Module 5. Cardiovascular System and Blood

5 Types of Vessels • Arteries –Carry blood away from the heart to body tissues – Aorta and pulmonary trunk • Arterioles –Within a tissue or organ branch into numerous microscopic vessels called capillaries • Capillaries –Groups of capillaries reunite to form small veins: • Venules –Merge to form larger vessels: • Veins –Blood vessels that carry blood from the tissues back to the heart Blood reservoirs –Certain veins function as reservoirs b/c contain so much of blood

Structure of vasculature changes in response to different needs Blood flows down a pressure gradient

Vascular system possesses different mechanis ms for promoting continuous flow of blood to the capillaries

Blood pressure kidneys nervous system Stretch receptors cardiac walls

Blood pressure The kidneys, which regulate blood pressure by removing excess water (and salt) from the body. The higher the blood pressure, the more water is forced out in the nephrons; this reduces the volume of lymph and lowers the blood pressure. But it makes the blood thicker (thus more likely to clot).

Blood pressure The nervous system, which regulates heart rate. The level of CO2 in the blood is monitored in the carotid artery and the aorta and this information is sent to the cardiovascular centre in the brain. This sends impulses down either the accelerator nerve (of the sympathetic nervous system), which speeds up heart rate, or down the vagus nerve (of the parasympathetic nervous system), which slows it down. Both nerves lead to the sino-atrial node (SAN).

Regulation Of Blood Pressure • Baroreceptor reflex – changes in arterial pressure – medulla (brain stem) • Location : left and right carotid sinuses, aortic arch • Renin – angiotensin system (RAS) • Long – term adjustment of arterial pressure • Kidney - compensation • Endogenous vasoconstrictor – angiotensin I • Aldosterone release (adrenal cortex) • Stimulates sodium retention and potassium excretion by the kidney • Increases fluid retention and indirectly arterial pressure

Blood pressure Stretch receptors in the walls of the heart. When exercising, more blood is returned to the heart, causing the walls to stretch more than normal. The heart responds to this by beating faster and harder. Blood pressure that is too high (risk of thrombosis) or too low (risk of fainting) are undesirable.

Substances causing contraction in vascular smooth muscle Chemical Physiologic role Source Type NE Baroreceptor reflex Sympathetic Neural neurons Local Endothelin Paracrine Vascular Local, neural Local, neural Serotonin Platelet aggregation, endothelium Hormonal smooth muscle contraction Neurons, digestive Hormonal Substance P Pain, increased capillary tract, platelets local Vasopressin permeability Neurons, digestive Angiotensin Increase blood pressure tract II during hemorrhage Posterior pituitary Prostacyclin Increase blood pressure Plasma hormone Minimize blood loss from endothelium damaged vessels before coagulation

Substances that mediate vascular smooth muscle relaxation Chemical Physiologic role Source Type Nitric oxide Paracrine mediator Endothelium Local Atrial natriuretic Reduce blood pressure Atrial myocardium, Hormonal peptide brain Neural, hormonal Digestive secretion, relax Vasoactive smooth muscle Neurons intestinal peptide Increase blood flow Mast cells Local, systemic Histamine Epinephrine (b2) Enhance local blood flow Adrenal medulla Hormonal to skeletal muscle, heart, neural Acetylcholine Parasympathetic Local (muscarinic) liver neurons local Erection of clitoris, penis Bradykinin Multiple tissues Increase blood flow via Adenosine nitric oxide Hypoxic cells Enhance blood flow to match metabolism

All four tubes have the same driving pressure. Which tube has the greatest flow? The least flow? Why?

Vascular Resistance: opposition to blood flow due to friction b/w blood and the walls of blood vessels Depends on: • 1. size of lumen • 2. Blood viscosity • 3. Total blood vessel length













Measuring Pulse Pulse can be taken on several places • Temporal – side of forehead • Carotid – at the neck • Brachial–inner aspect of the forearm at the crease of the elbow • Radial- at the inner aspect of the wrist, above the thumb • Femoral-inner aspect of the upper thigh • Popliteal-behind the knee • Dorsalis pedis-at the top of the foot arch

Pulse • Adults have a range of 60 – 90 beats per minute • Children over 7 - a range of 70 – 90 beats per minute • Children age 1 – 7 have a range of 80 – 110 • Infants 100 – 160 beats per minute – Any variation or extremes in pulse rate should be reported immediately – Bradycardia is a pulse rate under 60 beats per minute – Tachycardia is a pulse rate over 100 beats per minute (except in children)

Measuring Pulse – Rhythm and Volume Rhythm • Rhythm refers to the regularity of the pulse or spacing of the beats. • An arrhythmia is an irregular or abnormal rhythm, usually caused by a defect in the electrical conduction pattern of the heart. (prefix a- means without) • Volume is the strength or intensity of the pulse. It is described as strong, weak, thready, or bounding

Factors that can change pulse rate Pulse will be increased by: • Exercise • Stimulant drugs • Excitement • Fever • Shock • Nervous tension Pulse will be decreased by: • Sleep • Depressant drugs • Heart disease • Coma • Physical training

Apical Pulse • Taken with a stethoscope at the apex of the heart. • The actual heartbeat is heard and counted. • An apical pulse is taken because of illness, hardening of the arteries, a weak and rapid pulse, or the patient is on heart medication. • Because infants and small children have a rapid pulse, an apical pulse is always done.

