HSCI 210: Respiratory System

respiratory system

move air into body & remove waste products, oxygen used for cells & carbon dioxide released

nasal cavity

air enters body & gets warmed up/moisturized through nasal conchae, vascular ciliated columnar epithelium & cilliated psudostratified columnar epithelium

nasal conchae (turbinates)

filters dirt/bacteria, can adjust size to control airflow, helps with sense of smell

sinuses

warm & humidify air, produce mucous to trap unwanted particles from getting to lungs, minimizes weight of head

nasal mucosa

has nerve cells to transfer chemical signals into electrical impulses through olfactory bulb

oral mucosa

moist lining of mouth for protection/sensation/oral function, stratified squamous epithelium

tonsils & adenoids

lymphoid tissue used as first line of defense for immune system

larynx

voice box, leads to trachea and lungs, controlled by muscles

epiglottis

cartilage flap to close larynx, prevent food from getting into trachea

vocal cords

superior part of trachea, muscles open & close

thyroid cartilage

large protrusion in throat, “adams apple”

pharynx

leads to esophagus, posterior to trachea

trachea

long tube connecting mouth to nasal cavity, hyaline cartilage rings to keep open (not posterior), esophagus posterior, ciliated pseudostratified columnar epithelium

bronchi

branches coming off from trachea, deep to manubrium, each enter lungs, ciliated pseudostratitifed columnar epithelium

lobar bronchi

secondary bronchi

bronchioles

smaller tubes coming off bronchi

alveoli

sacs in terminal bronchiole ends where gas exchange takes place, covered with capillaries, simple squamous epithelium (thin for gas exchange)

type I pneumocytes

thin flat cells that allow gas exchange, cannot replicate themselves

type II pneumocytes

progenitor cells (stem cells) that can turn into type I cells, secrete surfactant to prevent alveolus from collapsing/inner walls from sticking together

surfactant

hydrophilic lipoprotein that prevents alveoli from collapsing & inner walls from sticking together, keeps alveoli open, premature babies dont produce surfactant yet

lungs

located in thoracic cavity, each lung sits in pleural cavity

right lung

3 lobes (superior/middle/inferior), separated by horizontal & oblique fissures

left lung

2 lobes (superior/inferior), separated by oblique fissure

cardiac notch

where heart lays

lung layers (pleura)

• thoracic wall

• parietal pleura (lines pleura)

• pleural cavity (filled with intrapleural fluid, helps with smooth contraction of lung)

• visceral pleura (lines lungs)

inspiration

low pressure in lungs & air comes inside lungs, diaphragm pulls down, pleural cavity increases size

principal muscles for inspiration

diaphragm & external intercostals

diaphragm

sheet of skeletal muscle, moves down during contraction (inhalation) & up during relaxation (exhalation), aids in digestion

external intercostals

expands ribcage, fibers superior to inferior

accessory muscles for inspiration

sternocleidomastoid/scalenes group/pectoralis minor, last option to elevate ribs

expiration

high pressure in lungs released outside, diaphragm relaxed/releases up, pleural cavity decreases in size

quiet breathing for expiration

no muscle contraction, passive/elastic recoil of diaphragm & external intercostals

active breathing muscles for expiration

internal intercostals/abdominals/quadratus lumborum, pulls ribs down

neural breathing controls

• higher centers of brain

• chemoreceptors in carotid/aortic body

• stretch receptors in lungs

• proprioceptors in joints/muscles

• receptors for touch/temperature/pain stimuli

val salva maneuver

increase internal pressure by holding air in lungs, affects those with heart issues (pass out), need to exhale to prevent injuries

• decreases cardiac output (volume of blood pumped out of heart per minute)

• decreases venous return

• decreases blood pressure

• increases heart rate

sinusitis

inflammation/swelling of lining of sinuses reduces sinus drainage, sinus fills with fluid, due to allergic reactions/virus/bacteria

pulmonary disorders

air/fluid gets into pleural cavity, due to trauma/medial procedure/lung diseases

pneumothorax

lung tissue collapses due to air/hole in tissue or excessive fluid in tissue, treatment: drain chest with tube

covid-19

mutated virus connects to angiotensin converting enzyme (ACE-2) (protein receptor on surface of heart/kidneys/lungs) to enter cell, causes excessive T-cell presence & inflammation, damages alveolar epithelium & capillary endothelium, difficulty breathing & death

pneumonia

bacteria/virus attacks lung tissue, inflamed bronchioles & increased mucus production in alveoli

acute respiratory distress syndrome (ARDS)

fluid build up in alveoli, caused by trauma/blood transfusions/surgery, treatment: conservative fluid management/prone ventilation/lung protective ventilation