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. fff
5. Arteries, Veins and Capillaries
5.1. Arteries
5.1.1. Have 3 layers
5.1.1.1. Tunica intima / Inner layer; Endothelium
5.1.1.2. Tunica media / Middle layer; Smooth muscle and Elastic tissue
5.1.1.2.1. More Elastic tissue than smooth muscle
5.1.1.3. Tunica adventitia / Outer layer; Fibrous tissue
5.1.2. Have thick walls
5.1.2.1. needed to withstand the the high pressure blood flow
5.1.2.1.1. means when cut blood spurts out
5.1.3. Arteries = Away from the heart
5.1.4. Types of artery
5.1.4.1. Arterioles
5.1.4.1.1. Small arteries
5.1.4.1.2. 3 Layers
5.1.4.1.3. also know as resistance vessles
5.1.4.2. Anastomoses
5.1.4.2.1. Form a link between main arteries supplying an area eg palm of the hand, soles of the feet or brain
5.1.4.2.2. can provide collateral circulation
5.1.4.2.3. provide adequate blood supply when artery is occluded
5.1.4.3. End arteries
5.1.4.3.1. Sole source of blood supply to tissues eg central artery to the retina of the eye
5.1.4.4. when occluded tissue it supply dies as no alternative blood supply
5.1.5. Main arteries
5.1.5.1. Renal
5.1.5.1.1. kidney
5.1.5.2. Hepatic
5.1.5.2.1. liver and gall bladder
5.1.5.3. Gastric
5.1.5.3.1. Stomach
5.1.5.4. Splenic
5.1.5.4.1. spleen and pancreas
5.1.5.5. Carotid
5.1.5.5.1. neck and brain
5.1.5.6. Coronary
5.1.5.6.1. heart
5.1.5.7. Peripheral
5.1.5.7.1. limbs
5.2. Veins
5.2.1. 3 layers
5.2.1.1. Tunica intima / Inner layer; Endothelium
5.2.1.2. Tunica media / Middle layer; Smooth muscle and Elastic tissue
5.2.1.2.1. not as much as in arteries as they don't need to stretch
5.2.1.3. Tunica adventitia / Outer layer; Fibrous tissue
5.2.2. Have thin walls
5.2.2.1. withstand the low pressure blood
5.2.2.1.1. when cut slow, steady blood flow escapes
5.2.3. Veins = Carry blood towards the heart
5.2.4. also know as capacitance vessels
5.2.4.1. distensible
5.2.4.2. have capacity to hold a large proportion of the bodies blood
5.2.4.2.1. 2/3 of the body's blood is in the venous system
5.2.4.2.2. allows vascular system to absorb sudden changes in blood volume
5.2.5. Have valves
5.2.5.1. prevent backflow
5.2.5.1.1. ensuring blood flows to the heart
5.2.5.1.2. assisted by skeletal muscles surrounding the veins
5.2.5.2. formed by fold of endothelium and strengthened by connective tissue
5.2.5.3. semilunar in shape
5.2.5.3.1. concave toward the heart
5.2.5.4. abundant in veins of the limbs
5.2.5.4.1. especially lower limbs where blood has to travel a considerable distance against gravity
5.2.5.5. absent in very small and very large veins in the thorax and abdomen
5.2.6. types of vein
5.2.6.1. venules
5.2.6.1.1. small veins
5.3. Capillaries
5.3.1. Wall consists of one single layer of endothelial cells
5.3.1.1. allows water and other small molecules pass through it
5.3.1.2. blood cells and plasma proteins are usually too big to pass through the capillary wall
5.3.2. form a network that joins small arterioles to small venules
5.3.3. they are the site of exchange of substances between the blood and tissue fluid that bathes the body cell
5.3.4. Entry capillary beds are guarded by precapillary sphincters (rings of smooth muscle)
5.3.4.1. they direct blood flow
5.3.4.2. Hypoxia (low oxygen levels in the tissue) and high levels of tissue waste dilate the sphincters
5.3.4.2.1. this increases blood flow through affected beds
5.3.5. types of capilllary
5.3.5.1. Sinusoids