• When listening to the heart two sounds will be heard: lubb – dupp. • Each lubb – dupp counts as one heart beat. The sound is caused by the closing of the heart valves as blood flows through the chambers of heart. • If an abnormal sound is heard contact the physician.

Pathophysiology of Hypertension • There is increased in peripheral resistance and or cardiac output secondary to – increased sympathetic stimulation, – increased renal sodium reabsorption, – increased rennin angiotensin aldosterone system activity, – decreased vasodilation of the arterioles or – resistance to insulin action.

Primary vs. Secondary Hypertension • Most cases are called “primary” – No identifiable cause – Family history likely • ~5-10% are secondary – Caused by underlying conditions: • Kidney abnormalities • Tumor of adrenal gland • Congenital heart failure defects • Pregnancy • Certain medications

Complications • Renal Haemorrhage • Heart failure • Renal insufficiency and Failure • Cardiovascular Accident (CVA) • Transient Ischemic Attack (TIA) • Myocardial Infarction (MI) • Left Ventricular Hypertrophy

Classification • Optimal- systolic 120 mmhg diastolic 80 mmhg (120/80) • Normal- systolic 130 mmhg diastolic 85 mmhg (130/85) • High normal- systolic 130 to 139 mmhg diastolic 85 to 89 mmhg (130 • Stage 1- systolic 140 to 159 mmhg diastolic 90 to 99 mmhg • Stage 2- systolic 160 to 179 mmhg diastolic 100 to 109 mmhg • Stage 3- systolic 180 mmhg or higher diastolic 110 mmhg or higher



“Which patient has a better blood pressure, the patient with a blood pressure of 110/40 or the patient with a blood pressure of 90/60?

How to calculate your patients Mean Arterial Pressure. • MAP is defined as the average arterial blood pressure during a single cardiac cycle. • The reason that it is so important is that it reflects the haemodynamic perfusion pressure of the vital organs. • The simple way to calculate the patients MAP is to use the following formula: MAP = [ (2 x diastolic) + systolic ] divided by 3.

• The reason that the diastolic value is multiplied by 2, is that the diastolic portion of the cardiac cycle is twice as long as the systolic. • Or you could say, it takes twice as long for the ventricles to fill with blood as it takes for them to pump it out….. at a normal resting heart-rate. • A MAP of at least 60 is necessary to perfuse the coronary arteries, brain, and kidneys. Normal range is around 70 – 110 mmHg.

MAP • MAP = SBP + 2 (DBP) 3 • MAP = 83 +2 (50) 3 • MAP = 83 +100 3 • MAP = 183 3 • MAP = 61 mm HG

MAP • MAP = 1/3 (SBP – DBP) + DBP • MAP = 1/3 (83-50) + 50 • MAP = 1/3 (33) + 50 • MAP = 11 + 50 • MAP = 61 mm Hg

“Which patient has a better blood pressure, the patient with a blood pressure of 110/40 or the patient with a blood pressure of 90/60? 110/40 =MAP 63 90/60 = MAP 70

Even though there are many mechanisms for altering the radius of the vascular system, pressure still drops as blood moves further away from the heart.





• Movement Detection • Real Fuzzy Technology • Hypertension Risk Indication • Irregular Heartbeat Detection (IHB) • 90 memories • Average of last 3 readings • One-touch automatic operation • Latex-free patented universal cone cuff • Adaptor socket • Lifetime Calibration • Carrying bag

Lymphatic system blood passes through the capillaries, about 10% of its fluid leaks into the surrounding tissues. This is known as tissue fluid carries chemicals such as glucose and hormones to the cells and removes waste

Mechanism of tissue fluid formation The high blood pressure (‘hydrostatic pressure’)at the arteriole end of the capillary bed is much greater than the solute potential (‘osmotic pressure’) of the surrounding cells. Thus fluid is forced out of the capillary. at the venous end of the capillary bed, the blood pressure (‘hydrostatic pressure’) is low, whilst the solute potential (‘osmotic pressure’) of the blood is much stronger, since the blood is

Mechanism of tissue fluid formation The proteins in the blood are generally too big to leave the capillaries, whilst the blood cells (and their proteins) all remain behind. This causes some water to be returned to the blood in the capillaries by osmosis. The overall effect is to ensure that the tissue fluid is constantly on the move and so every cell in the body receives a fresh supply of nutrients.



Mechanism of tissue fluid formation Not all of the fluid forced out of the capillaries is returned by osmosis the lymphatic system collects this excess fluid and returns it to the circulatory system. lymph – flows through wider and wider vessels Lymph vessels contain valves to ensure a one-way flow Blood is returned in the vena cava, just outside the right These lymph vessels pass through small bean-shaped enlargements (organs) called lymph nodes, which produce one type of white blood cell (lymphocytes) which are an important source of antibodies and help us to fight infection. Examples of lymph nodes are the tonsils, the appendix, the spleen and the thymus gland





Tissue fluid build up or inactivity leads to fluid build up in the feet and ankles - pedal oedema common in elderly and long-distance flights blood being thicker - more likely to clot forming DVT or deep vein thrombosis.

Thank you for your attention

Blood and blood products

Objectives To be able to: • Discuss the blood ordering process • List the requirements for ordering red cell concentrate • Explain the potential risks associated with transfusion • Discuss different transfusion reactions and their management