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Review slides Lecture Exam 2 1 Respiratory System Respiration (in the respiratory system) is the process of exchanging gases between the atmosphere and body cells. It consists of the following events (in order): • *pulmonary ventilation • *external respiration • transport • internal respiration • cellular respiration Functions of the respiratory system You should know the order of these events. We breathe: 1. To provide O2 for cellular respiration and 2. To rid our bodies of CO2 (waste gas) 2 Organs of the Respiratory System Upper respiratory tract – nose, nasal cavity, sinuses, and pharynx Lower respiratory tract – larynx, trachea, bronchial tree, lungs Conducting portion carries air; nose to the terminal bronchioles Respiratory portion exchanges gases; respiratory bronchioles and alveoli 3 1 Mucous in Respiratory Tract Respiratory mucosa lines the conducting passageways and is responsible for filtering, warming, and humidifying air. Pseudostratified, ciliated columnar epithelium with goblet cells Respiratory epithelium is interrupted by stratified squamous epithelium in the oroand laryngopharynx 4 Nose and Paranasal Sinuses The nose: 1) warms 2) cleans 3) humidifies air Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Be able to label this… Paranasal sinuses are mucus membranelined, air-filled spaces in maxillary, frontal, ethmoid, and sphenoid bones that drain into the nasal cavity Sinuses: 1. Reduce skull weight 2. Serve as resonating chambers 5 Larynx Prevents swallowed material from passing into trachea = major components of larynx Inelastic Vestibular folds Covered by folds of laryngeal epithelium that project into glottis Protective Posterior Sound Vocal folds (cords) Elastic Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 6 2 Trachea & Primary Bronchi Posterior (S mooth muscle) Note that the trachea is anterior to the esophagus (T5) (T6) Anterior C-rings of cartilage: 16-20 incomplete rings completed posteriorly by trachealis muscle keep trachea open (patent) Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001 7 Bronchial Tree Bronchi Bronchioles Alveolar structures Primary Alveolar ducts Secondary (lobar) Alveolar sacs Tertiary (segmental) Alveoli Intralobular Trachea Terminal Respiratory conducting portion respiratory portion Know this chart 8 Bronchial Tree Hilus of lung is the medial opening for air passageways, blood vessels, nerves, and lymphatics. Bronchi - Primary; w/ blood vessels - Secondary (lobar); two on left, three on right - Tertiary (segmental); supplies a broncho- pulmonary segment; 10 on right, 8 on left Bronchioles - Intralobular; supply lobules, the basic unit of lung - Terminal; 50-80 per lobule - Respiratory; a few air sacs budding from theses Carina Bronchioles are to the respiratory system what arterioles are to the circulatory system Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Intralobular 9 3 Lobules of the Lung The Lobule is the basic unit of structure and function in the lung (Intralobular) Terminal and respiratory bronchioles are lined with cuboidal epithelium, few cilia, and no goblet cells Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 10 Gases and Pressure • Our atmosphere is composed of several gases and exerts pressure – 78% N2, 21% O2, 0.4% H2O, 0.04% CO2 – 760 mm Hg, 1 ATM, 29.92” Hg, 15 lbs/in2,1034 cm H2O • Each gas within the atmosphere exerts a pressure of its own (partial) pressure, according to its concentration in the mixture (Dalton’s Law) – Example: Atmosphere is 21% O2, so O2 exerts a partial pressure of 760 mm Hg. x .21 = 160 mm Hg. – Partial pressure of O2 is designated as PO2 11 Normal Inspiration • Intra-alveolar (intrapulmonary) pressure decreases to about 758mm Hg as the thoracic cavity enlarges (P 1/V) • Atmospheric pressure (now higher than that in lungs) forces air into the airways • Compliance – ease with which lungs can expand An active process Phrenic nerves of the cervical plexus stimulate diaphragm to contract and move downward and external (inspiratory) intercostal muscles contract, expanding the thoracic cavity and reducing intrapulmonary pressure. Attachment of parietal pleura to thoracic wall pulls visceral pleura, and lungs follow. 