Respiratory System Chapter 21 – Day 2 3/17/08

Pathway of Air/ O2 Nose – external nares → nasal cavity → internal nares  Pharynx – nasopharynx → oropharynx → laryngopharynx Larynx – epiglottis → larynx Trachea – trachea Bronchi – primary bronchi → secondary bronchi → tertiary bronchi → bronchioles Lungs – alveoli → blood stream 3/17/08

Pathway of Air/ O2 Each component is composed of special tissues which aid in their function Passageways & accessory structures in the nose and pharynx = upper respiratory system Nose: external & internal nose Outside: cartilage & skin structure with 2 openings = external nares Directs air into nasal passageways External = object of “vanity’ “nose job” = Rhinoplasty – surgery to repair or alter nose structure – involves addition or removal of tissue Involves inconspicuous incisions & local anesthesia 3/17/08

Pathway of Air/ O2 - Skull Nostrils lead into 2 chambers separated by the nasal septum Right and left chambers of the nasal cavity Walls of the nasal septum = ethmoid & vomer bones Protrusions of the bone = nasal conchae (superior, middle, inferior) Allows air to swirl in the nasal cavity – airborne particles get trapped in mucus Cavity is lined with mucous membrane Mucus is secreted by the paranasal sinuses (=air cavity with epithelium in the skull) Floor of the nasal cavity = hard palate (roof of the mouth) 3/17/08

Function of the Nose Directs air into the nasal passageway Warms air via blood circulation Location for olfaction sensation Traps particles & microbes = non-specific defense These then get swallowed with mucous 3/17/08

Pathway of Air/ O2 – Pharynx and on From the nasal cavity, air enters internal nares then the pharynx (throat) Pharynx Shared by digestive and respiratory systems It is a muscular tube lined with mucous epithelium Just behind the nasal cavity = nasopharynx The oropharynx is located right under the soft palate – base of the tongue at the opening of the throat It is lined with stratified squamous epithelium (b/c it is shared with the digestive system Fig. 21.3 3/17/08

Pathway of Air/ O2 – Pharynx and on Laryngopharynx Below oropharynx = cavity Opening to esophagus & trachea Common area for air & food Stratified squamous epithelium Next air enters the Larynx Top of the trachea Epiglottis = elastic cartilage Allows distinguish food vs. air It closes the glottis (opening of the larynx) if food is passing into the pharynx The ligaments stretch during swallowing to prevent food from entering the nasal passageway Fig. 21.5 Fig. 21.3 3/17/08

Pathway of Air/ O2 – Larynx (& sound) Cylinder made of cartilage, ligaments & skeletal muscle Note large pieces of hyaline cartilage The larynx contains 2 ligaments stretched from cricoid cartilage to thyroid cartilage = vocal ligaments (commonly called “vocal cords” Air brushes against the vocal cords and creates vibrations = sound The Larynx is important for air passage and speech Skeletal muscles lengthen and shorten vocal cords – produces different sounds Fig. 21.4 3/17/08

Pathway of Air/ O2 – Trachea aka “windpipe” Tube made of smooth muscle from larynx to bronchi Supported by cartilage rings C-shaped cartilage – open at back = flexibility & expansion Posterior wall – pseudostratified epithelium Bifurcation at bottom of trachea (into 2) Ridge @ the bifurcation =carina Contains the cough reflex center 2 branches = Primary bronchi (to right and left lung) Cartilage rings support the bronchi Fig. 21.6 3/17/08

Pathway of Air/ O2 – Bronchi Primary bronchi Each Primary bronchi branches into secondary (lobar) bronchi These go to individual lobes of the lung These then branch into the tertiary (segmental) bronchi These are branches within each lobe Branch to bronchioles End in lobules The bronchi regulate the air flow through the lungs Bronchitis = infection/inflammation of the bronchi Acute bronchitis is usually caused by a virus (sometimes by bacteria) Cough, mild fever, yellow/green mucous Fig. 21.9 3/17/08

Pathway of Air/ O2 – Lung Collection of lobules containing alveoli Air sacs = light consistency Whole lung = paired organ - Right and left side Each lung is divided into lobes Right = divided into 3 lobes by fissures Left = divided into 2 lobes (know names of fissures and lobes for lab) The shape of the lungs accommodates neighboring organs Heart is slightly to left = left lung is less broad & has cardiac notch Right side – liver is just below diaphragm = right lung is shorter Fig. 21.7 3/17/08

