Respiratory System

• Why do we breathe? Think of all the

reasons why we need a respiratory

system.

THINK

IT

OUT

1.Exchange of gases into the blood and

tissues. Diffusion of Oxygen into blood from

the lungs and then into the tissues.

Diffusion of wastes such as Carbon Dioxide

from tissues into blood and out of blood into

the lungs.

2.Cellular Respiration requires oxygen in

order to produce useable energy in order to

carry out cellular processes and to prevent

the build up of lactic acid via anaerobic

respiration.

Respiration

• “Respiration” is used several different ways:

• Cellular respiration is the aerobic breakdown

of glucose in the mitochondria to make ATP.

• Respiratory systems are the organs in

animals that exchange gases with the

environment.

• “Respiration” is an everyday term that is

often used to mean “breathing.”

Respiration

• External Respiration

• Internal Respiration

The exchange of gases between the

atmosphere and blood

The exchange of gases between the

blood and cells in our bodies

Respiratory system function

• Respiratory systems allow animals to

move oxygen (needed for cellular

respiration) into body tissues and

remove carbon dioxide (waste product of

cellular respiration) from cells.

Gas exchange by Diffusion

• Some animals simply allow gases to diffuse through their skins

• These animals have a low metabolic rate

• All of these are aquatic animals

Specialized structures

• Structures

specialized for gas

exchange include:

• gills (aquatic

animals)

• spiracles

(terrestrial insects)

• lungs (most

terrestrial

vertebrates)

Fish Gills

• Fish increase gas

exchange efficiency

using countercurrent

exchange.

• Running blood through

the system in the

opposite direction to

water keeps a diffusion

gradient throughout the

entire exchange.

Countercurrent Exchange

• In a concurrent

system, exchange is

inefficient.

Equilibrium is

reached at one end.

• In a countercurrent

system, equilibrium

is not reached, so

gas exchange

continues, increasing

efficiency.

Gills exchange gases in fish. What is the

site of gas exchange in mammals?

1. Alveoli

2. Tracheids

3. Bronchi

4. Esophagus

• Why are gills so widely seen in aquatic

animals but not in land animals?

THINK

IT

OUT

1.Gills are an adaptation developed to

support gas exchange underwater

because gases must diffuse from the

water in order to fuel the tissues of the

aquatic organisms. Conversely,

terrestrial organisms do not require

gills but respiratory organs that can

diffuse the readily available gases

directly into the organisms blood and

tissues.

Human respiratory system

• Parts of the

respiratory system

include:

• Pharynx

• Trachea

• Larynx

• Epiglottis

Human respiratory system

• Parts of the

respiratory system

include:

• Bronchi

• Bronchioles

• Alveoli

• Lungs

Pharynx

• Known as the throat

• A tube at the back

of the nasal cavity

and mouth

• Acts as a main

passageway for

both food and air

Epiglottis

• A cartilaginous flap

that covers the air

passage when food

is swallowed

• It presses down,

sealing the pathway

• When air is taken

in, the epiglottis

stands upright

Trachea

• Known as the

windpipe

• This is a

cartilaginous tube

that allows air to

pass

• Roughly 10-12cm

long and has

ciliated cells

Larynx• Known as the

voicebox

• Has two ligaments

that are stretched

across it. (these are

our vocal cords)

• The amount of air

as well as the

tension on the

cords determine the

sounds produced

Bronchi• We have two.

Singular =

Bronchus

• They both lead to

the lungs and are

made of both

smooth muscle and

cartilage.

• Also lined with

ciliated cells and

mucus

Bronchioles

• The smallest

divisions of the

Bronchi

• Structurally similar

to bronchi

• Also lined with

ciliated cells and

mucus

Alveoli• Described as

clusters of tiny air

sacs

• Singular =

alveolus

• Each houses a

network of

capillaries

• Function = gas

exchange

Lungs• We have two:

The right lung has three

lobes and the left has only

two

• Pleura- membranes that

secrete a sticky fluid that

decrease friction

• Lines the entire

thoracic cavity and

lungs

• Function = gas exchange

between atmosphere and

blood

The Path of Air

Moving air in and out

• During inspiration

(inhalation), the

diaphragm and

intercostal muscles

contract.

