Breathing and Exchange of Gases Flashcards
Ribs 1-7
True ribs
They are called so because there are directly connected to the sternum
Ribs 8, 9, 10
False ribs
Called so because they are not connected directly to the sternum. Instead these ribs are connected to the 7th rib.
Ribs 11 and 12
Floating ribs
Not connected to the sternum at all
Nostrils
Nostrils are the openings of the nasal cavity at the lower end of the nose just above the mouth
Nasal cavity- location
A pair of chambers present above the palate
Three regions of the nasal cavity
- Vestibular region
- Respiratory region
- Olfactory region
Vestibular region
> Anterior region of the cavity
> Contains hairs and sebaceous glands which secrete an oily secretion called sebum
Respiratory region
> Vascular middle part of the nasal cavity.
Lined by pseudo-stratified ciliated columnar epithelium
Rich is mucous cells (viscid fluid- mucus) and serous cells (watery fluid)
Olfactory region
> Upper posterior region of the cavity
> Lined by highly sensory olfactory epithelium cells which help in detecting the odour of the inspired air.
Nasopharynx- location
> Situated at the base of the skull behind the nasal cavities.
Nasopharynx extends to the oral pharynx which leads to two openings- the Trachea in the front and the Oesophagus at the back.
The nasopharnyx bears the openings of the eustachian tubes in its lateral walls by which it is connected to the middle ear.
Location of the larynx
Situated in the neck region parallel to the 4th-6th cervical vertebrae.
Largest cartilage seen in the larynx
Thyroid cartilage
Adam’s Apple
Protrusion of the larynx visible externally in the neck is called the Adam’s Apple.
Glottis
The larynx opens into the oral pharynx by a slit like aperture called the glottis.
What cells provide a mucous covering to the epithelium of the trachea?
Goblet cells and subepithelial mucous glands
How is meaningful sound or speech made in human beings?
> The meaningful sound or speech in human beings is made by the combined action of the tongue, vocal cords, larynx, and lips
In the normal condition, the vocal cords lie apart and the glottis is open, allowing the passage of air.
For sound production, vocal cords come close together, vibrate when air passes through the glottis and produce sound.
Trachea- location
> The trachea extends downward from the larynx.
> It bifurcates in the thoracic cavity along the level of the 4th-5th thoracic vertebrae into primary bronchi.
Why are the rings supporting the trachea and primary bronchi C-shaped?
The trachea and primary bronchi are supported by 16-20 C-shaped cartilaginous rings which provide flexibility and prevent them from collapsing.
Name the cells that line the trachea
Pseudo-stratified ciliated mucous epithelium
How do the bronchi divide until they become alveoli?
- Bronchi
- Bronchioles
- Alveolar ducts
- Atria
- Alveolar sacs
- Alveoli
Lungs- location
Situated in the thoracic cavity on either side of the heart
What encloses the lungs?
The lungs are enclosed in double walled sacs called pleura with pleural fluid between them.
Main site of respiration in the lungs
Alveoli
How does exchange of respiratory gases take place?
Respiratory gases are exchanged between the walls of the alveoli and blood through the process of diffusion.
Name the steps involved in the mechanism of breathing
- Breathing (Pulmonary ventilation)
- Diffusion of gases across the alveoli
- Transport and exchange of gases in the tissues
- Internal respiration
What concept is pulmonary ventilation based on?
Pulmonary ventilation is based on Gas Laws.
Volume is inversely proportional to pressure.
Inspiration
Breathing in fresh air (atmospheric air) into the lungs. It is an active process.
Expiration
Expelling out foul air from the lungs is called expiration. It is a passive process.
Before inhalation
- Diaphragm and intercostal muscles are relaxed.
- Air pressure within lungs equals outside air pressure.
During inhalation
- Diaphragm contracts and moves downwards.
- Intercostal muscles contract, and rib cage moves upward.
- Thoracic cavity enlarges, and lungs inflate.
- Air pressure within lungs decreases.
- Air flows passively into lungs.
During exhalation
- Diaphragm relaxes and moves upward.
- Intercostal muscles relax and rib cage moves downward.
- Thoracic cavity decreases in volume and lungs deflate.
- Air pressure within lungs increases.
- Air flows passively out of lungs.
