The Respiratory System Flashcards
How do we breath?
Medulla oblongata chemoreceptors detect carbon dioxide changes and adjust rate and depth of breathing.
The human body needs oxygen to release energy from food, this happens within the mitochondria in cells.
Carbon dioxide is the waste product of this process and needs to be removed from the body.
What is metabolism?
Food + Oxygen= Energy (ATP) + Carbon Dioxide + Water + Heat (also lactic acid in anaerobic)
Describe the properties of the lungs
One on each side of the mediastinum (mid thoracic cavity)
Cone shaped with apex, base rests on the diaphragm, costal and medial surfaces
Right lung- 3 lobes, superior, middle and inferior
Left lung- 2 lobes, superior and inferior. Smaller because the heart is to the left of the lung
Each lung is made up of a number of lobules, alveoli and alveolar ducts
What is the pleura?
2 pleural membranes (really a folding of a single membranous sheet) surround the lungs and line the thoracic cavity
Name the layers of the pleural membrane
Parietal pleura (outer) adheres to inner chest wall and diaphragm Visceral pleura (inner) adheres to outer surface Between the layers: fluid filled potential space called the pleural cavity containing pleural fluid
Describe the function of pleural fluid
Reduces friction so membranes slide over each other freely (also causes them to adhere to each other like water between 2 panes of glass)
What is the diaphragm?
A large dome shaped sheet of muscle that separates the thoracic and abdominal cavities
Describe what happens in inspiration and expiration
Diaphragm is the main muscle of inspiration on normal quiet inspiration. When the diaphragm contracts it moves downwards increasing the size of the thoracic cavity. External intercostals can also be used. Situated between ribs, contraction causes ribs to swing outwards and upwards, again increases the size of the thoracic cavity. When thoracic cavity enlarges on inspiration, lungs also expand as they are adhered to chest wall and diaphragm by pleural membranes. If greater inspiration is needed accessory muscles are also used. In expiration, it is a passive process where muscles relax and elastic recoil of the lungs occurs. There is a decrease in volume causing an increase in pressure, pushing air out via diffiusion
Describe active and passive breathing
Expiration is usually passive, if outflow of air to be controlled or forcefully expelled intercostal and abdominal muscles can be used
Inspiration is active, requiring energy and muscle use
What is internal respiration?
The process taking place in the tissues by which gasses are exchanged between the blood and tissue cells. Oxygen moves in CO2 moves out
What is external respiration?
The means by which gasses move between the atmosphere and the body. Oxygen moves from the atmosphere into the bloodstream. Carbon dioxide moves from the blood into the atmosphere.
What is the purpose of accessory muscles in respiration?
Increase the size of the thorax (inspiration) or decrease it further (or with greater control) in expiration
What are the signs of increased work of breathing in children?
Head bobbing Nasal flaring Tracheal tug Shoulder shrugging Sternal recession Intercostal recession Subcostal recession Abdominal breathing
What are the signs of respiratory distress in children?
Snoring Gurgling Stridor Grunting Gasping Wheeze
What are the structures involved in respiration?
Nose Pharynx Larynx Trachea (windpipe) Bronchi (2, one goes to each side) Bronchioles Alveolar ducts- Alveoli Pleural membranes (lung coverings) Muscles of respiration
Outline the structure of the nose
Nostrils or Nares: irregular cavities divided into two passages by a nasal septum
Highly vascular, lined with ciliated epithelium with goblet cells secreting mucus
Hairs present at anterior nares/nostrils
Contains the olfactory nerve
Protruding from the side walls of the nasal cavity are 3 small bones called the conchae
What is the main mode of breathing in children up to 6 months?
Obligate nasal breathers
What are the functions of the nose?
