Anatomy
The Respiratory System
The body needs energy for survival. Most of this energy can only be produced in the presence of oxygen. The waste product of this energy production is carbon dioxide. The respiratory system is responsible for supplying oxygen and the excretion of carbon dioxide.
The respiratory system consists of the following organs:
· Nose
· Pharynx
· Larynx
· Trachea
· Bronchi
· Bronchioles
· Lungs
· Muscles – intercostal muscles and diaphragm
The Nose
The function of the nose is to warm, moisten and filter inhaled air.
The air is warmed by the blood vessels lining the nasal cavity.
The air is moistened by the mucosa covering the nasal cavity.
Hairs in the front of the nasal cavity trap larger particles and the smaller particles are filtered by the mucosa.
Nerve endings in the nose are stimulated by chemical substances given off by odorous materials. These impulses are conveyed by the olfactory nerves to the brain where the sensation of smell is perceived.
The nasal cavity opens into the paranasal sinuses:
· Maxillary sinuses
· Frontal and sphenoid sinuses
· Ethmoid sinuses.
The sinuses function in speech and also lighten the skull.
The Pharynx
The pharynx is a passageway for both air and food.
Air is warmed and moistened by the pharynx.
Olfactory nerve endings in the pharynx play a role in taste.
The tonsils are situated in the pharynx and produce antibodies in response to infections.
The pharynx gives the voice its’ individual characteristics.
The auditory tube extends from the pharynx to the middle ear, and assists with hearing.
The Larynx
The larynx (or voice box), extends from the root of the tongue to the trachea. It is composed of several irregularly shaped cartilages.
The larynx controls the pitch, volume, and resonance of the voice.
The vocal cords produce sound.
The epiglottis closes during swallowing to ensure that food does not enter the lungs.
The Trachea
The trachea is composed of 16 to 20 C-Shaped rings of hyaline cartilage.
The trachea supports the movement of air into and from the lungs.
Cilia lining the trachea move mucous up towards the larynx to be expelled.
Nerve endings in the trachea are sensitive to the presence of particles and this stimulates the cough reflex.
The Bronchi
The brochi are lined with columnar epithelium. This ensures the removal of particles from the air.
The bronchi warm and moisten the air.
Nerve endings also stimulate the cough reflex.
The bronchioles and alveoli
The alveoli are tiny sacs at the end of the bronchioles. This is where gas exchange occurs. The walls become gradually thinner and are lined with squamous epithelium. The alveoli are surrounded by a network of capillaries. Gases move from a higher concentration to a lower concentration by means of diffusion. Therefore oxygen moves from the alveoli into the capillaries and carbon dioxide moves from the capillaries into the alveoli.
Lymphocytes and plasma cells produce antibodies to protect against pathogens.
The Lungs
The lungs are surrounded by the pleura. One layer is attached to the wall of the thoracic cavity and the other layer is attached to the lung. Between these 2 layers is a serous fluid, allowing the 2 layers to glide over one another.
The pulmonary artery supplies deoxygenated blood to the lungs, and the pulmonary veins leave the lungs with oxygenated blood.
The muscles of respiration
Intercostal muscles are arranged in 2 layers between the ribs, external and internal intercostals muscles. When they contract they pull the ribs outwards and upwards therefore enlarging the thoracic cavity.
The diaphragm forms the floor of the thoracic cavity. When it contracts it moves downwards and enlarges the thoracic cavity.
The diaphragm and intercostals muscles contract at the same time to enlarge the thoracic cavity.
The body needs energy for survival. Most of this energy can only be produced in the presence of oxygen. The waste product of this energy production is carbon dioxide. The respiratory system is responsible for supplying oxygen and the excretion of carbon dioxide.
The respiratory system consists of the following organs:
· Nose
· Pharynx
· Larynx
· Trachea
· Bronchi
· Bronchioles
· Lungs
· Muscles – intercostal muscles and diaphragm
The Nose
The function of the nose is to warm, moisten and filter inhaled air.
The air is warmed by the blood vessels lining the nasal cavity.
The air is moistened by the mucosa covering the nasal cavity.
Hairs in the front of the nasal cavity trap larger particles and the smaller particles are filtered by the mucosa.
Nerve endings in the nose are stimulated by chemical substances given off by odorous materials. These impulses are conveyed by the olfactory nerves to the brain where the sensation of smell is perceived.
The nasal cavity opens into the paranasal sinuses:
· Maxillary sinuses
· Frontal and sphenoid sinuses
· Ethmoid sinuses.
The sinuses function in speech and also lighten the skull.
The Pharynx
The pharynx is a passageway for both air and food.
Air is warmed and moistened by the pharynx.
Olfactory nerve endings in the pharynx play a role in taste.
The tonsils are situated in the pharynx and produce antibodies in response to infections.
The pharynx gives the voice its’ individual characteristics.
The auditory tube extends from the pharynx to the middle ear, and assists with hearing.
The Larynx
The larynx (or voice box), extends from the root of the tongue to the trachea. It is composed of several irregularly shaped cartilages.
The larynx controls the pitch, volume, and resonance of the voice.
The vocal cords produce sound.
The epiglottis closes during swallowing to ensure that food does not enter the lungs.
The Trachea
The trachea is composed of 16 to 20 C-Shaped rings of hyaline cartilage.
The trachea supports the movement of air into and from the lungs.
Cilia lining the trachea move mucous up towards the larynx to be expelled.
Nerve endings in the trachea are sensitive to the presence of particles and this stimulates the cough reflex.
The Bronchi
The brochi are lined with columnar epithelium. This ensures the removal of particles from the air.
The bronchi warm and moisten the air.
Nerve endings also stimulate the cough reflex.
The bronchioles and alveoli
The alveoli are tiny sacs at the end of the bronchioles. This is where gas exchange occurs. The walls become gradually thinner and are lined with squamous epithelium. The alveoli are surrounded by a network of capillaries. Gases move from a higher concentration to a lower concentration by means of diffusion. Therefore oxygen moves from the alveoli into the capillaries and carbon dioxide moves from the capillaries into the alveoli.
Lymphocytes and plasma cells produce antibodies to protect against pathogens.
The Lungs
The lungs are surrounded by the pleura. One layer is attached to the wall of the thoracic cavity and the other layer is attached to the lung. Between these 2 layers is a serous fluid, allowing the 2 layers to glide over one another.
The pulmonary artery supplies deoxygenated blood to the lungs, and the pulmonary veins leave the lungs with oxygenated blood.
The muscles of respiration
Intercostal muscles are arranged in 2 layers between the ribs, external and internal intercostals muscles. When they contract they pull the ribs outwards and upwards therefore enlarging the thoracic cavity.
The diaphragm forms the floor of the thoracic cavity. When it contracts it moves downwards and enlarges the thoracic cavity.
The diaphragm and intercostals muscles contract at the same time to enlarge the thoracic cavity.