1. smooth muscle in the tunica media of both veins and arteries are supplied with nerves from the autonomic nervous system
1.1. they arise from the vasometer centre in the medulla oblongata
1.2. they change the diameter of the blood vessel controlling volume of blood they can contain
2. The cardiac cycle
2.1. at rest healthy heart beat for an adult is roughly 60-80 beats per min
2.2. during each hear beat the heat contracts (Systole) and then relaxes (Diastole)
2.3. stages of the cardiac cycle
2.3.1. each cycle lasts about 0.8 of a second
2.3.2. consists of 3 components
2.3.2.1. Atrial Systole
2.3.2.1.1. contraction of the artia
2.3.2.1.2. last rougly 0.1 seconds
2.3.2.2. Ventricular Systole
2.3.2.2.1. contraction of the ventricles
2.3.2.2.2. lasts roughly 0.3 seconds
2.3.2.3. Complete cardiac diastole
2.3.2.3.1. relaxation of the atria and ventricles
2.3.2.3.2. lasts roughly 0.4 seconds
2.3.3. Direction of blood flow
2.3.3.1. Atrial systole
2.3.3.1.1. Atria contract
2.3.3.1.2. AV valves open
2.3.3.1.3. Ventricles relaxed
2.3.3.1.4. Aortic/ pulmonary valves closed
2.3.3.2. Ventricular systole
2.3.3.2.1. Atria relaxed
2.3.3.2.2. AV valves closed
2.3.3.2.3. Ventricles contract
2.3.3.3. Atria and ventricles relaxed
2.3.3.4. Aortic / pulmonary valves open
2.3.3.5. Complete cardiac diastole
2.3.3.5.1. AV valves open
2.3.3.5.2. Aortic / pulmonary valves closed
3. Blood Pressure (bp)
3.1. Blood pressure is the force / pressure that blood exerts on the walls of blood vessels
3.2. systemic arterial bp maintains the essential flow of blood into and out of organs of the body
3.3. can vary according to
3.3.1. time of day
3.3.1.1. bp falls at rest and during sleep
3.3.2. posture
3.3.3. gender
3.3.3.1. usually higher in women
3.3.4. age
3.3.4.1. increases with age
3.4. if bp gets too high it can
3.4.1. damage blood vessels
3.4.2. cause clots
3.4.3. bleed from sites of blood vessel rupture
3.4.4. result of discharge of blood from left ventricle into the already full aorta
3.5. if bp gets too low
3.5.1. blood flow through tissue bed can be inadequate
3.5.1.1. dangerous for essential organs
3.5.1.1.1. heart
3.5.1.1.2. kidneys
3.5.1.1.3. brain
3.6. Systolic
3.6.1. Arterial blood pressure
3.6.1.1. written as systolic pressure written above the diastolic pressure
3.6.1.2. measured using a sphygmomanometer
3.6.2. when the left ventricle contracts and pushes blood into the aorta
3.6.3. in adults this can be about 120 mmHg
3.7. diastolic
3.7.1. in complete cadiac diastole the pressure in the arteries is much lower
3.7.2. in adults this can be about 80 mmHg
3.8. Control of blood pressure
3.8.1. Short term regulation
3.8.1.1. on a moment to moment basis
3.8.2. long term regulation
3.8.2.1. slower longer lasting changes in blood pressure
3.8.2.1.1. Cardiovascular centre
3.8.2.1.2. affected by renin-angiotensin-aldosterone system
3.8.2.1.3. also action antidiuretic hormone
4. Arteries, Veins and Capillaries
4.1. Arteries
4.1.1. Have 3 layers
4.1.1.1. Tunica intima / Inner layer; Endothelium
4.1.1.2. Tunica media / Middle layer; Smooth muscle and Elastic tissue
4.1.1.2.1. More Elastic tissue than smooth muscle
4.1.1.3. Tunica adventitia / Outer layer; Fibrous tissue
4.1.2. Have thick walls
4.1.2.1. needed to withstand the the high pressure blood flow
