The Cardiovascular System Flashcards
What system consists of blood, circulatory systems and the heart?
The cardiovascular system
What system has the functions of delivering gases, nutrients and hormones to the cells and tissues, and to remove waste products?
The cardiovascular system
What part of the cardiovascular system suspends substances?
Blood
What part of the cardiovascular system carries blood to and from the cells and tissues?
The circulatory system
What part of the cardiovascular system acts as a pump to circulate the blood?
The heart
What are the 2 types of blood vascular systems?
Systemic Circulation and Pulmonary Circulation
There are 3 circulatory systems in the cardiovascular system. 2 of these are blood (systemic and pulmonary), what is the third?
Lymphatic system
The circulatory systems transport fluid throughout the body to deliver what 3 things?
oxygen
nutrients
hormones
The circulatory systems transport fluid throughout the body to remove what 2 things?
carbon dioxide
waste products
Do the blood vascular systems form complete circuits?
Yes
Blood travels away from the heart in what?
Arteries
Blood returns to the heart in what?
Veins
What are the arteries and veins connected by?
Capillaries
What are the site of gas and nutrient exchange in the blood vascular system?
Capillaries
Which blood vascular system delivers blood rich in oxygen from the left side of the heart to most BODY TISSUES?
Systemic Circulation
Which blood vascular system returns blood low in oxygen to the right side of the heart?
Systemic Circulation
Which blood vascular system is a high pressure system and forms an extensive network?
Systemic circulation
Carotid, radial, ulna, facial, temporal, dorsalis pedis and posterior tibial are examples of what?
Arterial Pulse Sites (where a superficial artery can be pressed against the bone) Carotid = neck Ulna = front of wrist Facial = jaw Tibial = ankle
Which blood vascular system delivers blood low in oxygen from the right side of the heart to the lungs?
Pulmonary Circulation
Which blood vascular system returns blood rich in oxygen to the left side of the heart?
Pulmonary circulation
Which blood vascular system is a low pressure system?
Pulmonary circulation
In the circulatory systems, what must endure changes in pressure, move with surrounding structures and remain open under all conditions?
Blood vessels
What 3 layers are blood vessels made up of?
Tunica Intima (endothelium)
Tunica Media (muscle layer)
Tunica Externa (connective tissue)
What is the tunica externa made out of?
Connective tissue - this is the outer layer of a blood vessel
What is the tunica media made up of?
Muscle layer
What is the tunica intima made up of?
Endothelium *epithelium - but diff name as a vessel
Which type of vessel starts off as elastic when leaving the heart but becomes more muscular further down the body?
Arteries - they become arterioles
Which type of vessel is continuous, fenestrated and deals with microcirculation?
Capillaries
Do arteries or veins have valves?
Veins
Name 5 things that distinguish arteries from veins:
Arteries have: thicker walls, smaller lumens (greater pressure), maintain their shape, more resilient, no valves.
Which arteries are elastic? Why?
Aorta, brachiocephalic and common carotid.
Have to be elastic to withstand changes in pressure and ensure continuous blood flow.
This means they have a thick tunica media
What types of arteries are the most common, distribute blood to muscles and organs, have lots of smooth muscle in the tunica media and a thick tunica externa?
Muscular
Which types of arteries are capable of vasoconstriction/dilation and have 1-2 layers of smooth muscle in the tunica media?
Arterioles (resistance vessels)
What vessels have thin walls, made up of an endothelial layer and basement membrane?
Capillaries
What are the 3 types of capillary?
Continuous (everything)
Fenestrated (have filters for little solutes)
Sinusoids (in liver and allow through big solutes)
A capillary bed is supplied by a single what?
Metarteriole
Each capillary bed contains how many capillaries?
10-100
Each capillary bed has a metaarteriole, what does this connect?
Arterioles with venules
What are pre-capillary sphincters?
Sphincters located at the opening of each capillary, that control flow to the individual beds.
If the bed doesn’t need oxygen at the given time, they will keep closed and it will go straight through the metarteriole
What is the arteriovenous anastomoses?
It forms direct communication between the arteriole and venule - allowing dilated blood to bypass the capillary bed and flow directly to venous circulation when not needed
What collects blood from the capillary beds and delivers it to small veins?
