chapter 22 a&p 2

the respiratory system

respiration

ventilation of the lungs (breathing)

functions of the respiratory system

• gas exchange

• communication

• olfaction

• acid-base balance

• blood pressure regulation

• blood and lymph flow

• blood filtration

• expulsion of abdominal contents

anatomical divisions of the respiratory system

upper respiratory tract & lower respiratory tract

upper respiratory tract

• in head and neck

• nose - larynx

lower respiratory tract

• organs of the thorax

• trachea - lungs

functions of the nose

• warms, cleanses, and humidifies inhaled air

• detects odors

• serves as a resonating chamber that amplifies voice

vibrissae

stiff guard hairs that block insects and debris from entering nose

three regions of the pharynx

• nasopharynx

• oropharynx

• laryngopharynx

nasopharynx

receives auditory tubes and contains pharyngeal tonsil

oropharynx

contains palatine tonsils

laryngopharynx

esophagus begins at that point

primary function of the larynx

to keep food and drink out of the airway

structures located inside the larynx

• epiglottis

• vestibular folds

• vocal folds

• glottis

vocal cords

produce sound when air passes between them

glottis

the vocal cords and the opening between them

trachea

patent airway

mucocillary escalator

• mechanism for debris removal

• mucus traps inhaled particles & upward-beating cilia drive mucus toward pharynx where it is swallowed

right lung

• shorter than the left

• has three lobes: superior, middle, and inferior

left lung

• tall and narrow

• contains the cardiac impression

• has two lobes: superior and inferior

conducting zones

• right and left main (primary) bronchi

• secondary (lobar) bronchi

• tertiary (segmental) bronchi

• bronchioles

• terminal bronchioles

respiratory zones

• respiratory bronchioles

• alveolar ducts

• alveolar sacs (saccules)

alveoli

site of gas exchange

cells of the alveolus

• squamous (type I) alveolar cells

• great (type II) alveolar cells

• alveolar macrophages

squamous (type I) alveolar cells

• thin, broad cells that allow for rapid gas diffusion between alveolus and bloodstream

• cover 95% of alveolus surface area

great (type II) alveolar cells

• repair the alveolar epithelium when the squamous (type I) cells are damaged

• secrete pulmonary surfactant

alveolar macrophages

• most numerous of all cells in the lung

• wander the lumens of alveoli and the connective tissue between them

• keep alveoli free from debris by phagocytizing dust particles

respiratory membrane

• thin barrier between the alveolar air and blood

• consists of: squamous (type I) alveolar cells, endothelial cells of blood capillary, and their shared basement membrane

respiratory cycle

one complete inspiration and expiration

quiet respiration

while at rest, effortless, automatic

forced respiration

deep or rapid breathing

Boyle’s Law

at a constant temperature, pressure and volume are inversely related

muscles involved in quiet inspiration

• diaphragm

• external intercostals

• sternocleidomastoid

muscles involved in quiet expiration

• diaphragm

• internal intercostals

Charles’ Law

the volume of a gas is directly proportional to its absolute temperature

two factors that influence airway resistance

• diameter of the bronchioles

  • bronchodilation

  • bronchoconstriction

• compliance

stimulants of bronchodilation

epinephrine and sympathetic stimulants

stimulants of bronchoconstriction

histamine, parasympathetic nerves, cold air, and chemical irritants

pulmonary compliance

ease with which the lungs can expand

surfactant

secreted by great (type II) cells of alveoli and disrupts hydrogen bonds between water molecules and thus reduces the surface tension of the water film inside the alveoli

Infant Respiratory Distress Syndrome (IRDS)

premature babies lacking surfactant are treated with artificial surfactant until they can make their own

anatomic dead space

conducting division of airway where there is no gas exchange

physiologic dead space

sum of anatomic dead space and any pathological alveolar dead space

minute ventilation

amount of air moving into or out of the lungs in one minute

alveolar ventilation rate

AVR = frequency x (TV - dead space)

spirometry

the measurement of pulmonary function

restrictive disorders

those that reduce pulmonary compliance

obstructive disorders

those that interfere with airflow by narrowing or blocking the airway

examples of restrictive disorders

black lung disease & tuberculosis

examples of obstructive disorders

asthma & chronic bronchitis

ventral respiratory group (VRG)

