excretory and respiratory systems Flashcards
What is the primary function of the respiratory system?
Allows gaseous exchange to occur between the atmosphere and the blood stream
What happens if gaseous exchange in the respiratory system is inefficient?
Homeostasis within the body is disturbed
What structures are included in the upper respiratory system?
- Nose
- Pharynx (including tonsils and adenoid)
What structures are part of the lower respiratory system?
- Larynx
- Trachea
- Lungs
- Bronchi/Bronchioles
- Alveoli
What is the larynx commonly referred to as?
The voice box
How many pieces of cartilage make up the wall of the larynx?
9 pieces of cartilage (3 pairs and 3 single)
What is the function of the epiglottis?
Prevents food from entering the trachea when swallowing
What supports the trachea?
C-shaped rings of cartilage
What type of epithelial cells line the trachea?
Ciliated columnar epithelial cells
What are goblet cells responsible for?
Producing mucus
What is the process called that protects the lungs from damage?
Ciliary clearing
Where are the lungs located?
In the thoracic cavity
What is the function of the pleural membrane?
Encloses and protects the lungs
What is the pleural cavity filled with?
A lubricating fluid
What is pleurisy?
Inflammation of the pleural membranes causing pain
Where does gas exchange take place?
In the alveoli
What is the carina in the respiratory system?
The sensitive mucous membrane at the point of division of the trachea
How do the primary bronchi differ?
The right bronchus is wider and more vertical than the left
What happens to epithelial cells as bronchi divide into bronchioles?
They change to non-ciliated simple cuboidal epithelial cells
What controls smooth muscle surrounding bronchioles?
Both ANS and various chemicals
What is a potential risk associated with bronchioles during an asthma attack?
Small bronchioles can be closed off by constriction of smooth muscle
What are alveoli composed of?
- Type I cells (simple squamous epithelial cells)
- Type II cells (septal cells)
What is the role of type II cells in the alveoli?
Produce surfactant that reduces surface tension of mucus lining alveoli
What surrounds the alveoli?
A dense network of blood capillaries
What is the function of alveolar macrophages?
Act as the first line of defense against inhaled pathogens
What does Boyle’s law state?
The pressure of a gas varies inversely with its volume (constant temperature)
What is Dalton’s law?
Total pressure of gases in a mixture equals the sum of their partial pressures (at constant volume and temperature)
What is Charles’ law?
Volume of gas is directly proportional to its absolute temperature
What muscles are primarily involved in breathing?
- Diaphragm
- Intercostal muscles
What occurs during inspiration according to Boyle’s law?
Thoracic volume increases, pressure in lungs decreases, air moves inwards
How is expiration characterized under Boyle’s law?
Diaphragm relaxes, thoracic volume decreases, pressure in lungs increases, air is forced out
What is tidal volume?
Volume of air moved into and out of lungs during normal quiet breathing
What is inspiratory reserve volume (IRV)?
Max volume of air that can be inhaled after a normal breath
What is expiratory reserve volume (ERV)?
Max volume of air that can be expelled after a normal breath
What is residual volume (RV)?
Volume of air remaining in lungs after max exhalation
What does total lung capacity (TLC) represent?
The sum of all lung volumes (total volume lungs can hold ~6L in an adult)
What is the significance of gas exchange in breathing according to Dalton’s law?
Breathing brings oxygen needed for cellular respiration and removes CO2
How is oxygen primarily transported in the blood?
Mainly bound to haemoglobin (oxyhaemoglobin) in red blood cells (97%)
What is the direction of gas movement during gas exchange?
From areas of high partial pressure to areas of low partial pressure
What does the oxygen dissociation curve illustrate?
The relationship between the partial pressure of oxygen (pO2) and the saturation of haemoglobin (Hb)
What factors can cause a rightward shift in the oxygen dissociation curve?
- Increased carbon dioxide (pCO2)
- Increased temperature
- Increased H+ concentration
What is the role of foetal haemoglobin in oxygen transport?
Has higher affinity for O2, allowing it to load O2 when adult Hb is unloading it
Which brain centers are involved in the control of ventilation?
- Medullary rhythmicity area
- Pontine respiratory group
What is the role of the medullary rhythmicity area?
Sets the basic rhythm of breathing
How does an increase in pCO2 affect breathing rate?
Stimulates chemoreceptors, increasing breathing rate to expel more CO2
What is the role of the diaphragm in breathing?
The diaphragm contracts to increase the volume of the thoracic cavity, allowing air to be sucked in during inspiration. It relaxes, doming upwards, decreasing the volume and forcing air out during expiration.
What is the role of the intercostal muscles in breathing?
The intercostal muscles contract to move the ribcage outwards, increasing the thoracic cavity volume during inspiration and relaxing during expiration to decrease the volume.
Why are the rings of cartilage around the trachea not complete rings?
They are not complete to allow the oesophagus to expand into the same space when eating large pieces of food.
What effect does histamine have on the bronchioles?
Histamine causes the smooth muscle to contract, leading to constriction of the airways.
What type of cells line the alveoli?
Squamous epithelial cells, which are very thin and flat, allowing efficient diffusion of gases.
How is oxygen transported in the bloodstream?
As oxyhaemoglobin in red blood cells (RBC).
How is carbon dioxide transported in the bloodstream?
Mainly as bicarbonate ions, carbaminohaemoglobin, and dissolved in plasma.
What effect does rising carbon dioxide levels have on HbO2?
It causes them to dissociate.
What effect does rising carbon dioxide levels have on the rate of breathing?
It increases the rate of breathing.
If atmospheric pressure is 560mmHg, what is the partial pressure of oxygen?
117.6mmHg.
What causes oxygen to move from the alveoli to the bloodstream?
Differing partial pressures – diffusion of gases from high pressure to low pressure.
What causes carbon dioxide to move from the bloodstream to the alveoli?
Differing partial pressures – diffusion of gases from high pressure to low pressure.
