Ch 23 Respiratory System Learning Objectives & PPTs

Define the four phases of respiration

Pulmonary Ventilation, External Respiration, Gas Transport, Internal Respiration

Pulmonary Ventilation

movement of air into and out of the lungs

External respiration

exchange of gases between lungs and blood

Gas Transport

the process of carrying gases from the alveoli to the systemic tissues and vice versa

Internal Respiration

Exchange of gases between tissues of the body and the blood

Respiratory zone

where gas exchange occurs, bronchioles and alveoli

Conduction zone

Structures that simply conduct air with no gas exchange; everything but bronchioles and alveoli

Why is air filtered, warmed, and moistened in the conducting zone?

To protect delicate tissues of the respiratory system and allow for efficient gas exchange

Nasal cavity

hollow space behind the nose lined with vibrissae

Nasal capillaries

Warm the air within the nasal cavity

Respiratory mucosa

mucus-covered membrane that lines the tubes of the respiratory tree; filters and moistens

Nasal conchae

The scroll like ridges on the lateral walls of the nasal cavity; filter and moisten on inspiration, retain heat and moisture on expiration

Paranasal Sinuses

Spaces within the skull bones that are lined with pseudostratified ciliated columnar epithelium; warm and moisten air, resonate voice sounds, reduce weight of skull

Pharynx

connects the nasal cavity, oral cavity, larynx, and esophagus; nasopharynx, oropharynx, laryngopharynx

Uvula

small projection hanging from the back middle edge of the soft palate; part of pharynx

Larynx

voice box; passageway for air moving from pharynx to trachea; contains vocal cords; has cartilaginous structures and rings held together but connective tissue and muscle

Hyoid bone

a U-shaped bone in the neck that supports the tongue; provides an attachment point for muscles of the tongue, larynx, and mandible

Epiglottis

A flap of tissue that seals off the windpipe and prevents food from entering

Glottis

opening between the vocal cords in the larynx

Vocal cords

folds of tissue within larynx that vibrate and produce sounds; elastic fibers that appear white due to lack of blood vessels

Vestibular folds

(false vocal cords)

Superior to vocal folds;

No part in sound production;

Help to close glottis during swallowing

Vocal ligaments

pull on cartilages of the larynx to open and close vocal folds

Trachea

windpipe; extends from larynx into mediastinum, where it divides into main bronchi

Tracheal cartilages

cartilaginous rings that stiffen the tracheal walls and protect the airway

4 Layers of trachea

-Mucosa: ciliated pseudostratified epithelium with goblet cells

-Submucosa: connective tissue with seromucous glands

-Hyaline cartilage: form rings and support trachea

-Adventitia: outermost layer made of connective tissue

Bronchial Tree

highly branched system of air-conducting passages beginning at main bronchi and ending at alveoli of lungs

Main bronchi

division of trachea which divide into each lung; primary

Lobar bronchi

Airway leading into specific lobe of lungs; secondary

Segmental bronchi

Airways leading into specific lung segments; tertiary

Smaller bronchi

less cartilage and more smooth muscle

Bronchioles

smallest branches of the bronchi

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

Alveolar pores

connect adjacent alveoli, equalize air pressure throughout lung

Alveolar type I cells

simple squamous epithelial cells; form walls of alveoli and are included in gas exchange

Alveolar type II cells

cuboidal epithelial cells, produce and secrete pulmonary surfactant

Changes in bronchial tree

cartilage rings become irregular plates; cilia and goblet cells become more sparse; amount of smooth muscle increases for bronchioles to provide resistance

Alveolar macrophages

phagocytose small particles in alveoli; dust cells

Respiratory membrane

where gas exchange occurs between the air on the alveolar side and the blood on the capillary side; the alveolar and capillary walls form the respiratory membrane

Pleural membranes

double-layered serous membrane surrounding each lung; pleural fluid lies between

Pulmonary arteries

carry deoxygenated blood out of the right ventricle and into the lungs

Bronchiole arteries

provide oxygenated blood to lung tissue

Innervation of Respiratory structures

lungs are innervated by parasympathetic and sympathetic nervous system

Innervation of respiratory muscles

respiratory muscles are innervated by motor fibers of somatic nervous system

Parasympathetic fibers

cause bronchoconstriction via vagus nerve

Sympathetic fibers

cause bronchodilation via sympathetic chain ganglion

Motor fibers

innervate intercostal muscles (intercostal nerves) and diaphragm (phrenic nerve)

Atmospheric pressure

the pressure caused by the weight of the atmosphere

Intrapulmonary pressure

pressure in the alveoli

Intrapleural pressure

pressure in the pleural cavity surrounding the lungs that sucks lung outward; should always be negative

How do pulmonary pressures keep lungs from collapsing?

