Human Human RespirationRespirationDR Rana Amjad AliDR Rana Amjad Ali

What is Human Respiration?What is Human Respiration?• The human respiratory

system allows one to obtain oxygen, eliminate carbon dioxide.

• Breathing consists of two phases, inspiration and expiration – Inspiration- the process of

taking in air– Expiration- the process of

blowing out air

Organs in the Respiratory SystemOrgans in the Respiratory SystemSTRUCTURE FUNCTION

nose / nasal cavity warms, moistens, & filters air as it is

inhaled

pharynx (throat)  passageway for air, leads to trachea

larynx the voice box, where vocal chords are

located

trachea (windpipe)

 keeps the windpipe "open"

 trachea is lined with fine hairs called cilia which filter air before it reaches the lungs

bronchi two branches at the end of the trachea,

each lead to a lung

bronchioles a network of smaller branches leading from

the bronchi into the lung tissue & ultimately to air sacs

alveoli the functional respiratory units in the lung

where gases are exchanged

Malfunctions & Diseases of the Respiratory System

asthmasevere allergic reaction characterized by the constriction of bronchioles

bronchitisinflammation of the lining of the bronchioles

emphysemacondition in which the alveoli deteriorate, causing the lungs to lose their elasticity

pneumonia

condition in which the alveoli become filled with fluid, preventing the exchange of gases

lung cancerirregular & uncontrolled growth of tumors in the lung tissue

Respiratory CycleRespiratory Cycle• Respiration rate is the number of

breaths per minute• Human respiration rate is controlled

by a part of the brain called the medulla –Sends signals to adjust levels of oxygen

present in your body by changing your breathing rate

Respiratory Respiratory Overview Overview PicturePictureNasal

Cavity

Nose

Mouth

Bronchus

Bronchiole

Alveolus

Diaphragm

Throat

(pharynx)

Windpipe (Trachea)

Left lungs

Ribs

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Nose and Mouth PictureNose and Mouth Picture

Nasal Cavity

Nostril

Oral CavityPharynx

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The Pharynx and TracheaThe Pharynx and Trachea

our pharynx (throat) gathers air after it passes through our nose and then the air is passed down to

our trachea (windpipe).

our trachea is held open by “incomplete ringsof cartilage.” Without these rings our trachea might close off and air would not be able to get

to and from our lungs.

Pharynx

(Throat)

Mouth

Trachea

our trachea (windpipe) splits up into two bronchi tubes. These two tubes keep

splitting up and form our bronchiole.

The Bronchi Tubes The Bronchi Tubes and Bronchiole and Bronchiole IntroIntro

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The Bronchi Tubes and The Bronchi Tubes and BronchioleBronchiole

These bronchi tubes split up, like tree branches, and get smaller and smaller

inside our lungs.

The air flows past our bronchi tubesand into our bronchiole. These tubes

keep getting smaller and smaller until theyfinally end with small air sacs (called alveoli).

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Alveoli and Bronchi PictureAlveoli and Bronchi Picture

Trachea

Bronchi Tubes

Bronchiole

Alveoli

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The Alveoli and Capillary The Alveoli and Capillary NetworkNetwork

alveoli are tiny air sacsthat fill up with air/oxygen when we

breath in.

our alveoli are surrounded bymany tiny blood vessels called

capillaries.

The walls of our alveoli (and capillaries) are so thin that the oxygen or carbon dioxide can

pass through them, traveling right into, orout of our blood stream.

Alveoli PictureAlveoli Picture

Capillary

Red Blood Cell

Oxygen is picked up

Carbon Dioxide is dropped off

Wall of the air sac

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AlveolusAlveolus

Bronchiole

Respiratory Bronchiole

Alveolar Duct

Alveolar Sac

Capillaries

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Looking at the AlveoliLooking at the Alveoli

ChemicalsChemicals

Red blood cell carrying Carbon dioxide

Chemical change is taking place in cell

Red blood cell carrying oxygen

Alveolus

Contiguous Basal Laminae (Membrane)

Capillary

DiffusionDiffusion

Oxygen

Carbon Dioxide

Alveolus

Contiguous Basal Laminae (Membrane*)

Capillary

* A specialized thin layer of skin that oxygen and carbon dioxide can pass through.

Oxygen diffuses through the membrane into the blood stream. Carbon Dioxide diffuses through the membrane and enters the alveolus.

Cool picturesCool pictures

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Intro Intro to to

DiapDiaphraghragmm

The Diaphragm is an important factor in breathing.

