Chapter 22--The Respiratory System

respiratory system functions

area for gas exchange between air and blood

protect respiratory surfaces for dehydration, temperature changes, and pathogens

produces sounds and smells

relationship between respiratory and circulatory systems

closely coupled together

order of respiration

1. pulmonary ventilation—breathing

2. external respiration—exchange of oxygen and CO2 between lungs and blood

3. transport—throughout systemic circulation

4. internal respiration—exchange of oxygen and CO2 between blood vessels and tissues

upper respiratory tract

nasal cavity

paranasal cavities

nasopharynx

lower respiratory tract

larynx

trachea

tracheobronchial tree

respiratory compartment

the conducting zone

from the node to the terminal bronchioles

moves air in and out

cleans, warms, and humidifies air

the respiratory zone

the respiratory bronchioles and alveolar ducts

gas exchange

the nose

external part of the system

2 regions: external nose and nasal cavity

provides airway, warms and moistens air, filters and cleans junk/dust/dander, houses olfactory receptors

root (between eyebrows), bridge, and apex (nose tip)

nasal vestibule

area just inside the nostril

contains hair

nasal cavity

continuation of vestibule

divided into olfactory region and respiratory region

3 turbinates (upper, middle, and lower) to warm and humidify air and remove dust

choanae

internal nostrils

2 openings found at the back of the nasal passages, between the nasal cavity and pharynx

paranasal sinuses

located in frontal, ethmoid, sphenoid, and maxillary bones

secretes mucus

warms and moistens air

respiratory tract histology

pseudostratified columnar epithelium

contains goblet cells (that secrete mucus)
contains cilia to move mucus (and detect odor)

olfactory epithelium

the smell part of the nasal cavity at the top, cannot smell without mucus

pharynx

funnel shaped muscular tube, connects nasal cavity and mouth to larynx and esophagus

made of psuedostratified ciliated epithelium

nasopharynx

behind nasal cavity

soft palate (uvular) closes it during eating/drinking

contains pharyngeal tonsils

oropharynx

the mouth, stratified squamous epithelium

passage for food/drink and air

posterior to epiglottis

larynx

voice box—speech/sound production

connects pharynx to trachea

provides unobstructed airway

routes food into proper channels

made of cartilage that is connected by membranes and ligaments

epiglottis

opens and closes to block of open the passage way

hyoid bone

floating bone beneath the skull, protects trachea

thyrohyoid membrane

between thyroid cartilage and hyoid bone

thyroid cartilage

shield-shaped that contains laryngeal prominence

cricothyroid ligament

between cricoid and thyroid

cricoid cartilage

ring shaped

cricotracheal ligament

connects cricoid to trachea

vocal folds/vocal cords

twin infoldings, stretched horizontally across the larynx

vestibular folds

support the vocal cords, lubricates the vocal cords

trachea

extends fro larynx into medistinum, very flexible

tracheal cartilage rings are connected by annular ligaments

forks at carina

3 layers of the trachea

mucosa—lines airway, ciliated pseudostratified epithelium

submucosa—connective tissue with seromucous glands

adventitia—connective tissue that encases rings/serous membrane

trachealis

smooth muscle fibers that connect posterior parts of the cartilage rings

contracts during coughing to expel mucus

bronchial tree

trachea divides to form the left and right main broncus, which pierces and enters the lungs

main/primary

secondary/lobar

tertiary

bronchioles

respiratory zone structures

gas exchange process

in alveoli

alveolar sacs contain clusters, make up large surface areas for gas exchange

respiratory membrane

external surfaces of alveoli are covered with a cobweb of blood capillaries

made of capillary and alveolar tissue

very thing, allows efficient gas exchange by simple diffusion

the gross lungs

elastic connective tissue

occupy all the thoracic cavity except the mediastinem

hilum

where all the pipes enter and exit the lungs

apex

top of the lungs

base

bottom, semi-flat/oval shaped, rests on top of the diaphragm

cardia notch

left lobe of the lung, where the heart is

pulmonary circulation

brings deoxygenated blood to the lungs to be oxygenated and sent to the rest of the body

