2/7/17 Blood Vessels (II): Capillaries LO1: What is the baroreceptor reflex Negative feedback loop: Stimulus: BP increases Receptor: baroreceptors in carotid and aorta arteries detect increased BP Control center: medulla oblongata—site of nerve impulse integration Effectors/ response: Parasympathetic nerves inhibit syWe also discuss several other topics like characteristics that start with m
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mpathetic activity vasodilation and decreased heart rate **be able to attribute above 2 phenomena as causes of BP reduction response to excessively decreased BP would be akin to this loop, in the opp direction increased sympathetic activity vasoconstriction & increased heart rate to bring BP back up what hormones would affect (para)sympathetic activity? Review hormones from last class LO2: Describe the different types of capillaries and how their structure relates to function Basal lamina: same as tissue that cap feeds into Capillary: single layer squamous cells Thin for diffusion LO3: Describe the different types of capillaries and how their structure relates to function Need to be able to disting btwn 3 types Continuous Endothelial cells joined by tight junctions Tight junctions—seal off space btwn cells Prevents diffusion of large particles Most abundant Narrow range… Proteinmediated transport No wholesale diffusion Fenestrated Still tight junctions; fenestrations in addition Expedite process Every endocrine gland surrounded by fenestration rapid entry into blood supply similar setup for nutrient absorption in small intestine for solutes in kidneys structure: Endothelial cells contain fenestrations function: allow for rapid diffusion (endocrine glands, small intestine, kidneys) SinusoidalDiscontinuous Endothelial cells, irregular basil lamina, large pores Allow large substances like cells to cross capillary walls (e.g. bone marrow) LO3: Explain the roles of diffusion, filtration and osmosis in capillary exchange **99% of capillary questions on exam from slides/ lecture MAJORLY cut down from explanation/ depth in textbook Capillary exchange: Movement nutrients, gases, ions, wastes across capillary walls Diffusion: Movement nutrients, gases, ions and wastes across a membrane **down a concentration gradient Osmosis: Movement water across a membrane down a concentration gradient Filtration: Movement water across a membrane down a pressure gradient Easy to understand how substances move out (diffusion down conc gradient) Harder to understand water and solutes coming back in Explained by pressure **testlike q: arteriovascular anastomosis bypasses capillary bed metarteriole: def by precapillary sphincter deciding whether/not to shunt blood from one side to other (bypass) if open, goes to cap bed, will undergo diffusion if closed, bypass LO3: Explain the roles of diffusion, filtration and osmosis in capillary exchange Diffusion—Relies on concentration gradients • O2, glucose more concentrated in blood • CO2, wastes more concentrated in tissues • Fenestrations, intercellular clefts and endothelial membranes (e.g. O2) GlucoseNa symporter transports glucose into cell Creates glucose gradient that facilitates further active transport of glucose into cell Hydrophobic waste typ more conc in tissue (bc of cellular respiration) CO2 = product Exhaling gradient Filtration—Fluid filters out the arterial end of a capillary bed and is reabsorbed at the venous end • Delivers dissolved solutes to tissues, removes wastes • Blood hydrostatic pressure forces fluid out • Colloid osmotic pressure (albumins) draws fluid back in Starting w/ blood hydrostatic pressure Pressure: created by blood pushing against vessel wall 3050 mmHg forces fluid out of vessels fluid flows out increases hydrostatic P P on cap side of network lower than arterial side2 reasons increasing hsp inside; decreasing outside albumin: fluid ration increasing in blood increased osmotic P producing albumins ensures that wastes return to blood supply to be eliminated colloid OP particles in solution, but large enough to be seen CQ 1. Veins have smaller lumens, more elastic fibers, more smooth muscle than arteries F—have huge lumens, less elastic fiber 2. Which would increase peripheral resistance? A. increased blood viscosity (shorter vessels, vasodilation, increased radius opp effect) 3. Angiotensin II is hormone that induces thirst/ sodium ion retention by kindeys? A. True 4. What do capillaries consist of? C. thin sheet endothelium w/ basal lamina 5. Which of the following is leakiest? (XX) B. sinusoidal capillary Respiratory System LO1: Respiratory system Circulatory system about getting oxygen, etc, where it needs to go Respiratory system about gas exchange LO2: Functions 1. Respiration 1. Pulmonary ventilation Respiration NOT = ventilation (breathing in/out) Technical def: relate to cellular respiration 2. Pulmonary gas exchange –in alveoli 3. Gas transport –i.e. oxygen in hemoglobin 4. Tissue gas exchange –in capillary beds 2. Communication—cellcell signaling, long & short distance 3. Olfaction: smelling 4. Abdominal content expulsion: Diaphragm squeezes stomach vomiting 5. Venous blood and Lymph flow: Diaphragm and valves in veins venous blood overcoming gravity Less obvious… 