• During expiration

(exhalation), these

muscles relax. The

diaphragm domes

upwards.

Alveoli

• The alveoli are

moist, thin-walled

pockets which are

the site of gas

exchange.

• A slightly oily

surfactant prevents

the alveolar walls

from collapsing and

sticking together.

Circulation and Gas Exchange

• Recall the

interconnection

between circulation

and the respiratory

system.

• Gas exchange at

the lungs and in the

body cells moves

oxygen into cells

and carbon dioxide

out.

What happens when you breathe

in?1. The rib muscles

relax.

2. The diaphragm

contracts.

3. Air leaves the

alveoli.

4. Air moves between

the chest wall and

the lung.

• Premature infants sometimes die of lung

collapse and other lung problems. What

might preemies be missing? How could

this be remedied?

THINK

IT

OUT

Absence of or too little surfactant produced in the lungs at the site of the alveoli causing the alveoli to collapse on top of themselves and thus containing

no air and maintaining no lung capacity.

Also, infections while baby is in womb can lead to lung collapse.

In the alveolus

In the alveolus

• The respiratory

surface is made up

of the alveoli and

capillary walls.

• The walls of the

capillaries and the

alveoli may share

the same

membrane.

Gas exchange

• Air entering the lungs

contains more oxygen

and less carbon dioxide

than the blood that

flows in the pulmonary

capillaries.

• How do these

differences in

concentrations assist

gas exchange?

Oxygen transport

• Hemoglobin binds

to oxygen that

diffuses into the

blood stream.

• What are some

advantages to using

hemoglobin to

transport oxygen?

Oxygen transport• There are approximately 250 million hemoglobin molecules per

RBC

• Hemoglobin is a protein made up of 4 polypeptide chains, each

bonded is bonded to a haem (iron) group.

• Hemoglobin is able to increase the oxygen-carrying capacity of

blood by carrying 4 oxygen molecules. Thus, much more oxygen

can be transported around the blood in hemoglobin, rather than

being dissolved in plasma.

• Another advantage is that once 1 oxygen molecule binds to the

hemoglobin its ability to bind more oxygen molecules increases.

The bonding of each oxygen molecule slightly alters the shape of

the hemoglobin, making it easier for subsequent molecules to bind

to it.

Oxygen transport

• Another advantage is that hemoglobin's

capacity to release oxygen increases in the

presence of carbon dioxide. Once

hemoglobin releases oxygen it has an

increased ability to pick up carbon dioxide.

• The fact that hemoglobin is enclosed inside

red blood cells, means that it doesn’t disturb

the osmotic balance of the blood plasma.

Bohr Effect

• Bohr Effect- stating

that hemoglobin's

oxygen binding

affinity is inversely

related both to

acidity and to the

concentration of

carbon dioxide.

What does it mean?

Bohr Effect

• Since carbon dioxide reacts with water to form carbonic acid,

an increase in CO2 results in a decrease in blood pH, resulting

in hemoglobin proteins releasing their load of oxygen.

• Conversely, a decrease in carbon dioxide provokes an

increase in pH, which results in hemoglobin picking up more

oxygen.

• The dissociation of carbonic acid increases the acidity of the

blood (decreases its pH). Hydrogen ions, H+, then react with

oxyhemoglobin to release bound oxygen and reduce the

acidity of the blood. This buffering action allows large

quantities of carbonic acid to be carried in the blood without

major changes in blood pH.

Carbon dioxide transport

• Carbon dioxide can

dissolve in plasma,

and about 70%

forms bicarbonate

ions.

• Some carbon

dioxide can bind to

hemoglobin for

transport.

