BIOL 204 respiratory system

causes of increased respiration during exercise

- brains sends motor commands to muscles which also sends information to respiratory centers - increases pulmonary ventilation in antcipation of the needs of the exercising muscles - increased pulmonary ventilation keeps blood gas values at their normal levels in spite of the elevated O2 consumption and CO2 generation by the muscles

central chemoreceptor neurons

- brainstem neurons that respond to changes in pH of cerebrospinal fluid - regulates respiration to maintain stable pH

limts to voluntary control

- breaking point = when CO2 levels rise to a point where automatic controls override one's will

valsalva maneuver

- breathing technique used to help expel contents of certian abdominal organs - depression of the diaphragm raises adominal pressue - consists of taking a deep breath, holding it by closing the glottis and then contracting the abdominal muscles - aids in childbrith, urination, defecation, vomiting

peripheral chemoreceptors

- carotid and aoritc bodies - respond to O2 nad CO2 content of blood

lung cancer- causes and types

- causes = smoking and poor air quality - squamos-cell carcinoma (most common) = transformed bronchiole epithelium into stratified squamos cells - adenocarcinoma = originates in mucous glands of lamina propia - small-cell carcinoma = least common, most dangerous, originates in primary bronchi, invades mediastinum, metastasizes quickly to other organs

respiratory muscles function

- change lung volumes and create differences in pressure relative to the atmosphere

bronchioles

- ciliated cubodial epithelium - smooth muscle **terminal bronchioles = have no mucus, have cilia

anatomic dead space

- conducting zone of airway where there is no gas exchange - can be altered somewhat by sympathetic dilation (increases dead space by allows greater flow)

respiratory zone

- consists on alveooli and other gas exhange regions

bronchoconstriction

- decrease in diameter - histamine, parasympathetic nerves, cold air, and chemical irritants - decrease airflow - suffocation can occur from extreme bronchoconstriction brought about by anaphylactic schock and asthma

hypoxia

- deficiency of oxygen or the inability to use oxygen - a consequence of respiratory disease - often marked by cyanosis (blue skin)

quiet breathing

- dimensions of thoracic cage increase only a few millimeters in each direction - enough to increase its total volume by 500 mL so that what flows into respiratory tract

nasal cavity

- divided by the nasal septum - roof = ethmoid and sphenoid bones - floor = hard palate

atmospheric pressure function

- drives respiration - weight of air above us - 1 atm / 760 mm HG at sea level, decrease at higher elevations

pulmonary compliance

- ease with which the lungs can expand - reduced by degenerative lung disease in whichlungs are stiffened by scare tissue - limited by surface tension of the water film inside alveoli (surfactant reduces surfact tension

respiratory muscles in inspiration

- external intercostals (elevate ribs 2-12, widen thoracic cavity) - diaphragm (descends adn increases depth of thoracic cavity)

respiratory airflow

- governed by same principles of flow, pressure and resistance as blood flow - flow of fluid is directly proportional to the pressure differece betwee two points - flow of fluid is inversely proportional to resistance

chronic hypoxemia at low elevations

- if arterial PO2 <60 mm Hg, stimuates heavy breathing

physiologic (total) dead space

- in pulmonary disease, some alveoli unable to exchange gases - sum of anatomic dead space + pathological alveolar dead space

stretch receptors

- in smooth muscles of bronchi and bronchioles - in visera pleura that responds to inflation of lungs

conducting zone

- includes those passages that serve only for airflow - no gas exchange - nostrils through major bronchioles

bronchodilation

- increase in diameter - epinephrine and sympathetic stimulation - increase airflow

respiratory muscles in forced expiration

- internal intercostals, costal part (depress ribs 1-11, narrow thoracic cavity) - diaphragm (asecnds and reduces depth of thoracic cavity)

bronchi

- lined by pseudostratified columnar epithelium - mucous-secreting - smoothe muscle layer to constrict or dilate airway

chronic obstructive pulmonary disease

- long term obstruction of airflow and substantial reduciton in pulmonary vetilation - almost always associated with smoking - other risk factors: air pollution, occupational exposure to airborne irritants, hereditary defects

peak flow

- maximum speed of expiration - blowing into a handheld meter

histotoxic hypoxia

- metabolic poisons (ie- cyanide) prevents O2 use in tissues

dorsal respiratory group (DRG)