4.1.2.1.1. means when cut blood spurts out
4.1.3. Arteries = Away from the heart
4.1.4. Types of artery
4.1.4.1. Arterioles
4.1.4.1.1. Small arteries
4.1.4.1.2. 3 Layers
4.1.4.1.3. also know as resistance vessles
4.1.4.2. Anastomoses
4.1.4.2.1. Form a link between main arteries supplying an area eg palm of the hand, soles of the feet or brain
4.1.4.2.2. can provide collateral circulation
4.1.4.2.3. provide adequate blood supply when artery is occluded
4.1.4.3. End arteries
4.1.4.3.1. Sole source of blood supply to tissues eg central artery to the retina of the eye
4.1.4.4. when occluded tissue it supply dies as no alternative blood supply
4.1.5. Main arteries
4.1.5.1. Renal
4.1.5.1.1. kidney
4.1.5.2. Hepatic
4.1.5.2.1. liver and gall bladder
4.1.5.3. Gastric
4.1.5.3.1. Stomach
4.1.5.4. Splenic
4.1.5.4.1. spleen and pancreas
4.1.5.5. Carotid
4.1.5.5.1. neck and brain
4.1.5.6. Coronary
4.1.5.6.1. heart
4.1.5.7. Peripheral
4.1.5.7.1. limbs
4.2. Veins
4.2.1. 3 layers
4.2.1.1. Tunica intima / Inner layer; Endothelium
4.2.1.2. Tunica media / Middle layer; Smooth muscle and Elastic tissue
4.2.1.2.1. not as much as in arteries as they don't need to stretch
4.2.1.3. Tunica adventitia / Outer layer; Fibrous tissue
4.2.2. Have thin walls
4.2.2.1. withstand the low pressure blood
4.2.2.1.1. when cut slow, steady blood flow escapes
4.2.3. Veins = Carry blood towards the heart
4.2.4. also know as capacitance vessels
4.2.4.1. distensible
4.2.4.2. have capacity to hold a large proportion of the bodies blood
4.2.4.2.1. 2/3 of the body's blood is in the venous system
4.2.4.2.2. allows vascular system to absorb sudden changes in blood volume
4.2.5. Have valves
4.2.5.1. prevent backflow
4.2.5.1.1. ensuring blood flows to the heart
4.2.5.1.2. assisted by skeletal muscles surrounding the veins
4.2.5.2. formed by fold of endothelium and strengthened by connective tissue
4.2.5.3. semilunar in shape
4.2.5.3.1. concave toward the heart
4.2.5.4. abundant in veins of the limbs
4.2.5.4.1. especially lower limbs where blood has to travel a considerable distance against gravity
4.2.5.5. absent in very small and very large veins in the thorax and abdomen
4.2.6. types of vein
4.2.6.1. venules
4.2.6.1.1. small veins
4.3. Capillaries
4.3.1. Wall consists of one single layer of endothelial cells
4.3.1.1. allows water and other small molecules pass through it
4.3.1.2. blood cells and plasma proteins are usually too big to pass through the capillary wall
4.3.2. form a network that joins small arterioles to small venules
4.3.3. they are the site of exchange of substances between the blood and tissue fluid that bathes the body cell
4.3.4. Entry capillary beds are guarded by precapillary sphincters (rings of smooth muscle)
4.3.4.1. they direct blood flow
4.3.4.2. Hypoxia (low oxygen levels in the tissue) and high levels of tissue waste dilate the sphincters
4.3.4.2.1. this increases blood flow through affected beds
4.3.5. types of capilllary
4.3.5.1. Sinusoids
4.3.5.1.1. significantly wider and leakier capillaries
4.3.5.1.2. found in the liver and bone marrow
4.3.5.1.3. walls are incomplete and have larger lumens than normal
4.3.5.1.4. can come directly into contact with cells outside sinusoid walls
4.3.6. capillary refill time
4.3.6.1. when area of skin is pressed it turn white