5.3.5.1.1. significantly wider and leakier capillaries
5.3.5.1.2. found in the liver and bone marrow
5.3.5.1.3. walls are incomplete and have larger lumens than normal
5.3.5.1.4. can come directly into contact with cells outside sinusoid walls
5.3.6. capillary refill time
5.3.6.1. when area of skin is pressed it turn white
5.3.6.1.1. because blood has been squeezed out the capillary
5.3.6.2. should take less than 2 seconds for capaillary to refill (skin to turn pink again)
5.3.6.2.1. if takes longer can suggest poor perfusions or dehydration
6. CVC send autonomic nerves both sympathetic and parasympathetic to the heart and blood vessels
7. Due to closure of the atrioventricular valves
8. Heart sounds
8.1. 'Lub'
8.1.1. Fairly loud
8.1.1.1. corresponds with start of ventricular systole
8.2. conducting system of the heart
8.2.1. Direction of impulse
8.2.1.1. Superior Vena Cava
8.2.1.2. Sinoatrial (SA) Node
8.2.1.3. Atrioventricular (AV) Node
8.2.1.4. Atrioventricular bundle (AV) bundle / bundle of His
8.2.1.5. Left Atrioventricular (LAV) bundle
8.2.1.6. network of Purkinje Fibres
8.2.2. posses the property of autorhythmicity (generates its own electrical impulses and beats independently of nervous or hormonal control)
8.2.2.1. Heart rate
8.2.2.1.1. supplied with both sympathetic and parasympathetic nerve fibres
8.2.2.1.2. Heart responds to circulation hormones eg Adrenaline and thyroxine
8.2.3. small groups of specialised neuromuscular cells in the myocardium initiate and conduct impulses
8.2.3.1. causes coordinated and synchronised contraction of the heart muscle
8.2.4. Sino atrial (SA) node
8.2.4.1. is a small mass of specialised cells that lies in the wall of the right atrium
8.2.4.2. these cells generate these regular impulses because they are electrically unstable
8.2.4.2.1. this instability leads them to discharge (depolarise) regularly
8.2.5. Atrioventricular (AV) node
8.2.5.1. is a small mass of neuromuscular tissue situated in the wall of the atria septum near the atrioventricular valves
8.2.5.2. normally merely transmits electrical signals from the atria to the ventricles
8.2.5.2.1. there is a 0.1 second delay here to pass through the ventricles
8.2.5.3. has a secondary pacemaker function
8.2.5.3.1. takes over this role if there is a problem with the SA node or with transmission of impulses from the atria
8.2.5.4. atrioventricular bundle bundle (AV bundle / bundle of HIS)
8.2.5.4.1. this is a mass of specialised fibres that originate from the AV node
8.2.5.4.2. it divides into the right and left bundle branches
8.2.5.4.3. withing the ventricular myocardium the branches break up into fine fibres called the purkinje fibres
8.2.5.4.4. these fibres transmit electrical impulses from the AV node to the apex of the myocardium where the wave of ventricular begins
8.2.6. Direction of blood flow
8.2.6.1. Inferior vena cava
8.2.6.1.1. largest veins of the body
8.2.6.2. Superior vena cava
8.2.6.2.1. largest veins of the body
8.2.6.3. Right Atrium
8.2.6.3.1. and left atrium both contract at the same time
8.2.6.3.2. walls are thinner
8.2.6.4. Right Ventricle
8.2.6.4.1. and left ventricle simultaneously contract after the artias
8.2.6.4.2. walls are thicker
8.2.6.5. Pulmonary Valve
8.2.6.5.1. Tricuspid Valve / Right atrioventricular valve
8.2.6.5.2. formed by 3 semilunar cusps
8.2.6.5.3. prevents backflow of blood to the right ventricle when it relaxes
8.2.6.6. Pulmonary Arteries
8.2.6.6.1. left
