Mod D Tech 10 Cardiovascular System Flashcards
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
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
Three Main Components
what are they?
The heart
Blood
Blood vessels
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.
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
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
Heart Valves
Four valves:
- Pulmonary valve
- Aortic valve
- Two atrioventricular valves
–Right or tricuspid valve
–Left or mitral valve
Blood Flow through the Heart
describe the flow through the heart
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
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
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)
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
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
Functions of the Spleen
name them
- Produce new white blood cells
- Store red blood cells
- Destroy old red blood cells
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
•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
Lymph Vessels and Ducts
•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
Also provides the sites for the production and maturation of lymphocytes, which are the white blood cells concerned with immunity
Composition of Blood
describe
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
- 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
- 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:
•The Rhesus factors
•
•Minor blood groups
Coronary Circulation
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
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
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)