Venules
What are part of a low pressure system, are thin walled, easily distensible and hold about 54% of our blood volume?
Veins
Which circulatory system consists of a network of lymph vessels, lymph and lymphatic tissues and organs?
The lymphatic system
What are the 2 functions of the lymphatic system?
Involved in the body’s defence mechanisms
Provides a mechanism for the drainage of interstitial fluid
Lymph nodes lie along the network of lymph vessels. They will release a response and grab hold of what if they recognise it?
A foreign body/infection.
They swell when they do this
Blood leaves arteries into capillaries, taking oxygen and nutrients. It then takes waste products from the capillaries into the veins.
Due to the high pressure of the arterial system, fluid can move into the interstitial space at this end of the capillary.
And due to the low pressure at the venous end, fluid can fall back in.
What happens to this 15% of fluid that is left behind?
The excess fluid enters the lymphatic system and is returned to the blood.
What are lymph capillaries?
Blind ended tubes that are located adjacent to capillary beds, pick up fluids easily and drain into lymph vessels that drain into lymph trunks
When lots of excess fluid gets held by the lymph nodes, what does this cause?
Oedema
Fluid goes from the lymph capillaries, to lymph vessels, via the lymph nodes, to the lymph trunks - and then where?
Either the thoracic duct or the right lymphatic duct
Where does the right lymphatic duct re-enter the blood vascular circulation?
Right subclavian vein
Where does the thoracic duct reenter the blood vascular circulation?
Left subclavian vein
What is a cone shaped, muscular pump that is located in the thorax between the lungs?
The heart
What protects the heart?
The ribs and body of the sternum
How much of the heart lies to the left of the mid line?
2/3
Between what ribs does the heart live?
2nd and 5th
Where does the apex of the heart project?
Anteriorly to the left
Where abouts in the heart do the great vessels arise?
At the base, towards the back
What 2 things does the pericardium consist of?
Fibrous Pericardium
Serous Pericardium
What is an inelastic sac of dense connective tissue that wraps around the heart to prevent it overfilling?
Fibrous pericardium
What has parietal and visceral layers which are separated by a pericadial cavity which contains serous fluid to prevent friction?
Serous pericardium
What is cardiac tampanard?
When the serous pericardium leaks or bleeds into the sac, and stops the heart pumping
How many layers make up the heart wall?
3
List the 3 layers of the heart wall:
Endocardium (inner - endothelium)
Myocardium (middle - cardiac muscle)
Epicardium (outer - visceral pericardium)
The 2 upper chamber of the heart are called what?
atrium
The 2 lower chambers of the heart are called what?
ventricles
What valve connects the left ventricle to the left atrium?
bicuspid/mitral valve
What valve connects the right atrium to the right ventricle?
tricuspid valve
What valve connects the left atrium to the arch of aorta?
Aortic semilunar valve
What valve connects the right ventricle to the pulmonary trunk and arteries?
pulmonary semilunar valve
Where do the pulmonary veins connect to?
The left atrium, bringing in blood rich in oxygen
What are trabeculae carnae?
Meaty ridges in the heart
There are bands of fibrous connective tissue that separate the atria from the ventricles. Why?
This stops impulses that allow the atria to contract, to not set off the ventricles at the same time
What encircles the pulmonary trunk, aorta and heart valves?
Fibrous skeleton of the heart
The heart valves are attached to the fibrous skeleton. There are 4. Name them
Bicuspid valve
Pulmonary semilunar
Tricuspid
Aortic semilunar
Which valves are the atrioventricular valves?
the bicuspid and tricuspid
the ones that connect the atria to the ventricles
What opens the atrioventricular valves?
Blood flowing from the atria to the ventricles
What prevents the eversion of the valves during ventricular contraction?
They are anchored by chordae tenendinae to papillary muscles
Name the semilunar valves
Pulmonary and aortic
What opens the semilunar valves?
Blood being pushed out the ventricles
What happens to blood during ventricular relaxation?
It flows backwards into the aorta and pulmonary trunk, which pools into the cusps and pushes them shut - preventing backflow into the ventricles
Is the chordae tendinae attached to the semilunar or atrioventricular valves?
Artioventricular
Blood comes into the left atria in the heart from the pulmonary veins from the lungs.
