Human anat unit 3

Respiratory system functions

1. provides extensive gas exchange surface area between air and circulating blood

2. moves air to and from gas exchange surfaces of lungs

3. protects respiratory surfaces from outside environment

4. produces sounds- speech, singing, nonverbal communication

5. aids in olfactory sensations-smell

The respiratory tract

The structures and passageways that carry air to and from the gas exchange surfaces of the lungs

2 portions of the respiratory tract

Upper conducting portion (zone)

Lower respiratory protion (zone)

Upper conducting portion

Filters warms, humidifies air while transporting to lower portions

-includes structures starting from nasal cavity to terminal bronchioles

Transitional

Terminal bronchioles perform functions of both

Lower respiratory portion

Provides usrface for gas exchange

-includes terminal bronchioles to alveoli

Pleura, aka pleural sac, serousa the 3 parts

Parietal pleura(superficial)

visceral pleura(deep)

Pleural cavity- creates fluid bond that helps keep airspaces open

Hilum

Port for bronchi, blood and lymph vessels and nerves

Parts of the histology of the upper conducting portion

Lined by the respiratory mucosa

-pseudostratified columnar epithelium with goblet cells

-underlying lamina propria

-smooth muscle and cartilage

Histology functions of the upper conducting portion

Goblet cells coat the epithelium in mucus, trapping foreign particles, cilia sweet it toward the pharynx

-prevents contamination of delicate lower portion

External nares (nostrils)

Paired openings, coarse hairs catch sand, dust, insects.

Nasal septum

Divides cavity, cartilage, anterior bony posterior

Nasal conchae (turbinates)

Fleshy shelves, swirl and detects air (turbulence), increase surface area of mucosa that ait touches, increase time.

The paranasal sinuses

Air filled spaces in the skull

-located in the maxillary, frontal, ethmoid, and sphenoid bones

-reduced skull weight and produce mucus

Pharynx

3 part passageways that acts as a shared chanber for digestive and respiratory

3 regions of the pharynx

Nasopharynx-lined with respiratory mucus

oropharynx and laryngopharynx- lined with spmple stratified epithelium for food passage

Larynx AKA voice box

Cartilaginous structures joined by ligaments and skeletal muscles

Features of the larynx

glottis- narrow opening that holds vocal cords

epiglottis- folds over opening to prevent food from entering trachea

thyroid cartilage

cricoid cartilage

Larynx vocal cords

formed by a pair of smaller ligaments: Vestibular folds(false), vocal folds(true)

Vestibular folds (false)

Inelastic, protect true folds

Vocal folds (true)

Elastic, vibrate to produce sound, objects touching then triggers coughing reflux

Phonation

Sound production from air pushing through the vocal cords

Articulation

Modification of sound by the lips, tongue, and other structures to form speech.

Trachea AKA windpipe

Tough flexible tube about 1 inch in diameter

15 to 20 tracheal cartilages

c-shapped cartilage stiffens walla to pervent collapse as pressures change

Posterior portion of trachea

Contains a ligament and smooth muscle, which distorts to to allow larger food particles to pass through the espohagus

Bronchi

are divided into increasingly smaller segments (branches) first division (generation) of the trachea

R. and L. primary bronchi

-bifurcate at the carnia, supply each lung

-right pulmonary bronchi is larger, wider, and descends at a steeper angle

Secondary (lobar) bronchi

Second generation, supple each lobe. With each generation cartilage gets more sparse and the smooth muscle gets more common.

Tertiary (segmental) bronchi

third and fourth generation, supply larger segment. With each generation cartilage gets more sparse and the smooth muscle gets more common.