12 4 Maximal (Forced) Inspiration Thorax during normal inspiration Thorax during maximal inspiration • aided by contraction of sternocleidomastoid and pectoralis minor muscles Compliance decreases as lung volume increases Costal (shallow) breathing vs. diaphragmatic (deep) breathing 13 Normal Expiration • due to elastic recoil of the lung tissues and abdominal organs • a PASSIVE process (no muscle contraction involved, no energy needed) Normal expiration is caused by - elastic recoil of the lungs (elastic rebound) and abdominal organs - surface tension between walls of alveoli (what keeps them from collapsing completely?) 14 Maximal (Forced) Expiration • contraction of abdominal wall muscles • contraction of posterior (expiratory) internal intercostal muscles • An active, NOT passive, process 15 5 Terms Describing Respiratory Rate • Eupnea – quiet (resting) breathing • Apnea – suspension of breathing • Hyperpnea – forced/deep breathing • Dyspnea – difficult/labored breathing • Tachypnea – rapid breathing • Bradypnea – slow breathing 16 Know these Alveoli and Respiratory Membrane • Respiratory Membrane consists of the walls of the alveolus and the capillary, and the shared basement membrane between them Mechanisms that prevent alveoli from filling with fluid: 1) cells of alveolar wall are tightly joined together 2) the relatively high osmotic pressure of the interstitial fluid draws water out of them 3) there is low pressure in the pulmonary circuit Surfactant resists the tendency of alveoli to collapse on themselves. 17 Diffusion Through Respiratory Membrane The driving for the exchange of gases between alveolar air and capillary blood is the difference in partial pressure between the gases. alveolus tissues Because O2 and CO2 are relatively insoluble in H2O (plasma), RBCs are used 18 to carry or transform these gases. 6 Oxygen Transport • Most oxygen binds to hemoglobin to form oxyhemoglobin (HbO2) • Oxyhemoglobin releases oxygen in the regions of body cells • Much oxygen is still bound to hemoglobin in the venous blood Tissues Lungs But what special properties of the Hb molecule allow it to reversibly bind O2? 19 The O2-Hb Dissociation Curve Recall that Hb can bind up to 4 molecules of O2 = 100% saturation At 75% saturation, Hb binds 3 molecules of O2 on average Sigmoidal (S) shape of curve indicates that the binding of one O2 makes it easier to bind the next O2 This curve tells us what the percent saturation of Hb will be at various partial pressures of O2 20 Oxygen Release Amount of oxygen released from oxyhemoglobin increases as • partial pressure of carbon dioxide increases • the blood pH decreases and [H+] increases (Bohr Effect; shown below) • blood temperature increases (not shown) • concentration of 2,3 bisphosphoglycerate (BPG) increases (not shown) 21 7 Carbon Dioxide Transport in Tissues • dissolved in plasma (7%) • combined with hemoglobin as carbaminohemoglobin(15-25%) • in the form of bicarbonate ions (68-78%) CO2 + H2O ↔ H2CO3 H2CO3 ↔ H+ + HCO3- 22 CO2 exchange in TISSUES Carbon Dioxide Transport in Lungs 23 CO2 exchange in LUNGS Summary of Gas Transport PO2 = 40 mm Hg PO2 = 100 mm Hg PO2 = 100 mm Hg L U N G S T I S S U E S PO2 = 40 mm Hg PCO2 = 45 mm Hg PCO2 = 40 mm Hg PCO2 = 40 mm Hg PCO2 = 45 mm Hg 24 CO2 + H2O ← H2CO3 ← H+ + HCO3- H+ + HCO3- ← H2CO3 ← CO2 + H2O 8 Control of Respiration • Control of respiration is accomplished by: 1) Local regulation 2) Nervous system regulation • 1) Local regulation – alveolar ventilation (O2), Blood flow to alveoli – alveolar ventilation (O2), Blood flow to alveoli – alveolar CO2, bronchodilation – alveolar CO2, bronchoconstriction 25 Control of Respiration • 2) Nervous System Control – The DRG and VRG in medullary respiratory rhythmicity center control rate/depth of breathing • Changes in breathing – CO2 is most powerful respiratory stimulant – Recall: H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3– Peripheral chemoreceptors (aortic/carotid bodies) • PCO2, pH , PO2 stimulate breathing – Central chemoreceptors (medulla) • PCO2, pH stimulate breathing 26 Major Organs of Digestive System Digestion is the mechanical and chemical breakdown of food into a small enough form that cells can absorb - Two major movements stimulating digestion: 1) segmentation and 2) peristalsis Organs can be divided into the: -Digestive tract (primary) (alimentary canal); tube extending from mouth to anus (about 30 ft.); in contact with food -Accessory organs (secondary); teeth, tongue, salivary glands, liver, gallbladder, and pancreas; provide secretions for digestion 27 9 Alimentary Canal Wall Know the 4 layers of the alimentary canal 28 Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Innervation of the Alimentary Canal The alimentary canal has extensive sympathetic and parasympathetic innervation - mainly in the muscularis externa - regulates its tone and the strength, rate, and velocity of muscular contractions • submucosal plexus – controls secretions/blood flow • myenteric plexus – controls gastrointestinal motility/sphincters • parasympathetic division of ANS – increases activities of digestive system and relaxes sphincters • sympathetic division of ANS – generally inhibits digestive actions and contracts sphincters 29 Palate • roof of oral cavity Figure from: Hole’s Human A&P, 12th edition, 2010 (adenoids) Important in separating the nasopharynx from the pharynx during swallowing Epiglottis prevents food from entering trachea during swallowing 30 10 Secondary (Permanent) Teeth Figure from: Hole’s Human A&P, 12th edition, 2010 Total of 32 secondary (permanent) teeth; total of 20 primary (baby, milk) teeth Be able to label this diagram 16 1 I C Big Molars!!! 32 17 Know the order of these 31 Functions of Saliva • Moistens food • Binds food particles • Dissolves food for tasting • Begins chemical digestion of complex CHO (amylase) • Cleans teeth and mouth (pH = 6.5 – 7.5) • Anti-microbial (IgA and lysozyme) 32 Pharynx Figure from: Hole’s Human A&P, 12th edition, 2010 Pharynx aids swallowing by grasping food and moving it toward the esophagus. 33 11 Three Phases of the Swallowing Reflex Only voluntary phase is the buccal (oral) phase, i.e., the initiation of swallowing, then… • soft palate and uvula raise • hyoid bone and larynx elevate Pharyngeal phase • epiglottis closes off top of trachea • longitudinal muscles of pharynx contract reflexive • inferior constrictor muscles relax and esophagus opens Esophageal phase • peristaltic waves push food through pharynx 34 Esophagus conveys food from pharynx to stomach by peristalsis Key Overview of Gastric Control/Secretion Emptying of Stomach ( [H+ ]) ECL Cells + + + + D cells - G cells + Somatostatin Inhibition Endocrine Factor Exocrine Factor Histamine Parasympathetic NS + + Both + Stimulation - Mucous Cells Stomach Molility (Segmentation/Peristalsis) (cephalic/gastric phases) pH < 3.0 + Intrinsic Factor + B12 Parietal Cells H+ + Cl- Gastrin (intestinal phase) + Fats in Small Intestine + + + Stretch of stomach pH > 3.0 (dilution of H+) HCO3- (alkaline tide) + Peptides Chief Cells Pepsinogen Pepsin Protein Breakdown Food in Stomach Ileum Fat Breakdown 35 Lipases Key Regulation of Pancreas/Intestinal Digestion + Stimulation Acidic Chyme Enters Duodenum + Secretin + + Cholecystokinin (CCK) + + Gallbladder Contraction Bile and Pancreatic ducts -, (brush border) + Relaxation of hepatopancreatic sphincter + Pancreas Enterokinase Trypsinogen Trypsin Chymotrypsinogen Procarboxypeptidase Proelastase Chymotrypsin Carboxypeptidase Elastase (proenzymes, zymogens) Bile 3- HCO3 PO4 pH to ≈ 8 (req. for enzyme action) (emulsification) Triglycerides Cholesterol Fat Soluble Vitamins Lacteals Subclavian vein Proteins Lipases Fatty acids, monoglycerides Conversion to chylomicrons Nucleases (DNA, RNA) Nucleotides Portal Vein Amylase (glycogen, starches) Mono-, di-, trisaccharides Di- and tripeptides Action of