Bio11 Announcements TODAY Cell division (Ch 18) Exam 1: NEXT Tuesday Jan 25 100 pts Multiple choice (80 pts) and short answer (20 pts) Bring a scantron Study guide posted on my website To read pdf files, download Adobe Acrobat Extra credit 15 pts available see my website Extra Credit Visit the Body Worlds exhibit at the Tech Museum in San Jose Write a 1-2 page report (10 pts) See my website for details Ch 4: Organization of body systems How humans are organized Tissues Homeostasis 1
Tissues Epithelial Tissues Tissue = a group of cells of the same type Performs specific functions Types of tissues Muscle tissue Nervous tissue Know their functions! See Ch. 4 in your text Think coverings and linings Tightly connected cells cover body surfaces and line body cavities Shapes vary: squamous, cuboidal, columnar Layers of cells: simple = one stratified = several Some examples of organs lined with epithelial tissue: Heart Lung Stomach Small intestine Large intestine Urinary bladder Epithelial cells lining esophagus The structure of connective tissue is correlated with its function: to bind and support other tissues. lining small intestine Provides support, stores fat, forms blood cells Figure 21.3 2
Fat droplets Cell Collagen fiber (a) Loose connective tissue (under the skin) (b) Adipose tissue White blood cells Red blood cell Plasma (c) Blood Cell nucleus Collagen fibers (d) Fibrous connective tissue (forming a tendon) Matrix Bone Provides rigid support Made of a hard matrix of calcium salts deposited around protein fibers Bone cells (osteocytes) are found in lacunae arranged in concentric circles Bone is not static it s being remodeled constantly Cells Cells Matrix (f) Bone (e) Cartilage (at the end of a bone) Figure 21.4 Blood cells are produced in bone marrow Red blood cells transport oxygen White blood cells Platelets fight infection pieces of cells that clot blood Muscle tissue Muscles are the motors of the body 3 kinds of muscles Cardiac muscle Skeletal muscle Smooth muscle Walls of blood vessels, digestive tract 3
Nervous Tissue Nervous tissue Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. dendrite Makes communication of sensory information possible Is found in the brain and spinal cord Consists of a network of neurons 2 major cell types: Neurons Carry electrical impulses Neuroglia Support and nourish neurons Outnumber neurons 9:1 Astrocyte Neuron nucleus cell body Microglia Oligodendrocyte myelin sheath axon Capillary dendrite nucleus cell body Micrograph of neuron Ed Reschke How do cells connect within a tissue? (containing blood and lymph vessels) Smooth muscle tissue (two layers) How do cells connect within a tissue? Cells in epithelial tissues, muscle and nerve are connected by cell junctions Cell-cell adhesion Cell-extracellular matrix Figure 21.7a 4
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. plasma membranes tight junction proteins basement membrane Tight junction microvilli Tight junctions form an impermeable barrier plasma membranes join in a zipper-like fastening Allow epithelial cells to form a layer that prevents leakage Found in the stomach, intestines, kidneys plasma membranes cytoplasmic plaque intercellular filaments cytoskeletal fibers Adhesion junction Adhesion junctions Keep cells anchored to each other But the layer of cells can bend and stretch cytoskeletal fibers join between cells and have flexibility Found in the skin Level HIERARCHICAL ORGANIZATION OF ANIMALS Description Example membrane channels plasma membranes Gap junction Gap junctions membranes channels between cells allow small molecules to diffuse from one cell to another Found between cardiac muscle cells at intercalated disks Allow heart to beat as a coordinated whole Cell Tissue Organ Organ system Organism The basic unit of all living organisms A collection of similar cells that perform a specific function Multiple tissues forming a structure that performs a specific function A team of organs that work together A living being, which depends on the coordination of all structural levels for homeostasis and survival Muscle cell Cardiac muscle Heart Circulatory system Person Figure 21.UN01 5
Homeostasis Homeostasis Body s ability to maintain a relatively constant internal environment Blood glucose ph levels Body All organ systems contribute to homeostasis The digestive system regulates the amount of nutrients in the blood The urinary system regulates the amount of wastes in the blood The nervous and endocrine systems coordinate the other body systems How do animals maintain a constant body temp? Negative feedback External environment Homeostatic mechanisms Animal s internal environment Small internal changes The primary homeostatic mechanism Occurs when the system s output corrects the original stimulus Large external changes Figure 21.12 6
Mechanical example of negative feedback Home heating system Thermostat is set to 68 o F Thermostat turns off a heater when room rises to the set point And turns on a heater when temp drops There s a fluctuation above and below normal typical of negative feedback mechanisms Room drops Room rises Heating stops Set point: Room 20 C (68 F) Heating starts Room is above set point Room is below set point Thermostat (control center) turns heater off Above 68 o Below 68 o Thermostat (control center) turns heater on Figure 21.13 Human example: Regulation of body Sweat gland Skin 1. Blood vessels dilate 2. Sweat is produced Control center in brain activates cooling mechanisms Negative feedback system A body temp below normal brings about a change toward a warmer body temp Humans have homeostatic mechanisms that aid in thermoregulation, which: Cool or Heat the body Body drops Body rises Set point: Body near 37 C (98.6 F) Skin Above normal Below normal 1. Blood vessels constrict 2. Muscles shiver 3. Metabolic rate increases Body is above set point Body is below set point Control center in brain activates warming mechanisms Figure 21.14 7