- modifies rate and depth of breathing - receives influences fromm external sources

pons respiratory centers (PRG)

- modifies rhythm - adapts to sleep, emotion, exercise

pharynx

- musclar funnel - 3 parts naso-, oro-, laryngopharnyx - naso = pseudostratified olumnar epithelium - oro and laryngo = stratified squamous

irritant receptors

- nerve endings amid epithelial cells in the airway

neural control of breathing

- no autorhythmic pacemaker cells for respiration - exact mechanism for setting respiatory rhythm unkown - breathing depends on repeptitive stimulation of skeletal muscles from brain and will cease if spinal cord is severed high in neck (skeletal muscles require nervous stimulation; multiple respiratory muscles require coordination)

membrane thickness: normal vs pathological

- normal = only .5 um thick and presents little obstacle to diffusion - pathological = when membrane is thicker, gases have farther to travel between blood and air and cannot equilibrate fast enough to keep up with blood flow - **effects efficiency of alveolar gas exchange

voluntary control over breathing

- originates in the motor cortex of frontol lobe of the cerebrum - sends impulses down corticospinal tracts to respiratory neurons in spinal cord, bypassing brainstem

relaxed breathing

- passive process achieved mainly by elastic recoild of thoracic cage - recoil compresses lungs - volume of thoracic cavity decreases - raises intrapulmonary pressure to about 1 cm H2O - air flows down the pressure gradient and out of the lungs

ventral respiratory group (VRG)

- primary generator of respiratory rhythem - prodcues a respiratory rhythm of 12 breaths per minute

diaphragm

- prime mover of respiration - contraction flattens diaphram, enlarging thoracic cavity and pulling air into lungs - relaxation allows diaphragm to bulge upward again, compressing the lungs and expelling air - accounts for 2/3 of airflow

inferior vocal cords (folds)

- produce crude sounds - stratified squamos epithelium - controlled by intrinsic muscles

diseases related to pathological membrane thicknesss

- pulomary edema = in left ventricular failure causes edema and thickening of the respiratory membrane - pneumonia = causes thickening of respiratory membrane

define restrictive disorders

- reduction in pulmonary compliance - any disease that produces pulmonary fibrosis (ex- black lung disease, tuberculosis)

eupnea

- relaxed, quiet breathing - TV 500 mL and respiratory rate of 12-15 bpm

nasal mucosa

- rerpiratory epithelium = pseudostratified columnar, mucus secretion - olfactory epithelium = ciliated (non-motile), smell

hypoxic drive

- respiration driven more by low PO2 than by CO2 or pH - occurs during: emphysema, pneumonia, and high elevations after several days

bronchial artery

- services bronchial tree with systemic blood - arises from the aorta

chronicbronchitis

- severe, persistent inflammation of lower respiratory tract - thick, stagnant mucus

intrapleural pressure

- slightly negative pressure that exists between the two pleural layers

hypoxemic hypoxia

- state of low arterial PO2 - usually due to inadequate pulmonary gas exchange - causes: oxygen deficiency at high elevations, impaired ventilation, drowning, aspiration of a foreign body, respiratory arrest, degenerative lung diseases

alveolar gas exchange

- swapping of O2 and CO2 across respiratory membrane - for O2 to get into blood, it must dissolve in this water and pass through the respiratroy membrane separating the air from the bloodstream - for CO2 to leave the blood, it must pass the other way and then diffuse out of the water film into the alveolar air

