Cardiovascular System Flashcards
Duty of blood
Transports everything that must be carried from one place to another, including
- Nutrients
- Oxygen
- Wastes
- Hormones
- Body heat
- Acid base and electrolyte balance
Components of blood
▪ Formed elements (living cells) – 45% known as hematocrit as Erythrocytes sink to the bottom
▪ Plasma (nonliving fluid matrix) – 55%
▪ Buffy Coat (less than 1%) contains leukocytes and platelets – thin, whitish layer between the erythrocytes and plasma
Physical characteristics of blood
- Sticky, opaque fluid
- Heavier and thicker than water (5 times)as blood contains solid components such as plasma proteins, electrolytes
- Color range: oxygen-rich blood is scarlet red, oxygen-poor blood is dull red or purple
- Metallic, salty taste
- Blood pH is slightly alkaline, 7.35 – 7.45 pH
- Temperature 38 degrees
- Blood viscosity contributes to blood flow resistance. Blood viscosity increases with high altitudes, decreased blood temperature and increased proportion of red blood cells
Composition of plasma
90% water , 8% plasma proteins
Straw-coloured fluid
Dissolved substances (2%): nutrients, salts (electrolytes), respiratory gases, hormones, plasma proteins, waste products
electrolytes such as sodium, potassium, chloride, magnesium and calcium, maintain fluid and electrolyte balance
Describe and name the plasma proteins
- Most abundant solutes in plasma
- Most are made by the liver
- 3 types – fibrinogen, albumin and globulin
- Albumin – an important blood buffer and contributes to osmotic pressure
- Fibrinogen - Clotting proteins – help to stem blood loss when a blood vessel is injured
- Globulin - Antibodies – help protect the body from pathogens
Describe components of the formed elements
Each element starts as haematopoietic stem cell which morphs into another type of morph cell which turns into a blast cell. Depending on which growth factors and hormones influence them, these cells turn into either:
Erythrocytes – red blood cells (RBCs)
Leukocytes – White blood cells (WBCs)
Platelets – Cell fragments
Explain Erythrocytes
Main function is to carry oxygen and carry C02 away
Difference to other blood cells –
- Anucleate (no nucleus)
- Contains few organelles, no mitochondria
- Shaped like biconcave discs – increases surface area, flexibility is increased, restricts the cell’s life span to 120 days
- 7-8 micro mm
What is haemoglobin
- Binds oxygen, each can bind 4 oxygen molecules
- Transports C02 back to lungs
- Each erythrocyte has 250million haemoglobin molecules
- Normal blood contains 12-18g of haemoglobin per 100ml of blood
Describe Leukocytes
- Crucial in body’s defence against disease
- Complete cells, with nucleus and organelles
- Able to move into and out of blood vessels (diapedesis)
- Respond to chemicals released by damaged tissues (known as positive chemotaxis)
- Move by amoeboid motion
- 4,800 to 10,800 WBCs per mm3 of blood, for 1 wbc there are 700 rbc
- Produce antibodies, play role in allergic reactions, inflammatory response, destroy parasites
What are platelets
▪ Fragments of megakaryocytes (multinucleate cells)
Small, irregularly shaped, non-nucleated
Important in haemostasis
▪ Needed for the clotting process
▪ Normal platelet count is 300,000 platelets per mm3 of blood
Positioning and size of heart
Size of a human fist, weighs less than a pound
Located in the thoracic cavity, in the inferior mediastinum
▪ Apex is directed toward left hip and rests on the diaphragm 5th rib ▪ Base points toward right shoulder
Coverings of the heart
Pericardium – a double walled sac
- Fibrous pericardium is loose and superficial
- Serous membrane is deep to the fibrous pericardium and contains two layers
- Serous fluid fills the space between the layers of pericardium called the pericardial cavity
What are the walls of the heart
- Epicardium ▪ Outside layer; the visceral pericardium, the coronary artery lies here
- Myocardium ▪ Middle layer ▪ Mostly cardiac muscle, 2/3 of the heart muscle, contracts
- Endocardium ▪ Inner layer known as endothelium
What are the chambers of the heart and explain their duties
Atria (right and left) – superior - Receiving chambers - Assist with filling the ventricles - Blood enters under low pressure Ventricles (right and left) - Discharging chambers - Thick walled pumps of the heart - During contraction, blood is propelled into circulation
Name the septum and their duties
Interatrial septum
- Separates the two atria longitudinally
Interventricular septum
- Separates the two ventricles longitudinally
Explain the double pump
- Arteries carry blood away from the heart
- Veins carry blood toward the heart
Double pump - Right side works as the pulmonary circuit pump
- Left side works as the systemic circuit pump
What is the pulmonary Circuit pump
▪ Blood flows from the right side of the heart to the lungs and back to the left side of the heart
▪ Blood is pumped out of right side through the pulmonary trunk, which splits into pulmonary arteries and takes oxygen-poor blood to lungs
▪ Oxygen-rich blood returns to the heart from the lungs via pulmonary veins
What is the Systemic Circulation pump
▪ Oxygen-rich blood returned to the left side of the heart is pumped out into the aorta
▪ Blood circulates to systemic arteries and to all body tissues
