamic state of equilibrium • Homeostasis must be maintained for normal body functioning and to sustain life • Homeostatic imbalance – a disturbance in homeostasis resulting in disease Maintaining Homeostasis • The body communicates through neural and hormonal control systems – Receptor are stimulated to: • Responds to the changes in the environment (stimuli) • Sends information to control center This is achieved mostly by the nervous system & the endocrine system Maintaining Homeostasis – The Control center: • Analyzes information that is received from the receptors (affector) • Determines the appropriate response – Effector • Provides a means for response to the stimulus (sends a reaction message to the effector) Feedback Mechanisms • Homeostasis is maintained in the body through Negative feedback – It works in response to a change that counteracts another change. – Its output response that affects the initial input feedback decreases its effect – Works like a household thermostat: it can shut off the original stimulus, or reduces its intensity – Includes most homeostatic control mechanisms Feedback Mechanisms • Positive feedback: – Is the opposite of negative feedback – It intensifies the original change by increasing the original stimulus to push the variable farther, rather than reversing itself to return to a set point. – In the body this only occurs in blood clotting and birth of a baby Homeostasis (Positive Feedback) Body Tissues • Cells are specialized for particular functions • Tissues – Groups of cells with similar structure and function – Four primary types • Epithelium • Connective tissue • Nervous tissue • Muscle Cell Diversity Cell Diversity Cell Diversity Cell Diversity Epithelial Tissues • Layers of tissue – Simple – one layer – Stratified – more than one layer • Found in different areas – Body coverings – Body linings – Glandular tissue • Functions – – – – Protection Absorption Filtration Secretion Classification of Epithelium • Shape of cells – Squamous – flattened – Cuboidal – cube-shaped – Columnar – column-like Glandular Epithelial Tissues • Cells that produce and release substance • Exocrine glands – Have ducts – Sweat glands, oil glands, salivary glands • Endocrine glands – Ductless – Produce hormones – Excrete hormone into the extracellular fluid & diffuse into nearby capillaries. – Pancrease: glucogon & insulin Connective Tissue Characteristics • Supports and binds other tissues • Variations in blood supply – Some types are well vascularized and other types have poor blood supply • Cartilage: flexible & resilient – Consists of spaced cells and extracellular matrix – a non-living material that surrounds living cells Cartilage tissue Connective Tissue Types • Bone (osseous tissue) is composed of: • Bone cells in lacunae (cavities) • Hard matrix of calcium phsophate Adipose Tissue • Insulates the body • Protects some organs • Serves as a site of fuel storage Connective tissue: Blood • 3 types of connective tissues in blood: – RBC – WBC – Platelets • Blood cells surrounded by fluid matrix called: Plasma Muscle Tissue • Function is to produce movement • Three types: Skeletal, Cardiac, Smooth muscle Nervous Tissue • Neurons and nerve support cells • Function is to send impulses to other areas of the body – Irritability – Conductivity Regeneration of Tissues • Tissues that regenerate easily – Epithelial tissue – Fibrous connective tissue and bone • Tissues that regenerate poorly – Skeletal muscle • Tissues that are replaced largely with scar tissue – Cardiac muscle – Nervous tissue within the brain and spinal cord The Skin Organ System Overview • Circulatory System (Cardiovascular) – Transports materials in body via blood pumped by heart • Carbon dioxide • Nutrients • Wastes – Includes heart, blood vessels Organ System Overview • Lymphatic System – Returns fluids to blood vessels – Disposes of debris – Involved in immunity • Includes lymph, lymph nodes & vessels, WBC Organ System Overview & blood • Digestive System – Breaks down food – Allows for nutrient absorption into blood – Eliminates indigestible material Includes: mouth, esophagus, stomach, sm. & lg. Intestines, anal, rectum Organ System Overview • Excretory/ Urinary System – Eliminates nitrogenous wastes – Maintains acid – base balance – Regulates water and electrolytes Includes: kidneys, ureters, bladder, urethra Organ System Overview • Respiratory System – Keeps blood supplied with oxygen – Removes carbon dioxide • Includes: nose, trachea, & lungs; (gills in fish & some amphibians) Organ System Overview • Endocrine System – Secretes regulatory hormones for: • Growth • Reproduction • Metabolism • Includes: various hormone secreting glands Organ System Overview • Nervous System – Fast-acting control system – Responds to internal and external change – Activates muscles and glands • Includes: brain, spinal cord, peripheral nerves Organ System Overview • Muscular System – Allows locomotion – Maintains posture – Produces heat – Contractibility • Includes: skeletal, cardiac & smooth muscle Organ System Overview • Skeletal System – – – – – – Protects internal organs Supports body structure Provides attachment site for muscles, so they can move Site of blood cell formation Stores mineral Bone is live and functional tissue • Includes: bones, cartilage, tendons & ligaments Organ System Overview • Integumentary System – Forms the external body covering – Protects deeper tissue from injury – Synthesizes vitamin D – Location of cutaneous (skin) nerve receptors • Includes: skin, hair, nails, Organ System Overview • Reproductive System – Production of – Spermatogenesis, • Includes: male/female offspring oogenesis reproductive organs – Penis, testes, seminal vesicles – Mammary glands, vagina, uterus, ovaries & oviducts Abdominopelvic Major Organs