Tag (respiratory system)

Question 1

Functions of the respiratory system

Answer 1

Gas exchange- O2, CO2
Acid base balance- right balance of acid and basic compounds
Phonation (producing sounds)
Pulmonary defences and metabolisms
Heat and water elimination

Question 2

Anatomy of the respiratory system

Answer 2

Pharynx
Larynx
Trachea
Bronchi (left and right)
Bronchi
Bronchioles
Alveoli
Right upper and lower lobe
Left upper and lower lobe
Diaphragm
Thoracic cavity

Question 3

Upper airways of the respiratory system

Answer 3

Nose and mouth- warm, humid, traps foreign bodies, provide mucus.
It is better to breathe in through the nose as it gives the air and change to be warmer and moisturised.
Pharynx- common passageways of food and air for the respiratory and digestive system

Question 4

Lower airways of the respiratory system

Answer 4

Bronchial tubes
Bronchioles
Alveolar ducts
Alveolar sacs
Diffusion membranes

Alveoli do not regenerate so once we have lost them they are lost forever.

Question 5

Functional cells in the lungs

Answer 5

Pneumocyte type I: simple squamous epithelium where diffusion takes place. Very thin to reduce gap between blood wall cells and alveoli- reduces diffusion distance.
Pneumocyte type II: secretory cells, secrete mucus. Mucus needed to keep the lungs moist- cannot have gas exchange in a dry medium. It also traps foreign bodies.
Dust cells: macrophages

Question 6

Alveoli

Answer 6

300 million per lung.
Site of gas exchange.
rich blood supply.
In contact with blood capillaries.
Three types:
- Type 1 alveolar cells: single layer of epithelial cells, make up the wall of alveoli
- Type 2: secrete surfactant, reduce surface tension in alveolar walls, prevent alveolar collapse
- Alveolar macrophages: remove foreign particles from the lungs

Question 7

Chest wall and pleural sac

Answer 7

Chest wall- houses the lungs and other organs
Pleural sac- two layered membranous sac, found around each lung, attached to the chest, parietal pleura, visceral pleura, intrapleural space contains 15ml of fluid to prevent collapse of the lungs

Question 8

Ventilation

Answer 8

Inspiration (active)
Expiration (passive)

Question 9

Pressure changes during breathing

Answer 9

Gases in a closed container follow Boyle’s law (Pressure inversely proportional to Volume). P1V1 = P2V2
Three different pressures are involved in the ventilation.
1- Intrapulmonary pressure
2- Atmospheric pressure
3- Intrapleural pressure (negative)

When a sharp object punctures the intrapleural membranes, air is introduced into the space in-between the visceral and costal membranes (intrapleural pressure = 0)
This leads to end of negative intrapleural pressure, chest wall springs out and the lungs collapse

Question 10

Muscles involved in ventilation

Answer 10

External intercostal muscles.
Internal intercostal muscles.
Diaphragm.

Question 11

Inspiration

Answer 11

The external intercostal muscles contract pulling the rib cage upwards and outwards and the diaphragm contracts moving downwards. This increases the volume of the chest cavity. The pressure of the chest cavity decreases which creates a pressure gradient. Air flows into the lungs down the gradient. The alveoli are filled with air containing O2 which diffuses into blood vessels through alveolar walls. At the same time CO2 diffuses from blood vessels into alveoli.

Question 12

Expiration

Answer 12

The external intercostal muscles relax allowing the rib cage to move downwards and inwards and the diaphragm relates moving upwards. This decreases the chest cavity which increases the pressure. The air flows out of the lungs down the pressure gradient and CO2 is removed.

In forced expiration internal intercostal muscles contract and the abdominal muscles push further decreasing the volume of the thoracic cavity and more air is removed.

Question 13

Ventilation and respiration

Answer 13

Ventilation- moving air in and out of the lungs

Respiration- gas exchange through coordination of respiratory system and circulatory system

External respiration- exchange of O2 and CO2 between the external environment and tissues
- O2 in: air to lungs to blood to tissues
- CO2 out: tissues to blood to lungs to air

Cellular respiration- metabolism of nutrients in the cells using O2 and releasing waste CO2

Question 14

Air conduction

Answer 14

Air is conducting from out environment to the lungs as the air is moistened, warmed and filtered as it moves from the nasal passages to the bronchioles (conducting zone).
Then gas exchange between alveoli and blood begins from bronchioles to alveoli (the respiratory zone)

Question 15

Conducting zone structure

Answer 15

Trachea
Bronchi
Secondary bronchi
3 lobes of right lung
2 lobes of left lung
Tertiary bronchi
Branching
Millions of tubules
Bronchioles
Walls of elastic fibre
Terminal bronchioles

Question 16

The conducting zone function

Answer 16

Goblet cells- secrete mucus and trap any foreign bodies entering the system.
Ciliated cells- push the mucus up and help in the swallowing process.

