RESPIRATORY SYSTEM 🏴

  • consists of the respiratory and conducting zones

Respiratory zone:

  • site of gas exchange
  • consists of bronchioles, alveolar ducts, and alveoli

Conducting zone:

  • conduits for air to reach the sites of gas exchange
  • includes all other respiratory structures (nose, nasal cavity, pharynx, trachea)

Respiratory muscles - diaphragm and other muscles that promote ventilation (and mm for inspiration) NO mm for expirations d/t recoil ability


but there is accessory mm for force expirations: *pag cough, pag exhale

Breathing mechanics

Inspirations:(ACTIVE) Taking air into the lungs
Expirations:(PASSIVE) breathing the air out

  • this involves the changes of volume in the thoracic cavity
  • it also changes its dimensions
  • vertically, anteroposterior, transverse extension

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DIAPHRAGM

  • phrenic nerve
    originates from c3, c4, c5

INSPIRATION: when it contracts, it flattens, the vertical dimension will increase, the lungs expand then air enters the lungs

EXPIRATION: dia will relax, the thoracic volume will decrease, the lungs will contract and air breathes out

RIB CAGE can move up or down
INSPIRATION - when the ribcage moves up, the sternum will move forward, then the diameter will increase from front to back
EXPIRATION - when the ribcage moves down, the sternum will fall back, then the diameter reduces

The upper ribs moves with the PUMP-HANDLE MOVEMENT


The lower ribs have the BUCKET-HANDLE MOVEMENT

MUSCLES OF INSPIRATION:

  • External intercostals which attached to the ribs and directed forward and downward

accessory muscles are needed when force in inspiration is required

  • sternocleidomastoid
  • serratus anterior
  • scalene

diaphragmatic palsy

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EXTERNAL RESPIRATION

  • exchange of gases bet. the air filling in the alveoli and blood in the capillaries

INTERNAL RESPIRATION

  • exchange of gases bet. blood in the capillaries and the tissues of the body

the lungs are being stretched

inspiratory muscles and diaphragm are relaxed d/t recoil and elasticity

MUSCLES OF EXPIRATION:

  • Internal Intercostals - downwards and backwards. depressed the ribs by abdominal muscles: rectus abdominis, obliques, transverse abdominis

FUNCTIONS:

To supply the blood with oxygen and dispose of carbon dioxide

RESPIRATION:

Pulmonary ventilation: moving air into and out of the lungs

External respiration: gas exchange of CO2

Transport: transport of oxygen and CO2 bet lungs and tissues

Internal respiration: gas exchange bet systemic blood vessels and tissues

MAJOR PARTS OF RESPIRATORY SYSTEM

The airways includes nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, carries air bet lungs and body's exterior

Airway | Lungs | Muscles of respiration

The lungs act as the functional units of the respiratory system by passing oxygen into the body and CO2 out of the body

The muscles of respiration, including the diaphragm and intercostal muscles work together to act as pump, pushing air into and out of the lungs during breathing

NOSE AND NASAL CAVITY

Nasal area

the nose and nasal cavity form the main external opening for the respiratory system and are the first section of the body's airway

VESTIBULE: nasal cavity superior to the nares

VIBRISSAE: hairs that filter coarse particles from inspired air

Olfactory mucosa: lines the superior nasal cavity, contains small receptors

Respiratory mucosa: lines the balance of the nasal cavity, glands secrete mucus containing hysozyme and defensins to help destroy bacteria

Functions of nasal mucosa and conchae

  • during inhalation the conchae and mucosa filters, heat and moisten air
  • during exhalation these structures: reclaim heat and moisture, minimize heat and moisture loss

ORAL CAVITY

MOUTH

  • also known as oral cavity
  • secondary external opening for the respiratory tract

can be used to supplement or replace the nasal cavity's functions when needed

PHARYNX

  • also known as throat
  • is a muscular funnel that extends from the posterior end of the nasal cavity to the superior end of the esophagus and larynx
  • funnel-shaped tube of skeletal muscle that connects to the nasal cavity and mouth superiorly, larynx and esophagus inferiorly
  • extends from the base of the skull to the level of 6th vertebra

LARYNX

  • also know as voice box
  • short section of the airway that connects the laryngopharynx and the trachea
  • attaches to the hyoid bone and opens in the laryngopharynx
  • continuous with the trachea posteriorly

3 functions:

  • provide a patent airway
  • act as switching mechanism to route air and food into the proper channels
  • voice production

TRACHEA

  • windpipe, connects the larynx to the bronchi and allows air to pass through the neck and into the thorax
  • to provide a clear airway for air to enter and exit the lungs

Composed of:

  • mucosa: goblet cells and ciliated epithelium
  • submucosa: connective tissue deep to mucosa
  • Adventitia: outermost layer made of C-shaped rings of hyaline cartlage

CONDUCTING ZONE

BRONCHI

  • carina of the last tracheal cartilage marks at the end of the trachea and the beginning of the bronchi
  • Air reaching bronchi is: warm and cleansed of impurities, saturated with water vapor
  • bronchi subdivide into secondary bronchi, each supplying a lobe of the lungs
  • air passages undergo 23 orders of branching

Bronchial Tree

  • tissue walls of bronchi mimic that of the trachea
  • as conducting tubes becomes smaller, structural changes occur
  • cartilage support structures change
  • epithelium types change
  • amount of smooth muscles increases

BRONCHIOLES:

  • consists of cuboidal epithelium
  • have a complete layer of circular smooth muscle
  • lack cartilage support and mucus-producing cells

RESPIRATORY ZONE

  • defined by the presence of alveoli, begins as terminal bronchioles feed into respiratory bronchioles
  • respiratory bronchioles lead to alveolar tracts. then to terminal clusters sacs composed of alveoli

Approx 300 million alveoli:

  • account for most of the lungs volume
  • provide tremendous surface area for gas exchange

RESPIRATORY MEMBRANE

  • this air-blood barrier is composed of:
  1. alveolar and capillary walls
  2. their fused basal laminas

Alveolar walls:

  • are a single layer of type 1 epithelial cells
  • permit gas exchange by simple diffusion
  • secrete angiotensin converting enzyme (ACE)
  • type II cells secrete surfactant