ACSM Chapter 5, Exercise Physiology

The Heart: Atrioventricular Valve (AV)

The AV valves separate the atria from the ventricles.

The Heart: Pulmonic Valve

The pulmonic valve lies between the RV and the pulmonary artery.

Respiratory System

The respiratory system consists of the nose, nasal cavity, pharynx, larynx, trachea, bronchial tree, and the lungs. The primary function of the respiratory system is to filter air that enters the body and allow for gas exchange within microscopic air sacs in the lungs called alveoli.

The Heart: The Right AV

The right AV valve has three cusps and is called the "tricuspid" valve. The tricuspid valve controls the flow of blood from the RA to the RV.

Skeletal Muscle: Sarcolemma

The sarcolemma is the plasma membrane of the myofiber. The voltage-gated sodium channels regularly distributed along the sarcolemma allow electrical stimulation of the myofiber via the generation of Action Potentials.

The Heart: Semilunar Valve

The semilunar valves separate the ventricles from the aorta and pulmonary artery.

Energy Systems: Oxidative System

This ATP-producing pathway is also called the "aerobic" system because oxygen is required for it to proceed. Both carbohydrates and lipids (fats) can be used to synthesize ATP by this pathway. The metabolic by-product that result from oxidative phosphorylation are water and carbon dioxide, which have no fatiguing effects on working muscle. Primary system in activities lasting more than 3 minutes (with limited intensity); however, synthesization of ATP in this system is relatively slow.

Energy Systems: Phosphagen System

This energy pathway is composed of the ATP and phosphocreatine (PCr) stored in muscle fibers. Through the activity of the enzyme Creatine Kinase, PCr yields its phosphate group so that it can be added to ADP to synthesize ATP. although immediately available for use by the working muscle, the phosphagen system is limited in its capacity to supply energy. During exercise of all-out effort, stored ATP and PCr can sustain activity for no more than 30 seconds.

Energy Systems: Nonoxidative System

This system is sometimes referred to as the "anaerobic" pathway because oxygen is not required for it to produce ATP. In this system, only carbohydrates (glucose, glycogen) can be used to produce ATP. In the absence of oxygen, the breakdown of carbohydrates yields lactic acid (lactate), which can contribute to muscle fatigue. The nonoxidative system is the main provider of energy to the working muscles in athletic events lasting from 30 seconds to 3 minutes.

The primary purpose of the Cardiovascular System:

To deliver nutrients to and remove metabolic waste products from the tissues. The cardiovascular system assists with maintenance of normal function at rest and during exercise.

Maximal Oxygen Consumption

VO2max is defined physiologically as the highest rate of oxygen transport and use that can be achieved at maximal physical exertion. Oxygen consumption may be expressed as: VO2 (mLxkg-1xmin-1) = HR (bpm) x SV (mLxbeat-1) x (a-vO2 difference).

The Heart: Veins

Veins return blood to the heart. Veins receive blood from the venules. Generally, veins are thinner and more compliant than arteries and act as blood reservoirs.

Respiratory System: Distribution of Ventilation

Ventilation of the pulmonary system is accomplished in two major divisions, the upper and lower respiratory tracts.

Muscular System: Functional Strength

Functional strength is defined as performing work against a resistance specifically in such a way that the strength gained directly benefits the execution of activities of daily life and movements associated with sports.

The Heart: The Pericardium

A double-walled, loose-fitting membranous sac that covers the heart. The pericardium has both a fibrous (tough) layer and a serous (smooth) layer.

The Heart: The Blood Vessels

After blood flows from the heart, it enters the vascular system, which is composed of numerous blood vessels. The blood vessels form a closed system to deliver blood to the tissues; help promote the exchange of nutrients, metabolic wastes, hormones, and other substances with cells; and return blood to the heart.

The Ventilatory Pump: Pulmonary Ventilation

Pulmonary ventilation (Ve), the volume of air exchanged per minute, is approximately 6 L/min at rest. At maximal exercise, however, Ve often increases 15- to 25-fold over resting values.

Cardiovascular Exercise: Cardiac Output

Q in healthy adults increases linearly with increased work rate; however, maximum values of Q depend on many factors including age, posture, body size, and level of physical conditioning.

The Heart: The Left-Sided Heart

Consists of the left atria and the left ventricle. The left-sided heart collects blood from the lungs and pumps it throughout the body (systemic circuit).

The Heart: The Right-Sided Heart

Consists of the right atria and the right ventricle. The right side of the heart collects deoxygenated blood from the periphery and pumps it through the lungs (pulmonary circuit).

Blood Pressure: Diastolic Blood Pressure (DBP)

DBP is measured during the relaxation phase of the left ventricle (LV).