4.3.6.1.1. because blood has been squeezed out the capillary
4.3.6.2. should take less than 2 seconds for capaillary to refill (skin to turn pink again)
4.3.6.2.1. if takes longer can suggest poor perfusions or dehydration
5. CVC send autonomic nerves both sympathetic and parasympathetic to the heart and blood vessels
6. Due to closure of the atrioventricular valves
7. Heart sounds
7.1. 'Lub'
7.1.1. Fairly loud
7.1.1.1. corresponds with start of ventricular systole
7.2. conducting system of the heart
7.2.1. Direction of impulse
7.2.1.1. Superior Vena Cava
7.2.1.2. Sinoatrial (SA) Node
7.2.1.3. Atrioventricular (AV) Node
7.2.1.4. Atrioventricular bundle (AV) bundle / bundle of His
7.2.1.5. Left Atrioventricular (LAV) bundle
7.2.1.6. network of Purkinje Fibres
7.2.2. posses the property of autorhythmicity (generates its own electrical impulses and beats independently of nervous or hormonal control)
7.2.2.1. Heart rate
7.2.2.1.1. supplied with both sympathetic and parasympathetic nerve fibres
7.2.2.1.2. Heart responds to circulation hormones eg Adrenaline and thyroxine
7.2.3. small groups of specialised neuromuscular cells in the myocardium initiate and conduct impulses
7.2.3.1. causes coordinated and synchronised contraction of the heart muscle
7.2.4. Sino atrial (SA) node
7.2.4.1. is a small mass of specialised cells that lies in the wall of the right atrium
7.2.4.2. these cells generate these regular impulses because they are electrically unstable
7.2.4.2.1. this instability leads them to discharge (depolarise) regularly
7.2.5. Atrioventricular (AV) node
7.2.5.1. is a small mass of neuromuscular tissue situated in the wall of the atria septum near the atrioventricular valves
7.2.5.2. normally merely transmits electrical signals from the atria to the ventricles
7.2.5.2.1. there is a 0.1 second delay here to pass through the ventricles
7.2.5.3. has a secondary pacemaker function
7.2.5.3.1. takes over this role if there is a problem with the SA node or with transmission of impulses from the atria
7.2.5.4. atrioventricular bundle bundle (AV bundle / bundle of HIS)
7.2.5.4.1. this is a mass of specialised fibres that originate from the AV node
7.2.5.4.2. it divides into the right and left bundle branches
7.2.5.4.3. withing the ventricular myocardium the branches break up into fine fibres called the purkinje fibres
7.2.5.4.4. these fibres transmit electrical impulses from the AV node to the apex of the myocardium where the wave of ventricular begins
7.2.6. Direction of blood flow
7.2.6.1. Inferior vena cava
7.2.6.1.1. largest veins of the body
7.2.6.2. Superior vena cava
7.2.6.2.1. largest veins of the body
7.2.6.3. Right Atrium
7.2.6.3.1. and left atrium both contract at the same time
7.2.6.3.2. walls are thinner
7.2.6.4. Right Ventricle
7.2.6.4.1. and left ventricle simultaneously contract after the artias
7.2.6.4.2. walls are thicker
7.2.6.5. Pulmonary Valve
7.2.6.5.1. Tricuspid Valve / Right atrioventricular valve
7.2.6.5.2. formed by 3 semilunar cusps
7.2.6.5.3. prevents backflow of blood to the right ventricle when it relaxes
7.2.6.6. Pulmonary Arteries
7.2.6.6.1. left
7.2.6.6.2. right
7.2.6.7. Lungs
7.2.6.8. Pulmonary Veins
7.2.6.8.1. two pulmonary veins from each lung
7.2.6.8.2. carr oxygenated blood back to theheart