internal and external intercostal muscles functions

- synergirsts to diaphragm - contribute to change of thoracic cage volume - add about 1/3 of the air that ventilates the lungs

scalenes

- synergist to diaphragm - fix or elevate ribs to 1 and 2

repiratory membrane

- thin barrier between the alveolar air and blood - 3 layers = squamos alveolar cells, endothelial cells of blood capillary, shared basement membrane

vital capacity

- total amount of air that can be inhaled and then exhaled with maximum effort - important measure of pulmonary health - VC = ERV + TV + IRV (4,700 mL)

hyperbaric oxygen therapy

- treatment with oxygen at >1 atm of pressure - steeper gradient, so more oxygen diffuses into blood

boyle's law in action with inspiraiton

- two pleural layers cling together due to cohesion of water - parietal clings to ribs during inspiration and visceral follows - this stretches aleoli withing the lungs, expanding the lungs - as it increases in volume, its internal pressure drops, and air flows in

larynx

- voice box - cartilaginous chamber - primary function is to keep food and drink out of airway (epiglottis)

charles's law

- volume of a gas is directly proportional to its absolute temeprature - affects lung expansion (ex- 16 C / 60 F air is inhaled then warmed to 37 C / 99 F by the time it reaches the alveoli) - increase in temp = thermal expansion

oxygen toxicity

- when pure O2 breathed at 2.5 atm or greater - generates free radicals and H2O2 - destroys enzymes - damages nervous tissue (leads to seizures, coma, death)

trachea

- windpipe - anterior to esophagus - supported by hyaline cartilage - lined by pseudostratified solumnar epithelium - contains mucous-secreting goblet cells

which is more soluble in water: CO2 or O2?

CO2 is 20x more soluble than O2 (equal amounts of O2 and CO2 are exchanged across the respiratroy membrane becuase CO2 is much more soluble and diffuses more rapidly)

inspiratory capacity

maximum amount of air that can be inhaled after a normal tidal expiration IC = TV + IRV (3,500 mL)

total lung capacity

maximum amount of air the lungs can contain TLC = RV + VC (6,000 mL)

tachypnea

accelerated respiration

acidosis vs alkalosis

acidosis = blood pH <7.35 alkalosis = blood pH >7.45

expiratory reserve volume

air in excess of tidal volume that can be exhaled wiht maximum effort (1,200 mL)

inspiratory reserve volume

air in excess of tidal volume that cna be inhaled with maximum effort (3,000 mL)

venous reserve

amount of O2 remaining in the blood after it passes through the systemic capillary beds

functional residual capacity

amount of air remaining in lungs after a normal tidal expiration FRC = RV + ERV (2,500 mL)

how is breathing controlled by the brain?

at two levels - one = cerebral and conscious other = automatic and unconscious

apnea

temporary cessation of breathing

how is composition of CSF and blood monitored?

brainstem respiratory centers receive input from central and peripheral chemoreceptors that monitor composition

pulmonary artery

branches closely follow the bronchial tree on their way to the alveoli

two factors that influence airway resistance

bronchiole diameter and pulmonary compliance

how does respiratory system work with urinary system?

to regulate the body's acid-base balance

dalton's law

total atmospheric pressure is the sum of the contributions of the individual gases

carbon dioxide transport forms

transported in 3 forms: - gas dissolved in plasma (5%) - carbonic acid (majority, then dissociates into bicarbonate and hydrogen ions) (90%) - carbamino compounds (carbaminohemoglobin, HbCO2) (5%)

t or f: fluid in the lungs can be fatal

true; gases diffuse too slowly through liquid to sufficiently aerate the blood

t or f: blood gives up the disslved CO2 gas and CO2 from the carbamino compounds more easily than CO2 from bicarbonate

true; while most exchanged CO2 comes from carbonic acid, it is not the full percentage prsent in blood

tidal volume

volume of air inhaled and exhaled in one cycle of breathing (500 mL)