▪ Left ventricle has thicker walls because it pumps blood to the body through the systemic circuit
▪ Oxygen-poor blood returns to the right atrium via systemic veins, which empty blood into the superior or inferior vena cava
Explain the heart valves
Allow blood to flow in only one direction, to prevent backflow
▪ Atrioventricular (AV) valves—between atria and ventricles ▪ Left AV valve: bicuspid (mitral) valve ▪ Right AV valve: tricuspid valve
▪ Open during heart relaxation, when blood passively fills the chambers ▪ Closed during ventricular contraction
▪ Semilunar valves—between ventricle and artery ▪ Pulmonary semilunar valve ▪ Aortic semilunar valve
Closed during heart relaxation ▪ Open during ventricular contraction
Valves open and close in response to pressure changes in the heart
Components of blood supply to circulatory system
▪ Coronary arteries (right and left) —branch from the aorta to supply the heart muscle with oxygenated blood, filled when heart is relaxed
▪ Cardiac veins—drain the myocardium of blood
▪ Coronary sinus—a large vein on the posterior of the heart; receives blood from cardiac veins
Blood empties into the right atrium via the coronary sinus
Unifying regulatory systems are
- Autonomic nervous system – decrease or increase heart rate
- Intrinsic conduction system, or the nodal system
- Sets the heart rhythm ▪ Composed of special nervous tissue ▪ Ensures heart muscle depolarization in one direction only (atria to ventricles) ▪ Enforces a heart rate of 75 beats per minute
Components of the intrinsic conduction system
▪ Sinoatrial (SA) node - Located in the right atrium ▪ Serves as the heart’s pacemaker
▪ Atrioventricular (AV) node is at the junction of the atria and ventricles
▪ Atrioventricular (AV) bundle (bundle of His) and bundle branches are in the interventricular septum
▪ Purkinje fibers spread within the ventricle wall muscles
Steps of contraction coordination
- The sinoatrial node (SA node) starts each heartbeat
- Electrical impulses carried to left atrium
- Atria contract
- At the AV node, the impulse is delayed briefly
- Impulse travels through the AV bundle, bundle branches, and Purkinje fibers ▪ Ventricles contract; blood is ejected from the heart
Explain Tachycardia and Bradycardia
▪ Tachycardia—rapid heart rate, over 100 beats per minute ▪ Bradycardia—slow heart rate, less than 60 beats per minutes
Explain the ECG
▪ Recording of electrical activity of the heart
Three waves –
1. P wave – small, signal depolarization, firing of sinoatrial node
2. QRS complex – depolarization of ventricles, contraction of the ventricles
3. T wave – ventricle relax, repolarization
▪ Illustrates what is happening electrically in the atria and ventricles when the depolarize (contract) and relax (repolarize)
What are systole and diastole
- Systole = contraction (1/3 of the cycle)
- Diastole = relaxation (2/3 of the cycle)
What are the cardiac cycle steps
- Atrial Diastole – ventricular filling
- Atrial Systole
- Isovolumetric contraction
- Ventricular systole (ejection phase)
- Isometric relaxation
Explain the heart sounds
▪ Often described a “lub” and “dup” sounds - Correspond with closing of heart valves
Heart murmurs are abnormal or unusual heart sounds ▪ Reflect turbulent blood flow
▪ Lub—longer, louder heart sound caused by the closing of the AV valves
▪ Dup—short, sharp heart sound caused by the closing of the semilunar valves at the end of ventricular systole
What is cardiac output and Stroke volume
Cardiac Output (CO)
▪ Amount of blood pumped by each side (ventricle) of the heart in 1 minute
Stroke volume (SV)
▪ Volume of blood pumped by each ventricle in one contraction (each heartbeat) ▪ About 70 ml of blood is pumped out of the left ventricle with each heartbeat
What is heart rate and how is it calculated
▪ Cardiac output is the product of the heart rate (HR) and the stroke volume (SV) ▪ CO = HR × SV ▪ CO = HR (75 beats/min) × SV (70 ml/beat) ▪ CO = 5250 ml/min = 5.25 L/min
How is stroke volume regulated
how much cardiac muscle is stretched
▪ The more the cardiac muscle is stretched, the stronger the contraction
▪ Venous return is the important factor influencing the stretch of heart muscle
3 Factors modifying basic heart rate
- Neural (ANS) controls
▪ Sympathetic nervous system speeds heart rate
▪ Parasympathetic nervous system, primarily vagus nerve
fibers, slow and steady the heart rate - Hormones and ions
▪ Epinephrine and thyroxine speed heart rate
▪ Excess or lack of calcium, sodium, and potassium ions
also modify heart activity - Physical factors
▪ Age, gender, exercise, body temperature influence
heart rate
What are blood vessels and what are they called
Blood vessels form a closed vascular system that transports blood to the tissues and back to the heart
▪ Vessels that carry blood away from the heart - Arteries and arterioles
▪ Vessels that play a role in exchanges between tissues and blood - Capillary beds
▪ Vessels that return blood toward the heart - Venules and veins
Describe three tunic layers
- Tunica intima forms a friction-reducing lining ▪ Allows blood to flow smoothly. Endothelium
- Tunica media ▪ Smooth muscle and elastic tissue and collagen ▪ Controlled by sympathetic nervous system to dilate lumen or decrease opening. Allows blood flow to certain tissue and decreases flow to some.