- Warms and moistens air
- Conchae provides a large surface area, increase in air turbulence
- The membrane produces mucus and possess a rich blood supply, which permits rapid warming and moistening of the dry, inspired air - Filters
- Hairs filter dust and particles from the air, mucous also helps to trap (stick) dust particles
- Sneezing rapidly removes irritants - Smells
- Olfactory nerve (sensory nerve endings) detect smells
What are the 3 parts of the pharynx?
Nasopharynx (lies behind the nose)
Oropharynx (lies behind the mouth)
Laryngopharnx (extends from the mouth and continues as the oesophagus)
What are the 3 layers of the pharynx tissue?
Mucous membrane, fibrous tissue and muscle tissue which plays an important role in swallowing
What are the functions of the pharynx?
- Passageway for both food and air
- Further warming and humidification of air
- Helps with hearing, because the eustachian tube equalises air pressure on either side of the ear drum
- Protection- lymphoid tissue which produce antibodies
- Muscle tissues help with swallowing
What is the structure of the Larynx?
The larynx connects the pharynx and the trachea and is composed of 8 rigid hyaline cartilages, irregular shaped allowing attachment of vocal cords
What are vocal cords?
Folds of mucous membrane
1 pair of false vocal cords which do not produce sound and 2 pair of true vocal cords which vibrate to produce sound.
Pharyngeal muscles stretch cords to adjust pitch
What is the epiglottis?
A flap that closes airway during swallowing; made of elastic fibrocartilage
What is the trachea?
4 inch long tube connecting the larynx and bronchi. It contains 16-20 C shaped (incomplete) rings of cartilage, connective tissue and involuntary muscle complete the ring posteriorly (hold trachea open)
Inner lining of mucous membrane and ciliated epithelium
Divides into left and right main bronchus
What are the functions of the trachea?
Provide support, prevent kinking and obstruction as the head and neck move
Absence of cartilage in the posterior aspect, allows trachea to dilate/constrict in response to nerve stimulation and allows oesophagus to distend during swallowing (prevents friction)
Cough reflex: nerve endings in larynx, trachea and bronchi
Warms, humidifies, filters the air which is now at body temperature
What are bronchi?
Two primary bronchi are formed when the trachea divides
The right bronchus enters the right lung and divides into 3 branches (secondary bronchi), one passing to each lobe of the lung and further subdivides into progressively smaller tubes (wider and shorter and straighter than left bronchus)
The left bronchus enters the left lung and divides into 2 branches to enter each lobe of the lung then subdivides further into progressively smaller tubes
Composed of the same type of tissue as the trachea, i.e. mucous membrane and ciliated epithelium
What are bronchioles?
Bronchi subdivide into bronchioles and terminal bronchioles
Become progressively smaller, gradually lose ciliated mucous membrane
Cartilage not present
Form a huge network
Smooth muscle walls become thicker, responsive to autonomic nerve stimulation and irritation
What are alveoli?
Air sacs/pockets at the end of the respiratory tree
Each lung is made up of about 100-150 million alveoli, the abundance gives the lungs a spongey appearance
Surrounded by capillary network
Single layer of flat, simple, squamous epithelial cells
Form huge surface area, approximately 70 square metres, large surface area and thin cells
Gaseous exchange takes place
Cells secrete alveoli fluid and surfactant which reduces surface tension, so alveoli open easily (do not collapse)
Contain macrophages- phagocytose microbes
Describe diffusion in the alveoli
Huge surface area and very thin cells of alveoli and capillaries (endothelial cells) form the respiratory membrane
- Oxygen diffuses through the respiratory membrane into blood
- Carbon dioxide diffuses out of the blood into alveoli
Describe the exchange of gas in blood
Oxygen moves into blood in lungs, travels to tissues
-98.4% carried attached to haemoglobin as oxyhaemoglobin
-1.5% carried in solution in blood plasma
Carbon dioxide moves from tissues; blood travels to lungs
-70% carried as bicarbonate (prevents blood from becoming too acidic)
-23% carried attached to haemoglobin as carbaminohaemoglobin
-7% in solution in plasma
