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- description "Human Physiology"
- fileName "BIOL 273"
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- Respiratory pumping system?
- Bones and muscles of the thorax
Alveoli are wrapped with an extensive capillary network which covers __________% of the alveolar surface.
80 - 90
Gas exchange occurs by (active transport/diffusion)?
Characteristics of type 1 alveolar cells:
Large and thin, rapid gas diffusion
Characteristics of type 2 alveolar cells:
Smaller and thicker, synthesize and secrete surfactant --> reduces surface tension of alveolus
About ___% of total blood volume is in pulmonary circulation at any one time
Pumping system is closed off by:
- Top - neck muscles and connective tissue
- Bottom - diaphragm
- Wall - ribs and intercostal muscles
Total pressure of a mixture of gases are = ?
Sum of partial pressure of individual gases
Volume and ________ are inversely related
Amount of gas dissolved in a liquid is determined by:
- - Partial pressure of the gas
- - Solubility of the gas in the liquid
Pressure Volume relationships are described by:
- Boyle's Law: P1V1= P2V2
- - critical for VENTILATION
Lung volume depends on:
1. Transpulmonary pressure - difference between alveolar and intrapleural pressure
2. Degree of elasticity (more elastic, easier to breath)
Ventilation is the exchange between the lungs and __________ (the atmosphere/blood)
What is refered to as the 'mucus escalator'?
Steps during INSPIRATION:
- 1. Somatic motor neurons trigger contraction of diaphragm and inspiratory muscles
- 2. Thorax expands - thoracic volume increases
- 3. Intrapleural pressure decreases
- 4. Results in increase in transpulmonary pressure
- 5. Lungs expand
- 6. Alveolar pressure decreases
- 7. Air flows into lungs
Steps during EXPIRATION:
- 1. Impulses from somatic motor neurons stop
- 2. Muscle of diaphragm and thorax relax
- 3. Returns thorax to original position - volume decreases
- 4. Intrapleural pressure increases
- 5. Elastic recoil of the lungs decreases lung volume
- 6. Alveolar pressure increases
- 7. Air flows out of the lungs
Active expiration depends on:
contraction of internal intercostals and abdominal muscles (Heimlich manoeuvre)
When air getsinside intrapleural cavity and pressure increases, lung collapses
Treatment: suction to remove air and seal the hole
*having a lower pressure in the pleural fluid (outside) than inside the lung (at rest) helps keep the lung expanded and open
The work required to breathe depends on two main factors:
- 1. Complaince (stretchability of lungs)
- 2. The resistance - to air flowing in the airways
Lung compliance is:
The magnitude of change in lung volume produced by a given change in pressure
Diseases that affect lung compliance:
- Fibrotic lung disease (reduces complaince)
- - scar tissue
- Inadequate surfactant production
- - new-born respiratory distress syndrome: babies born before 8 weeks have very low compliance dur to inadequate surfactant production --> amniocentesis
Structure & function of SURFACTANTS:
Structure: mixture of lipoproteins
Function: disrupt the cohesive forces between water molecules, thus reducing surface tension. Makes lungs more compliant (easier to stretch)
Surfactants are secreted by type ___ alveolar cells.
Lung elastance is :
The degree and/or speed of return to resting volume after lung is stretched
Low elastance --> lung does not return to resting volume passively
Elastin fibres are destroyed.
Have high compliance but low elastance
Emphysema (damaged alveoli) affects lung elastance
Airway resistance is determined by:
R = 8Ln/(pi)r^2
Bronchiole diameter can be affected by the ____________ , ___________, and ___________.
Nervous system, hormones (circulating epinephrine), and paracrines.
_______ causes bronchodilation.
Neural control of bronchioles primarily by ________________ neurons that cause bronchoconstiction.
_____________ is an instrument that measures movement of air during breathing. Allows for the diagnosis of:
Spirometer; asthma, emphysema, chronic bronchitis
Tidal volume is:
Volume of air moved in a single normal inspiration or expiration
Inspiratory reserve volume is:
Maximum amount of air that can be inspired ABOVE tidal volume
Expiratory reserve volume is:
Amount of air that can be exhaled AFTER a normal expiration
Residual volume is:
Amount of air left in the lungs after MAXIMAL expiration
Vital capacity is:
Maximum amount of air hat can be volu tarily moved into or out of the respiratory system
Vc = IRV + ERV + Vt
Total lung capacity =
Vital capacity + Residual volume
Minute volume =
Tidal volume x respiratory rate (breaths per minute)
Alveolar ventilation =
Ventilation rate x ( tidal volume - dead space volume)
Dead space cvolume is the air inside the trachea, bronchi, and bronchioles
Gas exchange occurs by diffusion. The rate of diffusion across the lungs is:
- 1. Proportional to the partial pressure gradient.