8.2.6.6.2. right
8.2.6.7. Lungs
8.2.6.8. Pulmonary Veins
8.2.6.8.1. two pulmonary veins from each lung
8.2.6.8.2. carr oxygenated blood back to theheart
8.2.6.9. Left Atrium
8.2.6.9.1. and right atrium both contract at the same time
8.2.6.9.2. walls are thinner
8.2.6.10. Mitral Valve / Left atrioventricular valve
8.2.6.11. Left Ventricle
8.2.6.11.1. and right ventricle simultaneously contract after the artias
8.2.6.11.2. walls are thicker
8.2.6.12. Aortic valve
8.2.6.12.1. formed by 3 semilunar cusps
8.2.6.13. Aorta
8.2.6.13.1. first artery of general circulation
8.3. 'Dup'
8.3.1. softer sound
8.3.2. due to closure of aortic and pulmonary valves
8.3.3. corresponds with ventricular diastole
9. it controls BP by slowing down or speeding up heart rate and by constricting and dilating blood vessels
10. cardiovascular centre is a collection of interconnected neurones in the medulla and pons of the brain stem
10.1. the CVC receives integrates and coordinates input from Baroreceptors (pressure receptors), chemoreceptors and higher centres in the brain
11. Heart
11.1. Postion
11.1.1. lies in the thoracic cavity
11.1.2. in the mediastinum (space between the lungs)
11.1.3. lies slightly more on the left than the right
11.2. organs associated with the heart
11.2.1. Inferiorly
11.2.1.1. apex rests on the central tendon of the diaphram
11.2.2. superiorly
11.2.2.1. the great blood vessels
11.2.2.1.1. aorta
11.2.2.1.2. superior vena cave
11.2.2.1.3. pulmonary artery
11.2.2.1.4. pulmonary veins
11.2.3. posteriorly
11.2.3.1. oesophagus
11.2.3.2. trachea
11.2.3.3. left and right bronchus
11.2.3.4. descending aorta
11.2.3.5. inferior vena cava
11.2.3.6. thoracic vertibrae
11.2.4. laterally
11.2.4.1. the lungs
11.2.4.1.1. left lung overlaps the left side of the heart
11.2.5. anteriorly
11.2.5.1. the sternum
11.2.5.2. ribs
11.2.5.3. intercostal muscle
11.3. roughly cone shaped, hollow muscular organ
11.4. about 10cm long
11.4.1. about the size of a fist
11.5. Structure
11.5.1. the heart wall
11.5.1.1. composed of three layers of tissue
11.5.1.1.1. Pericardium
11.5.1.1.2. myocardium
11.5.1.1.3. endocardium
11.6. Blood supply to the heart
11.6.1. Arterial Supply
11.6.1.1. heart is supplied with arterial blood from fight and left coronary arteries
11.6.1.1.1. branches from the aorta
11.6.1.1.2. they recieve 5% of the blood pumped from the heart
11.6.1.1.3. traverse the heart eventually forming a vast network of capillaries
11.6.2. Venous drainage
11.6.2.1. most venous blood is collected into a number of cardiac veins
11.6.2.1.1. these join together forming coronary sinus which opens into the right atrium
11.6.2.1.2. the remainder passes directly into the heart chambers through venus channels
12. Control of blood vessel diameter
12.1. Baseline, Vasoldilation and vasoconstriction
12.1.1. vasodilation
12.1.1.1. caused by decrease nerve stimulation
12.1.1.1.1. relaxes the smooth muscle thinning the vessel wall and enlarging the lumen
12.1.1.2. increase blood flow at low pressure
12.1.2. Baseline (resting)
12.1.3. sympathetic activity / Vasoconstriction
12.1.3.1. diameter of vessel lumen and tone of the smooth muscle are determined by the degree of sympathetic activity
12.1.3.2. generally constricts vessels
12.1.3.2.1. vasoconstriction
12.1.3.2.2. this increases pressure inside the vessel
12.1.4. Relationship between sympathetic stimulation and blood vessel diameter
12.1.4.1. baseline ( Resting)
