Cardiovascular and pulmonary systems

Mid Session Quiz -25% Next week Will be on WebCT assessments From 9 am 25/8/08  5 pm 29/8/08 Multiple choice and matching Practice test (question types) up now, practice (content) on companion website for text. Covers all lecture, lab, text and reading materials from weeks 1-5 Time limit = ½ hour Grades will be released automatically Contact me if tech problems

Today Cardiovascular Pulmonary System review Acute adaptations to exercise Chronic adaptations to exercise Pulmonary

Major Cardiovascular Functions Delivers oxygen to active tissues Aerates blood returned to the lungs Transports heat, a byproduct of cellular metabolism, from the body’s core to the skin Delivers fuel nutrients to active tissues Transports hormones, the body’s chemical messengers

CV system Consists of; Blood ~ 5L or 8% body mass Heart- pump 55% plasma 45% formed elements (99%RBC, 1%WBC) Heart- pump Arteries- High pressure transport Capillaries- Exchange vessels Veins- Low pressure transport

NEED TO KNOW Heart LHS pic (Blue) right atrium = deoxygenated blood returning from the body  right ventricle  pumps it out the Pulmonary artery to lungs for aeration Left Aorta recieves blood from the lungs, goes through to the left ventricle where it is pumped throughout the body Atrioventricular valves ensure that blood movement is all one way RA RV = Tricuspid; LA LV = Bicuspid (Try before you buy) Lub Dub, Lub Dub LUB is simultaneous contraction of both atria; Dub is simultaneous contraction of both ventricles (70% of blood coming into atria actually flows into ventricels before contraction of atria)

http://www.guidant.com/condition/heart/heart_bloodflow.shtml See blood flow through the heart

Peripheral Vasculature Arteries Provides the high-pressure tubing that conducts oxygenated blood to the tissues Capillaries Site of gas, nutrient, and waste exchange Veins Provides a large systemic blood reservoir and conducts deoxygenated blood back to the heart WHY can we feel pulse through arteries and not veins? Arteries are pumping with heart beat. They contain layers of smooth muscle that constrict to regulate peripheral blood flow Arterial walls are too thick to allow gaseous exchange this must happen in the capilliaries Capillaries walls are thin enough to allow RBC through Once O2 out and wastes in, blood is transported back to the heart through the veins Veins  major structural component of the veins are their valves allows them to return the blood – milking- the way that we squeez a teat top to bottom

Valves prevent backflow of blood B- shows one way flow of blood through the veins Shows one way movement of the muscles assists with returning blood  Constriction of smooth muscle bands successively along vein “Milking” or the way a snake swallows something

Blood Pressure Systolic blood pressure Diastolic blood pressure Highest arterial pressure measured after left ventricular contraction (systole) e.g., 120 mm Hg Diastolic blood pressure Lowest arterial pressure measured during left ventricular relaxation (diastole) e.g., 80 mm Hg

BP changes with cardiac output- direct linear relationship, therefore as HR increases so does BP, systolic moreso than diastolic WHY??? Systolic is the force of the contraction, which needs to increase to pump the blood around, whereas diastolic (relaxation) would not change much due to exercise

Changes for different types of exercise- why do you think resistance exercise has higher SBP??? Sustained muscular force compresses peripheral arterioles which increases resistance Isometric exertion involves sustained muscle contraction against an immovable load or resistance with no change in length of the involved muscle group or joint motion. Get someone to push against a wall The result is a moderate increase in cardiac output, with little or no increase in oxygen consumption. Despite the increased cardiac output, blood flow to the noncontracting muscles does not significantly increase. This combination of vasoconstriction (the narrowing of blood vessels that restricts, or slows, the blood flow) and increased cardiac output causes a disproportionate rise in systolic, diastolic and mean blood pressures.

