Human Performance/Exercise Physiology Exam 2

Pulmonary Circulation

carries oxygen-poor blood away from the right side of the heart, through the lungs to exchange gases, and back to the left side of the heart

Systemic Circulation

carries oxygen-rich blood from the left ventricle of the heart to the rest of the body and returns oxygen-poor blood to the right atrium

Epicardium (visceral pericardium)

serous membrane including blood capillaries, lymph capillaries, and nerve fibers  Serves as a lubricative outer covering (outer layer)

Myocardium

cardiac muscle tissue separated by connective tissue and including blood capillaries, lymph capillaries, and nerve fibers. Provides muscular contractions that eject blood from the heart characteristics (middle layer)

Endocardium

Endothelial tissue and a thick subendothelial layer of elastic and collagenous fibers  Serves as a protective inner lining of the chambers and valves (inner layer)

Factors that Influence Arterial Blood Pressure

Blood Volume Increases

Heart Rate Increases

Stroke Volume Increases

Blood Viscosity Increases

• Dehydration

• Drug/Alcohol Abuses

• High Acids

Peripheral Resistance Increases

Electrocardiogram & Conduction System Defects

Action potentials originate in the sinoatrial (SA) node (the pacemaker) and travel across the wall of the atrium from the SA node to the atrioventricular (AV) node

Action potentials pass through the AV node and along with the AV bundle, which extends from the AV node, through the fibrous skeleton, into the interventricular septum

The AV bundle divides into right and left bundle branches, and action potentials descend to the apex

Sinus Rhythms

Normal Sinus Rhythm

• HR 60 to 100

Sinus Arrhythmia (Normal phenomenon)

• Subtle change in HR due to the respiratory cycle

• HR increases during inspiration and decreases during expiration

Tachycardia

heart rate exceeding 100 at rest

Bradycardia

heart rate below 60 at rest (elite athletes, people with hypotension, people with myocardial infarction)

When you breathe in, you temporary suppress the

vega activity and it decreases the parasympathetic tone and increases heart rate

When you breathe out, you release the

vega activity and heart rate decreases

For some individuals with too much calcium, they’ll be on calcium blockers which can

affect your heart (lowers heart rate and reduces workload)

People with high blood pressure have a very thick

left ventricle

Angle of degrees (shifting of the heart) can cause

electrical problems or contraction problems. Learn the degrees of axis off of an EKG

Cardiac Output

At rest for an average adult (most at 5.0 L/min)

It is the amount of blood leaving the heart to go to the rest of the body

• HR (72 bpm) x SV (70 ml) = CO (5.0 L/min)

• Lowest 3.5 L/min 

• Other considerations for being so low would be internal bleeding

• If the valves don’t close, there will be “internal bleeding” / leaking because they won’t close

• Valves can be damaged based on how much force hits the valves and the internal pressure in the heart

During periods of strenuous exercise CO

Can reach 25 L/min in untrained individuals

Can reach 45 L/min in elite individuals

Based on demands on the body for what is needed to supply the fluid needed

Second demand in the body (after fuel and energy) is

pH

Regulation of Stroke Volume (Frank Starling Mechanism)

Preload

Afterload

Contractility

Won’t see Frank Starling Law in weightlifting (high intensity - short period)

Preload

End diastolic volume (EDV)

Volume of blood in the ventricles at the end of diastole (“preload”)

Afterload

average aortic blood pressure

Pressure the heart must pump against to eject blood (“afterload”)

Contractility

Strength of the ventricular contraction enhanced by:

• Circulating epinephrine and norepinephrine

• Direct sympathetic stimulation of the heart

The Skeletal Muscle Pump

Rhythmic skeletal muscle contractions force blood in the extremities toward the heart

One way valves in veins prevent backflow of blood

Valsalva Maneuver

Forced expiration against a closed glottis causes

Increased intrathoracic pressure

Increased central venous pressure

Decreased venous return

Factors that Regulate Cardiac Output

Cardiac rate (parasympathetic and sympathetic nerves)

Stroke volume (contraction strength, stretch, Frank Sterling, end diastolic volume, and mean arterial pressure)

Diameter, length of vessel, and viscosity 

What 3 things will affect heart rate?

