The respiratory system

Question 1

requirements for respiration to take place:

Answer 1

*Large surface area – for a maximal O2 and CO2 and carbon dioxide exchange rate.
*Moist environment – to dissolve O2 and CO2.
Gases move from high to low pressure

Question 1

Stages in Respiration:

Answer 1

1. inspiration (inhaling) and expiration (exhaling).
2. External respiration exchange of gases between air and blood.
3. Internal respiration exchange of gases blood and body tissues.
4. Cellular respiration – energy releasing chemical reactions that take place within the cell.

Question 2

Nasal passages

Answer 2

o The passages are lined with ciliated cells and cells which secrete mucus. These cells filter and moisten incoming air.
o Mucous helps trap foreign invaders and sweep them into the pharynx where they are swallowed, sneezed or coughed out
o Turbinate bones increase surface area (helps you smell better!)
o Heat from blood vessels warms the air.

Question 3

Pharynx

Answer 3

Next the warmed air goes
through the passageway into
the respiratory system (a.k.a.
the throat)
o Also carries food/water to the
digestive system

Question 4

Epiglottis

Answer 4

o The air then passes a flap of
cartilage that lies behind the
tongue
o Serves to close the opening to
the trachea (the glottis) when
a person swallows

Question 5

Glottis

Answer 5

o The opening to the trachea
o Must be covered when swallowing in order to prevent food and drink from passing into the lungs. Failure of the epiglottis causes choking.

Question 6

Larynx

Answer 6

o Next the air passes through
the larynx
o Contains the vocal cords,
which contract and vibrate
when you speak (“voice box”)

Question 7

Trachea

Answer 7

o Carries air to the lungs (the windpipe)
o Supported by rings of cartilage
o The trachea is also lined with cilia and mucous-secreting cells, which beat 20 x per minute to move the trapped particles up to the pharynx

Question 8

Bronchi

Answer 8

o just above the heart, the trachea branches into two bronchi
o Supported by cartilaginous rings
o Lined with cilia and mucus-producing cells

Question 9

Bronchioles

Answer 9

o Subdivisions of bronchi within each lung
o Do not contain cartilage
o Lined with cilia and mucus-producing cells

Question 10

Alveoli

Answer 10

o terminal bronchioles (the last ones) end at a group of alveolar ducts and sacs called alveoli
o Tiny clusters of air sacs
o Site of gas exchange (CO2 dissolved in blood is exchanged for O2)
* Specialized for optimal diffusion
* moist membrane
* large surface area
* thin walls for diffusion
* immediately next to pulmonary
capillaries, which are just large
enough for a RBC to get through
* inner surface covered with single layer of lipid  surfactant
* reduces surface tension in alveoli so they easily expand to 2x size with each breath

Question 11

Gas Exchange in the
Alveoli

Answer 11

*O2 and CO2 must diffuse through layer of cells lining pulmonary capillary to enter/exit blood
*O2 moves from external environment through airway into alveoli (diffuses into blood and dissolves into plasma to be carried by hemoglobin)
*O2 rich blood travels to tissues
where it diffuses into cells to be
used in cellular respiration.

Question 12

Lungs

Answer 12

o The primary organ of the respiratory system
o Divided into lobes- the right lung has three lobes, whereas the left lung has only two in order to make room for the heart

Question 13

Pleural Membrane

Answer 13

A thin, fluid-filled membrane that surrounds the lungs
o Allows the lungs to expand and contract with the movement of the chest

Question 14

Diaphragm

Answer 14

o A dome-shaped layer of muscle that separates the lungs (“thoracic cavity”) from the stomach and liver (“abdominal cavity”)
o Works with rib
muscles to move air in and out

Question 15

Residual volume

Answer 15

the amount of air that remains in the lungs after maximum expiration

Question 16

tidal volume

Answer 16

the volume of air that is inhaled and exhaled when breathing normally

Question 17

vital capacity

Answer 17

o The largest breath you can take
o involves expanding the lungs to a greater extent than normal (recruiting the diaphragm, intercostals and neck muscles), and exhaling actively by recruiting the abdominal muscles Vital
o capacity includes tidal volume (normal breath)
o The extra you can inhale (inspiratory reserve volume)
o The extra you can exhale (expiratory reserve volume)