brush border enzymes Monosaccharides Amino acids 36 12 Liver Functions (over 200!) • Three general categories of function 1) Metabolic regulation • • • • • Interconversion of carbohydrates, lipids, amino acids Removal of wastes Vitamin and mineral metabolism Drug inactivation Know items Storage of fats, glycogen, iron, vit A/B 12/D/E/K 2) Hematological regulation • • • • • in red Phagocytosis and antigen presentation; ab removal Synthesis of plasma proteins Removal of circulating hormones Removal of worn-out RBCs (Kupffer cells) Removal or storage of toxins 3) Synthesis and secretion of bile (digestion) 37 Paths of Blood and Bile in Hepatic Lobule Figure from: Hole’s Human A&P, 12th edition, 2010 Liver’s role in digestion is production of bile Sinusoid Hepatic portal vein → sinusoids → central vein → hepatic veins → inferior vena cava Hepatic artery 38 Composition of Bile (Chole-) Yellowish-green liquid continually secreted by hepatocytes • water • bile salts (bile acids) • derived from cholesterol • emulsification of fats (increases surface area for digestive enzymes; large fat blobs become smaller blobs) • absorption of fatty acids, cholesterol, and fat-soluble vitamins • 80% are recycled (reabsorbed and reused) – enterohepatic circulation of bile • 20% excreted in feces (disposes of excess cholesterol) • bile pigments (bilirubin and biliverdin from breakdown of RBCs) • electrolytes The hormone secretin, released by the small intestine, stimulates the hepatocytes to produce a bicarbonate-rich bile that neutralizes acidic chyme coming from the stomach 39 13 Gallbladder [Cyst(o)-] Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Main function is to store and concentrate bile between meals, and release concentrated bile under the influence of CCK 40 Regulation of Bile Release from GB Figure from: Hole’s Human A&P, 12th edition, 2010 • fatty chyme entering duodenum stimulates the GB to release bile (via CCK) Secretin causes the bile ducts (and pancreatic ducts) to secrete bile rich in HCO3- 41 Actions of Cholecystokinin (CCK) on Digestion Figure adapted from: Barrett, K., Gastrointestinal Physiology, Lange, 2006 CCK Contraction of Gallbladder Secretion of pancreatic enzymes Reduced emptying of stomach Relaxation of hepatopancreatic sphincter Protein, CHO, lipid absorption and digestion Matching of nutrient delivery to digestive and absorptive capability 42 14 Small Intestine • Small Intestine – Three major parts • Duodenum – mixing chamber; mucus, buffers, enzymes • Jejunum – digestion and absorption • Ileum – connects to cecum of large intestine – Blood supply and drainage via superior mesenteric artery/vein – Surface area greatly increased, especially in the jejunum, by • Plicae • Villi • Microvilli 43 Know these things… Small Intestine (cont’d) – Secretions/Motility • mucus secretion (protective) stimulated by presence of chyme in small intestine • distension of intestinal wall activates nerve plexuses in wall of small intestine • motility/secretion stimulated by gastroenteric reflex • parasympathetics trigger release of intestinal enzymes – Absorption • Protein, CHO, electrolytes –> to hepatic portal vein into liver • Fats via chylomicrons and lacteals -> circulation (2nd pass) – Movements • Local via myenteric plexuses • Long distance via stomach filling – Gastroenteric reflex – Gastroileal reflex 44 Know these things… Secretions of Small Intestine • peptidase – breaks down peptides into amino acids • sucrase, maltase, lactase – break down disaccharides into monosaccharides Brush border • intestinal lipase – breaks down fats into fatty acids and glycerol • enterokinase – converts trypsinogen to trypsin • gastrin/somatostatin – hormones that stimulate/inhibit acid secretion by stomach • cholecystokinin (CCK) – hormone that inhibits gastric glands, stimulates pancreas to release enzymes in pancreatic juice, stimulates gallbladder to release bile, and relaxes hepatopancreatic sphincter (of Oddi) • secretin – stimulates pancreas to release bicarbonate ions in pancreatic juice; stimulates gall