Applied Anatomy and Physiology - Respiratory System

What is respiration?

The taking in of oxygen and the removal of carbon dioxide

Define Tidal Volume

The volume of air inspired and expired per breath

Define minute ventilation

the volume of air inspired or expired per minute

How can minute ventilation be calculated?

Number of breaths per min X Tidal Volume = Minute Ventilation (litres/min)

Why will there be changes to the volume of minute ventilation?

Due to the intensity of different types of exercise the more intense an exercise is the more breathing increases to meet the extra oxygen demand

Define inspiratory reserve volume

the volume of air that can be forcibly inspired after a normal breath

Define expiratory reserve volume

the volume of air that can be forcibly expired after a normal breath

Define residual volume

the amount of air remaining in the lungs after maximal expiration

How will tidal volume change during exercise?

increase

How will minute ventilation change during exercise?

big increase

How will inspiratory reserve volume change during exercise?

decrease

How will expiratory reserve volume change during exercise?

slight decrease

How will residual volume change during exercise?

remain the same

Define Gaseous exchange

the movement of oxygen from the air into the blood and carbon dioxide from the blood into the air

What is diffusion?

the movement of gas molecules from an area of high concentration or high partial pressure to an area of low concentration or low partial pressure

What is partial pressure?

pressure exerted by an individual gas in a mixture of gases

Name the adaptations of the alveoli to aid gaseous exchange

Thin cell wall that is one cell thick means there is a short diffusion pathway. Large capillary network surrounding the alveoli so large blood supply. Large surface area which allows for greater uptake of oxygen. Moist cell walls.

Describe the role of partial pressure in the diffusion of oxygen at the alveoli

The partial pressure of oxygen in the alveoli is 100mmHg and is at a higher partial pressure than in the capillaries 40mmHg. This difference in partial pressure is referred to as the concentration gradient. The bigger the gradient the faster diffusion will be. Oxygen will diffuse from the alveoli into the blood until pressure is equal in both.

Describe the role of partial pressure in the diffusion of carbon dioxide in the alveoli

Partial pressure is higher in the capillaries 46mmHg than in the alveoli so carbon dioxide diffuses into the alveoli from the blood until the pressure is equal in both.

Describe diffusion of oxygen from the capillaries to the working muscles

The partial pressure of oxygen in the muscle tissue is 5mmHg and 100mmHg in the blood this lower blood pressure allows oxygen to diffuse from the blood into the muscles until they are equal.

Describe diffusion of carbon dioxide from the working muscles to the capillaires

The partial pressure of carbon dioxide in the tissue is 46 and the pressure in the blood is 40 so the carbon dioxide will diffuse from the tissue into the blood until they are equal.

Define pulmonary ventilation

breathing

What are the three factors that regulate pulmonary ventilation during exercise?

neural control, chemical control and hormonal control

Describe neural control of pulmonary ventilation

Controlled by the sympathetic and parasympathetic nervous system which is controlled by the cardiac control centre in the medulla oblongata. The sympathetic nervous system will increase the breathing rate and depth and the parasympathetic will return the breathing rate to rest.

Describe the chemical regulation of pulmonary ventilation

increased concentration of carbon dioxide in the blood stimulates the respiratory centre to increase respiratory rate. The inspiratory centre sends out nerve impulses via the phrenic nerve to the diaphragm and intercostal muscles to cause them to contract. The stimulation acts for 2 seconds and then the impulse stop and passive expiration occurs due to the elastic recoil of the lungs.

Describe hormonal regulation of pulmonary ventilation during exercise

Adrenaline is released. This increases breathing rate in preparation for exercise and the demand to take in more oxygen and remove carbon dioxide.

How does smoking affect the respiratory system?

Carbon monoxide from cigarettes combines with haemoglobin in red blood cells more readily than oxygen. This reduces the oxygen carrying capacity of the blood which increases breathlessness during exercise.

Affects of smoking

irritation of the trachea and bronchi, reduced lung function and increased breathlessness, narrowing of the airways, damage to cells lining the airways leading to a build up in mucus and smokers cough