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
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
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:
- alveolar and capillary walls
- 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