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Diagram of DiaphragmDiagram of Diaphragm

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Respiratory Respiratory Overview ReviewOverview Review

CO2

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The Pharynx, or throat, is located where passages from the nose and mouth came together.

Air Passing over the mucus membrane of the nasal cavity is moistened, warmed, and filtered

Inside the lungs the Bronchi branch into small tubes called bronchioles

At the end of the bronchioles are bunches of alveoli, air sacs, arranged like grapes on a stemAir enters the trachea, or wind pipe which leads to and from the lungs

The trachea divides into two tubes called bronchi

If one lobe is injured or diseased, the other lobes may be able to function normally

The The RespiraRespira

tory tory SystemSystem

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Respiration IncludesRespiration Includes• Pulmonary ventilation

– Air moves in and out of lungs– Continuous replacement of gases in alveoli (air sacs)

• External respiration– Gas exchange between blood and air at alveoli– O2 (oxygen) in air diffuses into blood– CO2 (carbon dioxide) in blood diffuses into air

• Transport of respiratory gases– Between the lungs and the cells of the body– Performed by the cardiovascular system– Blood is the transporting fluid

• Internal respiration– Gas exchange in capillaries between blood and tissue

cells– O2 in blood diffuses into tissues– CO2 waste in tissues diffuses into blood

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Cellular RespirationCellular Respiration

• Oxygen (O2) is used by the cells• O2 needed in conversion of glucose

to cellular energy (ATP)• All body cells • Carbon dioxide (CO2) is produced as

a waste product• The body’s cells die if either the

respiratory or cardiovascular system fails

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The Respiratory OrgansThe Respiratory Organs

Conducting zone– Respiratory passages

that carry air to the site of gas exchange

– Filters, humidifies and warms air

Respiratory zone– Site of gas exchange– Composed of

• Respiratory bronchioles

• Alveolar ducts• Alveolar sacs

Conducting zone labeled

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NoseNose• Provides airway• Moistens and warms

air• Filters air• Resonating chamber

for speech• Olfactory receptors

External nose

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Nasal cavity– Air passes through nares (nostrils)– Nasal septum divides nasal cavity in midline (to right & left

halves)• Perpendicular plate of ethmoid bone, vomer and septal

cartilage– Connects with pharynx posteriorly through choanae

(posterior nasal apertures*)– Floor is formed by palate (roof of the mouth)

• Anterior hard palate and posterior soft palate

* palate

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Linings of nasal cavity• Vestibule* (just above nostrils)

– Lined with skin containing sebaceous and sweat glands and nose hairs

– Filters large particulars (insects, lint, etc.)• The remainder of nasal cavity: 2 types of mucous membrane

– Small patch of olfactory mucosa near roof (cribriform plate)– Respiratory mucosa: lines most of the cavity

*

Olfactory mucosa

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Respiratory Respiratory MucosaMucosa

• Pseudostratified ciliated columnar epithelium• Scattered goblet cells• Underlying connective tissue lamina

propria–Mucous cells – secrete mucous–Serous cells – secrete watery fluid with

digestive enzymes, e.g. lysozyme• Together all these produce a

quart/day–Dead junk is swallowed

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Nasal Conchae

•Inferior to each is a meatus*•Increases turbulence of air•3 scroll-like structures•Reclaims moisture on the way out

**

*

(its own bone)

Of ethmoid

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Paranasal sinuses–Frontal, sphenoid, ethmoid and maxillary

bones–Open into nasal cavity– Lined by same mucosa as nasal cavity and

perform same functions–Also lighten the skull–Can get infected: sinusitis

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The Pharynx (throat)The Pharynx (throat)

• 3 parts: naso-, oro- and laryngopharynx• Houses tonsils (they respond to inhaled antigens)• Uvula closes off nasopharynx during swallowing so

food doesn’t go into nose• Epiglottis posterior to the tongue: keeps food out of

airway• Oropharynx and laryngopharynx serve as common

passageway for food and air– Lined with stratified squamous epithelium for protection

*

*

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The Larynx (voicebox)The Larynx (voicebox)• Extends from the level of the 4th to the

6th cervical vertebrae• Attaches to hyoid bone superiorly• Inferiorly is continuous with trachea

(windpipe)• Three functions:

