PASSING THIS EXAM

type 1 alveolar cells

do the gas exchange, smaller, peripherally located, internal environment lining

type 2 alveolar cells

secrete surfactant to ensure gas exchange is effective, larger, centrally located, prevent alveolar collapse

gas exchange depends on

 partial pressure of gas, surface area of wall of alveoli, thickness of membrane in airways  

daltons law partial pressure

total pressure * fractional gas concetration

dry air PO2

160 mmHg

dry air PCO2

0 mmHg

moist air nostril PO2

150 mmHg

moist air nostril PCO2

0 mmHg

alveoli PO2

100 mmHg

alveoli PCO2

40 mmHg

pulmonary arteries PO2

40 mmHg

pulmonary arteries PCO2

46 mmHg

pulmonary veins PO2

100 mmHg

pulmonary veins PCO2

40 mmHg

fricks law

gases travel to membranes via simple diffusion. rate of diffusion proportional to diffusion coefficient and surface area, inversely proportional to rate of diffusion

lung diffusing capacity

time required for gas to combine with hemoglobin, measured with CO

emphysema

DL decreases because alveoli is destroyed, surface area decreases, decrease gas exchange

fibrosis/edema

DL decreases, thickness increases due to mucus and infalmmed tissue

anemia

DL decreases, hemoglobin decreases

exercise

DL increases, additional capillaries open around alveoli

perfusion limited

RBC with oxygen, do not participate in gas diffusion for a limited amount of time

limited diffusion

abnormalities in structures of lung or alveoli, limits diffusion

tidal volume

normal breathing, volume inspired or expired with each normal breath

inspiratory reserve volume

full breath inhale, volume that can be inspired above tidal volume, used in exercise

expiratory reserve volume

full exhale, volume that can be expired after expiration of tidal volume

residual volume

air left in lung after maximal expiration, cannot be measured by spirometry

deadspace

part of lungs that dont participate in gas exchange, trachea, nostril, primary, secondary, tertiary bronchi

anatomical dead space

volume of tubes that do not participate in gas exchange, around 150 mL

physiologic dead space

volume of lungs that do not participate in gas exchange, around equal to anatomic DS but can be higher because of ventilation defects

inspiratory capacity

full amount of air inhaled, sum of TV and IRV

functional residual capacity

volume remaining in lungs after exhale, ERV+RV, no spirometry

vital capacity

volume of air that can be forcibly expired after maximal inspiration, TV+IRV+ERV

total lung capacity

sum of all 4 lung volumes, volume in lungs after full inhale, YV+IRV+ERV+RV, no spirometry

diaphragm

most important muscle for inspiration, when contracts abdominal contents pushed down, ribs lifted up and out, increased volume of thoracic cavity

external intercostals

inspiration muscle, used during exercise not during normal breathing

muscles of expiration

diaphragm relaxes, push up lungs

abdominal muscles

expiration muscle, compresses abdominal cavity, push diaphragm up to push air out of lungs

internal intercostal muscles

expiration muscle, pull ribs down and inward

surfactant

line alveoli, reduces tension to prevent small alveoli from collapsing in type II alveolar cell

surfactant in fetus

present as early as gestational week 24, most always present by week 35

neonatal respiratory distress syndrome

occur in premature infants because of lack of surfactant, can lead to lung collapse, difficulty reinflating lungs, and hypoxemia

contraction or relaxation of bronchial smooth muscle

changes airway resistance by altering the radius of the airways

parasympathetic stimulation in airway

irritates, astma, decrease the radius, increase airflow resistance

sympathetic stimulation in airways

usoproternol, dilate airways via beta receptors, increase radius, decrease airflow resistance

lung volume affect on resistance

alters airway resistance because of the radial traction exerted on the airways by surrounding the lung tissue

viscosity affect on resistance

during a deep dive, higher visosity, higher airway resistance

breathing cycle, at rest

alveolar pressure=atmospheric pressure, intrapleural pressure negative, lung volume is the functional residual capacity, volume of air present in lungs at the end of passive expiration

breathing cycle, during inspiration

inspiratory muscles contract, thorax volume increase, alveolar pressure<atmospheric pressure, intrapleural pressure becomes more negative, elastic recoil of lungs increase

breathing cycle, during expiration

alveolar pressure>atmospheric pressure, intrapleural pressure returns to resting value negative, lung volume returns to functional residual cpacity

lung volume increases by one tidal volume

lungs receive fresh air

asthma

obstructive lung disease, airways constrict and become inflammed in response to cold/warm/moist air, exertion, or emotional stress, FEV1 more decreased than FVC

Forced vital capacity

total amount of air that you can forcibly blow out after full inspiration in liters