bronchial circulation

provide arterial blood to lung tissue

arise from aortic arch and enters lungs at hilum

parts of the pleurae

serous membrane

parietal—lines hallow chest cavity
visceral—lines organ

pleural fluid—fills the cavity, provides lubrication and surface tension that assists in expansion and recoil of lungs

how pressure affects air movement

volume cause pressure changes, which causes the air to move

negative respiratory pressure—the pressure in the lungs is lower than atmospheric pressure
positive respiratory pressure—the pressure in the lungs is higher than atmospheric pressure

Inspiration

breathing in

air moves from high (outside) pressure to low (inside) pressure

inspiratory muscles in use, and thoracic volume increases

expiration

breathing out

inspiratory muscles relax, thoracic volume decreases

air moves from high (inside) to low (outside)

external respiration

diffusion between environment and lungs

partial pressure gradient drives O2 into blood and CO2 out of blood

internal respiration

diffusion between the blood and all other body cells and tissues

partial pressure gradient drives O2 into tissue and CO2 into blood

oxygen transport in blood

some is dissolved in plasma

most is loosly bound to the iron on the hemoglobin

carbon dioxide transport in blood

10% is dissolved in plasma
20% bound to globin (protein)
the rest is transported as bicarbonate (through an enzyme reaction) in plasma

how does bicarbonate affect the blood

controls the pH, making it 7.4

it is carried to the lungs and liberated

neural controls of mechanisms

medullar and pons

medulla sets the basic rhythm

ventral respiratory group

part of the medulla

main breathing control

sets eupnea

neurons excite mucsles via phrenic nerve and intercostal nerves

dorsal respiratory group

part of the medulla

receives information from peripheral receptors

detects changes through chemoreceptors and sends info to VRG

pontline respiratory centers

modifies activity of rhythm to physiological changes during vocalization, sleep, and exercise

effects of CO2 on respiration

most tightly controled

respiratory centers increase depth and rate of breathing when there is too much CO2 in the blood

elevated CO2 equals decrease in pH, raising the breathing pattern
decreased CO2 equals increase in pH, lowering breathing pattern

eupnea

normal breathing rate, 12-15 per minute

tachypnea

increased respiratory rate

bradypnea

decreased respiratory rate

apnea

absence of breathing

apneustic

prolonged inspiratory phase with shortened expiratory phase

sinusitis

inflammation of mucosa in paranasal sinuses, excessive mucus

rhinitis

nasal cavity infection

inflammation of nasal mucosa in the nose causes excess mucus production and congestion

hypoxia

inadequate oxygen delivery to the tissues

anemic hypoxia

too few RBCs, casuing inadequate oxygen deliver to the tissues

ischemic hypoxia

impaired blood circulation due to clogged or severed artery

chronic obstructive pulmonary disease

chronic inflammation of the lining of the bronchial tubes and breakdown of alveoli

caused by smoking

tubercolosis

creates tubercles of rotted, decaying tissue that out body cannot clear out

lung cancer

leading cause is smoking

broadly classified into small cell lung cancers and non-small cell lung cancers

non-small cell cancer types

adenocarcinoma

squamous cell carcinoma

large cell carcinoma

adenocarcinoma

bronchial glands and alveolar cells

squamous cell carcinoma

bronchial epithelium/mucosa on the surface of tubes

large cell carcinoma

cells that originate in primary bronchi and metastasize

pneumonia

lung infection

mucus accumulation in alveoli

hard to get rid of because antibiotics dont work well/quickly

asthma

long term inflammatory disease of the airways of the lungs

no cure

caused by a combination of complex and incompletely understood environmental and genetic interactions

treated by inhaled corticosteroids

cystic fibrosis

caused by a faulty gene

the lungs are clogged with mucus