Heart Rate Regulation Cardiac muscle possesses intrinsic rhythmicity Without external stimuli, the adult heart would beat at about 100 bpm

Regulation of HR Sympathetic influence Parasympathetic influence Catecholamine (NE/E) Results in tachycardia Parasympathetic influence Acetylcholine Results in bradycardia Cortical influence Anticipatory heart rate Heart rate is controlled by autonomic nervous system (ANS) which maintains homeostasis in the body. These maintenance activities are primarily performed without conscious control or sensation. The ANS has far reaching effects, including: heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils, micturition - (the discharge of urine), and erection. Sympathetic influence - Sympathetic Nervous System (SNS) is always active at a basal level and becomes more active during times of stress. Its actions during the stress response comprise the fight-or-flight response. Activates when scared- quiz right now!! Catecholamine (NE/E) Norepinepherine is the neurotransmitter Results in tachycardia ( increased heart rate) Parasympathetic influence- works in a Complimentary way to sympathetic Acetylcholine (this system only uses acetylcholine (ACh) as its neurotransmitter) Results in bradycardia (slows heart rate) Cortical  anticipatory  heart rates before 12 min run!! Mild acttion sympathetic NS Sympathetic nervous system Promotes a "fight or flight" response, corresponds with arousal and energy generation, inhibits digestion: Diverts blood flow away from the gastro-intestinal (GI) tract and skin via vasoconstriction. Blood flow to skeletal muscles, the lung is not only maintained, but enhanced (by as much as 1200%, in the case of skeletal muscles). Dilates bronchioles of the lung, which allows for greater alveolar oxygen exchange. Increases heart rate and the contractility of cardiac cells (myocytes), thereby providing a mechanism for the enhanced blood flow to skeletal muscles. Dilates pupils and relaxes the lens, allowing more light to enter the eye. [edit] Parasympathetic nervous system Promotes a "rest and digest" response; promotes calming of the nerves return to regular function, and enhances digestion. Dilates blood vessels leading to the GI tract, increasing blood flow. This is important following the consumption of food, due to the greater metabolic demands placed on the body by the gut. The parasympathetic nervous system can also constrict the bronchiolar diameter when the need for oxygen has diminished. During accommodation, the parasympathetic nervous system causes constriction of the pupil and lens. The parasympathetic nervous system stimulates salivary gland secretion, and accelerates peristalsis, so, in keeping with the rest and digest functions, appropriate PNS activity mediates digestion of food and indirectly, the absorption of nutrients. Is also involved in erection of genitals, via the pelvic splanchnic nerves 2–4.

CV system during exercise Acute Adaptations Chronic adaptations Q: You have a set amount of blood in your system. What are the 2 ways that your body could send more blood around when you are exercising? Increase HR and Increase amt pumped with each beat (SV)

Heart rate At rest- 60-80 bpm Pre exercise- anticipatory response Trained athletes  lower (28-40 bpm) Pre exercise- anticipatory response Sympathetic nervous system release N/E and ephedrine Increases during exercise to steady state

Cardiovascular Dynamics Q = HR × SV (Fick Equation) Q: cardiac output HR: heart rate SV: stroke volume Excellent section text starts on page 352

Cardiac Output At Rest During Exercise Q = 5 L p/Min Trained RHR = 50 bpm, SV = 71 Untrained RHR = 70 bpm, SV = 100 During Exercise Untrained- Q = 22 000 mL p/min, MHR = 195 SV av 113 ml blood p/beat Trained- Q= 35 000 ml p/min, MHR = 195 SV av 179 ml blood p/beat Q = HR × SV At rest Q = same for trained/ untrained. RHR is lower for trained, therefore Sv is higher Reasons = heart muscle stronger- increased ventricular volume; and able to eject a greater volume with more power Slower HR allows Increased time for blood to fill up. During exercise blood flow increases in direct proportion to exercise intensity Training increases cardiac output – able to pump more per beat What do you get it you have higher cardiac output??? MORE OXYGEN!!! And MORE BLOOD GLUCOSE, as well as Better DISSIPATION OF LACTATE