It goes through the bicuspid valve into the left ventricle, through the aortic valve - and then where?
Through the aorta to systemic circulation
Blood comes back from the systemic circulation into the right atria, through the tricuspid valve in to the right ventricle, through the pulmonary valve, and then where?
Through the pulmonary arteries to the lungs
How many mls of blood does the heart receive per minute?
250mls per min
Why is blood delivered to myocardium during relaxation?
Lets as much in as possible and there is more force to pump it out again
Which artery is the circumflex and anterior interventricular?
The left coronary artery
Which artery is the marginal artery and is posterior interventricular?
right coronary artery
Where do most cardiac veins drain into?
The coronary sinus
Where does the coronary sinus drain into?
The right atrium
The anterior cardiac veins drain directly into the same place as the coronary sinus. What is this?
The right atrium
What is performed to confirm if there is a blockage in the coronary arteries?
Coronary Angiogram
What can a blockage in the coronary arteries lead to?
Angina or an MI
Cardiac muscles forms a branching network of cells, which are interconnected by intercalated discs which contain gap junctions.Gap junctions allow ion transport between cells which promote coordinated contraction.
What part of this allows contractions to pass through and start the next one?
Intercalated discs
Cardiac cells act as a f…………….. s………………..
functional synctium
Cardiac muscle is auto-rhythmic. What does this mean?
If given oxygen and nutrients it would pump by itself
What does the conducting system in the heart do?
Coordinate heart contraction
What system consists of non-contractile cells that initiate electrical impulses?
The conducting system in the heart
What 5 elements initiate the electrical impulses in the heart?
SA node AV node AV Bundle of His Right and left bundle branches Purkinje Fibres
What node in the heart spontaneously reaches threshold?
The SA node
What is the pacemaker in the heart?
The SA node
What modifies the rate of the heart?
ANS
After the impulse from the SA node spreads through the atria, how does it pass through the remainder of the heart?
The conductive system
In an electrocardiogram, define the P wave, the QRS complex and the T wave
P wave = depolarisation of the atria
QRS = depolarisation of the ventricles
T wave = repolarisation of the ventricles
Lots of p wave = atrial fribulation
What are lots of ups and downs on an electro cardiogram?
Ventrical fibullation
In what 2 ways is foetal circulation different?
Oxygen and nutrients are received from the placenta by the umbilical vein
It needs to bypass non functional lungs
What are the 3 shortcuts in foetal circulation?
The ductus venosus connects the umbilical vein to inferior vena cava
The foramen ovale connects the right and left atria
The ductus arteriosus connects the pulmonary artery to the arch of aorta
When a baby makes its first cry, what happens?
Lungs Expand, so resistance falls in the pulmonary circuit = decrease in pressure in pulmonary trunk
Ductus arteriosus closes = decreased pressure in pulmonary trunk
Umbilical vessels close = increased pressure in aorta
PRESSURE RISES IN SYSTEMIC CIRCULATION AND LEFT SIDE
PRESSURE FALLS IN PULMONARY CIRCULATION AND RIGHT SIDE
Foramen ovale shuts
What are the 5 series of events that occur in each heart beat?
1-3 = diastole 4-5 = systole
Ventricular filling (passive) Ventricular filling (atrial systole) Isovolumetric Contraction Ventricular Ejection Isovolumetric Relaxation
In which stage of the cardiac cycle are the atria and ventricles relaxed, the AV valves open, the semilunar valves closed -
and blood flows into the atria through the open AV valve into the ventricles?
Ventricular Filling (passive)
Which stage of the cardiac cycle corresponds to the P wave on an ECG, does the atria contract and force blood into the ventricles, and at the end of the phase the end diastolic volume is 130ml?
Ventricular filling (atrial systole)
Which stage of the cardiac cycle corresponds to the QRS complex on an ECG, has the atria relax and ventricles contract, the semilunar valves remain closed, the AV valves close (first lubb sound) and the volume in the ventricle remains unchanged?
Isovolumetric contraction
In which stage of the cardiac cycle does ventricular pressure exceed aortic and pulmonary pressure, forcing the semilunar valves open, is blood forced into the aorta and the pulmonary trunk, and at the end of the phase the systolic volume is 60ml (ejection fraction is 54%)?