Chrinic obstrucitve pulmonary disase

COPD, obstructive disease, combination of bronchitis and emphysema, increased lung compliance where expiration is impaired, decreased FVC and FEV1

pink puffers

mainly emphysema, milder hypoxia, normal pCO2, alveolar ventilation is better maintained, decrease FVC and FEV1

blue bloaters

mainly bronchitis, severe hypoxia and cyanosis, increases pCO2, alveolar ventialation is worse because of inflammation in alveoli, decreased FVC and FEV1

fibrosis

restrictibe disease, scarring of lung tissue and alveoli, lung volume decreases, inspiration impaired, membrane thickness increased, decreased lung diffusing capacity, FEV1 and FVC decreased

zone 1

blood flow lowest, alveolar pressure>arterial pressure>venous pressure

zone 2

blood flow medium, arteriole>alveolar>venous

zone 3

blood flow highest, arterial>venous>alveolar

regulation of pulmonary blood flow, hypoxic vasocontriction

hypoxia causes vasoconstriction, there there is infection in lung tissue, blood supply focuses on unaffected area before affected area

control of breathing

central chemoreceptors in medulla, peripheral chemoreceptors in carotid and aortic bodies

apneustic center

located in lower pons, stimulates inspiration producing deep and prolonged inspiratory gasp

pneutaxic center

located in upper pons, inhibits inspiration and regulates inspiratory volume and respiratory rate

oral cavity

first breakdown of food

esophagus

passage of food

stomach

storage, second breakdown of food

liver, pancreas, gallbladder, small/large intestine

digestion and absorption

GI wall

major and minor muscle layers, valve

small/large intestine

longitudinal, circular muscle tpes

stomach muscle

oblique, circular, and longitudinal muscle types

mucus membrane

composed of specialized epithilial cells for secretion and absorption

muscularis mucosa

widespread muscle fiber layer beneath lamina propia, its contraction causes a change in surface area for secretion and absorption

circular muscle

inner muscle layer, contraction decreases diameter of lumen in GI tract

longitudinal muscle

outer muscle layer, contraction causes shortening of segment in GI tract

serosa

external peritoneal covering layer

digestive system function

absorb nutrients, secrete waste, reabsorption of water, movement of food, circulation of blood through organs to transport nutrients

intrinsic parasympathetic innervation digestive tract

submucosal plexus of meisener, myentreric plexus of auerbach, coordinate motility, secretory, and endocrine functions of GI tract

Extrinsic parasympathetic innervation of GI tract

vagus nerve, S3S4

Extrinsic innervation of GI tract sympathetic

T5-L2, inhibits secretion of gastric hormones/acid

contractile tissue of GI tract

unitary smooth muscle

exception of unitary smooth muscle GI tract

pharynx, upper 1/3 esophagus, external anal sphincter - striated muscle

contraction of circular muscle

leads to decrease in diameter of segment

contraction of longitudinal muscle

decrease in legnth of segment

phasic contraction

in esophagus, gastric antrum, small intestine, which contract and relax periodically

tonic contraction

found in lower esophageal sphincter, orad stomach, ileocecal, and interal anal sphincter

slow wave

pacemaker of GI tract, weak contraction, located in cajal cells, occur spontaneously, determine pattern of action potentials and contraction, stomach 3/min, ileum 9/min, duodendum 12/min

spike wave

action potentials, number of spikes triggered is proprtional to the rise above threshold and time, strong contraction, resting membrane potential -65, depolarization of calcium sodium channels

Ca2+ and muscle contraction

acts through calmodulin not troponin

propulsive

peristalsis, foward flow, stimulation is primarily distension, 2-3 cm required, coodinated contraction of circular and longitudinal muscles

mixing

movement within bionmass of digesting contents, regional movements, defects in meissners plexus leads to malabsorption

chewing

lubricates food by mixing it with salvia, decreases size of food particles to facilitate swallowing and begin digestive process

swallowing

reflex coordinated in medulla by CNIX and CNX. Nasopharynx closes and brathing is inhibited. laryngeal muscles contract, upper esophageal sphincter relaxes to propel food towards esophagus

upper sphincter

prevents air entering esophagus

aortic narrowing

crossed by aortic arch, at T12

diaphragmatic narrowing

in the esophageal hiatus at T10

esophageal innervation

both vagus

gastric reflux

may occur if the tone of lower esophageal sphincter is decreases and gastric contents reflux into the esophagus, causing heartburn 

achalasia

 retrosternal pain, neuromotor disorder of lower esophageal sphincter, decreased cells in myenteric plexus, dysphagia for solid and liquid

esophageal atresia

when distal end of esophagus is closer, upper part not connected to lower part

trachesophageal fistual

when there is a hole between esophagus and trachea, in newborns milk goes from esophagus to respiratory tract causing severe problems