6. Acid base homeostasis—CO2 dissolved in plasma as carbonic acid rate inspiration / expiration helps control this blood acidity and body pH 7. Blood pressure regulation (assists in Angiotensin II production) 2/9/17 Respiratory System (II) cont LO3: Upper respiratory tract nasal cavity pharynx nasal pharynx—where nasal cavity (inside nose) meets back of throat oral pharynx—where larynx meets oral cavity (inside mouth) mouth not considered part of resp system Laryngopharynx—meeting of larynx w/ pharynx part of digestive system digestive syst separated from respiratory syst by larynx LO3: Nasal cavity external structures less important than internal anatomy lateral cartilages—shape of nose septal & atal cartilages—shape of nostrils apex: “tip” (same as tip of heart) superior olfactory mucosa: bipolar neurons—protect olfaction smell part of respiratory system vibrissae: nose hairs imp in filtration internal structures posterior nares vestibule—in anterior nares (where can stick finger in) stratified squamous epithelium covers it—abrasion resistant sinuses—named for bones that make their borders frontal, sphenoid, ethmoid, maxillary function: humidify / warm air secondary function: amplify sound nasal conchae & cavities function: create turbulence—traps dust in mucosae warming/ humidifying = function of most structures more efficient respiration in nose than mouth bc of these structuresLO3: Nasal cavity Functions • Warms & humidifies incoming air many structures dedicated to this functionimportant • Filters out debris and secretes antibacterial substances need to get rid of this before reaching delicate tissues in lungs • Detects odors through olfactory structures • Resonating chamber for amplifying the voice tissues stratified—abrasion resistant respiratory mucosa: Pseudostratified ciliated columnar epithelium & Goblet cells 1cell layer goblet cells just beneath epithelium—produce boogers cilia in trachea sweep particles upward; nasal cavity sweeps down converge in esophagus Why does one nostril always seem more open than the other? and then it changes? Erectile tissue in inferior concha (Lamina propria) • Extensive venous plexus • Every 3060 min, one side swells with blood, diverting airflow to the other side • Allows engorged side recovery time from drying out—humidifying time Switches sides for next round of engorgement LO3: Pharynx Pharynx: Muscular 90º turn in respiratory tract between Posterior nares and larynx Tonsil @ back—lots immune cells converge at this point Interaction btwn incoming air (containing microbes) and immune cells Tonsils trap; macrophages act 3 sections: • Nasopharynx: Passes only air, lined with pseudostratified ciliated columnar epithelium • Receives auditory tubes and house pharyngeal tonsil • 90º turn traps large particles (pathogens) – dealt with by ciliated mucous membranes and tonsil • Uvula and soft palate close off nasopharynx during swallowing • Oropharynx: Passes air, food and fluid, lined with stratified non keratinized squamous epithelium completely different tissue—food joining • Houses palatine tonsils (diff set) food introduces more microbes—come in pairs to handle new load • Laryngopharynx: Esophagus begins where laryngopharynx ends, lined with nonkeratinized stratified squamous epithelium transition back to thinner tissuefood filtered out; less abrasion resistance required LO3: Larynx Primary function is to keep food and drink out of the airways • In some organisms it has evolved a secondary function • phonation: sound production / modulation Epiglottis: Flap of elastic cartilage that guards the superior opening of the larynx • At rest, stands almost vertically • During swallowing • Extrinsic muscles pull larynx upwards • Tongue pushes epiglottis downwards to meet larynx • Closes airways and directs food to esophagus **cilia sweeping… if above esophagus, sweep up; if below, sweep down hyoid bone: point of attachment for various membrane epiglottis: elastic cartilage seal off opening elastic creates tight seal thyroid cartilage—comprises Adam’s apple; shield appearance cricoid cartilage 2 above connected by cricothyroid cart—mostly hyaline arytenoid cartilageabove, corniculate & cuneiform carilages (smallest) name 9 larynx cartilages 3 individual cartilages epiglottis, cricoid cartilage, thyroid cartilage 6 paired cartilages cuneiform cart, corniculate cart, arytenoid cart SOUND PRODUCTION NOT TESTED FOR EXAM 1 LO4: Lower respiratory tract Begins at trachea Branches 2 bronchi Key features R lung 3 lobes; L 2 lobes, indentation for heart (taking up space < lobes) Bronchial tree—less branched on L side LO4: Trachea • ~ 2 cm in diameter, 1012 cm Long • supported by Cshaped hyalin cartilage rings open in back flexibility bc esophagus runs posterior to trachea • function: Keep trachea open (like “drier hose”) • • Elastic connective tissue & smooth muscle spans C gap (allows contraction and expansion) • Carina (internal median ridge) directs air flow in lower most tracheal cartilage to left and right bronchi lots nerves so anything enetering forceful cough reflex LO4: The Bronchial tree Branching system of conducting air tubes in each lung • Main bronchus to ~ 65000 terminal bronchioles • Primary (main) bronchi supported by