Blood viscosity

Diameter of vessels

Length

Postural Changes & Blood Pressure

Going from a laying down to a standing position

Decrease both diastolic and systolic arterial pressure

Baroreceptors help initiate compensatory mechanism

Heart Rate Max Considerations

Heart Rate Max is likely affected by multiple factors 

• Age (so we can get max heart rate and keep between 60%-80%)

• Fitness Level (trained/untrained)

• Health Status

• Body Size

• Exercise Mode

(Currently no perfect method to estimate HR max)

Redistribution of Blood Flow During Exercise

The body will resend blood to the demanding cells. They need oxygen, fuel, and possibility of waste clean up

When working out, blood in the body is sent to places and taken from other places (blood flow cut off from digestive system and sent to where we need it)

Vessels based on the demand of blood flow, mechanical receptors on the vessels will constrict blood flow to the stomach but dilate blood flow to the muscles being used

From there, will signal to the cardiovascular control center electricity to make the heart contract harder (fill, reload, contraction, reload to increase cardiac output)

Blood pressure won't change massively, diastolic will

stay relatively normal, systolic will increase

Mean Arterial Blood Pressure (MAP) looks at the

mean of how the blood pressure is being affected based on how hard the heart has to work. The heart has to work harder if you need more oxygen, if you don’t need more oxygen it won’t work harder

What is the number 1 factor for oxygen to be able to go into a cell after prolonged working/exercise?

You do not want the cell surrounded by carbon dioxide. If you have too much oxygen already in the cell, you can’t push more in

Types of Exercise

Incremental Exercise

Arm vs Leg Exercise

Intermittent Exercise

Prolonged Exercise

High-Force-Isometric/Isotonic Exercise

Incremental Exercise

Heart Rate and Cardiac Output

• Increases linearly with increasing work rate

• Reaches plateau at 100% of VO₂ max

Blood Pressure

• Mean arterial pressure increases linearly

  • Systolic BP increases

  • Diastolic BP remains fairly constant

Double Product (Rate-Pressure Product)

• Increases linearly with exercise intensity

• Indicates the work of the heart

• Double Product = HR x Systolic BP

Intermittent Exercise

Recovery of heart rate and blood pressure between bouts depend on

• Fitness level

• Temperature and Humidity

• Duration and Intensity of Exercise

Heart Rate and Blood Pressure During Arm and Leg Exercise

AT the same oxygen uptake, arm work results in higher

• Heart rate

  • Due to higher sympathetic stimulation

• Blood pressure

  • Due to vasoconstriction of large inactive muscle mass

The major consideration we look at is prolonged exercise of plasma loss. A large loss is due to

water and salt from sweating. Increase in blood pressure, due to increasing capillary hydrostatic, which will increase filtration rate of capillaries

Arteries dilate and constrict - capillaries

do not

High-Force-Isometric/Isotonic Exercise:

Blood flow changes

• Blood flow increases to the muscles at <30% maximum voluntary contractions (MVC)

• Blood flow begins to decrease >30% MVC

Cardiac Output Changes

• Cardiac output increase

Blood Pressure Changes

• Dramatic increase in systolic, diastolic and MAP

• The higher the intensity, the larger the increase

Weight lifters get into fatigue a lot faster because of

pressure changes

When we have more myoglobin, we’ll go more of an

aerobic pathway

Myoglobin

an iron and oxygen-binding protein found in the heart and skeletal muscle fibers of vertebrates. Muscle cells that have oxygen

Aerobic

Leg

Endurance

Temperature

pH

Anaerobic

Arm

High Intensity Weightlifting

pH

Mechanics of Breathing

Ventilation is the exchange of air between the atmosphere and the alveoli

Pressure dependent

Pulmonary ventilation consists of two phases

Inspiration

gases flows into the lungs

Expiration

gases flows out of the lungs

Respiration Involves Four Processes

Ventilation

Gas exchange

Circulatory transport

Systemic gas exchange

As heart rate increases so does breathing rate but

reduces air flow

Lung Volumes and Capacities looks at what the value individuals

will breathe in and out

Residual volume (RV) is the

air left in the lung after expiration

Total lung capacity (TLC)  is the amount

of gas in the lungs after a maximum inspiration, measurement of pulmonary volumes and rate of expired airflow and expiration, uses lung capacity as a diagnosing tool for lung disease

