Cardiovascular System

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Cardiovascular System by Mind Map: Cardiovascular System

1. Heart sounds

1.1. 'Lub'

1.1.1. Fairly loud

1.1.2. Due to closure of the atrioventricular valves

1.1.3. corresponds with start of ventricular systole

1.2. conducting system of the heart

1.2.1. Direction of impulse

1.2.1.1. Superior Vena Cava

1.2.1.2. Sinoatrial (SA) Node

1.2.1.3. Atrioventricular (AV) Node

1.2.1.4. Atrioventricular bundle (AV) bundle / bundle of His

1.2.1.5. Left Atrioventricular (LAV) bundle

1.2.1.6. network of Purkinje Fibres

1.2.2. posses the property of autorhythmicity (generates its own electrical impulses and beats independently of nervous or hormonal control)

1.2.2.1. Heart rate

1.2.2.1.1. supplied with both sympathetic and parasympathetic nerve fibres

1.2.2.1.2. Heart responds to circulation hormones eg Adrenaline and thyroxine

1.2.3. small groups of specialised neuromuscular cells in the myocardium initiate and conduct impulses

1.2.3.1. causes coordinated and synchronised contraction of the heart muscle

1.2.4. Sino atrial (SA) node

1.2.4.1. is a small mass of specialised cells that lies in the wall of the right atrium

1.2.4.2. these cells generate these regular impulses because they are electrically unstable

1.2.4.2.1. this instability leads them to discharge (depolarise) regularly

1.2.5. Atrioventricular (AV) node

1.2.5.1. is a small mass of neuromuscular tissue situated in the wall of the atria septum near the atrioventricular valves

1.2.5.2. normally merely transmits electrical signals from the atria to the ventricles

1.2.5.2.1. there is a 0.1 second delay here to pass through the ventricles

1.2.5.3. has a secondary pacemaker function

1.2.5.3.1. takes over this role if there is a problem with the SA node or with transmission of impulses from the atria

1.2.5.4. atrioventricular bundle bundle (AV bundle / bundle of HIS)

1.2.5.4.1. this is a mass of specialised fibres that originate from the AV node

1.2.5.4.2. it divides into the right and left bundle branches

1.2.5.4.3. withing the ventricular myocardium the branches break up into fine fibres called the purkinje fibres

1.2.5.4.4. these fibres transmit electrical impulses from the AV node to the apex of the myocardium where the wave of ventricular begins

1.2.6. Direction of blood flow

1.2.6.1. Inferior vena cava

1.2.6.1.1. largest veins of the body

1.2.6.2. Superior vena cava

1.2.6.2.1. largest veins of the body

1.2.6.3. Right Atrium

1.2.6.3.1. and left atrium both contract at the same time

1.2.6.3.2. walls are thinner

1.2.6.4. Right Ventricle

1.2.6.4.1. and left ventricle simultaneously contract after the artias

1.2.6.4.2. walls are thicker

1.2.6.5. Pulmonary Valve

1.2.6.5.1. Tricuspid Valve / Right atrioventricular valve

1.2.6.5.2. formed by 3 semilunar cusps

1.2.6.5.3. prevents backflow of blood to the right ventricle when it relaxes

1.2.6.6. Pulmonary Arteries

1.2.6.6.1. left

1.2.6.6.2. right

1.2.6.7. Lungs

1.2.6.8. Pulmonary Veins

1.2.6.8.1. two pulmonary veins from each lung

1.2.6.8.2. carr oxygenated blood back to theheart

1.2.6.9. Left Atrium

1.2.6.9.1. and right atrium both contract at the same time

1.2.6.9.2. walls are thinner

1.2.6.10. Mitral Valve / Left atrioventricular valve

1.2.6.11. Left Ventricle

1.2.6.11.1. and right ventricle simultaneously contract after the artias

1.2.6.11.2. walls are thicker

1.2.6.12. Aortic valve

1.2.6.12.1. formed by 3 semilunar cusps

1.2.6.13. Aorta

1.2.6.13.1. first artery of general circulation

1.3. 'Dup'

