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Chapter 20: Tissues & Organ Systems The Importance of Homeostasis The maintenance of a relatively constant internal environment, i.e., homeostasis, is essential for life. Cellular conditions that need to be maintained within a narrow range include: Temperature pH concentrations of: minerals, nutrients, wastes Negative Feedback Homeostasis is largely maintained by what is known as Negative Feedback: • counteracting a change in body state to restore the original state e.g. • sweating to cool an overheated body • releasing insulin to lower blood sugar • accelerated breathing, pulse to increase oxygen **various sensory systems in the body detect changes and trigger negative feedback responses** 1 Organization of the Animal Body A B CELLULAR LEVEL Muscle cell TISSUE LEVEL Muscle tissue C D ORGAN LEVEL Heart ORGAN SYSTEM LEVEL Circulatory system E ORGANISM LEVEL Many organ systems functioning together The 4 Basic Tissue Types All tissues in the animal body fall into one of 4 basic tissue types: Epithelial Tissue Connective Tissue Muscle Tissue Nerve Tissue Epithelial Tissue Sheets of cells that line body surfaces, cavities: skin; digestive, urinary, reproductive tracts; vessels; glands Epithelial cells come in 3 basic shapes… • squamos (flattened) • cuboidal (cube-shaped) • columnar (elongated) …and in single or multiple layers: simple or stratified epith. 2 Examples of Epithelial Tissue simple squamous epithelium (lung) stratified squamous epithelium (lining the esophagus) simple cuboidal epithelium (kidney) Colorized SEM dead cells rapidly dividing cells stratified squamous epithelium simple columnar epithelium (intestine) (human skin) Connective Tissue Tissue that supports, binds, “fills” or provides structure. • contains few cells, mostly extracellular matrix (ECM) Connective Tissue (CT) comes in 3 basic types: Loose CT – underlies epithelium, loosely woven fibers, “gel-like” Fibrous or Dense CT – densely packed fibers as in tendons & ligaments Specialized CT – bone, cartilage, blood & lymph, adipose (fat) tissue Examples of Connective Tissue Fat droplets Cartilageforming cells adipose tissue Matrix Cell nucleus cartilage (end of a bone) Collagen fibers Central canal fibrous connective tissue (tendon) White blood cells Matrix Red blood cell Boneforming cells bone Plasma loose connective tissue (under the skin) blood 3 Muscle Tissue Made of cells that contract, comes in 3 types: Skeletal Muscle (striated, voluntary – moves skeleton) Cardiac Muscle (striated, involuntary – heartbeat) Smooth Muscle (unstriated, involuntary – visceral org., vessels) Muscle fiber Unit of muscle contraction Muscle fiber Junction between two cells Nucleus Nucleus Muscle fiber Nucleus cardiac muscle skeletal muscle smooth muscle Nerve Tissue Tissue that transmits electrochemical signals. neuron Contains 2 basic cell types: Cell body Neurons – cells that generate, transmit electrical signals Nucleus Glial cells (glia) – metabolic support, insulation for neurons Organs and Organ Systems Organs = multiple tissues that comprise a physically & functionally distinct structure Organ systems = multiple organs that work together to perform a common function • each tissue and organ has a distinct role e.g. – Integumentary System (skin, nails, etc) • skin, nails, hair each have different roles • each contains multiple tissues (epithelium, connective tissue, muscle, nerve) with diff. roles 4 Organs are made of all Tissue Types Small intestine (cut open) Lumen Lumen epithelial tissue (columnar epithelium) connective tissue smooth muscle tissue (2 layers) connective tissue epithelial tissue The 11 Major Organ Systems Endocrine System hypothalamus Skeletal System bone adrenal gland ovary (female) (endocrine glands) • hormone production pituitary gland thyroid gland parathyroid gland Endocrine System • physiological control cartilage Skeletal System pancreas testis (male) (bones, cartilage…) • structural support • blood production • calcium, phosphorus storage Organ Systems cont’d… Circulatory System (blood & vessels, heart) Circulatory System • transport of nutrients, wastes, cells, hormones • temperature control heart Respiratory System nasal cavity larynx trachea bronchus lung • pH balance Respiratory System blood vessels (pharynx, trachea, lungs) • gas exchange • pH balance 5 Organ Systems cont’d… Muscular System Muscular system (all 3 muscle types) • movement of skeleton Integumentary system skeletal muscles • movement in the hollow organs • heartbeat hair nails Integumentary System (skin, hair…) skin • protection from external threats • temperature balance Organ Systems cont’d… Digestive System Urinary system (esophagus, stomach, liver, intestines, pancreas) • digestion, absorption of food • waste disposal mouth kidney esophagus ureter liver stomach small intestine urinary bladder urethra Urinary System Digestive system large intestine (kidneys, bladder) • blood-borne waste disposal anus • salt & water homeostasis brain Nervous System sense organ (brain, spinal cord, nerves) spinal cord Nervous system • internal, external sensation • behavioral control • physiological control nerves Reproductive Systems Female oviduct ovary uterus vagina Male seminal vesicles prostate vas deferens penis urethra testis Reproductive Systems (ovaries, uterus, testes…) • gamete, production • hormone production • nurturing offspring 6 Organ Systems cont’d… Lymphatic and Immune Systems thymus Lymphatic & Immune Systems (lymph, lymphatic vessels, lymph nodes, thymus, spleen, white blood cells) • fluid balance, transport bone marrow spleen lymph nodes lymphatic vessels • fat transport • immune responses Key Terms for Chapter 20 • homeostasis • epithelium – squamous, cuboidal, columnar simple & stratified • connective tissue – loose, fibrous, specialized • skeletal, smooth & cardiac muscle • neurons & glial cells Relevant Review Questions: 2-14 7