Pathway of Air/ O2 – Lung Flat base at the bottom, pointed apex at the top Each lung is covered by a pleural membrane on the outside Review characteristics of pleural cavity Medial surface of lungs = surface in middle Entry point for bronchi & blood vessels (Hilus) Primary bronchus and pulmonary arteries & veins Fig. 21.7 3/17/08

Pathway of Air/ O2 – Lung Bronchus divides further inside the lungs – to each lobe Divided into segments within each lobe Bronchopulmonary segment Visceral pleura extends into the lung – divides segments into smaller sections Each section = Pulmonary lobule Each lobule Contains a cluster of alveoli Receives air from the Bronchioles Lymph vessel circulation Pulmonary arteries and venules Each alveolus within each lobule Hollow air sac Two or more air sacs may share a common opening = alveolar sac Recall what you saw in lab… Fig. 21.9 3/17/08

Alveoli In Pulmonary Lobule Fig. 21.9 3/17/08

Pathway of Air/ O2 – Alveoli Alveoli = location of gas exchange Each alveolus – is confined – consists of a layer of simple squamous epithelium Epithelium also contains Macrophages- to engulf any escaped pathogens Septal cells – special cells that secrete a liquid called surfactant A surfactant keeps alveoli from collapsing shut There is a continuous capillary adjacent to each alveolus These are connected by fused basement membranes of epithelial cells & endothelial cells Gas crosses 3 layers CO2 enters alveolus & O2 enters capillary 3/17/08

Alvioli – Capillary Interface Fig. 21.11 3/17/08

Mechanics of Respiration Ventilation = mechanical process involves the diaphragm and skeletal muscles (intercostal muscles) Breathing consists of 2 phases: Inspiration air is taken into the lungs Expiration Air passes out of the lungs 3/17/08

Mechanics of Respiration Air is moving in & out because of pressure gradients Air flows from high pressure to low pressure… For air to enter the lungs, pressure should be low in the lungs EXPANSION of lungs lowers pressure The Diaphragm contracts – pushed down = opens space in the lungs External intercostal muscles contract – elevates chest Pulls on parietal pleura Pulls on visceral pleura Expands space into the lung The pressure gradient forces air into the lungs (insp) ACTIVE process – powered by muscle 3/17/08

Mechanics of Respiration Inspiration = ACTIVE process – powered by muscle Expiration = PASSIVE process Objective = increase pressure in lungs to create high pressure gradient in TO out… The diaphragm and intercostals relax Pushes against pleura – close in on lungs Imagine a full balloon with hands pushing against it Increased pressure in lungs forces air out Process of regular breathing Deep breathing & forced expiration require additional muscles – abdominal muscles 3/17/08

Mechanics of Respiration The amount of air entering during breathing depends on several factors COMPLIANCE – degree of expandability of lungs Large compliance – more air enters Elastic fibers surround alveoli & surfactant in alveoli contribute to compliance & mobility of thoracic cage Less surfactant – alveoli collapse – decreases comp. Less elasticity = increases compliance Emphysema Shortness of breath, weak at exertion Destruction of alveolar surface = loss of elasticity Merged alveoli = larger space, but not enough capillary support, so gas exchange does not support demand Skeletal disorders Arthritis or rib injuries reduce compliance 3/17/08

Lung mechanics Fig. 21.13 3/17/08

Lung mechanics Fig. 21.14 3/17/08

Lung mechanics Fig. 21.15 3/17/08

Lung mechanics Fig. 21.16 3/17/08

Lung mechanics Fig. 20.18 3/17/08

Lung mechanics Fig. 20.19 3/17/08

Lung mechanics Fig. 20.14 3/17/08

Mechanics of Respiration 3/17/08

Mechanics of Respiration Air is moving in and 3/17/08

Mechanics of Respiration Air is moving in and out of the lungs due to pressure gradients We will cover the mechanism in more detail in lecture, but be sure you read the introduction to each lab and to each section/activity…you will be responsible for the information presented there in lab and lecture! Happy breathing 3/17/08

Nose Fig. 20.14 3/17/08