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 Cells Tissues Organs Organ Systems 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 dead cells epithelium (kidney) rapidly dividing cells Colorized SEM 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 Cartilage- forming cells adipose tissue Matrix Cell nucleus cartilage (end of a bone) Collagen fibers Central fibrous connective canal White blood tissue (tendon) cells Matrix Bone- Red blood forming cell cells Plasma bone 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 Unit of fiber muscle Junction between contraction Muscle two cells fiber Nucleus Nucleus Muscle fiber Nucleus cardiac muscle skeletal muscle smooth muscle Nerve Tissue Tissue that transmits electrical signals. neuron Contains 2 basic cell types: Neurons – cells that generate, transmit electrical signals 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 Lumen Small intestine (cut open) Lumen epithelial tissue (columnar epithelium) connective tissue smooth muscle tissue (2 layers) connective tissue epithelial tissue 10 Major Organ Systems (11 if you count the Integumentary System) The Circulatory System (blood & vessels, heart) • nutrient & waste transport • temperature control • pH balance • movement of cells, hormones Lymphatic/Immune System (lymph & vessels, lymphocytes) • fluid balance, transport • fat transport • immune responses Organ Systems cont’d… The Endocrine System (endocrine glands) • hormone production • physiological control The Nervous System (brain, spinal cord, nerves) • internal, external sensation • behavioral control • physiological control 5 The Digestive System (esophagus, stomach, liver, intestines, pancreas) • food breakdown, absorption • waste disposal The Urinary System (kidneys, bladder) • blood-borne waste disposal • salt & water homeostasis The Respiratory System (pharynx, trachea, lungs) • gas exchange • pH balance The Muscular System (all 3 muscle types) • movement of skeleton • movement in hollow organs • heartbeat The Skeletal System (bones, cartilage, tendons…) • structural support • blood production • calcium, phosph. storage The Reproductive System (ovaries, uterus, testes…) • gamete, production • hormone production • nurturing offspring 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 6 Chapters 21-23, 25: Organ Systems of the Body 1. Circulatory System 2. Respiratory System 3. Digestive System 4. Urinary System 1. The Circulatory System Organs of the Circulatory System Heart pumps the blood Blood vessels veins, arteries, capillaries Blood red & white blood cells, blood plasma (we’ll also look at lymph and lymphatic vessels) Roles of the Circulatory System • deliver O2, remove CO2 • transport nutrients, wastes, hormones • regulate temperature & pH • immune protection (antibodies, white blood cells) 7 Vertebrate Circulation Fish have a 2 chambered heart Reptiles & amphibians have a 3 chambered heart Mammals & birds have a heart with 4 chambers left right atrium atrium The Human Heart semilunar semilunar valve valve atrioventricular (AV) valve atrioventricular (AV) valve right left ventricle ventricle The Cardiac Cycle 1 2 3 oxygenated vs deoxygenated 1. Atria contract, forcing blood from right atrium & left atrium into ventricles systole 2. Ventricles contract, forcing blood into aorta (fr. LV) and pulmonary artery (fr. RV) 3. Atria & ventricles relax (diastole), cycle repeats… 8 superior capillaries of vena cava 8 head, chest, and arms pulmonary artery pulmonary artery 9 aorta capillaries of left lung capillaries 2 7 of right lung 2 3 3 4 5 10 pulmonary 4 vein pulmonary 6 1 vein right atrium 9 left atrium left ventricle right ventricle aorta inferior vena cava capillaries of 8 abdominal region Blood Circulation and legs Control of the Heartbeat The synchronous contraction of cardiac muscle cells is controlled by the sinoatrial (SA) & atrioventricular (AV) nodes. • ea beat starts at the SA node, stimulates AV node (delayed) Specialized Pacemaker muscle fibers (SA node) AV node Right ventricle 1 23Apex 4 ECG Oxygen Transport Oxygen is transported by red blood cells (RBCs) • aka erythrocytes • don’t have a nucleus! • vast majority of blood cells (~99%) are RBCs Oxygen binds to hemoglobin in RBCs • each hemoglobin molecule binds 8 O2 • vast majority of protein in RBCs is hemoglobin 9 Other Blood Cells Blood also contains: Platelets • essential for blood clotting • “pinch off” from cells in bone marrow called megakaryocytes White Blood Cells • collective term for all cells of immune system • B cells, T cells, monocytes, neutrophils… Blood Vasculature Arteries, arterioles: • conduct blood flow away from the heart • usually oxygenated blood Veins, venules: • conduct blood flow toward the heart • usu. deoxygenated blood Capillaries: • smallest vessels • where “exchange” occurs Capillaries Unlike larger vessels, capillary walls are only 1 cell thick, barely wide enough for RBCs to pass through • allows diffusion of gases, nutrients, wastes between blood & tissues • some fluid (plasma) “leaks out” as well 10 The Lymphatic System A vascular system distinct from the circulatory system • conducts fluid “leaked” from the blood called lymph • returned to blood at vena cava • lymph is filtered through structures called lymph nodes • full of immune cells, important part of the immune response • also transports fats from digestion in small intestine Lymphatic Vessels Fluid leaked from capillaries is taken up by “lymph capillaries” • lymph is conducted into larger lymphatic vessels • lymph passes through lymph nodes before being “dumped” into the blood at the vena cava 2. The Respiratory System 11 The Respiratory System Respiratory System function : • facilitate O2 uptake, waste CO2 removal Respiratory System Organs Nasal Cavity warms & moistens air Pharynx passage for air, food/water Larynx vocal chords; where air, food separate Epiglottis blocks airway when swallowing Trachea connects airway to lungs Lungs site of gas exchange Diaphragm muscle used for “inhaling” Inhalation & Exhalation Rib cage expands as Rib cage gets rib muscles air smaller as air contract inhaled rib muscles exhaled relax lung diaphragm Diaphragm contracts Diaphragm relaxes (moves down) (moves up) Inhalation Exhalation 12 The Lungs The bronchi of the lungs branch into smaller and smaller bronchioles which terminate in alveoli. • alveoli are the sites of gas exchange • arrangement maximizes the surface area for gas exchange Gas Exchange in the Alveoli O2 and CO2 simply diffuse from higher to lower concentration across the capillary, alveolar epithelia • O2 is more concentrated in the lungs than in the blood • CO2 is more concentrated in the blood than in the lungs *situation reversed in body tissues* Summary of Gas Exchange Deoxygenated blood from tissues returns to the right atrium & lungs ventricle of the heart which pumps it to the lungs. In the alveoli of the lungs blood is oxygenated and flows back to the left atrium & ventricle of the heart, from which