- Tunica externa forms protective outermost covering ▪ Mostly fibrous connective tissue ▪ Supports and protects the vessel
Describe arteries and aortas
Arteries have a heavier, stronger, stretchier tunica media than veins to withstand changes in pressure
Aortas – largest artery, leaves heart and branches into small arteries that turns into arteriole
Describe veins and venules
Veins have a thinner tunica media than arteries and operate under low pressure ▪ Veins also have valves to prevent backflow of blood ▪ Lumen of veins is larger than that of arteries ▪ Skeletal muscle “milks” blood in veins toward the heart
Venules form to make the largest veins, superior and inferior vena cava
Describe capillaries
Only one cell layer thick (tunica intima) ▪ Allow for gas exchanges between blood and tissue ▪ Form networks called capillary beds that consist of: ▪ A vascular shunt ▪ True capillaries ▪ Blood flow through a capillary bed is known as microcirculation
Describe True capillaries
▪ Branch off a terminal arteriole ▪ Empty directly into a postcapillary venule
Major arteries of Systemic circulation
Aorta - ▪ Largest artery in the body Regions:
▪ Ascending aorta—leaves the left ventricle
▪ Aortic arch—arches to the left ▪ Thoracic aorta—travels downward through the thorax ▪ Abdominal aorta—passes through the diaphragm into the abdominopelvic cavity
▪ Arterial branches of the ascending aorta - Right and left coronary arteries serve the heart
Arterial branches of the aortic arch
▪ Brachiocephalic trunk splits into the: ▪ Right common carotid artery ▪ Right subclavian artery
▪ Left common carotid artery splits into the: ▪ Left internal and external carotid arteries, serves the brain
▪ Left subclavian artery branches into the: ▪ Vertebral artery ▪ In the axilla, the subclavian artery becomes the axillary artery → brachial artery → radial and ulnar arteries
Digital arteries
Arterial branches of the thoracic aorta
▪ Intercostal arteries supply the muscles of the thorax wall
▪ Other branches of the thoracic aorta supply the:
▪ Lungs (bronchial arteries) ▪ Esophagus (esophageal arteries) ▪ Diaphragm (phrenic arteries)
Arteries of the head
Internal carotid artery – serves the brain
External carotid artery – serves skin and muscles of head and neck
Arterial branches of the abdominal aorta
▪ Celiac trunk is the first branch of the abdominal aorta. Three branches are: 1. Left gastric artery (stomach) 2. Splenic artery (spleen) 3. Common hepatic artery (liver)
▪ Superior mesenteric artery supplies most of the small intestine and first half of the large intestine
▪ Left and right renal arteries (kidney)
▪ Left and right gonadal arteries ▪ Ovarian arteries in females serve the ovaries ▪ Testicular arteries in males serve the testes
▪ Lumbar arteries serve muscles of the abdomen and trunk
▪ Inferior mesenteric artery serves the second half of the large intestine
Major Veins of systemic circualtion
▪ Superior vena cava and inferior vena cava enter the right atrium of the heart
▪ Superior vena cava drains the head and arms ▪ Inferior vena cava drains the lower body
Veins draining into the superior vena cava
▪ Radial and ulnar veins → brachial vein → axillary vein ▪ Cephalic vein drains the lateral aspect of the arm and empties into the axillary vein ▪ Basilic vein drains the medial aspect of the arm and empties into the brachial vein ▪ Basilic and cephalic veins are joined at the median cubital vein (elbow area)
▪ Subclavian vein receives: ▪ Venous blood from the arm via the axillary vein ▪ Venous blood from skin and muscles via external jugular vein
▪ Vertebral vein drains the posterior part of the head
▪ Internal jugular vein drains the dural sinuses of the brain
▪ Left and right brachiocephalic veins receive venous blood from the: ▪ Subclavian veins ▪ Vertebral veins ▪ Internal jugular veins
▪ Brachiocephalic veins join to form the superior vena cava → right atrium of heart
▪ Azygos vein drains the thorax
Veins draining into the inferior vena cava
▪ Anterior and posterior tibial veins and fibial veins drain
the legs
▪ Posterior tibial vein → popliteal vein → femoral vein →
external iliac vein
▪ Great saphenous veins (longest veins of the body)
receive superficial drainage of the legs
▪ Each common iliac vein
▪ Right gonadal vein drains the right ovary in females and
right testicle in males
▪ Left gonadal vein empties into the left renal vein
▪ Left and right renal veins drain the kidneys
▪ Hepatic portal vein drains the digestive organs and
travels through the liver before it enters systemic
circulation
▪ Left and right hepatic veins drain the liver
Arterial supply of the brain