bladder to release bicarbonate-rich bile 45 See Table 23.32 in Marieb for summary of digestive enzymes – great to use for XC!! 15 Absorption of Fats in the Small Intestine Figure from: Hole’s Human A&P, 12th edition, 2010 • fatty acids and glycerol • several steps • absorbed into lymph into blood Chylomicrons contain TG, cholesterol, and phospholipids 46 Functions of Large Intestine • little or no digestive function • absorbs water, bile salts, and electrolytes • secretes mucus (lubrication, binding, protection, pH) • conversion of bilirubin (uro- and stercobilinogen) • houses intestinal flora (~800 species of bacteria) and absorbs vitamins liberated by bacterial action (K, B5, and Biotin); produces intestinal gas (flatus) • forms and stores feces • carries out defecation 47 Large Intestine Blood supply/drainage via superior mesenteric arteries/veins 48 16 Movements of Large Intestine • slower and less frequent than those of small intestine • mixing movements (haustral churning every 30 min) • mass movements - usually follow meals (stimulated by distension of stomach and duodenum) - gastrocolic reflex - duodenocolic reflex - peristaltic wave from transverse colon through rest of large intestine 49 The Rectum, Anal Canal, and Anus Figure from: Hole’s Human A&P, 12th edition, 2010 Temporary storage of fecal material in rectum triggers the urge to defecate Rectal valves Internal anal sphincter is usually contracted but relaxes in response to distension. External sphincter must be tensed to retain feces Procto- = anus or rectum 50 (Keratinzed strat. squamous epithelium) Parasympathetic Defecation Reflex Note that this reflex: 1) relaxes (opens) the internal sphincter and 2) constricts (closes) the external sphincter Need voluntary relaxation of the external sphincter for defecation 51 17 Nutrients Nutrients – chemical substances supplied by the environment required for survival (used for growth, repair, or maintenance of the body) Macronutrients • carbohydrates • proteins • fats Micronutrients • vitamins • minerals Essential Nutrients • human cells cannot synthesize • include certain fatty acids, amino acids, vitamins 52 Nitrogen Balance Variety of compounds in the body contain nitrogen (N): amino acids, purines, pyrimidines, creatine, porphyrins. The body neither stores nor maintains reserves of N. There’s only about 1 kg of N in body at any one time. During starvation, N-containing compounds, like skeletal muscle, are conserved; CHO and fats are metabolized first (protein-sparing effect) • nitrogen balance - amount of nitrogen taken in is equal to amount excreted • negative nitrogen balance develops from starvation • positive nitrogen balance develops in growing children, pregnant women, or an athlete in training 53 Body Mass Index • occurs when caloric intake in the form of food equals caloric output from BMR and muscular activities • positive energy balance leads to weight gain • negative energy balance leads to weight loss Body Mass Index (BMI)* = Wt (kg) / Height2 (m) Thin < 18.5 Healthy or Normal 18.5 – 24.9 Overweight 25.0 – 29.9 Obese 30.0 – 39.9 Morbidly Obese 40.0 * Source: World Health Organization 54 18 Calculations of RDA/Maximums • Energy yields: – Protein, CHO = 4 Kcal/gm – Fats = 9 (or 9.5) Kcal/gm • No more than 30% of calories from fat • RDA for protein = 0.8 g/kg body weight – Recall: (2.2 lbs/kg) 55 Example Calculations - Fat What is the maximum number of grams of fat to be consumed per day for a patient on a 1500 calorie diet? 1) Find maximum number of CALORIES from fat: 1500 calories/day x 30% = 450 calories/day max from fat 2) Calculate number of GRAMS of fat in 450 calories 450 calories/day X 1 gram fat = 47 grams fat/day 9.5 calories 450 calories/day X 1 gram fat = 50 grams fat/day 9.0 calories 56 Example Calculations - Protein What is the minimum number of grams of protein recommended that should be consumed per day for a 175 lb patient? 