The Respiratory System

Lab 10 rev 4/11 • The primary function of the respiratory system is to deliver oxygen (O 2 ) to and remove carbon dioxide (CO 2 ) from the blood.

• The respiratory system also plays a role in maintaining the blood pH (acid-base balance).

Lab 10 Respiratory System 1

The Respiratory System Lab 10 Anatomy of the Respiratory System: • Upper Respiratory Tract (see picture on page 130) –

nose, nasal cavities, sinuses and pharynx

(throat) – The nose, nasal cavities and sinuses provide a large area of highly vascularized tissues which

warm, filter and add moisture to air

.

• As air comes into contact with the warm, moist tissue of the nasal passages, it is warmed and moistened. The sinuses also add moisture to the air.

Lab 10 Respiratory System 2

The Respiratory System Lab 10 – The

pharynx

(throat) connects the nasal cavity and mouth to the larynx (voice box).

– union of the nasal passages and the pharynx and the make it possible to breathe through your mouth.

• Other structures which enter or are located in the pharynx are: –

2 tear ducts

which carry fluid away from the eyes (this is why excess tears also make your nose runny) – the

esophagus

— the passage for food Lab 10 Respiratory System 3

The Respiratory System Lab 10 – The

2 Eustachian tubes

that drain the middle ear and equalize air pressure between the middle ear and outside air. –

Food

• Below the throat, the air passage crosses in front of the esophagus. This makes it possible for food or liquids to be accidentally sucked into the air passages and can cause us to cough or choke. These actions attempt to clear the food or liquid.

Lab 10 Respiratory System 4

The Respiratory System Lab 10 –

Epiglottis

-a flap of cartilage located in the back of the throat.

• During swallowing, the epiglottis forms a tight seal over the trachea so food can’t go down it.

– The

Uvula

-a flap of tissue in the back of the mouth that hangs from the roof of your mouth.

• This closes the upper air passages so food does not come out your nose. (This is also the part of the body that causes snoring when air passes over it.) Lab 10 Respiratory System 5

The Respiratory System Lab 10 • The lower respiratory tract includes – the

larynx, trachea, 2 bronchi, 2 lungs (including the bronchioles and alveoli)

– the larynx or voice box is below the epiglottis and pharynx and is protected by the

thyroid cartilage

(nicknamed the Adam’s apple).

–

Functions of the larynx

• maintains an open airway • route food and air into their appropriate tubes • assist in the production of sound Lab 10 Respiratory System 6

The Respiratory System Lab 10 – The

vocal cords

consist of 2 folds of connective tissue that extend across the airway. The opening of this airway is called the

glottis

.

• Vocal cords are supported by ligaments. Sound is produced as we expel air past them causing the cords to vibrate.

Lab 10 Respiratory System 7

The Respiratory System Lab 10 – The

trachea (or windpipe)

is a tube below the larynx. It is about 4 1/2 inches long, is composed of C-shaped rings of cartilage (to ensure that it stays open), and carries air to the bronchi (see picture page 132).

– The trachea branches into airways which are called the

right and left bronchi

. These further subdivide into smaller and smaller bronchi.

Lab 10 Respiratory System 8

The Respiratory System Lab 10 – The walls of the bronchi contain fibrous connective tissue and smooth muscle reinforced with cartilage. As the branches get smaller, the amount of cartilage declines. When they have no cartilage, their name changes into

bronchioles

.

– Surrounding the bronchi are the

lungs

. These fill the

thoracic cavity

and extend from the clavicles to the

diaphragm

(a thin sheet of muscle).

Lab 10 Respiratory System 9

The Respiratory System Lab 10 • Bronchioles lead to

alveoli

which are the air sacs of the lungs. Alveoli are composed of a single layer of flat, simple squamous cells and this is where gas exchange takes place.

Lab 10 Respiratory System 10

The Respiratory System Lab 10 • Breathing – Involves repetitive cycles of getting air into and out of the lungs.

– This requires muscular effort.

– Since the lungs themselves do not have any skeletal muscle tissue, expansion and contraction occurs because the surrounding bones and muscles expand the size of the chest cavity.

Lab 10 Respiratory System 11

• The Respiratory System Lab 10

Inspiration:

– As the

diaphragm

contracts and flattens, the external

intercostal muscles

contract and lift the ribcage. This causes a pressure drop in the thoracic cavity.

– The

scalene and sternocleidomastoid (SCM) muscles

also contract to help expand the thoracic cavity space.

– As the volume (space) in the thoracic cavity increases, air rushes in to fill this space.

Lab 10 Respiratory System 12

• Other things that help inspiration: – The lungs and chest cavity are surrounded by a membrane called

“pleura”

. There is fluid between the layers of the pleura so the lungs can stretch and contract with minimum friction.

• • There is also a

partial vacuum

between the 2 pleural layers. This causes the lungs to stick to the chest wall as it expands.

Alveolar surfactant

, a chemical within the lungs, decreases the surface tension so the lung tissue doesn’t stick to itself.

Lab 10 Respiratory System 13

The Respiratory System Lab 10 • Expiration: – The diaphragm relaxes and intra-abdominal pressure pushes the diaphragm up. The

internal intercostal muscles

and gravity help to drop the ribcage and thoracic cavity back to its smaller size. This increases pressure within the lungs and forces the air out of them.

Lab 10 Respiratory System 14

The Respiratory System Lab 10 • •

Respiratory Volumes Tidal volume

is the amount of air an individual normally inhales and exhales. • Our body's normal breathing strategy is to ventilate the air sacs and also keep a minimal residual volume in the lungs. This allows us to keep some air for the blood passing through the lungs between breaths. This air is referred to as

dead space volume

.

Lab 10 Respiratory System 15

The Respiratory System Lab 10 • The amount of air that can be forcibly inhaled after a normal inspiration (tidal volume) is called

inspiratory reserve volume.

• The amount of air that can be forcibly exhaled after a normal expiration (tidal volume) is called

expiratory reserve volume.

• The

vital capacity

is the maximal volume that you can forcibly exhale after a maximal inhalation.

• After you forcibly exhale, there is always some air left in the lungs. This is called the

residual volume.

Lab 10 Respiratory System 16

The Respiratory System Lab 10 • These lung capacities are measured with a

spirometer

, which you will be using in one of the activities.

• • Gases are transported from the lungs to the body primarily by hemoglobin. They can also be dissolved in the plasma. In plasma, carbon dioxide dissolves and becomes

carbonic acid or bicarbonate

. These are the chemicals that enable the experiment on page 136 to work. For more detailed explanation look in your textbook.

Lab 10 Respiratory System 17

The Respiratory System Lab 10

REMINDER , page 1 :

1. Learn anatomy of the respiratory system on the models (no pigs or slides). 2. On page 129, perform the activity of studying the Upper Respiratory System.

3. Do both activities on page 131; study and know the location of the nasal conchae, epiglottis, thyroid cartilage, cricoid cartilage, pharynx, vocal cords and trachea. 4. Learn everything listed in figure 14.4 (page 132) except the esophagus.

Lab 10 Respiratory System 18

The Respiratory System Lab 10

REMINDER , page 2 :

5. Perform activities on pages 131-137 with the following exception on

page 138—

DO NOT DO Deglutition Apnea

Lab 10 Respiratory System 19

REMINDER , page 3 :

6. When using the wet spirometer, – use the cardboard mouthpiece. – Push the arrow on the top all the way to the right – There is a white tub which floars on the water and you will push this up as you blow into the spirometer Lab 10 Respiratory System 20