1. Produces vocalizations (speech)2. Provides an open airway (breathing)3. Switching mechanism to route air and food

into proper channels• Closed during swallowing• Open during breathing

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• Framework of the larynx– 9 cartilages connected by membranes and

ligaments– Thyroid cartilage with laryngeal prominence

(Adam’s apple) anteriorly– Cricoid cartilage inferior to thyroid cartilage: the

only complete ring of cartilage: signet shaped and wide posteriorly

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– Behind thyroid cartilage and above cricoid: 3 pairs of small cartilages1. Arytenoid: anchor the vocal cords2. Corniculate3. Cuneiform

– 9th cartilage: epiglottis

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Epliglottis* (the 9th cartilage)Elastic cartilage covered by mucosaOn a stalk attached to thyroid cartilageAttaches to back of tongueDuring swallowing, larynx is pulled superiorlyEpiglottis tips inferiorly to cover and seal laryngeal inletKeeps food out of lower respiratory tract

*

*

Posterior views

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• Cough reflex: keeps all but air out of airways

• Low position of larynx is required for speech (although makes choking easier)

• Paired vocal ligaments: elastic fibers, the core of the true vocal cords

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• Pair of mucosal vocal folds (true vocal cords) over the ligaments: white because avascular

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• Glottis is the space between the vocal cords• Laryngeal muscles control length and size of opening by

moving arytenoid cartilages• Sound is produced by the vibration of vocal cords as air

is exhaled

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Trachea (the windpipe)Trachea (the windpipe)• Descends: larynx through neck into

mediastinum• Divides in thorax into two main (primary)

bronchi• 16-20 C-shaped rings

of hyaline cartilage joined by fibroelastic connective tissue

• Flexible for bendingbut stays open despitepressure changesduring breathing

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• Posterior open parts of tracheal cartilage abut esophagus

• Trachealis muscle can decrease diameter of trachea– Esophagus can expand when food swallowed– Food can be forcibly expelled

• Wall of trachea has layers common to many tubular organs – filters, warms and moistens incoming air– Mucous membrane (pseudostratified epithelium with cilia

and lamina propria with sheet of elastin)– Submucosa ( with seromucous glands)– Adventitia - connective tissue which contains the tracheal

cartilages)

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Carina*Carina*• Ridge on internal aspect of last tracheal cartilage

• Point where trachea branches (when alive and standing is at T7)

• Mucosa highly sensitive to irritants: cough reflex

*

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• Bronchial tree bifurcation– Right main bronchus (more susceptible

to aspiration)– Left main bronchus

• Each main or primary bronchus runs into hilus of lung posterior to pulmonary vessels

1. Oblique fissure2. Vertebral part3. Hilum of lung4. Cardiac impression5. Diaphragmatic surface

(Wikipedia)

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• Main=primary bronchi divide into secondary=lobar bronchi, each suppliesone lobe– 3 on the right– 2 on the left

• Lobar bronchi branch into tertiary = segmental bronchi

• Continues dividing: about 23 times• Tubes smaller than 1 mm called bronchioles• Smallest, terminal bronchioles, are less the 0.5

mm diameter• Tissue changes as becomes smaller

– Cartilage plates, not rings, then disappears– Pseudostratified columnar to simple columnar to

simple cuboidal without mucus or cilia– Smooth muscle important: sympathetic relaxation

(“bronchodilation”), parasympathetic constriction (“bronchoconstriction”)

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Respiratory ZoneRespiratory Zone• End-point of respiratory tree• Structures that contain air-exchange chambers are called alveoli• Respiratory bronchioles lead into alveolar ducts: walls consist of alveoli• Ducts lead into terminal clusters called alveolar sacs – are microscopic

chambers • There are 3 million alveoli!

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Gas ExchangeGas Exchange• Air filled alveoli account for most of the lung

volume• Very great area for gas exchange (1500 sq ft)• Alveolar wall

– Single layer of squamous epithelial cells (type 1 cells) surrounded by basal lamina

– 0.5um (15 X thinner than tissue paper)– External wall covered by cobweb of capillaries

• Respiratory membrane: fusion of the basal laminas of– Alveolar wall– Capillary wall

Alveolar sac

Respiratorybronchiole

Alveolarduct

Alveoli

(air on one side; blood on the other)

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Bronchial“tree” andassociatedPulmonaryarteries

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• This “air-blood barrier” (the respiratory membrane) is where gas exchange occurs–Oxygen diffuses from air in alveolus