▪ Internal carotid come from neck and temporal bone and arteries divide into: Anterior and middle cerebral arteries - supply most of the cerebrum
▪ Vertebral arteries join once within the skull to form the basilar artery ▪ Basilar artery serves the brain stem and cerebellum.
▪ Posterior cerebral arteries form from the division of the basilar artery ▪ These arteries supply the posterior cerebrum
▪ Anterior and posterior blood supplies are united by small communicating arterial branches
Name the brain arteries
Internal carotid artery Middle carotid artery Anterior communicating artery Anterior cerebral artery Posterior communicating artery Posterior cerebral artery Basilar artery Vertebral artery
Hepatic portal circulation
formed by veins draining the digestive organs, which empty into the hepatic portal vein ▪ Digestive organs ▪ Spleen ▪ Pancreas
Duty of hepatic portal vein
carries blood to the liver,
where it is processed before returning to systemic
circulation
Describe vital signs and arterial pulse
Vital signs
▪ Measurements of arterial pulse, blood pressure,
respiratory rate, and body temperature
Arterial pulse
▪ Alternate expansion and recoil of a blood vessel wall
(the pressure wave) that occurs as the heart beats
▪ Monitored at pressure points in superficial arteries,
where pulse is easily palpated
▪ Pulse averages 70 to 76 beats per minute at rest, in a
healthy person
Body sites where pulse is most easily palpated
Superficial temporal artery Facial artery Common carotid artery Brachial artery Radial artery Femoral artery Popliteal artery Posterior tibial artery Dorsalis pedis artery
What is blood pressure
▪ The pressure the blood exerts against the inner walls of the blood vessels ▪ The force that causes blood to continue to flow in the blood vessels (in arteries supplied by aorta)
What is the blood pressure gradient
When the ventricles contract:
▪ Blood is forced into elastic arteries close to the heart
▪ Blood flows along a descending pressure gradient
▪ Pressure decreases in blood vessels as distance from
the heart increases
▪ Pressure is high in the arteries, lower in the capillaries,
and lowest in the veins
How to measure blood pressure
▪ Two arterial blood pressures are measured
▪ Systolic—pressure in the arteries at the peak of
ventricular contraction
▪ Diastolic—pressure when ventricles relax
▪ Auscultatory method is an indirect method of
measuring systemic arterial blood pressure, most often
in the brachial artery
What factors effect blood pressure
▪ Arterial blood pressure (BP) is directly related to
cardiac output and peripheral resistance
▪ Cardiac output (CO; the amount of blood pumped out of
the left ventricle per minute)
▪ Peripheral resistance (PR; the amount of friction blood
encounters as it flows through vessels)
BP = CO × PR
Effects of neural factors on blood pressure
the autonomic nervous system
▪ Parasympathetic nervous system has little to no effect
on blood pressure
▪ Sympathetic nervous system promotes vasoconstriction
(narrowing of vessels), which increases blood pressure
Effects of renal factors on blood pressure
▪ Kidneys regulate blood pressure by altering blood
volume
▪ If blood pressure is too high, the kidneys release water
in the urine
▪ If blood pressure is too low, the kidneys release renin to
trigger formation of angiotensin II, a vasoconstrictor
▪ Angiotensin II stimulates release of aldosterone, which
enhances sodium (and water) reabsorption by kidneys
Effects of temperature on blood pressure
▪ Heat has a vasodilating effect
▪ Cold has a vasoconstricting effect
Effects of chemicals on blood pressure
▪ Various substances can cause increases or decreases
in blood pressure
▪ Epinephrine increases heart rate and blood pressure
Effects of diet on blood pressure
▪ Commonly believed that a diet low in salt, saturated
fats, and cholesterol prevents hypertension (high blood
pressure)
What is the normal human range for blood pressure
▪ Systolic pressure ranges from 110 to 140 mm Hg
▪ Diastolic pressure ranges from 70 to 80 mm Hg
What is hypotension
▪ Low systolic (below 100 mm Hg)
▪ Often associated with illness
▪ Acute hypotension is a warning sign for circulatory
shock
What is hypertension
▪ Sustained elevated arterial pressure of 140/90 mm Hg
▪ Warns of increased peripheral resistance
what are the four processes of capillary exchange of gases and nutrients
▪ Substances take various routes entering or leaving the
blood
1. Direct diffusion through membranes
2. Diffusion through intercellular clefts (gaps between
cells in the capillary wall)
3. Diffusion through pores of fenestrated capillaries
4. Transport via vesicles
Fluid movement out of or into a capillary depends on
what?
