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QOD: What are the functions of the digestive system? The Digestive System Functions Breaks down food into smallest components for absorption into blood – Proteins – Carbohydrates – Lipids Types – Mechanical – Chemical Structures Alimentary Canal – Mouth – Esophagus – Stomach – Intestines Accessory Organs – Pancreas – Liver – Gall bladder The Digestive System To return to the chapter summary click escape or close this document. Your Mouth To return to the chapter summary click escape or close this document. The Mouth Mechanical digestion – Teeth – Tongue Chemical digestion – Salivary glands – Salivary amylase Esophagus Digestion type? Connects mouth to stomach – Peristalsis Stomach Structure: J-shaped pouch – Cardiac sphinctor – Pyloric Sphinctor Mechanical digestion – Smooth muscle Chemical digestion – Pepsin Stomach To return to the chapter summary click escape or close this document. The Small Intestines First job: Chemical digestion with aid of accessory organs Pancreas – Pancreatic amylase – Trypsin – Pancreatic lipase – Nuclease Liver/Gall Bladder – Bile Pancreas & Liver To return to the chapter summary click escape or close this document. Small Intestines Continued Enzymes of the small intestines – Maltase – Sucrase – Lactase – Peptidase – Nuclease Small Intestines – Job 2 Structure: 3 main parts – Duodenum – Jejunum – Ileum Job 2 of Small Intestines: Absorption Longest organ: about 6m Contains villi – Villi contain microvilli Villi To return to the chapter summary click escape or close this document. Large Intestines Structure: – Cecum – Ascending Colon – Transverse colon – Descending colon – Rectum and anus Function: – Re-absorption of water – Synthesis of vitamins B and K The Circulatory System I. Function and Structure Function: – To send materials around your body through the blood stream Structures: – Heart – Blood vessels – Blood II. The Heart Composed entirely of muscle Pericardium Myocardium Right and Left side separated by the septum Four chambers: – Atria (Atrium) – Ventricles More Heart structures Valves – prevent back-flow of blood – – – – Tricuspid Bicuspid/Mitral valve Pulmonary valve Aortic valve III. Blood vessels Arteries – Arterioles Veins – Venules Capillaries IV. Circulation Pulmonary circulation Systemic circulation – Coronary circulation – Renal circulation – Hepatic portal circulation V. Pulmonary circulation Oxygen-poor blood returns to the heart through Superior vena cava and Inferior vena cava right atrium Right atrium contracts: blood tricuspid valve right ventricle Ventricle contracts: blood pulmonary valve pulmonary arteries Pulmonary circulation - continued Blood taken to lungs to pick up oxygen and drop off carbon dioxide Oxygen rich blood returns to heart through pulmonary veins left atrium Atrium contracts: blood bicuspid valve left ventricle •Ventricle contracts: blood aortic valve aorta systemic circulation Pulmonary Circulation To return to the chapter summary click escape or close this document. V. The Heartbeat When a single cardiac muscle fiber is stimulated, all fibers are stimulated and network contracts as a unit Impulse generated by sinoatrial node – Cluster of cells in right atrium – Called the “pacemaker” – Generates atrial contraction – Maintains rhythm of the heart beat Heartbeat…continued Signal from S-A node picked up by atrioventricular node. – Cluster of cells in the walls of the ventricles – Generates ventricular contraction Pacemaker To return to the chapter summary click escape or close this document. VI. Blood Pressure Force of blood on the walls of the arteries Measured with a sphygmomanometer Measurements: – Systolic – Diastolic VII. Disorders of the Circulatory System Artherosclerosis – Fatty deposits build up on walls of arteries – Can obstruct flow of blood – Can form clots – Can lead to high blood pressure, stroke, or heart attack High blood pressure: – Heart has to work harder – Can weaken heart and blood vessels Heart attack – Blockage in coronary arteries deprives heart tissue of oxygen – Can lead to heart tissue death Stroke – Blockage in arteries in brain (clots), depriving brain of oxygen – Can lead to brain tissue death The Respiratory System To return to the chapter summary click escape or close this document. I. Structures and Function Structure: – Pharynx, Trachea, bronchi, alveoli, lungs Function: – Gas exchange: take in air and exchange oxygen for carbon dioxide II. Pathway of Air Air is taken in through mouth and nose to – Pharynx, passes the epiglottis to – Larynx to – Trachea to – Bronchi to – Bronchioles to – Alveoli Air Into Lungs To return to the chapter summary click escape or close this document. III. Cleaning Air Respiratory tract is lined with ciliated