Percentage of oxygen transported by the RBCs in the blood
97%
Percentage of oxygen transported in the dissolved state through plasma
3%
Percentage of carbon dioxide transported by RBCs
20-25%
Percentage of carbon dioxide transported as bicarbonate
70%
Percentage of carbon dioxide dissolved in plasma
7%
How, where, and why does the chloride shift occur?
How: Diagram + Chloride ions that enter the RBC are formed by the dissociation of NaCl in the blood plasma.
Where: From the blood plasma to the RBC
Why: It occurs in order to maintian the electrolyte equilibrium, which was disrupted due to the exit of hydrogen carbonate from the RBC.
Primary respiratory control centre
Medulla oblongata
Main function of the medulla oblongata with respect to respiration
Sending signals to the intercostal muscles that control respiration
Neurons that stimulate:
Expiration
Inspiration
Expiration: Ventral respiratory group
Inspiration: Dorsal respiratory group
Function of Pons with respect to respiration
> It contains the pneumotaxic centre that will regulate the function of respiratory rhythm centre.
A chemotaxic centre is present near the rhythmic centre and is sensitive to changes in the carbon dioxide concentration in the blood.
Apnoea
A temporary cessation of breathing
Dyspnoea
Painful or laboured breathing
Eupnoea
Normal quiet breathing
Tachypnoea
Rapid breathing
Tidal volume
It is the amount of air inspired or expired with each breathing cycle by a resting person.
500 mL
IRV
Inspiratory reserve volume
The additional volume of air that can be breathed with maximum forceful inspiration is called IRV.
2500 mL
ERV
Expiratory reserve volume
Largest volume of air that can be expelled from the lungs during maximal expiration.
1500 mL
Total lung capacity
It is the amount of air in lungs and respiratory passage after the maximum inhalation effort.
5800 mL
Vital capacity
Volume of air breathed out by the most forceful expiratory effort after maximal inspiration.
Represents the maximum capacity of an individual to renew air in his respiratory system.
4500 mL
Residual volume
The volume of air left in the lungs and respiratory passage after even the severest expiratory effort.
1100 mL to 1200 mL
Emphysema- effect
It is an obstructive respiratory disease in which lung tissues get extensively damaged.
- Walls between adjacent alveoli break down.
- Lungs become distended.
- Alveolar ducts dilate.
- Loss of interstitial elastic tissue
Emphysema- causes
Cigarette smoking, acute inflammation of bronchi and lungs, increased pressure caused by coughing
What is asthma?
- Asthma is a chronic inflammatory disorder of the respiratory system that produces sporadic narrowing of airways.
- Attacks are brought out by spasms of the smooth muscles in the walls of smaller bronchi and bronchioles, causing the airways to close partially or completely.
Asthma- symptoms
- Periods of coughing, difficult breathing and wheezing.
- The patient has trouble during expiration.
- In acute cases, excessive secretion of mucus that may clog the bronchi and bronchioles and worsen the attack.
- In severe conditions, the inflammation continues, accompanied by fibrosis, oedema, and necrosis of the bronchial epithelial cells.
Asthma- causes
Allergen, emotional upset, exercise, and breathing cold air or cigarette smoke.
Pneumoconiosis
Disorders of the respiratory system in which the damage is done directly by the dust of the materials inhaled, such as metals, stone, coal or asbestos.
Coal workers pneumoconiosis
- Caused by inhaling large quantities of coal dust over a period of 10 to 15 years, common among coal miners.
- Particles of coal dust lodge in the upper 2/3rds of the lungs and are ingested by macrophages inside the alveoli.
Silicosis
- Found in workers who blast hard rock, for example in mining, quarrying.
- Silica particles which are inhaled accumulate in the alveoli.
- Progressive fibrosis is stimulated which eventually obliterates the blood vessels and respiratory bronchioles.
- Silicosis sufferers are prones to infection by tuberculosis of the lung.
Asbestosis
- Caused by inhaling asbestos fibre in dust.
- Exposure to asbestos dust greatly increases the chance of developing cancer of the lung or of its lining.
- Lung, trachea etc. get clogged, causes breathlessness.
- Can cause tachycardia
Byssinosis
- Caused by inhalation of fibres of cotton, flax and hemp over a period of years
- Causes bronchial irritation, can cause chronic bronchitis, and emphysema.