(singular of alveoli) to blood in capillary–Carbon dioxide diffuses from the blood

in the capillary into the air inthe alveolus

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Surfactant Surfactant

• Type II cuboidal epithelial cells are scattered in alveolar walls

• Surfactant is a detergent-like substance which is secreted in fluid coating alveolar surfaces – it decreases tension

• Without it the walls would stick together during exhalation

• Premature babies – problem breathing is largely because lack surfactant

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Microscopic detail of alveoliMicroscopic detail of alveoli• Alveoli surrounded by fine elastic fibers• Alveoli interconnect via alveolar pores• Alveolar macrophages – free floating “dust

cells”• Note type I and type II cells and joint

membrane

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Lungs and Lungs and PleuraPleura

Pleural cavity – slit-like potential space filled with pleural fluid

• Lungs can slide but separation from pleura is resisted (like film between 2 plates of glass)

• Lungs cling to thoracic wall and are forced to expand and recoil as volume of thoracic cavity changes during breathing

Around each lung is a flattened sac of serous membrane called pleura

Parietal pleura – outer layerVisceral pleura – directly on lung

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LungsLungs

• Each is cone-shaped with anterior, lateral and posterior surfaces contacting ribs

• Superior tip is apex, just deep to clavicle• Concave inferior surface resting on

diaphragm is the baseapex apex

base base

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• Hilus or (hilum)– Indentation on mediastinal (medial) surface– Place where blood vessels, bronchi, lymph vessel,

and nerves enter and exit the lung• “Root” of the lung

– Above structures attaching lung to mediastinum– Main ones: pulmonary artery and veins and main

bronchus

Medial view R lung Medial view of L lung

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• Right lung: 3 lobes–Upper lobe–Middle lobe–Lower lobe

• Left lung: 2 lobes–Upper lobe–Lower lobe

Oblique fissure

Oblique fissure

Horizontal fissure

Abbreviations in medicine:e.g.” RLL pneumonia”

Each lobe is served by a lobar (secondary) bronchus

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• Each lobe is made up of bronchopulmonary segments separated by dense connective tissue– Each segment receives air from an individual

segmental (tertiary) bronchus– Approximately 10 bronchopulmonary segments

in each lung– Limit spread of infection– Can be removed more easily because only small

vessels span segments

• Smallest subdivision seen with the naked eye is the lobule– Hexagonal on surface, size of pencil eraser– Served by large bronchiole and its branches– Black carbon is visible on connective tissue

separating individual lobules in smokers and city dwellers

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• Pulmonary arteries bring oxygen-poor blood to the lungs for oxygenation– They branch along with the bronchial tree– The smallest feed into the pulmonary capillary

network around the alveoli• Pulmonary veins carry oxygenated blood

from the alveoli of the lungs to the heart

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• Stroma – framework of connective tissue holding the air tubes and spaces – Many elastic fibers– Lungs light, spongy and elastic– Elasticity reduces the effort of breathing

• Blood supply– Lungs get their own blood supply from

bronchial arteries and veins• Innervation: pulmonary plexus on lung

root contains sympathetic, parasympathetic and visceral sensory fibers to each lung– From there, they lie on bronchial tubes and

blood vessels within the lungs

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• Bronchopulmonary – means both bronchial tubes and lung alveoli together– Bronchopulmonary segment – chunk receiving

air from a segmental (tertiary) bronchus*: tertiary means it’s the third order in size; also, the trachea has divided three times now

• “Anatomical dead space”– The conducting zone which doesn’t participate

in gas exchange

Primary bronchus:(Left main)

Secondary:(left lower lobar bronchus)

(supplyingleft lowerlobe)

Does this clarify a little?

*

Understand the concepts; you don’t need to know the names of the tertiary bronchi

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VentilationVentilation

• Breathing = “pulmonary ventilation”– Pulmonary means related to the lungs

• Two phases– Inspiration (inhalation) – air in– Expiration (exhalation) – air out

• Mechanical forces cause the movement of air– Gases always flow from higher pressure to

lower– For air to enter the thorax, the pressure of the

air in it has to be lower than atmospheric pressure• Making the volume of the thorax larger means the air

inside it is under less pressure(the air has more space for as many gas particles, therefore it is under less pressure)

• The diaphragm and intercostal muscles accomplish this

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Muscles of InspirationMuscles of Inspiration

• During inspiration, the dome shaped diaphragm flattens as it contracts– This increases the

height of the thoracic cavity

• The external intercostal muscles contract to raise the ribs– This increases the

circumference of the thoracic cavity

Together:

