Textbook Notes (362,879)
Canada (158,081)
HLTC22H3 (102)
Dan Silver (21)
Chapter 6

Chapter 6(1).docx

12 Pages
Unlock Document

University of Toronto Scarborough
Health Studies
Dan Silver

Chapter 6 Aging of the Internal Organ Systems Cardiovascular System Basic Anatomy and PhysiologyThe cardiovascular system is the bodys main transportation system and it send supplies like fluids nutrients hormones oxygen and antibodies to tissues in the body while at the same time removing waste products like carbon dioxide and hydrogen ionsCardiovascular system composed of the heart blood vessels and blood Blood is highly complex fluid composed of water red and white blood cells and platelets as well as nutrients like fat globules carbohydrates and proteins Also carries electrolytes to help maintain the acidbase balance and a host of other chemicals including hormones neurotransmitters and various other peptides necessary to regulate homeostasis cognition movement and every other function of the bodyHeart is the center of the circulatory system and is located behind the chest wall in a slightly canted position w the midsection somewhat to the left of the sternum or breastbone Enclosed in a fibrous sac called the pericardium The left and right sides of the heart each have two upper chambers atria which collect the blood and two lower chambers ventricles which pump blood to the lungs and the rest of the body The atria are thinwalled the walls of the ventricles are thicker and more muscular as they do the longdistance pumpingOxygenpoor blood is collected in the right atrium from the large veins of the body the superior and inferior vena cavaThen flows to the right ventricle and is pumped via the pulmonary arteries into the capillary system of the lungs for carbon dioxide and oxygen exchangeOxygenrich blood is sent via the pulmonary veins to the left atrium form where it flows to the left ventricle and is pumped out through the aortaThe blood from the aorta flows into the large arteries and then to the smaller arteries arterioles and capillaries The capillaries are so small that they are literally only one cell wide ensuring that all cells in the body have access to the bloodstreamFluid nutrients electrolytes hormones and other substances are exchanged in the capillariesVenules collect blood from the capillaries and move it into larger and larger veins until it finally reaches the superior and inferior vena cavaeThe walls of the arteries and veins are composed of flexible smooth muscle elastic fibres and collagenNerve cells in their walls regulate the expansion and contraction of the blood vessels helping to regulate blood pressure and blood flowFig 61 pg 122 Structure of the Heart and Blood Flow Through the ChambersValves from the atria to the ventricles and from the ventricles to the lungs and the rest of the body keep the blood flowing in one direction also control the timing and amount of blood flowThe right and left sides of the heart have no direct connection to one another and in a healthy heart oxygenpoor blood is never mixed w oxygenrich bloodThe timing of two pumps is exquisitely coordinated as a beat is started in the sinoatrial node in the upper right atriumOnce started the signal spread down the heart through the atrial myocardium to reach the atrioventricular nodeFrom there the impulse is conducted to the atrioventricular bundle and to the Purkinje fibres where it is sent on to both ventriclesAs the signal moves down contractionof the cardiac or heart muscle occurs and contraction of the heart is called systole and relaxation diastole asystole no heartbeatst 1loudest soundlub of a heartbeat is when the valves bw the atria and ventricles close and the ventricles contract nd 2softer beatdub occur w the closure of the valves bwthe ventricles and the large arteries pulmonary and aortaThe movement of arterial blood reflects the fact that it is being pumped rhythmically which creates a pulse felt in many different areas of the bodyOn the arteries reflect the heartbeat however veins do not have the benefit of the heart as a pump to help push the blood alongTo help keep blood moving up to the heart and to prevent it from pooling in the extremities some veins have valves and these valves consist of tissue inside the vein wall that extends into the vein forcing the blood to flow in only one direction toward the heart Venous blood can be seen in the distended veins of the hands and feet especially after exerciseEg if a person stands perfectly still for 15 minutes or more the venous pumps are less able to work and the normal flow of blood to the upper part of the body is lost which can cause faintingThe rate of blood flow is largely determined by physical demands on the bodyEg when exercising blood flow needs to be increased not only to deliver more oxygen and other nutrients but also to remove waste like lactic acidThus the heart alters its rate of pumping depending on both external and internal demandsStimulation to decrease and increase the heart rate is under the direction of the autonomic nervous system w the sympathetic nervous system increasing rate and strength of the heartbeat and to a lesser extent the parasympathetic system decreasing its rate and strength The value of the cardiovascular system to the functioning of every cell in the body is inestimable it serves as the conduit for communication among the organs AgeRelated ChangesMost studies show that a normal enlargement of the heart mass w age due to increase in size of the muscle cells or myocytes there is also a slowing of the electrical activity of the heart There is an increase in the amount of fat tissue around the sinoatrial node which interferes w the conduction system which can lead to an abnormally slow pulse called bradycardia Often treated by giving the person an artificial pacemaker that keeps the heart from falling below a preset rateChanges in the collagen in the middle layer of the large arteries of the body cause them to thicken and become stiffThese arteries widen and lengthen providing more space for blood which initially is helpful in controlling blood pressureOver time the larger size and rigidity of these large arteries require the heart to work harder eventually increasing blood pressureThere is a decreased ability of the smaller arteries to dilate or constrict when necessary however affecting the exercise tolerance of the older person as well as the bodys ability to cool or heat itselfThere capillaries become even narrower w age which impedes the normal flow of blood at the cellular level and there are minimal changes in the veins thus there is little impact on their normal functioning There is a decrease in cardiovascular responsiveness to exercise and a reduction in the max heart rate that can be reachedIt also takes longer for the heart rate and the blood pressure to return to normal resting levels following a stressful eventCardiovascular disease is very common in later life however and results in the majority of disability and deaths among older adultsDiseaseRelated Processes HypertensionBlood pressure is still considered normal at a reading of 13085 but at 14090 or greater it is classified as hypertensionHypertension is one of the most prevalent problems in the older populationSystolic hypertension increases throughout life whereas an elevation in diastolic pressure tends to level off in later yearsHigh blood pressure affects all the major arteries of the body and the organs and tissues that they serveHighly variable or liable blood pressure refers to the rapid expansion and contraction of the arteries Both conditions damage the collagen in the arterial walls making them stiffer and also damages the lining of the arteries contributing to artherosclerosis and increases the risk of heart and kidney disease etcOne of the dangers of hypertension is that damage from the disease occurs in the absence of symptomsIt has many causes including changes in kidney function obesity hormonal changes increased sensitivity to sodium and genetic propensities st 1 step in managing hypertension is to encourage lifestyle changes like weight control a decrease in sodium intake high calcium and magnesium intake st Diuretics are the 1 drugs of choice to control hypertension although they should be used cautiously as side effects can be severe including low blood pressure confusion impotence and depressionArteriosclerosis and Atherosclerosis
More Less

Related notes for HLTC22H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.