Pressure

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Circulatory system, respiratory
system and Aquatic systems
BIOLOGICAL PRESSURE
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Biological Pressures
• Bladder pressure
• Hydrocephalus: Cerebrospinal pressure
• Glaucoma: Pressure in the eye
• Heart burn: Pressure in the gastrointestinal cavity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
BLOOD PRESSURE
• The silent killer!!!!
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The Blood Vessels and the Cardiovascular System
Figure 15-1: Functional model of the cardiovascular system
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Blood Pressure (BP): Measurements
• "Blood pressure"
• Systolic over diastolic
• About 120/80 mmHg
• Sphygmomanometer
• "Estimation of pressure"
• Korotkoff sounds
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Blood Pressure (BP): Measurements
Figure 15-7: Measurement of arterial blood pressure
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More Blood Pressures:
Pulse and Mean Arterial Pressures
Figure 15-5: Pressure throughout the systemic circulation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Pressure Respiratory
Respiration involves 3 processes
1) Ventilation/ breathing- bulk movement of air
into and out of lungs
2) Gas exchange between air in lungs and blood
3) Gas exchange between blood and tissues
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Lungs
• Alveoli- small air sacs
• So numerous that the walls are little more than a
succession of alveoli
• Alveolar ducts end into alveolar sacs- chambers
connected to about 3 alveoli
• 300 million alveoli in each lung
• NO NEED TO SHAKE!!!
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Pleural Cavities
• Lungs are in thoracic cavity
• Lungs are surrounded by pleural cavity
• Cavity lined with serous membrane called pleura2 parts
• Parietal pleura- thorax, diaphragm, mediast.
• Visceral pleura- covers surface of lung
• Pleural cavity- between pleurae, filled with pleural
fluid, lubricate and stick pleurae together
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Ventillation
• 2 phases of ventilation
• Inspiration- inhalation
• Expiration- exhalation
• Due to changes in thoracic volumechanges in air pressure in lung
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Changing Thoracic Volume
• Muscles of inspiration- diaphragm, external
intercostals, others
• Diaphragm- dome shaped muscle separating
thoracic cavity from abdominal
• Muscles of expiration- internal intercostals,
abdominals
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Pressure Changes
•
Flow of air is governed by 2 principals
1) Changes in volume= changes in pressure
2) Air flows from high to low pressure- greater the
difference, the faster the flow
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Lung Recoil SA
•
During quiet expiration- recoil of lungs and
thoracic wall
•
Lung recoil- due to elastic fibers and surface
tension of fluid in alveoli
•
Two things prevent lung collapse
1) Surfactant
2) Pressure in pleural cavity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Surfactant
• Mixture of lipoproteins produced by epithelium
• Forms a thin layer inside lungs
• Reduces surface tension
• Reduces tendency of lungs to collapse
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Pressure
• There are three important pressure in respect to breathing:
• atmospheric pressure- the pressure of the air around us. At sea
level the atmospheric pressure is 760 mmHg, at higher altitudes the
pressure is lower.
• intrapleural pressure- the pressure within the potential pleural
space between the parietal and visceral pleura. Intrapleural pressure is
always slightly below atmospheric pressure. This is called negative
pressure because the elastic lungs are always tending to collapse and
pull the visceral pleura away from the parietal pleura. The serous fluid,
however, prevents separation of the pleural membranes.
• intrapulmonic pressure- the pressure within the bronchial tree and
alveoli. This pressure fluctuates below and above atmospheric pressure
during each cycle of breathing.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Gas Exchange – partial pressure
• Diffusion of gases between alveoli and pulmonary
capillaries
• Does not occur in bronchioles, bronchi and
trachea = dead space
• Diffusion is dependant upon the partial pressure
of that gas
• Partial pressure is very similar in concept to
concentration
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 15.13
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Carbon dioxide
• Plays a vital role in pH balance
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Chemical control
• Increase in pH = decrease in CO2 = decrease in
ventilation = increase in CO2 = decrease in pH
• Decrease in pH = increase in CO2 = increase in
ventilation = decrease in CO2 = increase in pH
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Aquatic system
• Gas solubility
• CO2 higher solubility
• O2 low solubility
• Temperature
• High temp – low solubility
• Low temperature – high solubility
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Metabolic functions
• How can we measure indirectly the rate of
photosynthesis?
• How can we indirectly measure the rate of
respiration?
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Aquatic System
• Photosynthesis and Respiration
• Plants – higher rate of photosynthesis high
concentration of DO and low dissolved CO2
• Plants – higher rate of photosynthesis lower
concentration of DO and low dissolved CO2
• Global warming and partial pressures of gas
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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