- 2. Propoetional tothe available surface area.
- 3. Inversely proportional to membrane thickness.
- 4. Greatest over short distances.
Diseases and conditions that can impact gas exchange:
Emphysema - results in physical loss of alveolar surface area.
Fibrotic lung disease - scarring thickens the alveolar membrane.
Pulmonary edema - increase in interstitial fluid in lungs leads to increase in diffusion distance.
Asthma - increase airway resistance (constricted bronchiole) decrease ventilation.
Gases are transported throught the body either dissolved in ____________ or _________.
- Plasma (2%)
- Red blood cells (98%)
Each haemoglobin molecule can bind up to ____ oxygen molecules.
___________________ is a competitive inhibitor of O2 binding.
Carbon dioxide is transported by what three mechanisms?
- 1. Dissolved in plasma.
- 2. Interact with proteins.
- 3. Converted to bicarbonate.
Carbon dioxide diffuses out of ______ → ______→_________.
RBC → plasma → alveoli
Diaphragm and intercostals are (skeletal/smooth/cardiac) muscles
- - not able to contract spontaneously
- - therefore, innervared by SOMATIC motor neurons
Contraction of respiratory akeletal muscles is initiated at the medulla oblongota by a group of neurons called the central pattern generator (brain)
What type of neurons are in the dorsal respiratory group snd what do they control?
Inspiratory neurons (I neurons); control external intercostals muscles and the diaphragm
What type of neurons are in the ventral respiratory group snd what do they control?
Active expiratory neurons (E neurons); control internal intercostal and abdominal muscles
Chemoreceptors modify or adjust the ____________ of the central pattern generator neurons.
________ and _________ chemoreceptors are responsible for ventilation regulation.
Peripheral and central
_________ chemoreceptors are located in the medulla oblongota and ___________ chemoreceptors are located in carotid & aortic bodies (glomus cells).
Central ; peripheral
Two types of mechanoreceptors:
- Irritant receptors
- - triggers parasympathetic neurons hat innervate bronhiolar smooth muscle → bronchoconstriction
- Stretch receptors
- - triggered if lungs are over inflated
- - terminate ventilation
- - only important during strenuous exercise
_________ receptors are located in airway smooth muscle and ________ receptors are located in airway mucosa.
During exercise, ventilation may increase as much as:
Possible stimuli that cause an increase in ventilation are:
- 1. Increased PCO2
- 2. Decreased PO2
- 3. Increased H^+
Does PCO2 increase during exercise?
- Venous PCO2 increases but arterial doesn't
- - Arterial PCO2 is set by alveolar PCO2
Does PO2 decrease during exercise?
Venous PCO2 decreases, but arterial doesn't
- haemoglobin is already 98% saturated
Does H^+ increase during exercise?
Increase only during severe exercise (as a result of lactic release into the blood from glycolysis)
__________ is the ability of the body to fight off invaders
Key features of the immune system (2):
Lymphoid tissues and immune cells
Chemicals that coordinate and execute function
Three major functions of the immune system:
1. Protect the body
- - microbes (bacteria, viruses, fungi, protozoa)
- - parasites (worms)
- - toxins produced by microbes
- - other foreign proteins or substances
2. Removes dead/damaged tissues and cells
- immune cells scavenge extracellular compartments
3. Tries to recognize and remove abnormal cells
- cells that are unable to control growth detected by immune system
What are the diseases of the immume system when it does not perform normally?
- - incorrect responses
- - ex. Destroying own cells
- - overactive responses
- - lack of response
Three types of pathogens:
- - paracites
- - bacteria
- - viruses
Characteristics of parasites:
- - generally extracellular
- - enter the body via a variety of routes
- - cause chronic illness, nutritional deficiencies, death
- - malaria
Characteristics of bacteria:
- - intracellular or extracellular
- - cells surrounded by a cell membrane and usually a cell wall
- - can survive & reproduce outside of host
- - most can be killed by drugs (antibiotics)
Characteristics of viruses:
- - intracellular
- - not cells → nucleic acid core w/ protein coat
- - cannot reproduce alone
- - cannot be killed by antibiotics (only some antiviral drugs)
- - takes over host cell
- - ruptures host cell or buds off
Immune system organs are called ________ organs because _________ are found here.