Cshaped cartilage rings (like trachea), 1 left 1 right • Secondary (lobar) bronchi (2 left, 3 right), supported by overlapping crescent shaped cartilage plates • Tertiary bronchi (10 per lung) continue to branch into bronchioles terminating in alveoli bronchioles = start of massive branching can ID (in lab) by transition Cshape crescent cartilage Conducting zone until end of bronchial tree; marks start of resp zone LO4: Bronchi All bronchi lined with pseudo stratified ciliated columnar epithelium • lamina propria contains numerous goblet cells and MALT (MALT = mucosa associated lymphatic tissue) • Elastic connective tissue and Smooth muscle (muscularis mucosae), relax or constrict airways NOT involved w/ inspiration/expiration (that’s for intercostals) • Bronchial tree serviced by the bronchial artery (oxygenated blood) BA = 1st artery to enter lung at hylum??? Supplies lungs w/ oxygen—much like coronary circuit (but it is considered systemic) • Pulmonary artery branching closely follows branches of bronchial tree (bring oxygenless blood to lungs to get oxygenated) LO5: Bronchioles Lack cartilage • < 1mm diameter • Each ventilates a Pulmonary lobule • Cuboidal epithelium No longer pseudostratified • Well developed layer of smooth muscle • Branches into 5080 terminal bronchioles LO5: Bronchioles Respiratory bronchioles branch off from terminal bronchioles ***Start of respiratory division common testq • Alveoli bud from walls (participate in gas exchange) • Respiratory bronchioles divide into 210 alveolar ducts, end in alveolar sacs (end), clustered around atrium • Simple squamous epithelium Final type present in alveolar sacs Special, for diffusion LO5: Alveoli (sing. alveolus) Alveolus 0.2 0.5 mm pouch • Respiratory membrane –2 cell types • Squamous (type I) alveolar cells cover 95% of surface • Rapid gas diffusion—surface devoted to gas exchange • Great (type II) cuboidal alveolar cells cover 5% of surface • Repair alveolar epithelium damage to this tissue heightened by smoking • Secrete pulmonary surfactant (prevents bronchioles collapsing during exhalation) prevent alveoli from collapsing in—nec for gas exchange • Alveolar macrophages • Most numerous alveolar cells not part of membrane LO5: Respiratory membrane Barrier between alveolar air and blood Alveoli are kept relatively dry by absorption of excess fluid by capillaries Lack surfactant dryness & collapse Shared basemet membrane Min distance—enables diffusion Btwn alveolar/ endothelial cells Airflow summary Conducting division Upper resp tract • Nasal cavity • Pharynx nasal oral laryngo • Larynx lower resp tract • Trachea • Main (primary) bronchi (2) • Lobar bronchi (5—2 on 1, 3 on other) • Segmental bronchi • Bronchioles • Terminal bronchioles Respiratory division • **Respiratory bronchioles start resp zone • Alveolar ducts • Alveolar sacs Respiratory System (III) LO1: Pressure, volume & breathing Boyles law: the pressure and volume of a gas are inversely related (assuming constant temperature and number of gas molecules) Inspiratory muscles: Diaphragm & External intercostals increase the size of the thoracic cavity indirectly increase lung volume decrease pressure creates pressure gradient –air flows fr high low P Diaphragm contraction flattening increased thoracic vol External intercostals contract lung vol increase low pressure air rush in Accessory muscles: Internal intercostals, abdominals & some back muscles Further increase size of thoracic cavity (or decrease it during expiration) For excess breath (further increase/ decrease vol) Voluntary control—skeletal muscles Breath largely voluntary until reflex kicks in Pulmonary ventilation Breathing (pulmonary ventilation) = repetitive cycle of inspiration and exhalation • Quiet respiration = effortless, autonomic breathing whilst at rest regulated by medulla oblongata • Forced respiration = deep, rapid breathing (e.g. during exercise) • Only muscle in lungs is smooth muscle of bronchial tree—change diameter of bronchioles skeletal muscles handle actual inspiration/ expiration • Breathing muscles = diaphragm, intercostals & various accessory muscles LO2: Pressure changes during respiration **Atmospheric pressure •760 mmHg at sea level (influence of gravity on air particles higher altitude decrease mmHg harder to breathe **Intrapulmonary pressure (avg 760): Air pressure within the alveoli, • variableRises and falls with inspiration and expiration, then equilibrates with atmospheric pressure creates pressure gradient at times, want it to be greater/ less than AP **Intrapleural pressure (avg (756): • Pressure within the pleural cavity (btwn pleural membranes) problem there lung collapse , • Rises and falls with inspiration and expiration (w/ thoracic vol), • ~ 4 mmHg less than intrapulmonary pressure • Tendency of lung to collapse and chest wall to expand (suction) • Pleural fluid constantly pumped out into lymphatic system rises/ falls but ALWAYS 4 mmHg LOWER than intrapulmonary pressure otherwise, lung collapse low P region inside cavity suction / vacuum (constant fluid removal) alveoli expand **KNOW #’s of starred pressures inhalation: Diaphragm & external intercostals contract exhalation: Diaphragm & external intercostals relax, elastic recoil of lungs