1.3.1. softer sound

1.3.2. due to closure of aortic and pulmonary valves

1.3.3. corresponds with ventricular diastole

2. smooth muscle in the tunica media of both veins and arteries are supplied with nerves from the autonomic nervous system

2.1. they arise from the vasometer centre in the medulla oblongata

2.2. they change the diameter of the blood vessel controlling volume of blood they can contain

3. it controls BP by slowing down or speeding up heart rate and by constricting and dilating blood vessels

4. cardiovascular centre is a collection of interconnected neurones in the medulla and pons of the brain stem

4.1. the CVC receives integrates and coordinates input from Baroreceptors (pressure receptors), chemoreceptors and higher centres in the brain

4.2. CVC send autonomic nerves both sympathetic and parasympathetic to the heart and blood vessels

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. Control of blood vessel diameter

6.1. Baseline, Vasoldilation and vasoconstriction

6.1.1. vasodilation

6.1.1.1. caused by decrease nerve stimulation

6.1.1.1.1. relaxes the smooth muscle thinning the vessel wall and enlarging the lumen

6.1.1.2. increase blood flow at low pressure

6.1.2. Baseline (resting)

6.1.3. sympathetic activity / Vasoconstriction

6.1.3.1. diameter of vessel lumen and tone of the smooth muscle are determined by the degree of sympathetic activity

6.1.3.2. generally constricts vessels

6.1.3.2.1. vasoconstriction

6.1.3.2.2. this increases pressure inside the vessel

6.1.4. Relationship between sympathetic stimulation and blood vessel diameter

6.1.4.1. baseline ( Resting)

6.1.4.1.1. Sympathetic stimulation

6.1.4.1.2. smooth muscle

6.1.4.1.3. thickness of vessel wall

6.1.4.1.4. diameter of lumen

6.1.4.1.5. peripheral resistance in arterioles

6.1.4.2. Vasodilation

6.1.4.2.1. Sympathetic stimulation

6.1.4.2.2. smooth muscle

6.1.4.2.3. thickness of vessel wall

6.1.4.2.4. diameter of lumen

6.1.4.2.5. peripheral resistance in arterioles

6.1.4.3. Vasoconstriction

6.1.4.3.1. Sympathetic stimulation

6.1.4.3.2. smooth muscle

6.1.4.3.3. thickness of vessel wall

6.1.4.3.4. diameter of lumen

6.1.4.3.5. peripheral resistance in arterioles

6.2. What vessels does it effect?

6.2.1. Mainly arterioles as their walls contain more smooth muscle

6.2.1.1. responds to sympathetic stimulation

6.2.2. Large arteries such as the aorta contain more elastic tissue meaning they can expand and recoil depending on the volume of blood passing through

6.2.3. Veins also respond to nerve stimulation but only have little smooth muscle in their tunica media

6.3. Blood flow

6.3.1. resistance to flow fluids along a tube is determined by three factors

6.3.1.1. the diameter of the tube

6.3.1.2. the length of the tube

6.3.1.3. the viscosity of the fluid

6.3.2. the diameter of the resistance vessel is known as the peripheral resistnace

6.3.2.1. major factor in blood pressure regulation

6.3.2.2. Constant adjustment of blood vessel diameter helps regulate peripheral resistance and systemic blood pressure

7. Heart

7.1. Postion

7.1.1. lies in the thoracic cavity

7.1.2. in the mediastinum (space between the lungs)