Increases in Stroke Volume Increases in response to exercise Is ability to fill ventricles, particularly left ventricle And more forceful contraction to pump blood out Training adaptations left ventricle hypertrophy Increased blood volume Reduced resistance to blood flow Increased ability to fill ventricles during diastole, or when heart is relaxed, lood is more efficiently able to come on in More forceful contraction to pump blood out- Systolic contraction increases in force. Governed by neurohormonal influence Training adaptations

Training Adaptations: Heart Eccentric hypertrophy Slight thickening in left ventricle walls Increases left ventricular cavity size Therefore increases stroke volume LV is the one that pumps all of the blood out into the body

Cardiac output distribution At rest ¼  liver; 1/5  kidney 7 muscles During exercise Varies according to many conditions, but essentially, for intense exerciseall blood is shunted to the muscles and away from other tissues

Oxygen transport When arterial blood is saturated with oxygen : 1 litre blood carries 200 ml oxygen During exercise Q = 22L p /min = 4.4L oxygen per minute At rest Q = 5L p/ min = 1 L oxygen per minute 250 ml required at rest Remainder- oxygen reserves Increase in cardiac output directly increases their Vo2 max  as we can see, the concentration of oxygen in the blood remains the same, so only option to increase vo2 max is to increase cardiac output How to we increase cardiac output? Increase HR/SV. If we assume that their HR is at max, not able to change that. Therefore the change comes from the increase in stroke volume

Stroke Volume and Cardiac Output Exercise  increases stroke volume during rest and exercise Slight decrease heart rate Increase in cardiac output comes from increased stroke volume Decrease in HR not enough to counteract effects of increased SV

Heart Rate Elite athletes have a lower heart rate relative to training intensity than sedentary people

Saltin, 1969 Endurance athletes Increase in Stroke volume and decrease in heart rate due to 55 day training program Essentially intensity along x axis Endurance athletes Sedentary college BEFORE 55 day aerobic training program Sedentary college AFTER

4 training sessions can increase plasma volume by 20% Total Blood Volume * Plasma volume 4 training sessions can increase plasma volume by 20% *Increased RBC - Number of RBC increases, but due to increase in Plasma volume, concentration stays the same Blood plasma is the liquid component of blood, in which the blood cells are suspended. Plasma is a yellow colored liquid. Plasma is the largest single component of blood, making up about 55% of total blood volume. Carry more RBC  more haemoglobin Increased RBC These things start a whole chain of events that leads to further training adaptations

Blood Pressure Aerobic exercise reduces systolic and diastolic BP at rest and during exercise Particularly systolic Caused by decrease in catecholamines Another reason for exercise to be prescribed for those with hypertension Resistance training not recommended due to acute high BP it causes Particularly systolic- what is systolic? Why would exercise reduce this? Catecholamines- sympathetic nervous system hormones

Oxygen Extraction Training increases quantity of O2 that can be extracted during exercise Not only are you getting a greater amount of blood per minute, but you are getting a higher concentration of oxygen How would you therefore explain increased Vo2 Max in 2 people ?

Chronic Adaptations to Exercise- Chapter 10 Cardiovascular adaptations to training are extremely important for improving endurance exercise performance, and preventing cardiovascular diseases. The more important of these adaptations are,  Size of heart  ventricular volumes  total blood volume -  plasma volume -  red cell mass  systolic and diastolic blood pressures  maximal stroke volume  maximal cardiac output  extraction of oxygen

Factors Affecting Chronic adaptations Initial CV fitness Training: Frequency- 3 x p/week Only slightly higher gains for 4 or 5 times p/week Intensity Most critical Minimum is 130/ 140 bpm = (av) 50-55% Vo2 max/ 70% HR max Higher = better Time Or duration- 30 min is minimum Type Specificity In terms of vo2 max initial- some have higher due to genetics etc Freq. – slight gains in vo2 max that come from training those extra 2 days are not worth the potential injury Intensity Time- does 2 x 15min = 30 min?? Research inconclusive, varies for each type of activity Improvements within a few weeks Continues on in chapter 13

Pulmonary System

Pulmonary Structure and Function The ventilatory system Supplies oxygen required in metabolism Eliminates carbon dioxide produced in metabolism Regulates hydrogen ion concentration [H+] to maintain acid-base balance 3 main functions http://health.howstuffworks.com/adam-200022.htm GAS EXCHANGE ANIMATION