12.1.4.1.1. Sympathetic stimulation
12.1.4.1.2. smooth muscle
12.1.4.1.3. thickness of vessel wall
12.1.4.1.4. diameter of lumen
12.1.4.1.5. peripheral resistance in arterioles
12.1.4.2. Vasodilation
12.1.4.2.1. Sympathetic stimulation
12.1.4.2.2. smooth muscle
12.1.4.2.3. thickness of vessel wall
12.1.4.2.4. diameter of lumen
12.1.4.2.5. peripheral resistance in arterioles
12.1.4.3. Vasoconstriction
12.1.4.3.1. Sympathetic stimulation
12.1.4.3.2. smooth muscle
12.1.4.3.3. thickness of vessel wall
12.1.4.3.4. diameter of lumen
12.1.4.3.5. peripheral resistance in arterioles
12.2. What vessels does it effect?
12.2.1. Mainly arterioles as their walls contain more smooth muscle
12.2.1.1. responds to sympathetic stimulation
12.2.2. Large arteries such as the aorta contain more elastic tissue meaning they can expand and recoil depending on the volume of blood passing through
12.2.3. Veins also respond to nerve stimulation but only have little smooth muscle in their tunica media
12.3. Blood flow
12.3.1. resistance to flow fluids along a tube is determined by three factors
12.3.1.1. the diameter of the tube
12.3.1.2. the length of the tube
12.3.1.3. the viscosity of the fluid
12.3.2. the diameter of the resistance vessel is known as the peripheral resistnace
12.3.2.1. major factor in blood pressure regulation
12.3.2.2. Constant adjustment of blood vessel diameter helps regulate peripheral resistance and systemic blood pressure
13. Electrical changes in the heart
13.1. body tissues and fluid can conduct electricity well this allows electrical activity in the heart to be recorded on the skin surface using electrodes
13.1.1. this recording is called and Electrocardiagram (ECG)
13.2. ECG
13.2.1. recording of electrical activity in the heart
13.2.2. shows the spread of electrical signals produced by the pacemaker as it travels through the atria, the AV node and the ventricles
13.2.3. normal ECG tracing
13.2.3.1. Shows five waves
13.2.3.1.1. P wave
13.2.3.1.2. QRS complex
13.2.3.1.3. T wave
13.2.3.2. originates from the SA node
13.2.3.2.1. called Sinus rhythm
13.2.3.2.2. the rate of sinus rhythm is usually 60-100 b.p.m
13.2.4. ECG abnormalities
13.2.4.1. Faster heart rate is called tachycardia
13.2.4.2. slower heart rate is called is called bradycardia
14. Pulse
14.1. normally represents the heart rate
14.2. measured in bpm
14.3. info obtained by pulse
14.3.1. rate at which the heart is beating
14.3.2. regularity of the heart beats
14.3.2.1. intervals between beats should be equal
14.3.3. volume / strenght of the beat
14.3.3.1. should be possible to compress the artery with moderate pressure
14.3.4. the tension
14.3.4.1. artery should feel soft and pliant under fingers
14.4. averaging 60-80 bpm at rest
14.5. factors affecting pulse
14.5.1. when arteries supplying peripheral tissues are blocked or narrowed
14.5.2. cardiac contraction disorders
14.5.2.1. atrial fibrillation
14.6. main pulse points
14.6.1. Temporal artery
14.6.1.1. by the eye
14.6.2. Facial artery
14.6.2.1. by the jaw
14.6.3. Common carotid artery
14.6.3.1. on the neck
14.6.4. Brachial artery
14.6.4.1. about halfway up on the inside arm
14.6.5. Radial artery
14.6.5.1. on inside of the wrist
14.6.6. Femoral artery
14.6.6.1. around the hip
14.6.7. popliteal artery
14.6.7.1. behind the knee
14.6.8. posterior artery
14.6.8.1. by the ankle
14.6.9. dorsalis pedis artery
14.6.9.1. by the toes
15. Cardiac Output
15.1. amount of blood ejected from each ventricle every minute
15.1.1. expressed in Litres per min (L/min)
15.1.1.1. Calculated by multiplying Stroke volume by the heart rate (b.p.m)
15.1.1.1.1. Cardiac Output = Stroke volume x Heart rate
15.1.1.1.2. This can increase during exercise this is called cardiac reserve
15.2. Stroke volume
15.2.1. amount of blood expelled by each contraction of each ventricle
15.2.2. is determined by the volume of blood in the ventricles immediately before they contract
15.2.2.1. ie the ventricular end-diastolic volume (VEDV)
15.2.2.1.1. Sometimes called the preload
15.2.3. in healthy adult stroke volume is approx. 70 mL
15.2.4. Summary of affacting factors
15.2.4.1. VEDV
15.2.4.2. Venous return
15.2.4.2.1. Position of the body
15.2.4.2.2. skeletal muscle pump
15.2.4.2.3. respiratory pump
15.2.4.3. strength of myocardial contraction
15.2.4.4. blood volume