: Respiratory System

Working Together The respiratory system works with the cardiovascular system to exchange gases

between the air and blood (external respiration) and between blood and tissue

fluids (internal respiration).

The Pharynx

The pharynx is a passageway from the nasal cavities to oral cavities and to the larynx

It contains the tonsils (what do they do again?) The pharynx takes

o air from the nose to the larynx and takes food from the oral cavity to the esophagus

The Larynx

Contains vocal cords

The epiglottis covers the glottis, an opening to the larynx In young men, rapid growth of the larynx and vocal cords changes the voice

The Trachea

The trachea, supported by C-shaped cartilaginous rings, is lined by ciliated cells which sweep impurities up toward the pharynx.

The trachea takes air to the bronchial tree. Blockage of the trachea requires an operation to form an opening, a

tracheostomy. The Bronchial Tree

The right and left primary bronchi divide into ever smaller bronchioles to conduct air to the alveoli

An asthma attack occurs when smith muscles in the bronchioles constrict and cause wheezing.

The Lung Lung lie on either side of the heart and within the thoracic cavity.

The right lung has three lobes, the left lung has two (come up with a thoughtful reason for this aka, why? [Answer uploading in the next update])

The lungs are bounded by the ribs and diaphragm.

The Alveoli

Alveoli are the air sacs lined by squamous epithelium and

surrounded by blood capillaries. Alveoli function in gas

exchange, oxygen diffusing into

bloodstream and carbon dioxide diffusing out.

Infant respiratory distress syndrome occurs in premature infants where underdeveloped lungs lack surfactant lipoprotein and collapse.

15.1 Questions 1) Why does crying produce a runny nose? The tear (lacrimal) glands drain into the nasal cavities by way of tear ducts. For this reason, crying produces a runny nose.

2) What causes a sinus headache? Sinuses are air-filled spaces in the nose that reduce the weight of the skull and act as

resonating chambers for the voice. A sinus headache is cause by malfunctioning of sinuses

which increases the weight of the skull and thus case headache.

3) What affect does smoking have on cilia? The cilia that project from the epithelium keep the lungs clean by sweeping mucus,

produced by goblet cells, and debris toward the pharynx. Smoking is known to destroy

these cilia, and consequently, the toxins in cigarette smoke collect in the lungs.

4) Why is surface tension important in breathing? What role does surfactant play in this? What role does the pleura play in this? Each lung is covered by a very thin serous membrane called a pleura. Another pleura covers

the internal chest wall diaphragm; both membranes produce a lubricating serous fluid that helps the pleurae slide freely against each other during inspiration and expiration.

Surface tension is the tendency for water molecules to cling to each other due to hydrogen bonding between the molecules. Surface tension holds the two pleural layers together when the lungs recoil during expiration. Gas exchange takes place across moist cellular

membranes, and yet the surface tension of water lining the alveoli is capable of causing

them to close up. The alveoli are lined with surfactant, a film of lipoprotein that lowers the surface tension and prevents them from closing.

Spirometer A spirometer allows measurement of the components of air during breathing

Respiratory Volumes Tidal volume, the normal amount of air moved in and out of the lungs when

relaxed, is usually about 500 ml. Vital capacity is the maximum amount of air moved in and out on deep breathing Inspiratory reserve volume is the maximum amount of forced inspired air Expiratory reserve volume is the maximum amount of forced expired air Vital capacity is the sum of tidal, inspiratory reserve, and expiratory reserve volumes http://www.youtube.com/watch?v=ndf7Mn_eBOI

Inspiration When we inhale (inspiration) impulses from the respiratory center in the medulla

oblongata cause the rib cage to ride and the diaphragm to lower, causing the thoracic cavity to expand. The negative pressure or partial vacuum causes the air to

come in Presence of CO2 and H+ increases breathing rate.

Expiration

When we exhale (expiration), lack of impulses from the respiratory center allow the rib cage to lower and diaphragm to resume dome shape

The elastic lung recoil and air goes out

A deep breath causes alveoli to stretch; stretch receptors then inhibit the respiratory center.

Control of Ventilation The rhythm of ventilation is controlled by the

respiratory center in the medulla oblongata of

the brain

The respiratory center is sensitive to levels of carbon dioxide and hydrogen ions in the blood (aka - chemical input in addition to

nervous input)

The thoracic cavity is bounded by the rib cage and diaphragm

Pleural membranes line the thoracic cavity and lungs and the intrapleural pressure is lower than atmospheric pressure, keeping the lobules from collapsing

www.youtube.com/watch?v=ipkSJi9l9PY

15.2 Questions What is residual volume? Why is this air not useful for respiration?

The residual volume is not

as useful for gas exchange

because it has been

depleted of oxygen. In some

lung diseases, the residual

volume builds up because

the individual has difficulty

emptying the lungs. This

means that the vital capacity

is reduced because the

lungs have more residual

volume.

External Respiration Gases exert pressure proportional to their portion of total pressure; this is called

partial pressure. (PO2 and PCO2) (recall: High partial pressure = push, low partial pressure = pull)

External respiration is the diffusion of CO2 from pulmonary capillaries into alveolar sacs and O2 from alveolar sacs into pulmonary capillaries, in both cases solely

because the partial pressures are higher causing diffusion across the capillary wall

Refers to gas exchange between air in alveoli and pulmonary capillaries (aka lungs) Most CO2 is carried as bicarbonate ions (H2CO3) in the blood The enzyme carbonic anhydrase speeds up the conversion of bicarbonate and

hydrogen ions to water and carbon dioxide gas/

H+ + HCO3- -> H2CO3 -> H2O + CO2

hydrogen ion + bicarbonate ion -> carbonic acid -> carbonic anhydrase -> water + carbon dioxide

Oxyhemoglobin Hemoglobin takes up oxygen and becomes oxyhemoglobin O2 diffuses into plasma and then into red blood cells in the lungs due to PO2 in alveoli

being higher than PO2 in alveoli being higher than PO2 in pulmonary capillaries Hb + O2 -> Hb

O2

deoxyhemoglobin + oxygen -> oxyhemoglobin Reduced Hemoglobin

The globin portion of hemoglobin combines with excess hydrogen ions to

become reduced hemoglobin or HHb

Internal Respiration Internal respiration is the

diffusion of O2 from systemic capillaries into tissues and CO2 from tissue field into systemic

capillaries PCO2 is greater in the tissues than

in the blood 15.3 Questions 1) What process is solely responsible for the movement of O2 and CO2 into and out of

cells and alveoli? 2) What happens when you hyperventilate? Hypoventilate? 3) In the lungs, using the terms PCO2, PO2 and alveoli, explain why CO2 leaves the circulatory system and why O2 enters it? 4) Why is PCO2 greater in the blood than in the tissues near the lungs?

5) What happens the HbO2 as it nears a cell that is doing a lot of work in your body? Talk

about PCO2 and PO2 in the cell and in the circulatory system, and relates this to HbO2.

6) What is reduced hemoglobin, and how does it affect pH?