7.1.3. lies slightly more on the left than the right

7.2. organs associated with the heart

7.2.1. Inferiorly

7.2.1.1. apex rests on the central tendon of the diaphram

7.2.2. superiorly

7.2.2.1. the great blood vessels

7.2.2.1.1. aorta

7.2.2.1.2. superior vena cave

7.2.2.1.3. pulmonary artery

7.2.2.1.4. pulmonary veins

7.2.3. posteriorly

7.2.3.1. oesophagus

7.2.3.2. trachea

7.2.3.3. left and right bronchus

7.2.3.4. descending aorta

7.2.3.5. inferior vena cava

7.2.3.6. thoracic vertibrae

7.2.4. laterally

7.2.4.1. the lungs

7.2.4.1.1. left lung overlaps the left side of the heart

7.2.5. anteriorly

7.2.5.1. the sternum

7.2.5.2. ribs

7.2.5.3. intercostal muscle

7.3. roughly cone shaped, hollow muscular organ

7.4. about 10cm long

7.4.1. about the size of a fist

7.5. Structure

7.5.1. the heart wall

7.5.1.1. composed of three layers of tissue

7.5.1.1.1. Pericardium

7.5.1.1.2. myocardium

7.5.1.1.3. endocardium

7.6. Blood supply to the heart

7.6.1. Arterial Supply

7.6.1.1. heart is supplied with arterial blood from fight and left coronary arteries

7.6.1.1.1. branches from the aorta

7.6.1.1.2. they recieve 5% of the blood pumped from the heart

7.6.1.1.3. traverse the heart eventually forming a vast network of capillaries

7.6.2. Venous drainage

7.6.2.1. most venous blood is collected into a number of cardiac veins

7.6.2.1.1. these join together forming coronary sinus which opens into the right atrium

7.6.2.1.2. the remainder passes directly into the heart chambers through venus channels

8. The cardiac cycle

8.1. at rest healthy heart beat for an adult is roughly 60-80 beats per min

8.2. during each hear beat the heat contracts (Systole) and then relaxes (Diastole)

8.3. stages of the cardiac cycle

8.3.1. each cycle lasts about 0.8 of a second

8.3.2. consists of 3 components

8.3.2.1. Atrial Systole

8.3.2.1.1. contraction of the artia

8.3.2.1.2. last rougly 0.1 seconds

8.3.2.2. Ventricular Systole

8.3.2.2.1. contraction of the ventricles

8.3.2.2.2. lasts roughly 0.3 seconds

8.3.2.3. Complete cardiac diastole

8.3.2.3.1. relaxation of the atria and ventricles

8.3.2.3.2. lasts roughly 0.4 seconds

8.3.3. Direction of blood flow

8.3.3.1. Atrial systole

8.3.3.1.1. Atria contract

8.3.3.1.2. AV valves open

8.3.3.1.3. Ventricles relaxed

8.3.3.1.4. Aortic/ pulmonary valves closed

8.3.3.2. Ventricular systole

8.3.3.2.1. Atria relaxed

8.3.3.2.2. AV valves closed

8.3.3.2.3. Ventricles contract

8.3.3.3. Atria and ventricles relaxed

8.3.3.4. Aortic / pulmonary valves open

8.3.3.5. Complete cardiac diastole

8.3.3.5.1. AV valves open

8.3.3.5.2. Aortic / pulmonary valves closed

9. Electrical changes in the heart

9.1. body tissues and fluid can conduct electricity well this allows electrical activity in the heart to be recorded on the skin surface using electrodes

9.1.1. this recording is called and Electrocardiagram (ECG)

9.2. ECG

9.2.1. recording of electrical activity in the heart

9.2.2. shows the spread of electrical signals produced by the pacemaker as it travels through the atria, the AV node and the ventricles

9.2.3. normal ECG tracing

9.2.3.1. Shows five waves

9.2.3.1.1. P wave

9.2.3.1.2. QRS complex

9.2.3.1.3. T wave

9.2.3.2. originates from the SA node

9.2.3.2.1. called Sinus rhythm

9.2.3.2.2. the rate of sinus rhythm is usually 60-100 b.p.m

9.2.4. ECG abnormalities

9.2.4.1. Faster heart rate is called tachycardia

9.2.4.2. slower heart rate is called is called bradycardia

10. Cardiac Output

10.1. amount of blood ejected from each ventricle every minute

10.1.1. expressed in Litres per min (L/min)