Force expiratory volume (FEV) is the

volume of air expired during time

There is maximum minute ventilation (MMV) where we have individuals

breathe as quickly and possibly for 1 minute, almost as if they are hyperventilating. Looked upon for the rate of breathing at a maximum velocity

As you inspire

The intrapleural pressure becomes more negative

The transpulmonary increases

Lung volume increases 

During expiration the events are reversed

Diaphragm and inspiratory intercostals contract → thorax expands → P_IP becomes more subatmospheric → transpulmonary pressure increases → lungs expand → P_alv becomes subatmospheric → air flows into alveoli 

Partial Pressure of Gases

Dalton’s Law

• Total pressure of a gas mixture is equal to the sum of the pressure that each gas would exert independently

Calculation of partial pressure

• P_air = PO₂ + PCO₂ + PN₂

Pneumothorax 

a collapsed lung that happens when air gets trapped in the space between your lung and your chest wall

Diffusion of Gases

Fick’s Law of Diffusion

The rate of gas transfer (V gas) is proportional to the tissue area, the diffusion coefficient of the gas, and the difference in the partial pressure of the gas on the two sides of the tissue, and inversely proportional to the thickness

V_gas = A/T x D x (P₁ - P₂)

• V_gas = rate of diffusion

• A = tissue area

• T = tissue thickness

• D = diffusion coefficient of gas

• P₁ - P₂ = difference in partial pressure

Biggest thing we can associate with partial pressure

rate (time, duration)

Greater diffusion when the surface area is

large, tissue thickness is small, and the driving pressure is high

The oxygen will go wherever it is needed to

live and maintain homeostasis

Energy Expenditure of Breathing

3 to 5% of the total body’s energy expenditure is used for quiet breathing

2 factors that greatly influence the amount of work needed for breathing

• Lung Compliance (stretchability of the lung tissue and the surface tension at the air-water interfaces within the alveoli)

• Resistance of the airways to air flow (as airway resistance rises, breathing movements become more strenuous, and see 3 specific things that affect that - physical obstruction, bronchoconstriction will happen because of an increase level in CO₂ in the body, and bronchodilation)

Males have a larger chest size which means they have

a higher chest capacity

Get used to having less oxygen (high altitude) by

increasing saturation rate. The more hemoglobin you have, the more you can exercise

Changes in the Affinity of HB for O₂

Factors that alter the affinity of HB for oxygen

• 2,3-diphosphoglycerate (2,3-DPG or 2,3-BPG)

• Temperature

• pH

• PCO₂

The more base you are,

the more hemoglobin

The more acid you are,

the less hemoglobin

Hotter you are,

less oxygens

Colder you are,

more oxygen

Haldane Effect

When exercise happens the shift of the discretion curve to the right allows more oxygen to be unloaded at the tissue level. Hemoglobins need to let go of oxygen so the tissue has more

Carbonyl Effect

forming carbon on the red blood cells

pH refers to Bohr effect which means there are

extra ions that will bond to hemoglobin 

During exercise the mechanism is going to promote more unloading of oxygen at the muscles to help produce energy or reduce heat. Specifically right at the tissue, we have hydrogen binds to

hemoglobin, HCO₃ diffuses out of the blood cell into the plasma, Cl diffuses into the red blood cell and now this red blood cells is going to shift to the lung, oxygen will bind to the hemoglobin which will drive off one hydrogen bond, and with this reaction carbon dioxide will be released and set into the lung

As the cell level decreases too much with carbon dioxide,

buffers will come into play

Ventilation During Exercise

Rest-to-Work Transition & Steady State Exercise

• Slight changes to arterial PO₂ and PCO₂ at the onset of exercise

• However, they quickly stabilize and values are similar to rest

Prolonged Exercise & Hot Environment

• Prolonged - slight upward “drift” in ventilation

• Hot environment - upward drift is exacerbated, no change in arterial PCO₂ level

