Download The Respiratory system

The Respiratory
System
Day 2 Notes – Process of Breathing
Inhalation vs.
Exhalation
Muscles of the
Respiratory System
 Diaphragm: dome-shaped muscle separating thoracic
and abdominal cavities
 External intercostals: pulls ribs to elevate rib cage;
inspiratory muscles
 Internal intercostals:
depresses rib cage
Inspiratio
n
 Diaphragm contracts &





flattens
External intercostals lifts
rib cage
Lungs stretched to larger
size
Volume in thoracic cavity
increases
Air pressure inside lungs
decrease
Air sucked into lungs
Expiratio
n
 Inspiratory muscles





relax
Internal intercostals
depress ribcage
Rib cage descends, lungs
recoil
Volume in thoracic
cavity decreases.
Pressure in thoracic
cavity increases
Gases forced out
Air Content
Inspiration
Content
Exhalation
21%
Oxygen
17%
0.04%
Carbon Dioxide
4.04%
78%
Nitrogen
78%
0.96%
Inert Gases
0.96%
 Vital Capacity (VC): total exchangeable air
VC = TV + IRV + ERV
 Tidal Volume (TV): amount of air in/out during
normal, relaxed breathing (~500ml)
 Inspiratory Reserve Volume (IRV): additional air
that can be forcibly inhaled breathing in a normal
tidal volume (~3100)
 Expiratory Reserve Volume (ERV): additional air
that can be forcibly exhaled after the expiration of a
normal tidal volume(~1200)
 Residual Volume (RV): air still left in lungs (~1200)
 allows gas exchange to continue between breaths
Respiratory capacity
 Factors that affect capacity: size, age, sex,
physical condition
spirometer
 Used to measure respiratory capacities
Gas transport in blood
 Oxygen: attaches to hemoglobin molecules
inside RBC’s
 Hemoglobin: respiratory pigment, contains 4
heme groups with iron (Fe)
Gas transport
in blood
Carbon dioxide:
Transported as
bicarbonate ions
(70%)
Bound to
hemoglobin (23%)
Dissolved in plasma
(7%)
Controlling Respiration
 Control center =
medulla oblongata
 Responds to pH changes in
blood
 High CO2  carbonic acid
forms  lowers pH
 O2 sensors in the aorta
and carotid arteries
External Respiration
 Ventilation
– exchange of air between lungs and atmosphere
 Physical process during which oxygen is taken up
by capillaries of lung alveoli and carbon dioxide is
released from blood.
 Gas Exchange in
pulmonary capillaries
 Breathing is largely an
involuntary activity
Internal Respiration
• Tissue respiration/cellular respiration
• Refers to a metabolic process in which oxygen is
released to tissues or living cells and carbon dioxide is
absorbed by the blood.
• Once inside the cell the
oxygen is used for producing
energy in the form of ATP
• All cells require oxygen for
metabolism
• All cells require means to
remove carbon dioxide
• Gas exchange at cellular level