unit 5: respiration

Question 1

Upper respiratory tract

Answer 1

Air is inhaled through the external nares (nostrils)

Air then passes through the nasal cavity

As air enters it passes through shelves called the nasal conchae> filters air

The posterior portion of the nasal cavity is the internal nares this connects to the pharynx

Question 2

Larynx

Answer 2

Connects the pharynx with the trachea (formed by 9 pieces of cartilage)
Contains vocal cords, glottis and epiglottis

Glottis: an opening between the vocal folds

Epiglottis: flap of elastic cartilage that moves during the swallowing of food; covers the glottis and prevents food from entering the larynx

Question 3

Trachea

Answer 3

Extends of the larynx towards the lungs

16-20 stacked C-shaped hyaline cartilage connected by dense connective tissue

Cartilaginous rings provide structural support and prevent trachea from collapsing

Question 4

Lungs

Answer 4

Lungs are separated by the heart and other structures

Each lung is surrounded by two membranes:

-Visceral pleura: adheres to the surfaces of the lungs

-Parietal pleura: lines the walls of the thoracic cavity

Between the two pleura is the pleural cavity which contains a small amount of lubricating fluid

Question 5

Lower respiratory tract

Answer 5

Primary bronchi divide to form secondary and tertiary bronchi that supply the lobes of each lung

Tertiary bronchi divide into bronchioles that in turn branch again   

The smallest of these branches are called terminal bronchioles, which  

form pulmonary lobules        

Up to this point, all the structures are part of the conducting zone of the respiratory system (no exchange of gases with cells)

In each lobule, there are alveoli, which is a collection of cup-shaped pouches: why do you think they are this shape?         
This is the site of gas exchange

Question 6

Alveoli

Answer 6

Type I alveolar cells:
Gas exchange occurs between these cells and pulmonary capillaries

Type II alveolar cells:

Secrete surfactant: a layer of fluid found between cells and air

Prevents collapsing of the alveoli and allows for easier breathing

Starts being produced by fetal lungs after 26 weeks’ gestation

Macrophages (dust cells)

Question 7

Gas exchange of alveoli

Answer 7

Each alveolus is surrounded by a layer of simple squamous epithelium

The layers that gas molecules must cross to move from inside the alveoli to the inside of the red blood cell:

alveolar epithelium
endothelium (capillary cell wall)
plasma membrane of red blood cells

Question 8

Boyles law: volume and pressure and inversely correlated

Answer 8

Gases fill a container completely, unlike liquids

If the volume of a container increases, the pressure of the gases inside will decrease and vice versa

As volume capacity increases pressure decreases

As volume capacity decreases pressure increases

Question 9

Breathing

Answer 9

Volume of thoracic cavity changes by the action of surrounding muscles

Question 10

Normal quiet inhalation (inspiration)

Answer 10

Diaphragm and external intercostals contract

This increases the volume of the thoracic cavity

Pressure in the lungs (intrapulmonary pressure) decreases, making it lower than atmospheric pressure

Air rushes into the lungs

During labored inhalation, sternocleidomastoid, scalenes, and pectoralis minor also contract

Question 10

normal quiet exhalation

Answer 10

Diaphragm and external intercostals relax

This decreases the volume of the thoracic cavity

Pressure in the lungs (intrapulmonary pressure) increases, making it higher than atmospheric pressure

Air is pushed out of the lungs

During forceful exhalation, abdominal and internal intercostal muscles also contract

Question 11

Nervous control of breathing

Answer 11

Control breathing is found in the medulla oblongata and pons of the brainstem

Question 12

dorsal respiratory group and ventral respiratory group

Answer 12

Found in the medulla oblongata
DRG contains inspiratory centre
VGR contains expiratory centre

When the DGR is activated, it stimulates the diaphragm and external intercostals to contract

When the DRG is inactive the diaphragm and external intercostals relax leading to quiet exhalation

For forceful exhalation the VGR will be activated by the inspiratory center leading to the contraction of abdominal muscles and internal intercostals

Question 13

potine respiratory group

Answer 13

Found in the pons

Contains
Pneumotaxic center: resposible for shorter inspirations (ex. During exercise); works by inhibiting inspiratory center