Hemoglobin mostly affected by

pH and temperature

pH and temperature will also have an affect on

metabolism, specifically on enzymes

As blood lactate goes up, hydrogen bond

(acids) concentration increases

Ventilation and Acid-Base Balance

Pulmonary ventilation removes H+ from blood by the HCO₃^- reaction

Increased ventilation results in CO₂ exhalation

• Reduces PCO₂ and H+ concentration (pH increases)

Decreased ventilation results in buildup of CO₂

• Increases PCO₂ and H+ concentration (pH decreases)

Buffers attach to hemoglobin to go to

the lungs and remove acids from the body (H₂CO₃ and HCO₃^-)

An acid is a molecule that

releases hydrogen ions in solution

A base is a molecule that can

accept a hydrogen ion

A buffer is a substance that

reversibly bind hydrogen ions

An increase in body temperature will hold onto less

oxygen and make it harder to remove acids from the body. If you are exercising, homeostasis will occur and oxygen will begin to bind to sweat to help remove the acids from your body

pH of Blood

Normal: 7.4 +- 0.05

Acidosis: <7.4

Alkalosis: >7.4

Abnormal pH can disrupt normal body function and affect performance (6.8 - 7.8)

Acid-Base Buffer Systems

Acid-base balance maintained by buffers

Intracellular Buffers

Extracellular Buffers

Acid-base balance maintained by buffers

Release H+ ions when pH is high

Accept H+ ions when pH is low

Intracellular Buffers

Proteins

Phosphate groups

Bicarbonate

Extracellular Buffers

Bicarbonate

Hemoglobin

Blood Proteins

Bicarbonate Buffering System

CO₂ + H₂O <-> H₂CO₃ <-> H+ + HCO₃^-

Henderson-Hasselbalch Equation

Henderson-Hasselbalch Equation

Describes ability of bicarbonate-carbonic acid to act as buffer system

The ratio between bicarbonate and carbon dioxide is critical in determining blood pH

To maintain a normal blood pH of 7.4, need a ratio of 20:1 (HCO₃^- : CO₂)

A dehydrated cell, the cell will

shrink, cell signaling will not work as well, and anaerobic ATP will decline. An injury/strain can occur because the cell can’t keep up with the work

Other Extracellular Buffers

Hemoglobin System 

• H+ + HB <-> HHB (will make hemoglobin not pull in oxygen but can remove the hydrogen bonds through urine)

Serum Phosphate System

• H+ + HPO₄^- <-> H₂PO₄ (will leave the body through breathing, sweat, or urine)

Respiratory Influence on Acid-Base Balance

Carbonic acid dissociation equation

• CO₂ + H₂O <-> H₂CO₃ <-> H+ + HCO₃^-

When pH decreases H+ increases

• Reaction moves to the left

• CO₂ is “blown off” by the lungs, raising pH

An increase in blood PCO₂ lowers pH, whereas a decrease in blood PCO₂ raises pH

Regulation of Acid-Base Balance via Kidneys

Plays an important role in the long-term regulation of acid-base balance

Regulate blood bicarbonate concentration

• When blood pH decreases

  • Reduced rate of bicarbonate excretion

• When blood pH increases

  • Increased rate of bicarbonate excretion

Can also regulate the amount of acid [H+]

Acid-Base Disturbances

Respiratory Acidosis - within the lungs, specifically within the cells for cellular respiration

Respiratory Alkalosis

Metabolic Acidosis

Metabolic Alkalosis

High blood pressure does not slow the heart down, but

taking medication (aneurysm in aortic vessel) and age can decrease resting heart rate to a low number

Acids are defined as molecules as a

hydrogen ion

Causes - Respiratory Acidosis

Hypoventilation

Obstruction of airways (COPD)

Damage to chest cavity

Depression of CNS

• Narcotics, sedatives, anesthetics, alcohol

Strokes / Meningitis = Brain Stem Trauma

• Neuromuscular Disorders

Ventilation / perfusion mismatch

How do we compensate at the kidneys?

• Increase excretion of acid in the urine

• Increase reabsorption / regeneration of bicarbonate

Three ways to solve acid-base issues:

Lungs

Sweating

Through the kidneys