1) Find patient’s weight in Kg. 175 lbs X 1 Kg = 79.5 Kg 2.2 lbs. 2) Calculate number of GRAMS of protein required per day 79.5 Kg X 0.8 g protein/day = 63.5 grams protein/day Kg 57 19 Summary of Lipoproteins Designation Origin Action Chylomicron GI tract Transports dietary fats (mainly triglycerides) to liver for processing Very Low Density Lipoprotein (VLDL) Liver Transports triglycerides from liver to adipose cells Low Density Lipoprotein (LDL) Liver Transports cholesterol from liver to cells in body High Density Lipoprotein (HDL) Liver Removes excess cholesterol from cells and transports to liver 58 The Fat-soluble Vitamins • Absorbed with fats in digestive tract • Function/Other sources – Vitamin A; structural component of retinal (night vision) – Vitamin D • increases absorption of calcium and phosphorus from intestine • skin and UV light – Vitamin E • stabilizes internal cellular membranes • antioxidant – Vitamin K • Clotting (‘K’lotting) • bacteria in intestine and green, leafy vegetables 59 Water-soluble Vitamins • Rapidly exchanged between fluid compartments of digestive tract and circulating blood • Excesses excreted in urine • Vitamins B12 and C are stored in larger quantities than other water-soluble vitamins – B vitamins [know these functions] • as a group, are coenzymes used to harvest energy • Vitamin B12 is important in hematopoiesis and maintenance of myelin sheath and epithelial cells – Vitamin C (ascorbic acid) [know these functions] • collagen production • Antioxidant / immune system booster • absorption of iron 60 20 Minerals *Mineral *Symbol *Major/Trace Primary Distribution *Major Function(s) Major Sources Conditions *Calcium Ca Major Bones & Teeth Structure of bone/teeth; nerve impulse conduction; muscle contraction milk; + kidney stones - stunted growth *Phosphorus P Major Bones & Teeth Structure of bone/teeth; ATP; Nucleic acid & proteins meats; cheese; milk + none - stunted growth *Potassium K Major Intracellular Fluid maintenance of resting membrane potential (RMP) avocados; bananas; potatoes + none - muscular & cardiac problem s *Sodium Na Major Extracellular Fluid maintenance of RMP, electrolyte, water, & pH balance table salt; cured ham + hypertension, edema - cramps, convulsi ons *Chlorine Cl Major Extracellular Fluid maintenance of RMP, electrolyte, water, & pH balance table salt; cured ham + vomiting - muscle cramps 61 Minerals *Mineral *Symbol *Major/Trace Primary Distribution *Major Function(s) Major Sources Conditions *Magnesium Mg Major Bones needed in mitochondria for cellular respiration; ATP/ADP conversion milk; dairy; legumes + diarrhea - neuromuscular problems *Iron Fe Trace Blood part of hemoglobin liver + liver damage - anemia *Iodine I Trace thyroid essential in the synthesis of thyroid hormones iodized table salt + thyroid hormone imbalance - goiter *Zinc Zn Trace liver, kidneys, brain wound healing; part of several enzymes meats; cereals + slurred speech - decreased immunity 62 Metabolism -olysis breakdown of -genesis creation of -neo new Hormones: Fed – Insulin Fasted – Glucagon, Corticosteroids, Epi/NE • Glycolysis – metabolism of glucose to pyruvate (Fed) • Gluconeogenesis – metabolism of pyruvate to glucose (CHO from non-CHO source) – (Fasted) • Glycogenesis – metabolism of glucose to glycogen (Fed) • Glycogenolysis – metabolism of glycogen to glucose (Fasted) • Lipogenesis – creation of new triglyceride (fat) – (Fed) • Lipolysis – breakdown of triglyceride into glycerol and fatty acids (Fasted) Major purpose of BOTH states is to maintain homeostatic levels of glucose in blood 63 21 Basal Metabolic Rate Basal metabolic rate (BMR) • rate at which body expends energy at rest (kcal/hr) • primarily reflects energy needed to support activities of organs BMR is proportional • varies with gender, body size, body to body weight temperature, and endocrine function Energy needed Body’s basal • to maintain BMR metabolic rate • to support resting muscular activity (BMR) falls 10% • to maintain body temperature during sleep and • for growth in children and pregnant about 40% during women prolonged starvation BMR is profoundly affected by circulating 64 thyroid hormone levels 22