Apneustic center: responsible for longer inspirations (high altitude); works by stimulation inspiratory center

Question 14

stimuli that changes respiratory rate

Answer 14

Voluntary control

Involuntary control

Receptors are present that detect different things that affect breathing

For example, stretch receptors in the lungs detect the stretching of lungs during inhalation. At a certain point, they will send a message to the brain which will shut down the inspiratory centre to allow exhalation to occur (Hering-Breuer reflex

Chemoreceptors found in the brainstem and also near main blood vessels also monitor levels of CO2, O2 and H+ ions

Question 15

determining respiration status

Answer 15

Spirometer is an apparatus that can be used to measure the volume of air exchanged during breathing and the respiratory rate

The record is called a spirogram

Question 16

terms of spirgram

Answer 16

Tidal volume: the volume of air inspired or expired during normal quiet breathing

Expiratory reserve volume: the volume of additional air expired during a forced exhalation

Inspiratory reserve volume: the volume of additional air inspired during a very deep inhalation

vital capacity: all the air that can be exhaled after maximum inspiration (sum of inspiratory reserve, tidal volume, and expiratory reserve)       Residual volume: volume of air still present in the lungs after a forced exhalation

Total lung capacity: all the air that can be contained in the lungs (sum of vital capacity and residual volume)

Question 17

transport of gases: oxygen

Answer 17

Only a small amount of O2 is dissolved in plasma (1.5%)

Most of the O2 is attached to hemoglobin (98.5%)

O2 attached to hemoglobin= oxyhemoglobin

One hemoglobin molecule can bind up to four O2 molecules

O2 must be released by hemoglobin before it can diffuse across membranes

Question 18

transport of gases: carbon dioxide

Answer 18

7% of CO2 is dissolved in plasma

23% is attached to the globin portion of hemoglobin = carbohemoglobin or carbaminohemoglobin

One hemoglobin molecule can bind to four CO2 molecules

70% is converted into carbonic acid (H2CO3) by an enzyme called carbonic anhydrase, which is found in red blood cells

Carbonic acid can also be broken down to bicarbonate and hydrogen ions

At any point, there are varying concentrations of CO2, H2CO3, HCO3-, and H+

Question 19

respiratory patterns

Answer 19

Eupnea: normal breathing dyspnea       

Dyspnea: difficult breathing (eg. asthma) tachypnea

Tachypnea: fast breathing (eg. anxiety) hyperpnea      
Hyperpnea: deep breathing (eg. exercise) apnea      
Apnea: breathing stops (eg. choking)       

• NOTE: these are patterns and not the same as having a disorder

Question 20

Hypoxia

Answer 20

Reduced supply of oxygen reaching the tissues
* Internal causes:
Decreased ability of oxygen exchange (e.g., fluid in the lungs)
Decreased hemoglobin or ineffective hemoglobin (anemia)
Obstructions in blood vessels
Hypotension
Edema (too much interstitial fluid)
Congenital heart defects
Obstruction of airways (eg. asthma, bronchitis)
Diffusion deficiency in the lungs (eg. emphysema, pneumonia)

• External causes:
  *Low oxygen levels in environment (eg. high altitudes, overcrowded rooms, diving)

Question 21

Hypoxia physiological consequences

Answer 21

Cyanosis: bluish colour to the skin due to the accumulation of deoxygenated blood
* Tachycardia: autonomic nervous system mediated increased heart rate
* Dizziness: insufficient oxygen supply to the brain

Question 22

hyperventilation

Answer 22

Increased rate of breathing in which the rate of CO2 breathed out exceeds the body’s production of CO2

• Respiratory causes:
  Abnormal functioning of the lungs which include conditions such
  as emphysema
• Non-respiratory causes:
  Increased metabolism (eg. hyperparathyroidism, exercise, fever) * Anxiety

Question 23

hyperventilation physiological consequences

Answer 23

Drastically reduces the amount of CO2 because person is breathing out CO2 faster than his/her tissues produce it (but does not affect oxygen levels)

Blood pH increases (more alkaline) which can lead to respiratory alkalosis

Vasodilation occurs and blood pressure drops

Can lead to dizziness, brain dysfunction and unconsciousness