Skeletal Muscle: Sarcoplasmic Reticulum

Located in the myofiber, this richly developed organelles stores calcium needed to stimulate muscle contraction.

Blood Pressure: Systolic Blood Pressure (SBP)

SBP is measured during the contraction phase of the left ventricle (LV).

Muscular System: Skeletal Muscle

Skeletal muscle is the muscle that attaches to the skeleton so as to produce physical movement. Skeletal muscle accounts for 50% of the body's mass. As with all types of tissue, skeletal muscle is composed of individual cells, typically termed "myocytes" or "myofibers"

The Heart: The Chambers

The heart has two pumps in a single until with four chambers or "cavities". The right-sided heart (RA and RV) and the left-sided heart (LA and LV) make up the two pumps.

Energy Systems: Adenosine Diphosphate (ADP)

In releasing its energy, ATP is broken down into ADP.

The Heart: The Fibrous Skeleton

A network of criss-crossing connective tissue fibers within the myocardium. The fibrous skeleton separates the atria from the ventricles and provides support for the myocardium and the valves of the heart.

Energy Systems: Adenosine Triphosphate (ATP)

ATP is the immediate source of energy for all cellular activities, including muscle contraction. Because only a limited amount of ATP is stored in the cell, ATP is replenished via other energy pathways.

The Heart: Arteries

Arteries carry blood away from the heart. Large arteries branch into smaller arteries and eventually to smaller arterioles.

The Heart: Arterioles

Arterioles branch into capillaries. The arterioles play a major role in regulating blood flow to the capillaries because of their ability to vasoconstrict (narrow the opening of the blood vessel) or vasodilate (widen the opening of the blood vessel).

Cardiovascular Exercise

As exercise intensity increases, oxygen consumption and carbon dioxide production by working muscles increase. The cardiorespiratory system is required to deliver oxygen to, and transport carbon dioxide from, these tissues in an attempt to maintain cellular homeostasis.

Cardiovascular Exercise: Blood Flow

At rest, 15% - 20% of the Q is distributed to the skeletal muscles; the remainder goes to visceral organs, the heart, and the brain. During exercise, as much as 85% - 90% of the Q is selectively delivered to working muscles.

Cardiac Function: Blood Pressure

Blood pressure (created by the contraction and relaxation of the heart muscles, which causes pressure to be exerted on the atrial wall by the movement of blood) is measured as either the Systolic Blood Pressure (SBP) or the Diastolic Blood Pressure (DBP).

Cardiac Function: Cardiac Output

Cardiac Output (Q) is the volume of blood pumped by the heart per minute and is calculated by multiplying the HR by the SV. The resting Q for adults is approx. 4 to 5 liters per minute; however, the maximal is higher for trained individuals.

Cardiovascular Exercise: Stroke Volume

During exercise, SV increases curvilinearly with the work rate until it reaches a near-maximal level equivalent to approximately 40% - 50% of aerobic capacity.

Energy Systems: Excess Postexercise Oxygen Consumption (EPOC)

EPOC is the consumption of more than usual amounts of oxygen after exercise. Oxygen uptake remains elevated above rising levels for several minutes during recovery from exercise. The effect of EPOC is to restore PC is muscles and oxygen in blood and tissues.

Stroke Volume: EDV and ESV

End-diastolic volume (EDV) and end-systolic volume (ESV) are the total volume of blood in the ventricles at the end of the diastole and systole, respectively.

Cardiovascular Exercise: Heart Rate

HR increases in a linear fashion with the work rate and oxygen uptake during dynamic exercise. The formula to approximate maximum HR is: "max HR = 220 - age".

Cardiac Function: Heart Rate

Heart Rate (HR) is the number of beats per minute (bpm). The average normal resting HR is approximately 60-80 bpm (women are typically 10 bpm higher). HR can be measured by counting the number of pulses over a given time period (normally 15-30 seconds).

The Heart: The Chordae Tendineae and Papillary Muscles

Help the AV valves stay closed, preventing them from swinging back into the atria, which would result in reversed blood flow.

Cardiovascular Exercise Physiology examines:

How oxygen and other important nutrients are transported by the cardiovascular system and used by the muscles during exercise.

Cardiac Function: Stroke Volume

Stroke volume (SV) is the amount of blood ejected from the LV in a single contraction. SV is equal to the difference between the end-diastolic volume (EDV) and end-systolic volume (ESV).

Skeletal Muscle: Connective Tissue

The Endomysium is a layer of connective tissue that is found wrapped around each myofiber. A group of 150 or more myofibers lying in parallel are bundled together to form a Fasciculus, which are encased by a layer of tissue called the Perimysium. The layer of connective tissue that surrounds the entire muscle is referred to as the Epimysium.