nasal conchae

cleans, warms, and moistens air

superior vestibular folds

close larynx during swallowing

kussmaul respiration

deep, rapid breathing often induced by acidosis

spirometer

device that recaptures expired breath and records such variables as rate and depth of breathing, speed of expiration, and rate of oxygen consumption

anemic hypoxia

due to inability of the blood to carry adequate oxygen

orthopnea

dyspnea that occurs when person is lying down

functions of the respiratroy system (9)

gas exchange communication olfaction acid-base balance blood pressure regulation blood and lympth flow platelet production blood filtration (of small blood clots) expulsion of abdominal contents

main job of respiratory system

help you do ATP synthesis (drives the need to breathe since ATP synthesis requires oxygen and produces carbon dioxde)

describe cardiopulmonary system

how respiratory and cardiovascualr system work together to deliver oxygen to tissues and remove carbon dioxise

hyperventilation vs hypoventilation

hyper = corretv homeostatic response to acidosis hypo = corrective homeostatic response to alkalosis

ischemic hypoxia

inadequate circulation of blood (congestive heart failure)

hyperventilation

increased pulmonary ventilation in excess of metabolic demand

hyperpnea

increased rate and depth of breathing inresponse to exercise, pain, or other conditions

dyspnea

labored, gasping breathing; shortness of breath

hypovenilation

reduced pulmonary ventilation leading to an increase in blood CO2

how to prevent fluid accumulation in the lungs?

- alveoli are kept dry by low blood pressure in capillaries (mean blood pressure = 10 mm Hg) - reabsorption (osmotic uptake of water) overrides filtration and keeps the alveoli free of excess fluid - lungs have more extensive lymphatic drainage than any other organ in the body

factors that adjust the rate of oxygen unloading

- ambient PO2 - ambient pH - bisphosphoglycerate (BPG) - temperature

minute respiratory volume (MRV)

- amount of air ihaled per minute - TV x respiratroy rate (at rest = 500 x 12 = 6,000 mL)

CO2 unloading - alveolar gas exchange

- as Hb loads O2, its affinity for H+ decreases, H+ dissociates from Hb and binds with HCO3- - reverse chloride shift = HCO3- diffuses back into RBC in exchange for Cl-, free CO2 that is genereated diffuses into alveolus to eb exhaled

boyle's law

- at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume - describes air flow in and out of lungs during ventilation (ex- if lung volume increases, intrapulmonary pressure falls -> if the pressure falls below atmospheric pressure, air moves into the lungs)

henry's law in action

- at alveolus, the bloos unloads CO2 and loads O2 through erythrocytes - efficiency = depneds on how long an RBC stays in alveolar capillaries - each gas in mixture behaves independently

utilization coefficient

% O2 load that is delivered to tissues

forced expiratory volume (FEV)

- % of vital capacity that can be exhaled in a given time interval - healthy adult reading in 75-85% in 1 second

cells of the alveolus

- 95% squamous (type 1) alveolar cells - 5% great (type II) alveolar cells; secrete surfactant - alveolar macrophages (dust cells)

ambient pH

- Bohr effect - active tissue has increases CO2 - lowers pH of blood - promotes O2 unloading

CO2 loading- systemic gas exchange

- CO2 gas diffuses into blood and RBCs - carbonic anhydrase in RBC transfers Co2 to carbonic acid - chloride shift (co-transporter exchanges HCO3- for Cl-; H+ binds to hemoglobin)

oxygen unloading- systemic gas exchange

- H+ binding to HbO2 reduces its affinity for O2, gives up 22% of CO2 load ini typical resting tissue

maximum voluntary ventilation (MVV)

- MRV during heavy exercise - may be as high as 125 to 170 L/min

hypercapnia

- PCO2 greater than 43 mm Hg - most common casue of acidosis

hypocapnia

- PCo2 less than 37 mm Hg - most common cause of alkalosis

bisphosphoglycerate (BPG)