Ventricular Ejection
Which stage of the cardiac cycle corresponds to the T wave on an ECG, the ventricles relax, semilunar valves close (second dubb sound), AV valves remain closed and the volume in the ventricle unchanged?
Isovolumetric Relaxation
After isovolumetric relaxation, what happens?
The AV valves reopen and cycle begins again
The volume of blood expelled by the heart in one minute, is otherwise known as cardiac output. What is the formula for this?
CARDIAC OUTPUT = STROKE VOLUME X HEART RATE
(CO) ml/min (SV) ml/beat (HR) beats/min
Cardiac output varies to meet the demands of the body. In what ways can it be altered?
Stroke volume or heart rate
What do you call the volume of blood ejected per heart beat?
Stroke volume
The degree of stretch of myocytes (preload), forcefulness of contraction (contractility) and the pressure required to eject blood (afterload) all affect what?
Stroke Volume
PRELOAD, CONTRACTILITY, AFTERLOAD
What determines preload?
EDV - End Diastolic Volume
End Diastolic Volume determines preload (which increases stroke volume). What determines EDV?
Venous Return
Venous Return determines End Diastolic Volume, which determines preload.
What determines venous return?
The volume of circulating blood
also aided by pressure gradient between veins and heart, respiratory pump, skeletal muscle pump and gravity
What increases contractility in the heart?
and therefore stroke volume
Norepinephrine and Eprinephrine
Hypercalcaemia
What decreases contractility of the heart?
Hyperkalaemia
Hypocalcaemia
Myocardial hypoxia
Myocardial hypercapnia
What pressure needs to be in the ventricles to eject blood?
Must be more pressure in the ventricles than in the atria/valves
In a newborn the resting pulse rate is about 120 beats per min.
How many is it in an adult?
64-80 bpm
rises with age
What is tachycardia?
Fast heart rate above 100bpm
What is bradycardia?
Slow heart rate below 60bpm
At what rate does the SA node fire?
100 bpm
What can modify the rate of the heart via the SA node?
The cardiac centre of the medulla oblongata:
Cadrioaccelarator centre - sends sympathetic impulses to increase the rate of firing at SA node - and increases contraction
Cardioinhibitory centre - sends parasympathetic impulses to decrease the rate of firing
Vagal tone - PNS maintains the HR at approx 70-80bpm
What is the force that the blood exerts on the walls of the blood vessels known as?
Blood Pressure
What is systolic blood pressure?
Maximum pressure when ventricles contract
What is diastolic blood pressure?
Maximum pressure when ventricles relax
What is an average BP?
120 over 80
What is hypertension?
Chronic resting bp of 140 over 90
What is hypotension?
Chronic low resting bp
What is the formula for blood pressure?
BP = cardiac output X total peripheral resistance
(stroke vol and heart rate)
What 3 things determine total peripheral resistance?
Viscosity
Vessel Length
Vessel Radius
What determines the vessel radius?
The SNS - it maintains the blood vessels in a state of partial vasoconstriction - sympathetic tone
Increased SNS activity constricts it, and decreased activity dilates it
It is controlled by vasomotor centre in medulla oblongata
In the local control of blood pressure, tissues have the ability to regulate their own blood supply. What is this known as and how does it work?
Autoregulation
Metabolites stimulate vasodilation (hypoxia, CO2, lactic acid)
Vasoactive chemicals cause vasodilation (histamine, bradykinins, proastaglandine
Endothelins cause vasoconstriction
Short term mechanisms by neural control can affect BP. How do the cardiovascular centres work in this?
Vasomotor centre - SNS = vasoconstriction to increase TPR
Cardiac Accelerator Centre = increases HR and force of contraction
Cardiac Inhibitor Centre = PNS - decreases HR
Aortic and carotid sinuses transmit continual signals to the cardiac and vasomotor centres, and increase/decrease BP accordingly. What is this known as?
Baroreceptor Reflex
If cardiac output decreased and so did BP, this would decrease the baroreceptor output. What then happens?
The cardioaccelerator and vasomotor centre are stimulated
The cardioinhibitor centre in inhibited
This increases HR and force of contraction and speeds everything up
