Cardiovascular system Part III

Vital Signs Vital signs indicate the efficiency of a persons circulatory system – respiratory rate and temperature are also vitals even though they do not directly evaluate the circulatory system.

Vital Signs Arterial Pulse: – When the arteries expand and recoil with each beat of the left ventricle. – Measure Pulse rate by taking the patients pulse at the radial or carotid arteries – Regular pulse rate should be between bpm – Pulse will be influenced by activity, postural changes, emotions or by where it is taken on the body.

Vital Signs Blood Pressure: – Pressure the blood exerts against the inner walls of the blood vessels. It is the force that keeps blood circulating throughout the body continuously. – Blood Pressure Gradient: The pressure of blood will move from an area of higher to lower concentrations. Pressure is higher in larger arteries and decreases as the arteries become arterioles and moves into veins.

Measuring Blood Pressure Systolic Pressure: – The pressure in the arteries as the ventricles contract. Diastolic Pressure: – The pressure in the arteries as the heart is relaxing between beats. When taking a blood pressure you will pump the blood pressure cuff up to approx 160 mmHg and as you let the air out the first time you hear the heart beat is the systolic pressure. When you can no longer hear the beat the last number you heard it at is the diastolic pressure. Normal blood pressure should be around 120/80.

Effects of Various Factors on BP Peripheral resistance: – The amount of friction encountered by the blood as it flows through the vessels. – This is increased by the constriction of blood vessels, especially by the arterioles and is increased by the bloods viscosity. – If PR increases then BP will also increase Age Weight Time of Day Body Position Emotion

Neural Factors Affecting BP Autonomic Nervous system: – The sympathetic system will respond to changes by: Vasoconstriction: Narrowing of blood vessels to increase venous return so that circulation can continue Vasodilation: occurs in muscles to increase blood flow to working muscles and to help with the loss of heat.

Renal Factors Affecting BP Kidneys: – Alter blood volume – As BP increases the kidneys allow water to leave the body through urine and blood volume decreases bringing the BP down as well – If arterial BP decreases the kidneys retain water to increase BP – RENIN: is an enzyme released into the blood by the kidneys which triggers a chemical reaction to create … – Angiotestin II: A vasoconstriction chemical

Factors Affecting BP Temperature: – Cold has a vasoconstriction effect – Heat has a vasodilating effect Chemicals: – Epinephrine: increases heart rate and BP – Nicotine: Increases BP and causes vasoconstriction – Alcohol and Histamine: cause vasodilation and decrease in BP Diet: – Low salt, saturated fats and cholesterol help to decrease your chances of getting … Hypertension: high BP – anything above 140/90

Variations in Blood Pressure Variations occur with age, weight, race, mood, physical activity and posture but the following are problems with the variations: – Hypotension – Orthostatic Hypotension – Chronic Hypotension – Circulatory Shock – Hypertension

Hypotension Low blood pressure Systolic is below 100 mm Hg Usually just reflects an individual difference and is not a problem associated with physical condition, length of life or wellness For example: a smaller size adult may have a lower systolic pressure because of their size not because of a physical defect.

Orthostatic Hypotension Temporary Hypotension that occurs when a person is changing position quickly such as: – Rising suddenly from a sitting or reclined position – Sitting up suddenly from a lying position Person experiences brief dizziness with these changes indicating the blood pressure has dropped quickly but then regains its normal pressure

Chronic Hypotension Hypotension that has become prolonged It is not explained by physicians but is thought to be due to poor nutrition and inadequate blood protein levels.

Circulatory Shock Blood vessels are inadequately filled and cannot circulate normally The most common cause of circulatory shock is dramatic loss of blood.

Hypertension Most common abnormality in BP Increase in BP where systolic is above 140 and diastolic is above 90 Called the “silent killer” Slowly strains the heart and damages the arteries The myocardium will become enlarged and the heart will weaken Affects more females than males and more African Americans than whites

Physiology of circulation Capillary Exchange: – The capillaries form a complex network among body cells so that nothing has to move too far to move in and out of a particular cell. Interstitial fluid: – The space between capillaries where substances diffuse through to move into the cells.

Routes of Getting Substances Across a Plasma Membrane 1. Directly through the plasma membrane – Substances must be lipid soluble (ex: gases) 2. Endocytosis/Exocytosis: – Lipid soluble substances leave the blood through epithelial cells within the vesicles. 3. Intercellular clefts: – Gaps between cells – Limited passage of fluids and small solutes – Most of our capillaries are like this EXCEPT the brain capillaries which contain tight junctions.

Routes of getting substances across a Plasma Membrane Fenestrated Capillaries: – Gives free passage of fluids and small solutes – Found where absorption is a priority/necessity or where any type of filtration occurs – Fenestra: Oval pore covered by a thin membrane which is very permeable – Protein molecules and blood cells are unable to leave or enter these capillaries

Developmental Aspects of the Cardiovascular system In the embryo the heart begins as a small tube and begins to beat and pump blood by the 4 th week of pregnancy. After the 7 th week of pregnancy the circulatory system begins to grow

Developmental Aspects of the Cardiovascular system Congenital Heart Defects: – Account for ½ of all infant deaths – Major causes are environmental factors and maternal infections or drug intake during the first 3 months of pregnancy – Ductus Arteriosus: When the ductus arteriosus does not fully close to complete the circulatory system after birth. Varicose Veins: – Venous valves weaken because of stress – Common in people who stand for long periods of time or are overly obese – Caused by a lack of venous return from inactivity or excessive pressure on the veins – Overworked veins may give way and twist or dilate permanently.

Developmental Aspects of the Cardiovascular system Thrombophlebitis: – Complication of varicose veins – Inflammation of the vein resulting from a clot forming in a vessel with poor circulation. – May turn into a … Pulmonary Embolism: – Clot detachment – This is life threatening as the clot may move up and block blood supply to the brain or heart.

Developmental Aspects of the Cardiovascular system Coronary Artery disease: – Blood vessels fill with fatty or calcified deposits causing them to become blocked. 30% of all adults have hypertension by age 50 Cardiovascular diseases result in ½ of all deaths over age 65 Most of this is due to poor diet or malnutrition!