Intrapleural pressure must be negative and intrapulmonary pressure cannot be zero

How do pulmonary pressures change with inspiration

Intrapleural pressure decreases (becomes less negative), intrapulmonary pressure decreases to -1mmHg of atmospheric pressure

How do pulmonary pressures change with expiration

Intrapleural pressure increases (becomes more negative), intrapulmonary pressure increases to +1mmHG of atmospheric pressure

Boyle's Law

A principle that describes the relationship between the pressure and volume of a gas; if volume increases, pressure decreases; if volume decreases, pressure increases

Respiration

the process involved in supplying the body with oxygen and disposing of carbon dioxide

Muscles of quiet breathing

diaphragm and external intercostals

Muscles of forced inspiration

sternocleidomastoid, pectoralis major, erector spinal

Muscles of forced expiration

internal intercostals, abdominal muscles

How do changes in volume of thoracic cavity affect pulmonary inspiration and expiration

inspiration: muscles of quiet breathing contract, volume of thoracic cavity increases, pressure decreases, and air flows in

expiration: muscles of quiet breathing relax, volume of thoracic cavity decreases, pressure increases, air forced out

Dorsal respiratory group

integrates input from chemoreceptors and other sensory receptors

Ventral respiratory group

generates rhythm by firing during inspiration and expiration; sends impulses to the diaphragm and intercostal muscles; when VRG output stops, muscles relax and recoil

3 Factors that influence pulmonary ventilation

Airway resistance;

Alveolar surface tension;

Lung compliance

Factors that increase airway resistance

increased bronchoconstriction; loss of surfacant; reduced lung compliance

Alveolar surface tension

-Attracts liquid molecules to one another at a gas-liquid interface

Alveolar film

contains surfactant which decreases the cohesiveness of water molecules to prevent the walls of alveoli from sticking together

Lung compliance

the measure of change in lung volume that occurs with a given change in transpulmonary pressure; a measure of "stretch" the lung has

Spirometry

a measurement of breathing (or lung volumes)

Tidal volume

Amount of air that moves in and out of the lungs during a normal breath

Residual volume

Amount of air remaining in the lungs after a forced exhalation

inspiratory reserve volume

The amount of air that can be inhaled after a normal inhalation; the amount of air that can be inhaled in addition to the normal tidal volume.

expiratory reserve volume

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation

Alveolar ventilation rate

the volume of air per minute entering alveoli

AVR Formula

AVR = RR(TV-DS)

Dalton's Law of Partial Pressures

states that the total pressure of a mixture of gases is equal to the sum of the pressures of all the gases in the mixture

Partial Pressure of O2 in alveolar air

high

Partial pressure of O2 in alveolar capillary bed

low

Partial pressure of O2 in arterial blood

high

Partial pressure of O2 in venous blood

low

Partial pressure of CO2 in alveolar air

low

Partial pressure of CO2 in alveolar capillary bed

high

Partial pressure of CO2 in arterial blood

low

Partial pressure of CO2 in venous blood

high

2 Ways oxygen is carried in blood

1) 99% bound to hemoglobin - this represents oxygen saturation of Hgb

2) 1.5% is dissolved in the plasma

Henry's Law

gases dissolve the same in fluid as in gases

Hemoglobin dissociation curve

shows how saturated Hb is at various partial pressures of O2

Oxygen-Hemoglobin saturation in lungs

PO2 high, Hb 99% sat

Oxygen-Hemoglobin saturation in tissue at rest

PO2 low, Hb 75% sat

Oxygen-Hemoglobin saturation in tissues during exercise

PO2 low, Hb 35%, muscles pull O2 from blood

3 ways CO2 is transported in the blood

1) freely dissolved in blood as carbon dioxide

2) bound to globin portion of hemoglobin

3) freely dissolved in blood plasma as bicarbonate

Conversion of CO2 in systemic capillaries

1) CO2 enters RBC

2) CO2 is combined with H2O by enzyme carbonic anhydrase to form bicarbonate

3) bicarbonate diffuses into plasma, in exchange, Cl- ion enters RBC (chloride shift)

Conversion of CO2 in pulmonary capillaries

1) Bicarbonate diffuses into RBC, in exchange, Cl- ion transported out of RBC (chloride shift)

2) Bicarbonate binds to free H+ ion, producing H3CO3, this molecule is broken into H2O and CO2 by carbonic anhydrase

3) CO2 exits RBC, diffuses into alveolus for expiration

carbonic acid-bicarbonate buffer system

chemical system that helps maintain pH homeostasis of the blood

Increasing pH

bicarbonate mops up free H+ ions to become carbonic acid, increases pH

Decreasing pH

carbonic acid dissociates to release H+, decreases pH

Slow/Shallow breathing

CO2 accumulates, carbonic acid accumulates, dissociates more H+, pH decreases

Rapid/Deep breathing

more CO2 blown off, less carbonic acid, H+ binds to bicarbonate, pH increases