The conducting zone is 150ml in volume.
The functions:
- air passageway
- dead space volume
- control air temperature and humidity

Question 17

Structures of the respiratory zone

Answer 17

Respiratory membrane
Alveoli epithelial cells
Capillary endothelial cells

Question 18

Methods of respiration

Answer 18

Cellular respiration (internal respiration)
- metabolic processes (inside the mitochondria)
- uses O2 and produces CO2 while making energy
- forms nutrient molecules

External respiration (pulmonary ventilation)
- movement of O2 in and CO2 out of lungs
- exchange (diffusion) O2 and CO2 between the alveoli and blood pulmonary capillaries
- transportation and exchange of O2 and CO2 between the lungs and the tissues

Question 19

The respiratory membrane

Answer 19

0.2 micrometers thick
Barrier for diffusion
Alveoli (type 1 cells and basement membrane)
Capillaries (endothelial cells basement membrane)

Question 20

Oxygen transport

Answer 20

External respiration
- exchange of gases between air in alveolus and blood
- exchange of gases between blood and tissues
- partial pressures of gases determine rate and amount

Haemoglobin
- heme- red chromophore bing O2 at Fe
- globin protein- 2 alpha chains and 2 beta chains

Fe bonds
- 4 to heme
- 1 to globin
- 1 weak reversible bond to O2 (if it was irreversible it would not be delivered to cells)

Question 21

Carbon dioxide transport

Answer 21

3 ways CO2 is transported from the tissue to the lungs
- dissolved in solution (plasma shifted by chloride)
- buffered with water as carbonic acid
- bound to haemoglobin forming carbaminohemoglobin

75% of CO2 is transported in the RBCs and 25% in the plasma.

Question 22

Pulmonary gas exchange

Answer 22

The rate of gas exchange depends on the partial pressure differences. As ppCO2 is higher in the capillaries than in the alveoli, it diffuses into the alveoli where it is exhaled.
The ventilation/perfusion ratio ensures that alveoli receives the ideal amount of blood gas for efficient gas exchange.

Question 23

Respiratory control

Answer 23

Respiration is controlled by the brain medullary inspiratory centre which generates nerve impulses which stimulate contraction of the diaphragm and external intercostal muscles.

The inspiratory centre facilitates expiration by stimulating the internal intercostal muscles and abdominal muscles.

The pneumotaxic area inhibits the inspiratory centre preventing inspiratory muscles contraction and protecting the lungs from over-inflating.

The apneustic area stimulates the inspiratory centre and extending the inspiratory muscles contraction.

Question 24

Lung volume and capacity

Answer 24

Lung volume is measured by the Spirometer. It includes the:
- tidal volume (TV)
- expiratory reserve volume (ERV)
- inspiratory reserve volume (IRV)

Residual volume is the volume of the lung that represents the amount of air left in the lungs after a forced exhalation.
Residual volume cannot be measured but only calculated.

Question 25

Factors that affect lung capacity

Answer 25

Size
Age
Sex
Physical condition

Question 26

Lung diseases

Answer 26

Blocked airglow makes breathing difficult.
Emphysema- lose elasticity of lung tissue.
chronic bronchitis- excess mucus.
Smoking problems
- difficulty breathing, wheezing, shortness of breath
- coughing
- hypoxic - inadequate O2 delivery

Examples
- Bronchitis- bronchi swollen and clogged
- Pneumonia- inflammation of the lung caused by infection
- Tuberculosis- infectious disease caused by M. tuberculosis bacterium

Question 27

Lung cancer

Answer 27

Uncontrolled growth of abnormal cells in lungs.
Main cause is long term smoking.,
Low survival rate.
May leas to atherosclerosis (thickening and hardening of arteries), heart disease .
Treatment- surgery, radiation, chemotherapy.
Prevention- avoid risk factors including smoking and air pollution.

Question 28

Bronchitis

Answer 28

Irreversible bronchoconstriction.
Causes- infection, pollution, smoking.
Symptoms- enlargement and over activity of mucous glands.
Hypertrophy and hyperplasia, blocks bronchi and lumen of airway.
Microbial retention in lower airways, susceptible to infectious bronchitis and pneumonia.
Permanent inflammatory changes in epithelium, narrow sputum, coughing.

Question 29

Emphysema

Answer 29

One of the chronic obstructive pulmonary diseases (COPD).
Permanent enlargement of airways with swelling of alveolar walls
- thickened bronchial submucosa
- oedema and cellular infiltration
- dilation of air spaces and destruction of alveolar walls
Lower respiratory tree destruction
- respiratory bronchioles, alveolar. ducts, and alveolar sacs
Main cause is smoking.

Question 30

Cystic fibrosis

Answer 30

Thick mucus coagulates in ducts resulting in their obstruction.
Body systems affected:
- Respiratory tract
- GI tract
- Reproductive tract
Inherited disease.
Most common fatal genetic disorder.
Abnormal electrolyte composition in sweat and saliva.

Question 31

Asthma

Answer 31

A respiratory condition marked by inflames bronchial passages that respond to irritants or allergic reaction in form of attacks of spasm in the bronchi and difficulty breathing.

Treatment is based on:
- Severity
- Control
- Patient responsiveness
Treat the cause of the symptoms.

Question 32

Asthma risk factors

Answer 32

Having a close relative with asthma.
Having another allergic condition, such as hay-fever.
Being overweight.
Smoking.
Exposure to smoke.
Exposure to fumes or pollutants.

Question 33

The gains of the respiratory system

Answer 33

Ventilation declines steadily after 20s.
Costal cartilages and joints become less flexible.
Less elastic tissues in the lungs.
Less capable of clearing lungs of irritants and pathogens.
More susceptible to respiratory infections.