Kpe264 postmidterm

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• Module 4 focuses on the respiratory system and its function in gas exchange

Respiratory System

• The respiratory system is responsible for the intake of air, diffusion of oxygen and carbon dioxide in the lungs and muscles, and the removal of carbon dioxide
• Oxygen and carbon dioxide diffuse at the lungs and muscle

Key Terms

External Respiration

• External respiration involves pulmonary ventilation, which is air movement in and out of the lungs (breathing)
• Pulmonary diffusion is gas exchange between the lungs and blood at the alveoli

Internal Respiration

• Internal respiration involves gas transport, which is the movement of oxygen and carbon dioxide via the blood
• Capillary diffusion is gas exchange between capillary blood and tissues like the liver and skeletal muscle, being more local

Tidal Volume

• Tidal volume (VT) refers to the air moved with each breath at rest

Alveolar Volume

• Alveolar volume (VA) refers to the fresh air that reaches the alveoli
• It is calculated by subtracting the dead space volume (air trapped in the conducting zones) from the tidal volume

Conduction vs Respiratory Zones

• COPD, asthma, and other respiratory diseases lead to increases in dead space.
• Strategies to compensate are breathing more frequently or increasing the depth of breath

Ventilation

• Ventilation Volumes and Rates
• Residual volume refers to the air always remaining in the lungs after exhaling
• Total lung capacity typically ranges from 6-8L in healthy individuals
• Minute ventilation is calculated by multiplying tidal volume by respiratory rate
• A standard value for minute ventilation at rest is 6 L/min
• Alveolar ventilation is the product of frequency and the difference between tidal volume and dead space volume
• A standard value for alveolar ventilation is 4.2 L/min
• Smokers may have lower alveolar ventilation

Ventilation Rates during Exercise

• Ventilation rates during maximal exercise can vary, with an average untrained male reaching a minute ventilation is 120 L/min, around 20 times higher than at rest
• Alveolar ventilation is 113 L/min, which is ~27 times greater than rest
• Larger individuals have larger lungs, and males typically have a larger lung capacity than females

Ventilatory Response

• Pulmonary ventilation increases alongside exercise intensity
• The body anticipates metabolic demand, causing anticipatory drive

Gas Exchange

• Pulmonary diffusion facilitates gas exchange between alveoli and pulmonary capillaries
• Inspired air travels the bronchial tree to the alveoli, while blood moves from the right ventricle through pulmonary arteries to pulmonary capillaries, then alveoli
• Gas exchange involves replenishing blood oxygen and removing carbon dioxide

Factors Affecting Gas Exchange

• Gas moves from one medium to another due to a partial pressure gradient
• The greater the pressure difference, the more movement occurs
• Diffusion capacity ("solubility") of gas and characteristics of the respiratory membrane influence gas exchange

Gases in the Air

• Nitrogen accounts for 79.03% (or 0.7903) of atmospheric air
• Oxygen accounts for 20.93% (or 0.2093) of atmospheric air
• Carbon dioxide accounts for 0.03% (or 0.0003) of atmospheric air
• Partial pressure refers to the pressure exerted by a single gas in a mixture
• Altitude affects partial pressure
• In "dry" atmospheric air at sea level, PO2 = 0.2093 x 750 mm Hg = 159 mm Hg
• Atmospheric pressure varies with gravity, with molecules closer to the Earth's surface experiencing higher pressure
• Water molecules disperse gas molecules, increasing the total air volume, which decreases gas pressure
• The body humidifies air upon intake, and gases spread at water molecules which affects PO2 throughout the body
• Oxygen levels decrease slightly in the trachea due to water vapor
• Oxygen decreases significantly in the alveoli due to mixing with venous blood, which is deoxygenated and has low PO2
• Arterial PO2 determines how much O2 binds to hemoglobin, influencing O2 delivery to tissues
• Large decrease in oxygen occurs at tissue cells as it gets used in muscle cells
• Venous blood oxygen depends on how much oxygen is "left over" after muscle use

PO2 Levels

• Atmospheric PO2 reads at around 160 units
• Tracheal PO2 reads just under 150 units
• Alveolar PO2 measures around 105 units
• Arterial PO2 measures around 100 units

Heavy Exercise

• During heavy exercise, PO2 measures 15 units and PCO2 measures 60 units

Oxygen Transport

• Key factors are alveolar PO2 (PAO2), influencing arterial PO2, and saturation of hemoglobin
• Pa02 (arterial PO2) determines SaO2 (Arterial O2 "Saturation")

Hemoglobin

• Hemoglobin (Hgb) is measured in g/100 ml or “g%,” with a normal range of 13-18
• 1 g of Hgb binds 1.34 ml of O2 when “100% saturated."
• Blood O2 content=[Hgb] x 1.34 x % sat. Women typically have lower levels
• Blood doping increases red blood cell count, increasing carrying capacity
• Anemia limits O2 carrying capacity

Oxygen and Blood

• CaO2, for example in arterial blood, is 15g/100ml x 1.34 ml O2 / g x 0.98 = 197 ml/L
• There is also a small amount of dissolved O2 in plasma, approximately 3 ml / L
• The 'loading' portion of the curve remains high with PO2 input
• The 'unloading' portion allows saturation changes in PO2 which support oxygen unloading to tissues, especially at the muscles and to the veins

Blood

• Arterial blood has a higher PO2 of more O2 bound to Hgb
• Venous blood has less O2 bound to hemoglobin
• Shifts alter the ability of O2 to bind hemoglobin which affects saturation. Leftward = increased affinity. Rightward = affinity decrease
• Right shift of blood promotes oxygen absorption

