Tech Cardiovascular System Flashcards by Andrew Chapman

The Cardiovascular System is divided into how many Parts

how many and what are they?

Circulatory system,consisting of the heart, blood vessels and blood
Lymphatic system, consisting of lymph nodes, lymph vessels and lymph

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The circulatory system

describe

The circulatory system is a closed system which transports essential food, oxygen and water to the cells and removes the waste they produce. It is closely linked with the respiratory and digestive system

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Three Main Components

what are they?

The heart

Blood

Blood vessels

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The Heart

describe the heart

Hollow coned shaped muscular organ -approximately size of the owners fist
It lies in the thoracic cavity, obliquely in the mediastinum, behind the sternum.
2/3 lies to the left of the midline,
Base above, apex below, resting on the diaphragm.

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Three layers of the walls of The Heart

describe

Pericardium – fibrous outer sac –2 layers
Myocardium – muscle layer, thickest in the left ventricle, has its own intrinsic stimulus, coronary arteries found here
Endocardium – smooth inner lining continuous with blood vessels

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Heart Chambers

Name them

Four chambers

•

•Left and right atria

•

•Left and right ventricles

•

•Left and Right sides are divided by muscular partition called the septum

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Heart Valves

Four valves:

Pulmonary valve
Aortic valve
Two atrioventricular valves

–Right or tricuspid valve

–Left or mitral valve

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Blood Flow through the Heart

describe the flow through the heart

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Pulmonary & Systemic Circulation

Describe

Pulmonary – involves pumping deoxygenated blood to the lungs and returning re-oxygenated blood to the heart
Systemic – involves circulating oxygenated blood throughout the body to the tissues and returning deoxygenated blood to the heart

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Blood Vessels

The heart pumps blood into vessels that vary in structure, size, and function, and there are several types: name them

arteries
arterioles
capillaries
venules
veins

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Structure of Blood Vessels

All vessels are structured in three layers:

Tunica Adventicia (Outer fibrous sheath)
Tunica Media (middle layer of muscle and elastic tissue)

•

•Tunica Intima (Inner layer of smooth endothelium)

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Portal Circulation

describe

A branch of the systemic circulation
Carries blood to and from the liver
Hepatic artery supplies oxygenated blood
Hepatic portal vein carries blood rich in nutrients from the digestive tract to the liver
Hepatic Veins carry deoxygenated blood from Liver to Inferior Venae Cava

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Spleen

describe

•Lies in the left hypochondrial region of the abdominal cavity, between fundus of the stomach and the diaphragm

•

•Size varies but usually approx. 12cm long, 7cm wide and 2.5cm thick

•

•Weighs approx. 200g

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Functions of the Spleen

name them

Produce new white blood cells
Store red blood cells
Destroy old red blood cells

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The Lymphatic System

describe

The fluid part of the blood which has exuded through the capillary wall becomes either extra-cellular or interstitial fluid
Much of this fluid is collected into the lymphatic vessels
Re-absorption directly into the blood stream is reduced by the higher osmotic and blood pressures contained within the blood vessels
Once in the lymphatic system it is classed as lymph

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•Lymph vessels (Begin in spaces between capillaries and cells)

–Similar to veins and capillaries but larger pores

•

•Lymph (Tissue fluid)

–Containing large molecules (Proteins and microbes and fragments of damaged tissue cells

•

•Lymph nodes

–Filter lymph and remove microbes and other material

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Lymph Vessels and Ducts

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•Lymphatic capillaries are slightly larger than blood capillaries

–They only allow fluid to enter them – not leave

Lymphatic vessels contain valves to prevent back-flow and drain lymph into the right and left lymphatic ducts
Lymphatic Ducts return the lymph to the circulation at the subclavian veins

Lymphatic System Also provides the sites for the production and maturation of lymphocytes, which are the white blood cells concerned with immunity

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Also provides the sites for the production and maturation of lymphocytes, which are the white blood cells concerned with immunity

Composition of Blood

describe

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Blood is composed of 55% liquid, 45% solids and contains four main elements:

Plasma (Liquid)
Red cells (erythrocytes)
White cells (leukocytes)
Platelets (thrombocytes)
Protect the body from infection
Distribute heat
Seal wounds by clotting

Principle Functions of Blood

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Carry oxygen and carbon dioxide
Carry nutrients and water
Carry waste products to excretory organs
Distribute secretion of glands (Enzymes and hormones)
Protect the body from infection
Distribute heat
Seal wounds by clotting

Blood Clotting Process

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Damaged platelets or tissue cells release thromboplastins (Enzymes)
Thromboplastins + Prothrombin (Plasma protein)

+ Calcium salts combine to form Thrombin

Thrombin is a proteolytic (protein-splitting)

enzyme that converts fibrinogen into fibrin

Fibrin + blood cells (inc platelets) = Clot

Blood Groups

Three main groups of factors are present in human red cells that differentiate individuals:

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•The Rhesus factors

•

•Minor blood groups

Coronary Circulation

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Two Major Coronary Arteries-Right and Left

•

•Right splits into:

–Posterior inter-ventricular branch

–Marginal branch

–

•Left splits into

–Anterior inter-ventricular branch

–Circumflex branch

Coronary Circulation

name

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Venous return from the heart muscle is mainly via the Coronary Sinus, which returns deoxgenated blood to the right atrium

the heart Electrical Conduction System

* Cardiac Muscle cells initiate contraction without the need of outside stimuli * Complex conducting pathways promote regular, rhythmic contraction of the myocardium

Electrical Conduction System Made up of three main parts name them

•The Sinoatrial Node –Located in the right atrium •The Atrioventricular Node –Located near the atrioventricular valves •The Atrioventricular Bundle (Bundle of His) –Located at the top of the interventricular septum

Sinoatrial Node (SA Node)

* Mass of specialised cells, located in the Right Atria * Natural ‘Pace Maker’ * Initiates contraction of the myocardium * Impulses spreading out from SA Node result in Atria contracting

Atrioventricular Node (AV Node)

* Located near the atrioventricular valves * Stimulated by the impulse originating at the SA Node * Relays the impulse through the atrio-ventricular junction to the Bundle of His Capable of initiating a pulse but at a slower rate than the SA Nod

Atrioventricular Bundle | (Bundle of His)

* Located at the top of the interventricular septum * Divides into left and right bundle branches, which run through the septum * Bundle branches further divide into purkinje fibres * Fibres spread from base of the septum into walls of ventricles

Atrioventricular Node (AV Node)

P Wave =atrial depolarisation QRS Complex =ventricular depolarisation T Wave =ventricular repolarisation

The pulse describe

Is a rhythmic pulsation of the arteries that can be felt at certain points where it passes over a bone e.g. –Wrist (radial) –Elbow (Brachial) • It is palpated and recorded to record rate, rhythm and strength

Factors affecting pulse rate

* Sex * Age * Body Temp * Digestion * Pain * Emotion * Exercise * Blood Pressure

Cardiac Cycle The sequence of events that constitute one heart beat

* Atrial systole (0.1 second) * Ventricle systole (0.3 second) • •Complete cardiac diastole (0.4 second)

Cardiac Cycle

* At a heart-rate of 75bpm the cardiac cycle lasts 0.8 seconds * It has three phases: –Isovolumetric relaxation –Ventricular filling Ventricular systole

Cardiac Output

The amount of blood ejected from the heart in one minute * Cardiac output = stroke volume x heart rate * Normal stroke volume in healthy adult is 70ml :- If HR is 72 Cardiac Output is: 70ml x 72 = 5040ml (Approx 5lts)

Blood Pressure describe

* Is the force exerted by the blood on the walls of the blood vessels. * Systemic arterial BP maintains the flow of blood into and out of the organs of the body * BP = Cardiac Output x Peripheral resistance

Blood Pressure Systolic Diastolic

•Systolic Pressure (Systole) –Blood forced into arteries by contraction of the left ventricle –Normal healthy adult approx 120mmHg – •Diastolic Pressure (Diastole) –Between systolic contractions elastic recoil of the arteries –Normal healthy adult approx 80mmHg

Pulse Pressure

Pulse pressure is the difference between Systole and Diastole e.g. • BP = 120mmHg :- Pulse Pressure = ? 80mmHg 40mmHg

Nervous Control of Circulation

* The cardiovascular centre in the medulla oblongata is the main region for nervous system regulation of the heart and blood vessels. * It provides output to both the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS)

Output from Cardiovascular centre

* Flows along sympathetic and parasympathetic fibres of the ANS * Sympathetic (stimulatory) impulses reach the heart via the ***_cardiac accelerator nerves_*** • * Parasympathetic (inhibitory) stimulation is conveyed along ***_vagus nerve_*** * The centre also continually sends impulses to smooth muscle in blood vessels via ***_vasomotor nerves_***

Control of Blood Pressure ## Footnote Blood pressure is controlled in two ways:

•Short-term –Baroreceptors –Chemoreceptors –Circulating hormones • •Long-term –Regulation of blood volume by kidneys –Renin-angiotensin-aldosterone system (RAAS) –Antidiuretic hormone (ADH) –Heart releases atrial natriuretic peptide (ANP)

Mean Mean Arterial Pressure (MAP)Arterial Pressure (MAP) how is it worked out

BP is 150/75 Use the following formula to calculate MAP: Diastolic + 1/3 (Systolic – Diastolic) 75 + 1/3 (150-75) = 100mmHg Cerebral blood flow is reliant on cerebral perfusion pressure (CPP) which should be above 60mmHg to perfuse the brain. CPP is related to MAP and intracranial pressure (ICP) and the following formula is used to calculate CPP:

Tech Cardiovascular System Flashcards

(42 cards)