• primary generator of the respiratory rhythm

• produces a respiratory rhythm of 12 breaths per minute

dorsal respiratory group (DRG)

• modifies the rate and depth of breathing

• receives influences from external sources

pontine respiratory group (PRV)

• modifies the rhythm of the VRG by outputs to both the VRG and the DRG

• adapts breathing to special circumstances such as sleep, exercise, vocalization, and emotional responses

central chemoreceptors

the pH of cerebrospinal fluid reflects the CO2 level in the blood

peripheral chemoreceptors

found in the carotid and aortic bodies & respond to the O2/CO2 content and the pH of the blood

stretch receptors

found in the smooth muscles of bronchi and bronchioles, and in the visceral pleura & respond to inflation of the lungs

Inflation (Hering-Breuer) Reflex

triggered by excessive inflation & inhibits neurons associated with inhalation

apnea

temporary cessation of breathing

dyspnea

labored, gasping breathing; shortness of breath

hyperpnea

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

hyperventilation

increased pulmonary ventilation in excess of metabolic demand

hypoventilation

reduced pulmonary ventilation leading to an increase in blood CO2

Kussmaul respiration

deep, rapid breathing often induced by acidosis

orthopnea

dyspnea that occurs when person is lying down

respiratory arrest

permanent cessation of breathing

tachypnea

accelerated respiration

Dalton’s Law

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

partial pressure

the separate contribution of each gas in a mixture

three influences that cause the composition of inspired and alveolar air to differ

• air is humidified by contact with mucous membranes

• air in alveolar mixes with residual air left from previous respiratory cycle

• alveolar air exchanges O2 and CO2 with blood

alveolar gas exchange

the swapping of O2 and CO2 across the respiratory membrane

Henry’s Law

the amount of gas that dissolves is determined by the partial pressures of the gases in the mixture

ventilation-perfusion coupling

the ability to match air flow and blood flow to each other

venous reserve

lots of oxygen remaining in venous blood

BPG

a breakdown product in glycolysis

hormones that promote oxygen delivery to tissues by stimulating BPG synthesis

• testosterone

• thyroxine

• growth hormone

• epinephrine

Haldane effect

• low level of oxyhemoglobin enables the blood to transport more CO2

• the rate of CO2 loading into the blood is increased in metabolically active tissues

standard pH level

7.35 to 7.45

standard CO2 level

40 mmHg

standard PO2 level

95 mmHg

acidosis

blood pH is lower than 7.35

alkalosis

blood pH is higher than 7.45

hypocapnia

PaCO2 is less than 35 mmHg (most common cause of alkalosis)

hypercapnia

PaCO2 is greater than 45 mmHg (most common cause of acidosis)

hypoxic drive

respiration driven more by low PO2 than by CO2 or pH

extrinsic ligaments of the larynx

• cricothyroid

• cricotracheal

• thyrohoid

valsalva maneuver

increasing abdominal pressure by holding a deep breath while contracting the abdominal muscles — the depressed diaphragm increases abdominal pressure and helps push out organ contents during childbirth, urination, and defecation

atelectasis

the collapse of a lobe or lung due to equalizing the intrapleural and atmospheric pressure

role of the dorsal respiratory group

adjusts respiratory rate based on stimuli from peripheral chemoreceptors

role of the ventral respiratory group

sets basal respiratory rate

role of the pontine group

adjusts respiratory rate based on stimuli from limbic system or cerebral cortex

alveolar gas exchange

movement of oxygen and carbon dioxide across the respiratory membrane

systemic capillary beds

where most CO2 is loaded into the blood

alveolar sacs

where CO2 is unloaded in the lungs

the Bohr effect

the rate of O2 unloading is increased in metabolically active tissues due to increased acidity

two factors that facilitate systemic unloading of oxygen from hemoglobin in the peripheral tissues

• lower PO2 in tissue fluid

• binding of protons to hemoglobin

carbonic anhydrase

converts CO2 and H2O to carbonic acid which dissociates into bicarbonate and hydrogen ions