A&P 2 Respiratory System

Respiration

exchange of gases between the atmosphere, blood, and cells.

Basic Steps of Respiration

ventilation (breathing)

external (pulmonary) respiration

internal (tissue) respiration

Ventilation Respiration

inhalation and exhalation of air between the atmosphere and the alveoli of the lungs

External Respiration

exchange of gases between the alveoli of the lungs and the blood in pulmonary capillaries across the respiratory membrane

-gas moves from high partial pressure to low partial pressure

-in lungs of resting person oxygen moves from alveoli (PO2= 105mmHg) into capillaries (PO2= 40mmHg) carbon dioxide moves in the opposite direction

-blood vessels pick up oxygen and deoxygenated blood becomes oxygenated

Internal Respiration

exchange of gases between blood in systemic capillaries and tissue cells. Blood loses Oxygen and gains Carbon Dioxide

What is the respiratory system made up of?

nose, pharynx, larynx, trachea, bronchi and lungs

upper respiratory tract

superior to larynx

lower respiratory tract

inferior to larynx

Conducting system

cavities and tubes that act as passageways for air. Nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles

Respiratory portion

structure where gas exchange occurs. Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

External Anatomy of Nose

-made up of skin and cartilage

-lined with mucous membrane

-bony framework; made by frontal, nasal, and maxillary bones

-opens to the outside by two external nares or nostrils

-hard palate separates the nasal cavity from the oral cavity

Internal Structures of the Nose

-nasal cavity is inside nose and is divided into 2 chambers separated by the nasal septum

-lined by pseudostratified ciliated columnar epithelium with goblet cells

Internal Nares (choanae)

connect the nasal cavity to the pharynx

conchae

bony swelling on lateral walls

paranasal sinuses

resonating chambers in the bones of the skull that connect to the nasal cavity

Functions of the nose

interior structures of the nose are specialized for warming, moistening, and filtering incoming air

-receive olfactory stimuli through olfactory receptors

-paranasal sinuses serve as large, hollow resonating chambers to modify speech sounds

resonation

helps with clarity of sound

pharynx

commonly known as the throat

-extends from the internal nares to cricoid cartilage of the larynx

Function of the pharynx

-passageway for food and air

-resonating chamber for speech production

-tonsil (lymphatic tissue) in the walls protects entryway into body

Regions of the pharynx

-nasopharynx

-oropharynx

-laryngopharynx

Nasopharynx

-from choanae to soft palate

-FOR AIR ONLY

-contains pharyngeal tonsils (adenoids)

Oropharynx

begins at soft palate and ends at the epiglottis

-has an opening called fauces from the mouth

-palatine tonsils found in side walls, lingual tonsil in tongue

-for food and air

laryngopharynx

begins at the epiglottis and ends at cricoid cartilage

-extends inferiorly from hyoid bone

-for food and air

openings of the nasopharynx

-2 internal nares

-2 openings that connect with Eustachian tube- equilibrate pressure between the middle ear and atmosphere

-one that connects to oropharynx

Openings of the laryngopharynx

2 at the inferior end

-opens into esophagus

-opens into larynx

Lining of laryngopharynx

non keratinized stratified squamous epithelium

Lining of the Oropharynx

non keratinized stratified squamous epithelium

Lining of the Nasopharynx

pseudostratified ciliated columnar epithelium with goblet cells. Cilia help movement of mucous

Larynx (Voice Box)

contains the vocal folds used for voice production

-lined mainly with pseudostratified ciliated columnar epithelium which helps to move the mucus backwards toward the pharynx

-connects pharynx to the trachea

glottis

an opening that connects the pharynx with the trachea

How many pieces of cartilage does the larynx have?

