Lesson 7 – Structure and Processes of Respiratory System

4 Important Structural Features

The human respiratory system has four important structural features that enable it to function properly:

A thin permeable respiratory membrane through which diffusion can occur

A large surface area for gas exchange A good supply of blood A breathing system for bringing oxygen-

rich air to the respiratory membrane

How do cells get the oxygen ?

Ventilation: the process in more complex organisms that ensures a flow of oxygen-rich air to the lungs. (aka: breathing)

Gas Exchange: the processes whereby the body cells obtain oxygen and get rid of carbon dioxide. (aka: diffusion of gases)

Ventilation & Gas Exchange:

Structures of the Respiratory System:

MUCUS CELLS (in red)

CILIA (in pink)

Mucus

The oil in the machine of our body We make about 1 – 1.5 litres per day When sick, consistency changes (or

from dehydration) Allergies (and some infections) cause

leakage of mucus producing cells Green colour can be from neutrophils

(most abundant white blood cell in humans)

Pathway of Air:

Pathway of Air:

Alveoli (air sacs)

Alveoli – site of gas exchange

Gas Exchange in the Alveoli

High Surface area Air is 37oC and moist Membrane is one cell thick Passive Transport.

The Mechanism of Ventilation:

Breathing is based on negative pressure

Model of the lung

http://www.youtube.com/watch?v=CBv2BqqAydE

Pleural Membranes Pleura space (area between visceral

and parietal pleura) is filled with fluid to minimize friction

Pneumothorax

If air is introduced into the pleural cavity (ie: through a stabbing or broken rib), the membranes separate. This causes the lung to collapse in a condition called pneumothorax. If pneumothorax occurs, the lung cannot inflate because nothing is pulling on it to increase its volume and reduce its air pressure. This leads to difficulty breathing.

 

Pneumothorax

Pneumothorax

http://www.youtube.com/watch?v=i-sZzZ4TMnY

Lung Capacity:

Lung CapacityTOTAL LUNG CAPCITY:The maximum volume of air that can be inhaled during a single breath.

TIDAL VOLUME:The volume of air inhaled or exhaled during a normal, involuntary breath. It's about 0.5L in the average adult or 10% of the total lung capacity.

INSPIRATORY RESERVE VOLUME:The amount of additional air that can be inhaled after a normal inhalation.

EXPIRATORY RESERVE VOLUME:The volume of additional air that can be exhaled after a normal exhalation.

RESIDUAL VOLUME:The volume of air that remains in the lungs after a forced exhalation. The residual volume of air prevents the lungs from collapsing.

VITAL CAPACITY:The maximum amount of air that can be inhaled or exhaled. During periods of high demand for oxygen the reserve volumes decrease and tidal volume increases. The maximum tidal volume is the vital capacity. Vital capacity is about 4.4L to 4.8L in males and 3.4L to 3.8L in females.

Oxygen Usage:

Physical activity depends on the energy released during aerobic cellular respiration which depends on the rate of oxygen delivery

a high maximum rate of oxygen usage indicates an efficient respiratory system.

The rate of oxygen usage can be calculated using a spirometer.

VO2: It is an estimated or measured value representing the rate at which oxygen is used in the body. It is measured in millilitres per kilogram per minute (mL/kg/min)

VO2max: The maximum rate at which oxygen can be used in an individual. It is the maximum amount of oxygen that an individual can use during sustained, intense physical activity. It is also measured in mL/kg/min.

Performance Enhancement

EPO -- a hormone naturally produced by human kidneys to stimulate red blood cell production

Lung Transplants:

http://www.youtube.com/watch?v=_3HVzBMFcD8

http://www.youtube.com/watch?v=7dG4b7Pz-J4