The Ventilatory Pump: Tidal Volume

The amount of air entering or leaving the lungs in a single breath.

The Heart: Aortic Valve

The aortic valve is between the LV and the aorta.

The Heart: Atrioventricular Node (AV)

The area where the electrical impulse is delayed (approx. 0.12 seconds, which allows the atria to contract and full the ventricles with blood).

The Heart: Capillaries

The capillaries allow the exchange of blood and other nutrients with various tissues (e.g., digestive system, liver, kidneys, muscles). Capillaries form dense networks that branch throughout all tissues. Capillaries also have extremely thin walls and are the site of exchange of nutrients between blood and the interstitial fluid. Capillaries converge into small venules, which converge to form larger vessels called veins.

Exercise Physiology takes into account the effects of exercise on various systems of the body such as:

The cardiovascular or circulatory systems, respiration, muscles and bones, and the nervous system.

The Ventilatory Pump: The Chest Wall

The chest wall includes muscles of respiration (primarily intercostal muscles) and bones (spine, rib, sternum).

The Heart: The Conduction System

The components of the conduction system include the sinoatrial (SA) node, AV node, AV bundle, right and left bundle branches, and the Purkinje fibers.

Energy Systems: Anaerobic Threshold/Lactate Threshold

The exercise intensity at which inadequate oxygen is delivered to the working muscles, resulting in energy production from the nonoxidative system, which creates an accumulation of lactate.

The Cardiovascular System consists of:

The heart and blood vessels (there are 60,000 miles of blood vessels in the body, which originate from and terminate at the heart).

The Cardiovascular System: The Heart

The heart has four chambers; the two upper chambers are the atria and the two lower chambers are the ventricles. The external deep grooves of the heart (called sulci) define the boundaries of the four chambers of the heart. The sulci also contain the major arteries and veins that provide circulation to the heart. The Heart has a base and an apex. The base consists mainly of the left atrium (LA), the right atrium (RA), and parts of the proximal portion of the large veins that enter the heart from behind.

The Heart: The Valves

The heart has four valves, whose function is to maintain blood flow in one direction: the atrioventricular valve (AV), semilunar valve, the right AV, and the left AV. There are also two semilunar valves in the heart: the pulmonic valve and the aortic valve.

The Heart: The Epicardium

The interior lining of the heart.

Respiratory System: The Larynx

The larynx contains the vocal cords, which contribute to speech and participate in coughing.

The Heart: The Left AV

The left AV valve has two cusps and is called the mitral or "bicuspid" valve. The mitral or bicuspid valve controls the blood flow between the LA and the LV.

Respiratory System: Lower Respiratory Tract

The lower respiratory tract begins at the trachea just below the larynx and includes the bronchi, bronchioles, and alveoli.

The Ventilatory Pump: Respiratory Muscles

The muscles of respiration are the only skeletal muscles essential to life (e.g. the diaphragm).

The Heart: Atrioventricular Bundle (bundle of His); Right and Left Bundle Branches; and the Purkinje Fibers

The next phase of the electrical impulse, which moves rapidly through the bundle of His, through the right and left bundle branches, and through the network of Purkinje fibers in the myocardium of both ventricles.

Respiratory System: The Pharynx

The pharynx is divided by the soft palate into the nasopharynx and the oropharynx.

The Heart: Sinoatrial Node (SA)

The place where the electrical impulse, which initiates cardiac contraction, begins.

Exercise Physiology

The study of the mechanism and effects of exercise on the body. Exercise physiology involves the scientific study of how exercise alters human systemic and cellular physiology both during and immediately after exercise, as well as in response to exercise training.

Energy Systems: Bioenergetics

The term "bioenergetics" refers to the body's ability to acquire, convert, store, and utilize energy.

The Heart: The Myocardium

The thickest layer of tissue in the heart. The myocardium is the "cardiac muscle".

Respiratory System: Upper Respiratory Tract

The upper respiratory tract, which includes the nose, sinuses, pharynx, and larynx, acts as a conduction pathway for the movement of air into the lower respiratory tract. The function of these structures is to purify, warm, and humidify air before it reaches the gas exchange unit.

Respiratory System: The Ventilatory Pump

The ventilatory pump consists of the chest wall, the respiratory muscles, and the pleural space.

The Ventilatory Pump: Pleura

The visceral (inner layer) and parietal (outer layer) pleura are thin membranes between the lung and the chest wall.

Muscular System

There are three major types of muscles in the body: skeletal, cardiac, and smooth.

Cardiovascular Exercise: Blood Pressure

There is a linear increase in SBP with increasing levels of exercise. Maximal values typically reach 190-220 mm Hg. SBP that fails to rise of fall with increasing workloads may signal a plateau or decrease in Q. DBP may decrease slightly or remain unchanged.