Breathing At rest Air in  Trachea- humidified and brought to body temperature  divides into 2 branches lungs Lungs hold 4-6 litres of ambient air- huge surface area 300 million alveoli 250 ml oxygen in and 200 ml Carbon dioxide out each minute Main idea of the lungs is that they are a very compact and convenient area for gas exchange Probably read in the text that, although lungs weigh only about 1 kg, if spread out, would cover the same area as ½ a tennis court, or 1 whole badminton court Alveoli Where all the action happens!! Latin for “little cavity” Alveoli is completely intertwined with capillaries; and the walls of the alveoli and the cappilaries are both thin enough to allow oxygen and carbon dioxide to travel through the walls

Diaphragm contracts (flattens) Moves downward (10cm) Thoracic volume Inspiration Ribs rise Diaphragm contracts (flattens) Moves downward (10cm) Thoracic volume Air in lungs expands Pressure to 5 mm Hg below atmospheric pressure Difference between outside air and lungs = air is sucked in until pressure inside and out is the same Lungs do not contain muscle that contracts them (Like the heart) Instead, diaphragm controls thoracic volume and subsequent pressure. Ribs rise due to contraction of intercostal muscles

Expiration Ribs move back down Diaphragm relaxes (rises) Thoracic volume Pressure Difference between outside air and lungs = air is pushed out until pressure inside and out is the same Ribs move down due to relaxation intercostal muscles (breathing at rest) Feel that pressure increase when you are swimming underwater, holding breath Expiration during exercise is far more forceful due to the actions of the intercostal and abdominal muscles  more forceful expiration to eliminate Co2  also increased differences in pressure that results in increased oxygen being drawn in. What do you notice about the arrows on both of these pages?? Up down up down or down up down up Can simplify and say that when diaphragm goes down, air goes in and when diapraghm goes up, air goes out

Pulmonary system during exercise

Lung Volumes Static lung volume tests Dynamic lung volume tests Evaluate the dimensional component for air movement within the pulmonary tract, and impose no time limitation on the subject Dynamic lung volume tests Evaluate the power component of pulmonary performance during different phases of the ventilatory excursion Static= space available Dynamic = power / force behind expiration

Spirometry Static and Dynamic lung volumes are measured using a spirometer

Static Lung Volumes Page 146 of text TV- breath normally- this is your tidal volume IRV- breath normally, breath out normally, then breath in as much as you can. This is inspiratory reserve- it is the max capacity for air in the lungs. Can be 2-3 litres Breath normally ERV- Breath in normally, then breath out as much as you can – average one litre of air FVC (Forced vital capacity) = maximum you can force in and out of lungs IRV + ERV RLV- residual- the lungs are never empty- RLV is the amount left in them after forced expiration. Usually one litre\ TLC- Total lung capacity = amount you can force in/ out + residual volume left- TLC = IRV + ERV + RLV

Dynamic lung volumes Depend on Volume of air moved and the Speed of air movement FEV/FVC ratio MVV Remember dynamic is looking at the power behind what you can breath

FEV/FVC Ratio Forced Expiratory Volume Forced Vital Capacity Ratio tells us the speed at which air can be forced out of lungs Normal = 85% FVC can be expired in 1 second. FVC= max amount expired after maximal inspiration Ususally used in the diagnosis of obstructive lung diseases such as emphysema, asthma etc

Maximal Voluntary Ventilation Breath as hard and fast as you can for 15 seconds Multiply by 4 And you have Maximal Voluntary Ventilation MVV- Males:140-180 Litres Females: 80-120 Litres Elite athletes up to 240 Litres

Minute Ventilation At Rest 12 breaths per minute Tidal volume = 0.5L per breath = 6 Litres of air breathed p/min During Exercise 50 breaths p/ minute Tidal Volume = 2 L per breath = 100L p/min