Carbon dioxide transport

• H2O + CO2 ↔ H2CO3↔

HCO3- + H+

• HCO3- + H+ ↔ H2CO3↔ H2O

+ CO2

Carbon dioxide transport1. CO2 diffuses into RBCs

2. Carbonic Anhydrase catalyzes CO2 into

carbonic acid in the presence of water

3. Carbonic acid is unstable and

disassociates into bicarbonate and protons

4. Bicarbonate is able to leave the RBC by

way of the RBC accepting Chloride in

exchange. This is called Chloride Shift.

5. This allows more CO2 to be taken in by

RBC and also for the bicarbonate to travel

to the lungs via plasma

Carbon dioxide transport6. Normally, too many H+ ions released into the

blood would alter the pH, but hemoglobin will bind

free H+

7. When blood reaches the lungs, bicarbonate is

transported back into RBC and chloride is

released

8. H+ ions disassociate from hemoglobin and binds

to bicarbonate

9. This produces carbonic acid which is then

catalyzed back into CO2 and expelled via

expiration

• Cells use up oxygen quickly for cellular

respiration. What does this do to the

diffusion gradient? How does this help

cells take up oxygen?

• Cells create carbon dioxide during

cellular respiration, so CO2 levels in the

cell are higher than in the blood coming

to them. How does this help cells get rid

of CO2?

THINK

IT

OUT

Here we are simply speaking about the concentration gradients fueled by the unbalanced

proportion of both O2 and CO2.This unbalance drives diffusion (the movement of molecules from an area of high concentration to an area of lower concentration) and allows the

cells to uptake O2 and to expel CO2

Respiration Rate

• Increased activity = Increased Breathing

SIMPLE

The oxygen in blood is:

1. Bound to

hemoglobin.

2. In the white blood

cells.

3. Combined with

carbon to make

carbon dioxide.

4. Dissolved in the

plasma.

Diffusion of O2 from lungs to blood

is rapid because:

1. Active transport

moves oxygen.

2. Hemoglobin takes up

oxygen, keeping

plasma

concentration low.

3. Blood plasma is

oxygen-rich.

Effects of smoking

Inhaled smoke contains:

• CO2, which affects the

CO2 diffusion gradient.

• Carcinogenic chemicals

that can trigger tumors.

• Toxic nicotine, which

paralyzes cilia that

normally clean the

lungs.

Emphysema

• Besides cancer,

smoking can also lead

to emphysema. Alveoli

become dry and brittle,

and eventually rupture.

• Both active and passive

smoking (“second-

hand” smoke) can lead

to can lead to lung

problems.All types of smoke, not just tobacco,

can cause cancers and emphysema.

Emphysema

Cystic Fibrosis

• Cystic fibrosis is one of

the most common

inherited respiratory

disorders in The U.S.

• CF is caused by

mutation of a single

gene, the CFTR gene,

which controls salt

balance in the lungs.

Cystic Fibrosis

• A normal CFTR protein

regulates the amount of

chloride ions across the

cell membrane of lung

cells.

• If the interior of the cell

is too salty, water is

drawn from lung mucus

by osmosis, causing the

mucus to become thick

and sticky.

Cystic Fibrosis

• At this point there is no

cure for CF, though

there are therapies that

have extended the lives

of CF patients, including

lung transplants.

• Gene therapy may one

day insert “good” CFTR

genes into lung cells to

make them operate

normally.

“Two lies and a truth” – which one

is true?1. Cigarette smoke

cures colds because

it kills bacteria in the

lungs.

2. “Passive” smoking

is less harmful than

“regular” smoking.

3. Nicotine is one of the

most potent

neurotoxins on earth.

• When people quit smoking, if the lungs

are not damaged they can often clean

themselves because the cilia are no

longer paralyzed. People with cystic

fibrosis have trouble with lung infections

because their lung mucus is thick and

sticky. What roles do cilia and mucus

play in lung health?

THINK

IT

OUT

Mucus is a sticky substance used

to trap dust and microbes.

Cilia are tiny hairs which line the

cells and tracts of the respiratory

system in order to sweep these

contaminates away from the lungs

and toward the throat.