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Inspiration continuedInspiration continued

• Intercostals keep the thorax stiff so sides don’t collapse in with change of diaphragm

• During deep or forced inspiration, additional muscles are recruited:– Scalenes– Sternocleidomastoid– Pectoralis minor– Quadratus lumborum on 12th rib– Erector spinae

(some of these “accessory muscles” of ventilation are visible to an observer; it usually tells you that there is respiratory distress – working hard to breathe)

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Expiration Expiration

• Quiet expiration in healthy people is chiefly passive– Inspiratory muscles relax– Rib cage drops under force of

gravity– Relaxing diaphragm moves

superiorly (up)– Elastic fibers in lung recoil– Volumes of thorax and lungs

decrease simultaneously, increasing the pressure

– Air is forced out

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Expiration continuedExpiration continued• Forced expiration is active

–Contraction of abdominal wall muscles• Oblique and transversus predominantly

– Increases intra-abdominal pressure forcing the diaphragm superiorly

–Depressing the rib cage, decreases thoracic volume• Some help from internal intercostals and

latissimus dorsi

(try this on yourself to feel the different muscles acting)

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Neural Control of VentilationNeural Control of Ventilation• Reticular formation in medulla

– Responsible for basic rate and rhythm– Can be modified by higher centers

• Limbic system and hypothalamus, e.g. gasp with certain emotions

• Cerebral cortex – conscious control

• Chemoreceptors – Central – in the medulla– Peripheral: see next slide

• Aortic bodies on the aortic arch• Carotid bodies at the fork of the carotid artery: monitor

O2 and CO2 tension in the blood and help regulate respiratory rate and depth

The carotid sinus (dilated area near fork) helps regulate blood pressure and can affect the rate (stimulation during carotid massage can slow an abnormally fast heart rate)

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Peripheral Peripheral chemoreceptors chemoreceptors

regulating respirationregulating respiration

• Aortic bodies*– On aorta– Send sensory info to

medulla through X (vagus n)

• Carotid bodies+– At fork of common

carotid artery– Send info mainly through

IX (glossopharyngeal n)

*

+

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• There are many diseases of the respiratory system, including asthma, cystic fibrosis, COPD (chronic obstructive pulmonary disease – with chronic bronchitis and/or emphysema) and epiglottitis

example:normal emphysema

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you might want to think twice about you might want to think twice about smoking….smoking….

IntroductionIntroduction• The Circulatory System is the

main cooling and transportation system for the human body

• The body has about 5 liters of blood continuously traveling through it by way of the Circulatory System

• In the Circulatory System, the heart, lungs, and blood vessels have to work together

• The Circulatory System has three different parts: pulmonary circulation (lungs), coronary circulation (heart), and systemic circulation, (the rest of the system’s processes).

The HeartThe HeartThis organ is what pumps oxygen rich blood, nutrients, hormones, and the other things your body needs to maintain your health, to your organs and tissues.

The pulmonary veins you see on the right side of the diagram come from your lungs, where the blood cells collect oxygen. It’s then pumped out to the rest of the body through the Aorta (Top).

All of the blue sections show blood cells carrying waste, (C02) moving back to the lungs (where the C02 will be replaced by oxygen) through the Pulmonary Artery (Top, blue)

Pulmonary Veins

Pulmonary Artery

(Inferior Vena Cava) From the Body

(Aortic Artery) To the body

Whenever the blood is pumped from one section of the heart another a valve closes behind it preventing the blood from moving backwards.

By The Way…

Valves: (tricuspid valve semilunar (pulmonary) valve, bicuspid (mitral) valve, and the semilunar (aortic) valve

(Superior Vena Cava) From the Body

Blood Flow through Blood Flow through HeartHeart

• Blood from the body travels into the right atrium, moves into the right ventricle, and is finally pushed into lungs in the pulmonary arteries

• The blood then picks up oxygen and travels back to the heart into the left atrium through the pulmonary veins

• The blood then travels through the to the Left Ventricle and exits to the body through the Aorta…

Right AtriumLeft Atrium

Circulation back to Circulation back to HeartHeart

• Capillaries carry the blood to…

• Venules that connect to veins and the…

• Veins (wide blood vessels) carries the oxygen-poor blood back to the heart.

To upper body

From upper

body

To lungTo lung

From lung

Left Atrium

Left Ventricle

To lower bodyFrom lower

body

Right Ventricle

Right Atrium

From lung