Differences In Blood

• Arterial blood measures PaO2 at 100 mmHg and O2 sat at 98%
• CaO2 = 15 g/100ml x 1.34 ml/g x 0.98 equals 20mL 2/100ml = 200 ml/L
• Venous blood resting PvO2 measures 40mmHg and an O2 sat of 75%
• The resting CvO2 measures around 15 g/100 ml x 1.34 ml/g x 0.75 ≈ 15ml 2/100ml = 150 ml/L

Muscles

• At rest in the muscle - Arteries measure 20mL O2, capillaries measure an a-v of 4-5ml O2 and veins measure 15-16ml O2 per 100ml of blood
• During intense exercise, the arteries measure 20 mL, the capillaries = - a-v diff 15ml O2 per 100ml blood, and veins measure approximately 5 ml

Oxygen in Red Blood Cells

• Resting blood diff in arterial measures 200 mL and venous measures 150ml for a diff of approximately 50 mL
• Venous blood during exercise has less oxygen, resulting in only 5 mL - The exercise diff measures 150 ml

Muscle Oxygen

• Myoglobin is only found in muscle, it binds tighter, and "shuttles" O2 to the mitochondria
• Muscle contractions, which use O2, reduce CaO2 and CvO2
• Key Factors in O2 are pressure, its effects on saturation and content
• "S" shape in graphs represent more soluble gases = easier diffusion

Blood & Carbon

• Role of bicarbonate ion (HCO3-) in blood CO2 transport. This process happens "primarily @ skeletal muscle
• Freely dissolvable O2 flows freely.

Key CO2 Facts

• Most arterial blood O2 dictates O2 levels of blood to deliver to tissues.
• There's a key enzyme in red blood cells. H+ from build-up is triggered there for CO2 to drop. H2CO3 - carbonic acid is also present
• Lungs have lower (decr. HCO3 as CO2 released). Tissues use a forward process

Breathing

• Breathing rate is controller by the respitory center in the brai
• Centers measure inspiration/expiration and are trigger breathing signals from the breath
• The brain stem medulla oblongata contains the Pons/Respitory centers
• Voluntary function via the cortex

Breathing in the brain

• Neural signals can be sent by central command of the brain, or from active muscle
• Central Chemoreceptors in the brain are used to stimulate increased CO2, or the removal of oxygen from the body
• Peripheral chemoreceptors work as a result of sent changes to oxygen flow and other factors

Mechanoreceptors

• Mechanoreceptors/stretch receptors sense lung movement, in the pleurae, bronchiole and alveoli which are part of the lungs

Respiration Process

-The central and periphrial chemoreceptors work together, when lung stretching triggers the expansion to the appropriate areas

• Internal and abdominal muscles force air in/out of the air cavities

"Neurohumoral" Factors

• Chemical input has neuro effects to trigger the breathing process

Ventilation

• Ventilation during exercise is linked to energy metabolism
• During most exercise intensities increases are matched
• When rates are 60 % V02max, VE increases. These are disproportionally high at the ventilatory point-VT
• In order to handle the incr. in PC02

Ventilatory System

• The ventilatory system's primary job is to maintain arterial PCO2 and PO2
• The key stimulus comes to make things work
• Changes are "fine tone" to regulate chemical function
• Chemical in blood increases ventilation - V02
• At higher it increases and more air flows out.

Adjustments in Blood Movement

• Blood moves to the muscles and tissues throughout exercise. This system also eliminates other bad things to balance.
• V0 is increased
• During heavy workouts the driving pressure in the system is also high so adjustments are automatic

Cardiovascular (CV) System

• Transports oxygen, substrates and also waste products from the body

Key CV Functions

Key parts in the cardiovascular system are the tubing i.e bloodstreams, vasculature and fluid in blood.

• The increase in cardiovascular activity raises Q
• Muscles adjust rates for oxygen level
• Blood flows and blood is pumped

Cardiac Info

The heart must increase driving pressure to function normally

• Anatomy : LV delivers aortal pressure. MV delivers blood flow which causes Tricuspid. The atriums work to maintain pressure

Values

• SA Node sends contractile signal
• The SA node is the heart's pacemaker; if there's a malfunction, it can be surgically corrected
• The SA node is located in the upper posterior wall of the right atrium and signals the atria to contract
• The signal spreads through both atria to the AV node, causing atrial kick, which moves all blood from the atrium to the ventricle

AV Nodes

• AV node delays, relays signal from atria to ventricles
• Conducting electrical impulses from the atria with delays for the filling process
• The AV Node is located in the right atrial wall near the center of the heart and only relays signals after the delay takes place

Other Nodes

• Bundle and Purkinje nodes relay signals and send messages toward the wall
• ECG = electrical process in heart

Cardiac Cycle Facts

• HR At Rest - 75 BPM cycle
• Diastole .05 seconds vs .3 seconds for systole
• HR = 150 for 4 seconds. Systole = ؐ .25. Diastole is 15

Phase Context

• Ventricals move blood and isovolumetric happen

Important Numbers/Details at Volume

• End dials . Volume, or EDV is about a 100. Preload = stretch vol.
• SV beats from a 60.
• Ventricle starts are at a baseline level.
• Exercise increases stroke volume with increased heart strength
• SV is the ability a heart has to contract which increases with workload

Aerobic Training

• Cardio increases V02 which means it can increase SV, and Q