- RBCs produce BPG whihc binds to Hb; O2 is unloaded - increased body temp (fever), thyoxine, growth hormone, testosterone, and epinephrine all raise BPG and promote O2 unloading

forced breathing

- accessory muscles raise intrapulmonary pressure as high as +40cm H2O

accessory muscles of respiration

- act mainly in forced respiration - greatly increase thoracic volume - includes = erector spinae, sternocleidomastoid, pectoralis major, pectoralis minor, serrats anterior muscles and scalenes

partial pressure

separate contribution of each gas in the mixture

pulmonary ventilation

- action of breathing - repetitive cycle (inspiration, expiration) - respiratory cycle (one complete inspiration and expiration) - quiet respiration (breathing while at rest, effortless, and automatic) - forced respiration (deep, rapid breathing, such as during exercise)

ambient PO2

- active tissue has decreases PO2 - O2 is released from Hb

temperature

- active tissue has increases temp - promotes O2 unloading

henry's law

- at the air-water interface, for a given temperature, the amount of gas that dissolves in the water is determined by its solubility in water and its partial pressure in air (ex- the greater the PO2 in the alveolar air, the more O2 the blood picks up)

how is pH of the brain maintained?

- adjustments to pulmonary ventilation - central chemoreceptor in medulla produce about 75% of the change in respiration induced by pH shift (H+ from carbonic acd strongly stimulate central chemoreceptors) - hydrogen ions also stimulte peripheral chemoreceptors, which produce 25% of teh respiratory response to pH changes

ventilation- perfusion coupling

- air flow and blood flow are matched to each other - ex = pulmonary blood vessels change diameter depending on air flow to an area of the lungs; bronchi change diameter depending on blood flow to an area of the lungs - **affects alveolar gas exchange efficiency

how is composition of inspired / alveolar air influenced?

- air is humified by by contact wiht mucous membrane (alveolar PH2O is 10x higher than inhaled air) - alveolar air mixes with residual air (oxygen gets diluted and air is enriched with CO2) - alveolar air exchanges O2 and CO2 with blood (PO2 of alveolar air is about 65% that of inspired air; PCO2 is more than 130x higher)

residual volume

- air that cannot be exhaled with maximum effort (1,300 mL) - allows some gas exchange wiht blood before next breath

alveolar ventilation rate

- air that ventilates alveoli (350 mL) x respiratory rate - crucially relevant to the body's ability to get oxygen to the tissues and dispose of carbon dioxide

emphysema

- alveolar walls break down (much less respiratory membrane for gas exchange) - lungs fibrotic and less elastic

membrane surface area

100 mL blood in alveolar capillaries, spread thinly over 70 m^2

divisions of bronchi / bronchioles

2 main (primary) -> lobar (secondary) -> segmental (tertiary) -> bronchioles -> terminal bronchioles (65,000)

the pleurae

3 kinds - visceral pleura (serous membrane) - parietal pleura (adheres to mediastinum) - pleural cavity (potential space, contains a film of slippery pleural fluid)

composition of air

78.6% N 20.9% O .04% CO2 0-4% water vapor (depending on temeprature and humidity) minor gases = argon, neon, helium, methane and ozone

oxygen transport destinations

98.5% bound to hemoglobin vs 1.5% is gas dissolved in plasma

normal pressure gradient PO2 nad PCO2 values

PO2 = 104 mm Hg in alveolar air vs 40 mm Hg in blood PCO2 = 46 mm Hg in blood arriving vs 40 mm Hg in alveolar air

principal organs

nose pharynx larynx trachea bronchi lungs

What air is available for gas exchange?

only air that enters alveoli, but not all inhaled air gets there (150 mL to conducting zone)

ideal arterial blood levels of pH, PCO2, PO2

pH = 7.35 - 7.45 (most potent stimulus for breathing) PCO2 = 40 mm Hg PO2 = 95 mm Hg (least potent stimulus for breathing)

respiratory arrest

permanent cessation of breathing