10.1.1.1. Calculated by multiplying Stroke volume by the heart rate (b.p.m)

10.1.1.1.1. Cardiac Output = Stroke volume x Heart rate

10.1.1.1.2. This can increase during exercise this is called cardiac reserve

10.2. Stroke volume

10.2.1. amount of blood expelled by each contraction of each ventricle

10.2.2. is determined by the volume of blood in the ventricles immediately before they contract

10.2.2.1. ie the ventricular end-diastolic volume (VEDV)

10.2.2.1.1. Sometimes called the preload

10.2.3. in healthy adult stroke volume is approx. 70 mL

10.2.4. Summary of affacting factors

10.2.4.1. VEDV

10.2.4.2. Venous return

10.2.4.2.1. Position of the body

10.2.4.2.2. skeletal muscle pump

10.2.4.2.3. respiratory pump

10.2.4.3. strength of myocardial contraction

10.2.4.4. blood volume

11. Blood Pressure (bp)

11.1. Blood pressure is the force / pressure that blood exerts on the walls of blood vessels

11.2. systemic arterial bp maintains the essential flow of blood into and out of organs of the body

11.3. can vary according to

11.3.1. time of day

11.3.1.1. bp falls at rest and during sleep

11.3.2. posture

11.3.3. gender

11.3.3.1. usually higher in women

11.3.4. age

11.3.4.1. increases with age

11.4. if bp gets to high it can

11.4.1. damage blood vessels

11.4.2. cause clots

11.4.3. bleed from sites of blood vessel rupture

11.4.4. result of discharge of blood from left ventricle into the already full aorta

11.5. if bp gets too low

11.5.1. blood flow through tissue bed can be inadequate

11.5.1.1. dangerous for essential organs

11.5.1.1.1. heart

11.5.1.1.2. kidneys

11.5.1.1.3. brain

11.6. Systolic

11.6.1. Arterial blood pressure

11.6.1.1. written as systolic pressure written above the diastolic pressure

11.6.1.2. measured using a sphygmomanometer

11.6.2. when the left ventricle contracts and pushes blood into the aorta

11.6.3. in adults this can be about 120 mmHg

11.7. diastolic

11.7.1. in complete cadiac diastole the pressure in the arteries is much lower

11.7.2. in adults this can be about 80 mmHg

11.8. Control of blood pressure

11.8.1. Short term regulation

11.8.1.1. on a moment to moment basis

11.8.2. long term regulation

11.8.2.1. slower longer lasting changes in blood pressure

11.8.2.1.1. Cardiovascular centre

11.8.2.1.2. affected by renin-angiotensin-aldosterone system

11.8.2.1.3. also action antidiuretic hormone

12. Pulse

12.1. normally represents the heart rate

12.2. measured in bpm

12.3. info obtained by pulse

12.3.1. rate at which the heart is beating

12.3.2. regularity of the heart beats

12.3.2.1. intervals between beats should be equal

12.3.3. volume / strenght of the beat

12.3.3.1. should be possible to compress the artery with moderate pressure

12.3.4. the tension

12.3.4.1. artery should feel soft and pliant under fingers

12.4. averaging 60-80 bpm at rest

12.5. factors affecting pulse

12.5.1. when arteries supplying peripheral tissues are blocked or narrowed

12.5.2. cardiac contraction disorders

12.5.2.1. atrial fibrillation

12.6. main pulse points

12.6.1. Temporal artery

12.6.1.1. by the eye

12.6.2. Facial artery

12.6.2.1. by the jaw

12.6.3. Common carotid artery

12.6.3.1. on the neck

12.6.4. Brachial artery

12.6.4.1. about halfway up on the inside arm

12.6.5. Radial artery

12.6.5.1. on inside of the wrist

12.6.6. Femoral artery

12.6.6.1. around the hip

12.6.7. popliteal artery

12.6.7.1. behind the knee

12.6.8. posterior artery

12.6.8.1. by the ankle

12.6.9. dorsalis pedis artery

12.6.9.1. by the toes