Alveolar Ventilation Minute ventilation is just total amount of air Alveolar ventilation refers to the portion of minute ventilation that mixes with the air in the alveolar chambers Minute ventilation minus anatomical dead space (150-200 ml)- the air that is in the trachea, bronchi etc Anatomical dead space = air that isn’t in alveoli and is therefore no good at all as is not involved with gas exchange in the blood

Alveolar Ventilation = Minute ventilation (TV x breathing rate) – dead space

Gas exchange

Gas Exchange in the Body The exchange of gases between the lungs and blood, and their movement at the tissue level, takes place passively by diffusion

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Oxygen Transport in the Blood Combined with hemoglobin — In loose combination with the iron-protein hemoglobin molecule in the red blood cell Each Red Blood Cell contains 250 million hemoglobin molecules Each one can bind 4 oxygen molecules

CO2 Transport in Blood In physical solution As carbamino compounds (~7%) dissolved in the fluid portion of the blood As carbamino compounds (~20%) in loose combination with amino acid molecules of blood proteins As bicarbonate (~73%) combines with water to form carbonic acid

Regulation of Pulmonary Ventilation Temp- increse in body temp directly stimulates neurons to fire to tell the diaphragm and intercostal muscles to act

Regulation at rest: Plasma Pco2 and H+ Concentration The partial pressure of CO2 provides the most potent respiratory stimulus at rest [H+] in the cerebrospinal fluid bathing the central chemoreceptors provides a secondary stimulus driving inspiration If you hold your breath, the thing that forces you to breath again is the high Co2

Ventilatory Regulation During Exercise Chemical control Po2 Pco2 [H+] Nonchemical control Neurogenic factors Cortical influence Peripheral influence During exercise Remember oxygen debt and deficit? Start exercise- rapid increase in breaathing rate- 1st 20 seconds = plateau Stop exercise- fairly rapid slowing down, but remains at 40% of what was happening during exercise Think about what happened in lactate threshold test Chemical- levels of these three prompt action Co2 is by product of atp production; Hydrogen is produced in glycolysis  Kreb’s cycle Nonchemical- Neural control- brain tells the neurons to tell the diaphragm and intercostals to relax/ contract  inflate Cortical- anticipatory effect Peripheral- respiration increases because the joints/muscles are moving  receptors

Ventilation in steady rate exercise Of oxygen ( V E/ V O2) Quantity of air breathed per amount of oxygen consumed Remains relatively constant during steady-rate exercise- 25 L air breathed per 1L o2 consumed at 55% Vo2 max Of carbon dioxide ( V E/ V CO2) Remains relatively constant during steady-rate exercise

Ventilatory Threshold The point at which pulmonary ventilation increases disproportionately with oxygen uptake during graded exercise The excess ventilation relates to the increased CO2 production associated with buffering of lactic acid Have to increase ventilation to increase amount of oxygen to enable aerobic respiration

Pulmonary adaptations to Exercise

Goals of aerobic training

Adaptations to Maximal exercise Minute ventilation increases Increased oxygen uptake Pulmonary adaptations often some of the first to be noticed basically reduced feeling of breathlessness in untrained 20 weeks of training increased pulmonary muscle strength by 16%  intercostals and diaphragm better able to create pressure differences which result in inspiration/ expiration

Submaximal Exercise Ventilatory equivalent for oxygen Ventilatory muscles stronger Ventilatory equivalent for oxygen ( V E/ V O2) reduces indicates breathing efficiency This leads to Reduced fatigue in ventilatory muscles O2 that would have been used by those muscles can be used by skeletal muscle. Ventlatory equivalent for oxygen is the ratio of the amount of air breathed to the amount of oxygen obtained

Pulmonary Adaptations Increased tidal volume Decreased breathing frequency Increased time between breaths (Increased time for oxygen to get into bloodstream) Therefore less oxygen in exhaled air

Summary Need to know Cardiac and pulmonary Structure and Function Veins/arteries/cappilaries Flow of blood through the heart Alveoli bronchii etc Flow of inspired air and pulmonary exchange Acute adaptations to exercise Chronic adaptations to exercise