cells that secrete mucus – Mucus traps dirt/dust – Cilia move dirt to your throat to be expelled or swallowed IV. Alveoli and Gas Exchange Alveoli: air sacs in lungs where gas exchange takes place – Lie next to bed of capillaries – Oxygen diffuses from alveoli into blood – Carbon dioxide diffuses from blood into alveoli Aveoli To return to the chapter summary click escape or close this document. V. Mechanics of Breathing Breathing is controlled by the diaphragm – Inhale: Diaphragm contracts and flattens. Rib cage rises. Chest expands – Exhale: Diaphragm relaxes and becomes dome-shaped. Rib cage lowers and chest contracts. – Creates a vacuum effect Breathing VI. Control of Breathing Control center: medulla oblongata – Part of brain stem – Contains respiratory center – Responds to carbon dioxide levels in blood – Sends nerve impulses to diaphragm The Urinary System Kidneys Removes – Urea – Mineral salts – Water Structure – Cortex – Medulla – Renal pelvis – Renal arteries/veins Kidneys To return to the chapter summary click escape or close this document. The Nephron Functional unit of the kidneys Structures: – Bowman’s capsule – Glomerulus – Renal tubule Proximal convoluted tubule Loop of Henle Distal convoluted tubule Filtrates blood by nutrient exchange Nephron To return to the chapter summary click escape or close this document. Filtration, Reabsorption and Secretion Filtration – Materials forced out of blood into Bowman’s capsule – Out: water, urea glucose, vitamins, salts Reabsorption – Active transport of needed materials out of filtrate back into blood (Water, Glucose, Minerals – Mostly in proximal convoluted tubule Secretion – Some materials added to filtrate in distal convoluted tubule Formation of Urine Urine formed from remaining material in distal convoluted tubule Urine from several nephrons flow into collecting duct More water reabsorbed here Loop of Henle promotes reabsorption of water Elimination of Urine From collecting ducts Ureter Urinary bladder Urethra The Nervous System I. Structure and Function Function: – To communicate messages throughout your body using impulses Structures: – Neurons are the basic unit of the nervous system II. The Neuron Three categories of neurons – Sensory – Motor – Interneurons III. Parts of a Typical Neuron Dendrites Cell body – Nucleus Axon – Axonal hillock – Myelin sheath – Nodes of Ranvier Axon terminals (endings) – Synaptic end bulbs Fig. 9.04 IV. Relaying an Impulse Receptors in skin sense a stimulus Sensory neurons transmit the message Message is interpreted by the brain Brain sends a response through motor neurons Motor neurons relay that message to muscles to act in response V. Neurons at Rest High K+ ions inside the cell, high Na+ ions outside cell Na+/K+ pump maintains this difference Outside of the membrane has a positive charge, inside has a negative charge Called a polarized membrane VI. Impulse Transmission Membrane at rest is polarized – High K+ ions inside cell – High Na+ outside cell – Na+/K+ pump – Positive charge outside the cell – Negative charge inside the cell A stimulation sets off an action potential – Na+ gates open and it rushes inside cell This depolarizes the cell (brings it close to neutral charge) – After a delay, Na+ gates close and K+ gates open and K+ rushes out This repolarizes cell to send cell back to rest. – This action is propagated down the neuron The Impulse…animated. VII. The Synapse Synapse – the junction between neurons When an impulse reaches the end of one neuron: – Neurotransmitters are released from vessicles inside the synaptic end bulbs – NT’s “jump” from one neuron to the next, stimulating an action potential down that neuron The Synapse…animated! VIII. Divisions of the Nervous System Central Nervous System Peripheral Nervous System – Somatic Nervous system – Autonomic Nervous System Sympathetic Nervous System Parasympathetic Nervous System IX. The CNS Control Center of body Coordinates all body activities Include brain and spinal cord X. The Brain Cerebrum – Separated into two hemispheres, connected by bundles of nerves – Outer portion = cerebral cortex – Responsible for higher thinking, memory, reasoning, speaking, etc. Cerebellum – Located in back – Responsible for coordination, balance and posture Brain Stem – Located under cerebrum – Connects brain to spinal cord 3 parts to brain stem – Medulla oblongata: Breathing and heart rate – Pons – Midbrain XI. The PNS Somatic Nervous System – Responsible for voluntary movements Autonomic nervous system – Responsible for involuntary movements Divisions of the Autonomic NS Sympathetic – Controls internal structures in times of stress (“Fight or Flight” response) – Releases epinephrine and norepinephrine Parasympathetic – Controls body at times of rest
