Chapter Note 17 PDF

10/19/20 Lecture 17 Tissues, Organs, and Organ Systems Structural Organization of the Body 1 10/19/20 Tissue • Tissue – group of similar cells that perform a common function • Basic types of tissue in the human body: - Epithelial - Connective - Muscle - Nervous Epithelial Tissue - tightly pac...

10/19/20 Lecture 17 Tissues, Organs, and Organ Systems Structural Organization of the Body 1 10/19/20 Tissue • Tissue – group of similar cells that perform a common function • Basic types of tissue in the human body: - Epithelial - Connective - Muscle - Nervous Epithelial Tissue - tightly packed sheets of cells that form the covering or lining of all internal and external body surfaces (a) Examples of organs lined with epithelial tissue: (b) Epithelial cells in skin Heart and blood vessels Respiratory tract Epidermis (external) Digestive tract Urogenital tract (c) Epithelial cells lining the small intestine Endothelium (internal) Figure 16.1 2 10/19/20 • Epithelial tissues are typically anchored on one face, but free on another - The free side is typically exposed to the environment of body fluids or atmosphere - Can be single layer or many layers thick - Function in protection, secretion, and absorption - Epithelial cells are continuously sloughing off and are replaced by cell division Connective Tissue – loosely organized; composed of cells embedded in a matrix; bind organs or tissues to one another • Six different types: 1. Loose connective tissue: under the skin, most widespread Adipose tissue: fat tissue Blood: blood cells, plasma Fibrous connective tissue: tendon, ligament Cartilage: chondrocytes Bone: osteocytes 2. 3. 4. 5. 6. 3 10/19/20 Figure 16.2b (b) Adipose tissue Loss connective tissue: connect epithelia to underlying tissues; hold organs in place Cell nucleus Fat droplets Adipose tissue: connect skin to underlying structures; protect organs; storage of energy Figure 16.2c (c) Blood Platelet Red blood cell Plasma Fibrous connective tissue: connect muscles to bones (tendons); connect bones to bones at joints (ligaments) White blood cell Blood: carry oxygen and nutrients; fight infection Ossifying Cartilage Marrow cavity Cartilage Cartilage vs. Bone: bone is distinguished from cartilage by the presence of inorganic calcium salts in its ground substance, which makes it rigid. - Cartilages cushions joint - Bones make up skeleton - Bone marrow produces blood cells 4 10/19/20 Muscle Tissue – contractile tissue (capable of shortening); muscle fibers contain two proteins (actin and myosin) that cause the cell to contract (a) Skeletal muscle (biceps) Muscle fiber Nucleus (b) Cardiac muscle (heart) Muscle fiber Nucleus (c) Smooth muscle (intestine) Muscle fiber Nucleus Similarities and Differences among Three Muscle Tissue Types Skeletal Cardiac Smooth Location Attach to bone Heart Digestive tract, blood vessel Fiber Striated, Not branched Striated, Branched Not striated, Not branched Movement Voluntary Involuntary Involuntary 5 10/19/20 Nerve Tissue – composed of cells called neurons that conduct electrical signals; found in the brain and spinal cord • Main function of neurons: Sense stimuli - Process stimuli - Transmit signals - • Most neurons do not undergo cell division - Once dead, brain cells cannot recover Organs and Organ System • An organ: formed of two or more tissue types; carry specific function • An organ system: formed by organs that act together • An organism: formed by all the organ systems of a body 6 10/19/20 An Example of An Organ – Blood Vessel • Can you find how many types of tissues the blood vessel is made of ? Organ Donation • Organ donors may be living, or brain dead • In cardiac death, organs deteriorate due to lack of oxygen, and thus are less suitable for transplant. • Commonly transplanted organs: kidney, liver, heart, intestine, and pancreases 7 10/19/20 Paired Exchange of Organs Organ donors must have a compatible blood type with the recipient. Johns Hopkins Comprehensive Transplant Center http://www.hopkinsmedicine.org/transplant/ programs/kidney/incompatible/paired_kidney _exchange.html 8 10/19/20 Regulating the Internal Environment • Homeostasis: The ability of the body to maintain balanced conditions - Through feedback controls: - Negative (mostly): e.g. body temperature blood sugar - Positive (special event) e.g. childbirth • Negative feedback: the outcome of a process inhibits that process - Pancreas secretes different hormones to regular liver function controlling blood sugar content Liver converts glucose to glycogen. (a) If blood glucose level rises... Pancreas secretes insulin. Glucose Glycogen Liver Blood glucose level falls. (b) If blood glucose level falls... Homeostasis Normal blood glucose level Glucose levels rise. Glucose Glycogen Pancreas secretes glucagon. Liver Liver breaks down glycogen into glucose and releases glucose into bloodstream. Figure 16.11 9 10/19/20 • Positive feedback: the outcome of a process increases or intensifies that process. - In childbirth, pressure in cervix stimulates hormone à uterus contracts à pressure in cervix increases à more hormone is produced à uterus further contracts 10