Question 18

Inspiratory reserve volume (RV) vs Expiratory reserve volume (ERV)

Answer 18

○Inspiratory reserve volume (RV)
= additional volume of air that
can be taken into the lungs
beyond regular (tidal) inhalation
○Expiratory reserve volume (ERV) = additional volume of air that can be forced out of the lungs beyond regular (tidal) exhalation

Question 19

Total Lung Capacity

Answer 19

Vital capacity + Residual Volume

Question 20

Muscles for
Breathing

Answer 20

• Diaphragm – dome-shaped layer of muscle separating thoracic cavity from abdomen.
  Regulates the pressure within the lungs.
• Rib muscles (intercostal muscles) – found between ribs and ventral side of ribs; extend to diaphragm.
• Neck muscles - for deep and laboured breathing
  Both help

Question 21

Inspiration/Inhalation

Answer 21

*An active process (using energy) where one breath is drawn into the lungs with the aid of muscle contractions
*Air is drawn into the lungs when the thoracic cavity expands in size, and since the pleural cavity is sealed, decreasing the pressure of the cavity, which pulls air in from the environment

Question 22

Inspiration/Inhalation
Steps:

Answer 22

• rib cage up and outward
• diaphragm downward
• volume thoracic cavity increases
• air pressure in lungs decreases
• air rushes in

Question 23

Expiration/
Exhalation

Answer 23

*Generally a passive process (unless breathing very deeply) where one breath is expelled as the muscles above relax
*As the muscles relax, the size of the thoracic cavity is decreased, increasing the pressure, forcing the gas out of the lungs

Question 24

Expiration/
Exhalation
Steps:

Answer 24

diaphragm and rib muscles
relax:
- rib cage down and inward
- diaphragm upward
- volume thoracic cavity decreases
- air pressure in lungs increases
- air leaves the lungs

Question 25

Regulation of
Breathing
Movements

Answer 25

*Breathing movements are controlled by the
medulla oblongata (a section of the brain)
The medulla oblongata
detects the levels of oxygen
and carbon dioxide concentrations and signals
the muscles in the heart, the
lungs and diaphragm to
increase or decrease the
breathing.

Question 26

How do we regulate our
breathing?

Answer 26

1. High acidity of blood (excess carbon dioxide) detected
   by chemoreceptors in the medulla oblongata (brain).
   * Chemoreceptors stimulate a nerve response to increase
   breathing
   * Expels more carbon dioxide and acidity eventually decreases
2. Low levels of oxygen detected by chemoreceptors in carotid artery
   * Sends nerve impulse to brain
   * Increases breathing rate = more oxygen

Question 27

Internal
Respiration

Answer 27

*Oxygen – 99% is transported via hemoglobin; the remainder is carried in blood plasma.
*When the oxyhemoglobin passes a tissue requiring
oxygen, the oxygen falls off and diffuses through the capillary into the tissue.
*At rest, 70% of hemoglobin heading back to lungs
have their oxygen’s still bound!

Question 28

Conditions for Oxygen
Internal

Answer 28

• The attaching of oxygen to hemoglobin is
  affected by the following
• concentration of oxygen –  oxygen,  binding, 
  oxygen,  binding (allows oxygen to be released and
  diffuse into tissues over the entire capillary length –
  gradually)
• pH -  pH,  binding ( pH means  CO2)
• temperature -  temp,  binding
  These conditions favour the release of oxygen in tissues
  that are metabolically active (undergoing lots of cellular
  respiration)

Question 29

Internal
Respiration –
Carbon Dioxide

Answer 29

• When there is a build up of carbon dioxide in the tissues,
  the carbon dioxide will move out of the tissues to the
  blood (lower partial pressure)
• Carbon dioxide is more soluble in blood than oxygen
• Carbon dioxide – 23% is carried by hemoglobin; 7% in
  blood plasma; ~70% dissolved and carried by blood in the
  form of bicarbonate ion (HCO3−)