- Blood pressure forces fluid and solutes out of
capillaries - Osmotic pressure draws fluid into capillaries
Fluid pressures at capillary bed
▪ Blood pressure is higher than osmotic pressure at the
arterial end of the capillary bed
▪ Blood pressure is lower than osmotic pressure at the
venous end of the capillary bed
▪ Thus, fluid moves out of the capillary at the beginning
of the bed and is reclaimed at the opposite (venule)
end
Name and explain some heart diseases
Diseases of the arteries ▪ Aneurysms ▪ Coronary artery disease Heart attack ▪ Myocardial infarction Heart murmurs ▪ Caused by one of the heart valves not closing properly Diseases ending in –itis ▪ Pericarditis ▪ Myocarditis ▪ Endocarditis Heart failure ▪ Occurs when the heart cannot adequately pump blood
Name the arteries that supply the lower limb (8)
Common iliac artery External iliac artery Femoral artery Popliteal artery Anterior tibial artery Posterior tibial artery Dorsalis pedis artery Arcuate artery
Name the arteries that supply the upper limb (8)
Subclavian artery Axillary artery Brachial artery Radial artery Ulnar artery Deep palmar arch Superficial palmar arch Digital arteries
Name the arteries of the head and trunk (12)
Internal carotid artery External carotid artery Common carotid arteries Vertebral artery Subclavian artery Brachiocephalic trunk Aortic arch Ascending aorta Coronary artery Thoracic aorta (above diaphragm) Celiac trunk Abdominal aorta
Name the veins of the upper limb
Subclavian vein Axillary vein Cephalic vein Brachial vein Basilic vein Median cubital vein Ulnar vein Radial vein Digital veins
Name veins of the lower limb
External iliac vein Femoral vein Great saphenous vein Popliteal vein Posterior tibial vein Anterior tibial vein Small saphenous vein Dorsal venous arch Dorsal metatarsal veins
Veins of the head and trunk
Dural venous sinuses External jugular vein Vertebral vein Internal jugular vein Right and left brachiocephalic veins Superior vena cava Great cardiac vein
Describe cardiac contractions step - Atrial Diastole
1. ventricular filling Heart is relaxed Pressure in heart is low Atrioventricular valves are open Blood flows passively into the atria and into ventricles Semilunar valves are closed
Describe cardiac contractions step - Atrial Systole
▪ Ventricles remain in diastole
▪ Atria contract
▪ Blood is forced into the ventricles to complete ventricular filling
Describe cardiac contractions step - Isovolumetric contraction
▪ Atrial systole ends; ventricular systole begins
▪ Intraventricular pressure rises
▪ AV valves close
▪ For a moment, the ventricles are completely closed chambers
Describe cardiac contractions step - Ventricular Systole
▪ Ventricles continue to contract ▪ Intraventricular pressure now surpasses the pressure in the major arteries leaving the heart ▪ Semilunar valves open ▪ Blood is ejected from the ventricles ▪ Atria are relaxed and filling with blood
Describe cardiac contractions step - Isometric relaxation
▪ Ventricular diastole begins
▪ Pressure falls below that in the major arteries
▪ Semilunar valves close
▪ For another moment, the ventricles are completely closed chambers
▪ When atrial pressure increases above intraventricular pressure, the AV valves open