7.2.6.9. Left Atrium
7.2.6.9.1. and right atrium both contract at the same time
7.2.6.9.2. walls are thinner
7.2.6.10. Mitral Valve / Left atrioventricular valve
7.2.6.11. Left Ventricle
7.2.6.11.1. and right ventricle simultaneously contract after the artias
7.2.6.11.2. walls are thicker
7.2.6.12. Aortic valve
7.2.6.12.1. formed by 3 semilunar cusps
7.2.6.13. Aorta
7.2.6.13.1. first artery of general circulation
7.3. 'Dup'
7.3.1. softer sound
7.3.2. due to closure of aortic and pulmonary valves
7.3.3. corresponds with ventricular diastole
8. it controls BP by slowing down or speeding up heart rate and by constricting and dilating blood vessels
9. cardiovascular centre is a collection of interconnected neurones in the medulla and pons of the brain stem
9.1. the CVC receives integrates and coordinates input from Baroreceptors (pressure receptors), chemoreceptors and higher centres in the brain
10. Heart
10.1. Postion
10.1.1. lies in the thoracic cavity
10.1.2. in the mediastinum (space between the lungs)
10.1.3. lies slightly more on the left than the right
10.2. organs associated with the heart
10.2.1. Inferiorly
10.2.1.1. apex rests on the central tendon of the diaphram
10.2.2. superiorly
10.2.2.1. the great blood vessels
10.2.2.1.1. aorta
10.2.2.1.2. superior vena cave
10.2.2.1.3. pulmonary artery
10.2.2.1.4. pulmonary veins
10.2.3. posteriorly
10.2.3.1. oesophagus
10.2.3.2. trachea
10.2.3.3. left and right bronchus
10.2.3.4. descending aorta
10.2.3.5. inferior vena cava
10.2.3.6. thoracic vertibrae
10.2.4. laterally
10.2.4.1. the lungs
10.2.4.1.1. left lung overlaps the left side of the heart
10.2.5. anteriorly
10.2.5.1. the sternum
10.2.5.2. ribs
10.2.5.3. intercostal muscle
10.3. roughly cone shaped, hollow muscular organ
10.4. about 10cm long
10.4.1. about the size of a fist
10.5. Structure
10.5.1. the heart wall
10.5.1.1. composed of three layers of tissue
10.5.1.1.1. Pericardium
10.5.1.1.2. myocardium
10.5.1.1.3. endocardium
10.6. Blood supply to the heart
10.6.1. Arterial Supply
10.6.1.1. heart is supplied with arterial blood from fight and left coronary arteries
10.6.1.1.1. branches from the aorta
10.6.1.1.2. they recieve 5% of the blood pumped from the heart
10.6.1.1.3. traverse the heart eventually forming a vast network of capillaries
10.6.2. Venous drainage
10.6.2.1. most venous blood is collected into a number of cardiac veins
10.6.2.1.1. these join together forming coronary sinus which opens into the right atrium
10.6.2.1.2. the remainder passes directly into the heart chambers through venus channels
11. Control of blood vessel diameter
11.1. Baseline, Vasoldilation and vasoconstriction
11.1.1. vasodilation
11.1.1.1. caused by decrease nerve stimulation
11.1.1.1.1. relaxes the smooth muscle thinning the vessel wall and enlarging the lumen
11.1.1.2. increase blood flow at low pressure
11.1.2. Baseline (resting)
11.1.3. sympathetic activity / Vasoconstriction
11.1.3.1. diameter of vessel lumen and tone of the smooth muscle are determined by the degree of sympathetic activity
11.1.3.2. generally constricts vessels
11.1.3.2.1. vasoconstriction
11.1.3.2.2. this increases pressure inside the vessel
11.1.4. Relationship between sympathetic stimulation and blood vessel diameter
11.1.4.1. baseline ( Resting)
