Question

Prepare a lesson plan from anatomy and physiology from DIGESTIVE or RESPIRATORY SYSTEM. Use 3 objectives only. Write one objective from each domain.

Answer 1

The respiratory system is usually considered in two parts: the upper respiratory tract and the lower respiratory tract.

The Respiratory System

Upper Respiratory Tract

The major passages and structures of the upper respiratory tract include the nostrils, the nasal cavity, the pharynx, the epiglottis, and the larynx. The upper respiratory tract is lined a mucous membrane. Mucus helps to trap smoke, dust and other small particles. The membrane is lined with cilia (hair-like structures that move the mucous upwards only the upper respiratory tract). The lining of the tract and the close laying blood vessels (especially in the nose) help to warm and moisten air as it passes.

The pharynx, commonly called the throat, is a passageway that extends from the base of the skull to the level of the sixth cervical vertebra. It serves both the respiratory and digestive systems by receiving air from the nasal cavity and air, food, and water from the oral cavity. Inferiorly, it opens into the larynx and oesophagus.

The larynx, commonly called the voice box or glottis, is the passageway for air between the pharynx above and the trachea below. It extends from the fourth to the sixth vertebral levels. The larynx plays an essential role in human speech. During sound production, the vocal cords close together and vibrate as air expelled from the lungs passes between them.

The epiglottis acts like a trap door to keep food and other particles from entering the larynx.

Apnoea is the absence of breathing

Wheeze whistling noise

Agonal breathing gasping breaths

Lower Respiratory Tract

The major passages and structures of the lower respiratory tract include the trachea, the right & left bronchus, the bronchioles, and the lungs containing the alveoli. Deep in the lungs, each bronchus divides into secondary and tertiary bronchi, which continue to branch to smaller airways called the bronchioles. The bronchioles end in air sacs called the alveoli. Alveoli are bunched together into clusters to form alveolar sacs. Gas exchange occurs on the surface of each alveolus by a network of capillaries carrying blood that has come through veins from other parts of the body.

The trachea, commonly called the windpipe, is the main airway to the lungs. It divides into the right and left bronchi at the level of the fifth thoracic vertebra, channeling air to the right or left lung. The cartilage in the tracheal wall provides support and keeps the trachea from collapsing. The mucous membrane that lines the trachea is similar to that in the nasal cavity. Mucus traps airborne particles and microorganisms, and the cilia propel the mucus upward, where it is either swallowed or expelled.

The alveoli are grouped together like a lot of interlinked caves, rather than existing as separate individual sacs. The alveoli have a structure specialised for efficient gaseous exchange: the alveoli walls are extremely thin; they have a large surface area in relation to volume, they are fluid lined enabling gases to dissolve; and they are surrounded by numerous capillaries.

Aveoli showing capillary network

Breathing

During inspiration the dome-shaped muscle of the diaphragm flattens, and the inter-costal muscles pull the rib cage upwards and outwards. This increases the volume of the chest cavity and air is drawn into the lungs.

During expiration the diaphragm relaxes and resumes it's dome shape. The inter-costal muscles also relax and the rib cage falls inwards and downwards. This reduces the volume of the chest cavity and air is forced out of the lungs.

Inspiration and Expiration

In a normal average adult male, the lungs have a combined capacity of about 6 litres, with about 500 mls of air inspired at each breath. Breathing is normally very quiet, and without much effort.

During exertion the respiratory rate will increase, and so might the respiratory effort so that more air is pulled into the lungs and, therefore, more oxygen is made available to the cells in the body. This also allows the increasing amount of CO2 to be exhaled. It is easier to breathe when you are sitting or standing, as the diaphragm can more easily 'push' the contents of the abdomen downwards. Your age, size, gender, and general health can all affect your respiratory performance.

Gaseous Exchange

Once the inspired air reaches the smallest part of the lungs, the alveoli, gaseous exchange can take place. This refers to the process of Oxygen and Carbon Dioxide moving between the lungs and blood.

Diffusion occurs when molecules move from an area of high concentration (of that molecule) to an area of low concentration. This occurs during gaseous exchange as the blood in the capillaries surrounding the alveoli has a lower oxygen concentration of Oxygen than the air in the alveoli which has just been inhaled. Both alveoli and capillaries have walls which are only one cell thick and allow gases to diffuse across them. The same happens with Carbon Dioxide (CO2). The blood in the surrounding capillaries has a higher concentration of CO2 than the inspired air due to it being a waste product of energy production. Therefore CO2 diffuses the other way, from the capillaries, into the alveoli where it can then be exhaled. When Oxygen diffuses into the blood it attaches to haemoglobin in red blood cells to be transported via the circulatory system.

If the circulatory system is inadequate, or there is a reduced amount of haemoglobin or red blood cells (anaemia or blood loss, for example), then the respiratory rate and effort might increase to try and compensate.

Measuring Respiration

Respiratory rate can be counted by observing the rise and fall of a person's chest over a minute. You might need to place your hand on their chest to feel the movement if it is not obvious.

Respiratory effort can be observed, especially if the person is having to use their accessory muscles of respiration rather than only the diaphragm. You might see retractions or recessions - sucking in of the skin, around the ribs and the top of the sternum, and nasal flaring.

Respiratory sounds might include grunting with increased respiratory effort or a stridor if there is a blockage in the airway.

Oxygen Saturation measurement is done by using a monitor. The oxygen saturation of haemoglobin (sO2) is defined as the percentage of oxygenated haemoglobin in relation to the amount of haemoglobin capable of carrying oxygen. Normal sO2 will be between 95%-100%.

Definitions

Tachypnoea: abnormally rapid breathing

Dyspnoea: difficult or laboured breathing.

Oxygen saturation: the extent to which haemoglobin is saturated with oxygen

Hypoxic: a lower than normal level of oxygen in your blood.

Stridor: a harsh vibrating noise when breathing, caused by partial obstruction of the airway.