9

-thyroid

-epiglottic

-cricoid

-arytenoids, corniculate, and cuneiform

Thyroid cartilage

Adam's apple. Largest Cartilage

Epiglottic Cartilage

leaf shaped cartilage. Stem portion is attached, whereas leaf portion is unattached and moves up and down

Epiglottis during swallowing

moves down and closes the glottis, preventing the entry of food into the larynx

when is cough reflex initiated?

when food, dust, smoke, or liquids get into the larynx

Cricoid Cartilage

ring of cartilage at the base

Corniculate

horn like structure

-attached to thyroid ligament

What happens when a higher tone is produced?

the vocal folds stretch more and vibrate faster

Mucus membrane of the larynx

2 pairs of folds

-Vestibular (false vocal cords)

-True Vocal Cords

Vestibular (False Vocal Folds)

superior to vocal cords

-close the lower respiratory portion in situations like holding breath when lifting weight

True Vocal Folds

for voice production

-sound is produced by the vibrations of true vocal folds

Laryngitis

inflammation of larynx which causes vocal cords to swell. Can be caused by respiratory infection or irritants like cigarette smoke

Trachea (windpipe)

extends from larynx to the primary bronchi

Lining of the trachea

mucosa layer- pseudostratified ciliated columnar epithelium with mucus secreting goblet cells

-cilia sweep debris away from the lungs and back to the throat to be swallowed

Layers of wall of Trachea

air passageway with 16-20 incomplete C shaped cartilage rings. The cartilaginous rings provide support to prevent trachea from collapsing inward during inhalation

Trachealis

a smooth muscle band on the posterior side of the trachea that stabilizes the open ends of the cartilage rings

Carina (internal ridge)

-at the branch point, there is an internal ridge (carina) which is the most sensitive area of the entire larynx and trachea

where the cough reflex is generated

Trachea divides into...

right primary bronchus- to right lung, broader and more vertical

left primary bronchus- to left lung

Secondary bronchi

divisions of the primary one to each lobe of the lung. 3 on Right and 2 on left

Tertiary (segmental) bronchi

branch from secondary bronchi one to each bronchopulmonary segment of the lung

cartilage plates give

structure to bronchi

Bronchi divide into

bronchioles and continue to divide to the smallest bronchioles (terminal bronchioles)

Bronchial tree

divisions of the bronchi that consists of trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles

Changes on Bronchial Tree

-epithelium gradually changes from pseudostratified ciliated columnar to nonciliated simple cuboidal

epithelium

-incomplete rings of cartilage are first replaced with plates and then finally disappear

-amount of smooth muscle increase as we move down the tree. During exercise, activity of sympathetic ANS causes relaxation of smooth muscle thus dilating the air passageways. This improves lung ventilation. Due to parasympathetic activity of ANS or due to allergic reactions, histamine is released which causes constriction of passageways and can some times close airways. This is what happens during an asthma attack

antihistamine

breaks up mucus

Lungs

left an right, cone shaped in thoracic cavity separated by mediastinum

pleural membrane

enclose and protect the lungs

-parietal- line inside of thoracic cavity

-visceral- cover the lungs

-pleural- space between visceral and parietal pleura filled with lubricating serous pleural fluid

Base of the Lungs

inferior portion which fits over the diaphragm.

Apex of the Lungs

narrow superior portion

Hilum

point where the bronchi, pulmonary vessels, lymphatic vessels and nerves enter and exit

The right lung

3 lobes separated by two fissures (oblique and horizontal)

The left lung

2 lobes separated by one fissure (oblique) and a depression (cardiac notch)

Each lobe of the lung is separated into...

bronchopulmonary segments- each segment is supplied by a branch of the terminal bronchi and is further divided into lobules which receive air via the bronchioles

Respiratory Zone

extends from the terminal bronchioles to air chambers (alveoli)