11.1.4.1.1. Sympathetic stimulation
11.1.4.1.2. smooth muscle
11.1.4.1.3. thickness of vessel wall
11.1.4.1.4. diameter of lumen
11.1.4.1.5. peripheral resistance in arterioles
11.1.4.2. Vasodilation
11.1.4.2.1. Sympathetic stimulation
11.1.4.2.2. smooth muscle
11.1.4.2.3. thickness of vessel wall
11.1.4.2.4. diameter of lumen
11.1.4.2.5. peripheral resistance in arterioles
11.1.4.3. Vasoconstriction
11.1.4.3.1. Sympathetic stimulation
11.1.4.3.2. smooth muscle
11.1.4.3.3. thickness of vessel wall
11.1.4.3.4. diameter of lumen
11.1.4.3.5. peripheral resistance in arterioles
11.2. What vessels does it effect?
11.2.1. Mainly arterioles as their walls contain more smooth muscle
11.2.1.1. responds to sympathetic stimulation
11.2.2. Large arteries such as the aorta contain more elastic tissue meaning they can expand and recoil depending on the volume of blood passing through
11.2.3. Veins also respond to nerve stimulation but only have little smooth muscle in their tunica media
11.3. Blood flow
11.3.1. resistance to flow fluids along a tube is determined by three factors
11.3.1.1. the diameter of the tube
11.3.1.2. the length of the tube
11.3.1.3. the viscosity of the fluid
11.3.2. the diameter of the resistance vessel is known as the peripheral resistnace
11.3.2.1. major factor in blood pressure regulation
11.3.2.2. Constant adjustment of blood vessel diameter helps regulate peripheral resistance and systemic blood pressure
12. Electrical changes in the heart
12.1. body tissues and fluid can conduct electricity well this allows electrical activity in the heart to be recorded on the skin surface using electrodes
12.1.1. this recording is called and Electrocardiagram (ECG)
12.2. ECG
12.2.1. recording of electrical activity in the heart
12.2.2. shows the spread of electrical signals produced by the pacemaker as it travels through the atria, the AV node and the ventricles
12.2.3. normal ECG tracing
12.2.3.1. Shows five waves
12.2.3.1.1. P wave
12.2.3.1.2. QRS complex
12.2.3.1.3. T wave
12.2.3.2. originates from the SA node
12.2.3.2.1. called Sinus rhythm
12.2.3.2.2. the rate of sinus rhythm is usually 60-100 b.p.m
12.2.4. ECG abnormalities
12.2.4.1. Faster heart rate is called tachycardia
12.2.4.2. slower heart rate is called is called bradycardia
13. Pulse
13.1. normally represents the heart rate
13.2. measured in bpm
13.3. info obtained by pulse
13.3.1. rate at which the heart is beating
13.3.2. regularity of the heart beats
13.3.2.1. intervals between beats should be equal
13.3.3. volume / strenght of the beat
13.3.3.1. should be possible to compress the artery with moderate pressure
13.3.4. the tension
13.3.4.1. artery should feel soft and pliant under fingers
13.4. averaging 60-80 bpm at rest
13.5. factors affecting pulse
13.5.1. when arteries supplying peripheral tissues are blocked or narrowed
13.5.2. cardiac contraction disorders
13.5.2.1. atrial fibrillation
13.6. main pulse points
13.6.1. Temporal artery
13.6.1.1. by the eye
13.6.2. Facial artery
13.6.2.1. by the jaw
13.6.3. Common carotid artery
13.6.3.1. on the neck
13.6.4. Brachial artery
13.6.4.1. about halfway up on the inside arm
13.6.5. Radial artery
13.6.5.1. on inside of the wrist
13.6.6. Femoral artery
13.6.6.1. around the hip
13.6.7. popliteal artery
13.6.7.1. behind the knee
13.6.8. posterior artery
13.6.8.1. by the ankle
13.6.9. dorsalis pedis artery
13.6.9.1. by the toes
14. Cardiac Output
14.1. amount of blood ejected from each ventricle every minute
14.1.1. expressed in Litres per min (L/min)
14.1.1.1. Calculated by multiplying Stroke volume by the heart rate (b.p.m)
14.1.1.1.1. Cardiac Output = Stroke volume x Heart rate
14.1.1.1.2. This can increase during exercise this is called cardiac reserve
14.2. Stroke volume
14.2.1. amount of blood expelled by each contraction of each ventricle
14.2.2. is determined by the volume of blood in the ventricles immediately before they contract
14.2.2.1. ie the ventricular end-diastolic volume (VEDV)
14.2.2.1.1. Sometimes called the preload
14.2.3. in healthy adult stroke volume is approx. 70 mL
14.2.4. Summary of affacting factors
14.2.4.1. VEDV
14.2.4.2. Venous return
14.2.4.2.1. Position of the body
14.2.4.2.2. skeletal muscle pump
14.2.4.2.3. respiratory pump
14.2.4.3. strength of myocardial contraction
14.2.4.4. blood volume