Bronchioles

Begin at 1mmm in diameter, 12 to 15th generation. no cartilage but mostly smooth muscle. controls the resistance to airflow and distribution of the air to the lungs

Terminal bronchioles

TRansitional,, performs actions of both zones

Cube cells

Dome shaped secretory cell

-lipid rich fluid reduces surface tension

-performs detoxification

-repair-stem cell regeneration

Histology of bronchioles

Cartilage and goblet cells decrease

smooth muscle and elastic fibers increase

Epithelial transition

-simple columnar with scattered goblet

-simple cuboidal with scattered golblet

-club cells

Respiratory zone

Where gas exchange happens

Respiratory bronchioles

Branch from terminal bronchioles, first bronchioles to perform gas exchange

their walls contain scattered, pouch like air sacs (alveoli) celled “out croppings”

Histology of the lower conducting (respiratory membrane)

3 layered membrane for gas exchange

1. simple squamous epithelium

2. fused basal lamina (extracellular)

3. endothelial cells of adjacent capillary

*very thin- facilitates rapid transport of gasses across the membrane

Parenchyma and alveoli interstitium

Parenchyma

The functional tissue of the lung

Alveoli

Grape like, clustered air filled pockets

3 cells in the respiratory zone

Type 1 pneumocytes

type 2 pneumocytes

macrophages

type 1 pneumocytes

Flat, delicate epithelial cells (simple squamous)

type 2 pneumocytes

Secrete surfactant- a phospholipid fluid- reduces surface tension to prevent alveolar collapse, increase lung compliance

Macrophages

Clear debris and pathogens

Intersitium

The non cellular scaffolding/support system of the parenchyma

included parts of the interstitium

Extracellular matrix (ECM), blood, lymphatic, and other connective tissues

Extracellular matrix

made of collagen, for tensile strength and elastin, for elastic recoil to permit large changes in volume.

Re-

Back, again

Spir/o

Breathe

-Pena

Breathe

Eu

good

Dys

Difficult, bad

Eupena

Good breathing

Dyspena

Difficult breathing

characteristics of respiration

Rate- 12 to 20 breaths per minute

Rhythm- regularity

Depth- normal, deep, shallow

External respiration

Exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the pulmonary arteries

Internal respiration

Exchange of oxygen and carbon dioxide between the blood in systemic capillaries and tissue of the body

Cellular respiration

Process used by cells to turn food (like glucose) and oxygen into usable energy called ATP, relasing carbon dioxide and water as waste.

Respiratory cycle

One inspiration (inhalation) and expiration (exhalation) controlled via the medulla oblongata and pons

-muscles cause expansion or contraction of diaphragm and rib cage, which causes changes in volume of the thoracic cavity

-volume inversely affects pressure (boyle’s law)

-air follows the pressure gradient

Inspiration

Rib cage moves upward and out, diaphragm contracts and moves down. Pressure in lungs decreases, and air comes rushing in.

Expiration

Rib cage moves down a din, diaphragm relaxes and moves up. Pressure in lungs increases, and air is pushed out.

At rest

Pressure outside is the same as the pressure inside Po= Pi

Inhalation

Volume increases, pressure inside falls, and air flows in Po>Pi

Exhalation

Volume decreases, pressure inside rises, so air falls out Po<Pi

Quiet breathing

Active inhalation (diaphragm/intercostals) and passive exhalation (recoil)

Forced breathing (hyperpnea)

Both inhalation and exhalation are active, recruiting accessory muscles

Lung compliance

An indicator of how easily the lungs expand (resiliency of the lungs)

Higher compliance

Lungs expand easily with less force

Lower compliance

Requires greater force to fill the lungs

Factors that affect compliance

-connective tissues

-surfactant levels

-thoracic cage mobility

Emphysema

A chronic disease defined by permanent enlargement of airspaces distal to the terminal bronioled with destruction of alveolar walls. This structural damage leads to the loss of elastic recoil, airflow limitation, air trapping, and impaired gas exchange.

Idiopathic pulmonary fibrosis

A chronic, progressive lung disease of unknown cause that causes permanent scarring (fibrosis) of the tissue around the air sacs alveoli in the lungs

*causes decrease in compliance, difficulty inhaling.