-functions in gas exchange

Branching of Respiratory Zone

terminal bronchiole

respiratory bronchiole

alveolar ducts

alveolar sacs

alveoli

Alveolar Duct

similar to atrium

Alveoli

air filled sacs

2 types of Epithelial Cells

-Type1 alveolar

simple squamous epithelial forma continuous layer main site of gas exchange

-Type 2 alveolar

secrete surfact: lowers the surface tension and reduces tendency of alveoli to collapse

alveolar macrophages

(dust cells) remove dust particles

Respiratory Distress syndrome

deficiency of surfactant in premature infants

Surfactants

contains phospholipids

-prevent build up of fluid

atelectasis*****

collapsed lung (too much fluid)

pneumothorax*****

punctured lung. causes atelectasi

respiratory membrane

made up of alveolar and capillary walls

-site where exchange of oxygen and carbon dioxide between the lungs and the blood takes place by diffusion

-.5micrometers thick allowing rapid diffusion of gases

Layers of the Respiratory Membrane

-alveolar fluid

-epithelial cells of the alveolar wall

-epithelial basement membrane

-capillary basement membrane

-capillary endothelium

Blood supply to the lungs

-pulmonary trunk (deoxygenated blood) --right and left pulmonary arteries- lungs-pulmonary veins- left atrium

-aorta- bronchial arteries (oxygenated blood) - lungs- bronchial veins- superior vena cava- right atrium

Breathing

exchange of air between the atmosphere and the alveoli of he lungs

-air flow occurs because of pressure differenes created by contraction and relaxation of respiratory muscles

-pressure differences are governed by boyle's law

Inspiration (inhalation)

brings air into the lung

Expiration (exhalation)

movement of air out of the lungs

-occurs when alveolar pressure is higher than atmospheric pressure

-relaxation of the diaphragm and external intercostal muscles results in elastic recoil of the chest wall and lungs, which increases intrapleural pressure, decreases lung volume, and increases alveolar pressure so that air moves from the lungs to the atmosphere

Boyle's Law

states that in a closed container, the volume of the gas is inversely proportional to its pressure. Hence as the volume increases the pressure decrease and vice versa. Also the direction of movement of air is always from high to low pressure

Scalene muscles

hold clavicle and 1st and 2nd ribs in place

transversus (thoracic)

helps pull down diaphragm

stressful breathing

uses rectus abdominis or the internal and external oblique

external intercostal

pull ribs up and out

Forced expiration

employs contraction of the internal intercostals and abdominal muscles

Factors affecting pulmonary ventilation

1. surface tension

2. compliance

3. airway resistance

Surface tension

force exerted by a thin layer of fluid next to the air in the alveoli

-alveoli burst or collapse inward due to surface tension

-to prevent this, detergent like substance called surfactant (produced by alveolar cells) reduces the surface tension of alveolar cells and thus lowers the tendency of alveolus to collapse

What does a deficiency of surfactant in premature infants cause?

increases the surface tension which causes alveoli to collapse at the end of exhalation (respiratory distress syndrome)

Compliance

ease with which lungs and chest wall expand

-higher compliance value indicates that lungs and thoracic wall can expand easily

-due to elastic fibers in the lungs which let is expand and due to decreased surface tension by surfactant

Decreased compliance is associated with

-scarred lung tissue: tuberculosis, anthracosis, and emphysema

-lung tissue filled with fluid: pulmonary edema

-destruction of elastic fibers: emphysema

-deficiency in surfactant

-paralysis of muscles of respiration

Tuberculosis

hardening of lung wall

Anthracosis

hardening of lung wall

-black lung from coal dust

Airway Resistance

provided by the walls of the airways

-larger the diameter of the passageway the lower is the resistance

-if smooth muscle contracts airways decrease in diameter increasing resistance

-asthma, emphysema, chronic bronchitis, and chronic obstructive pulmonary disease (COPD), cause obstruction or collapse of airways, increasing resistance

aspiration**********

breathing in a foreign object

eupnea

normal pattern of quiet breathing

apnea

breath holding

dyspnea

painful or difficult breathing

tachypnea

rapid breathing

costal breathing

combinations of various patterns of external intercostal muscles; during need for increased ventilation

EX: exercise

Diaphragmatic breathing

usual mode of operation to move air by contracting and relaxing the diaphragm to change the lung volume