Cardiovascular system 2 Flashcards
Blood flow (heart);
Stage 1; Deoxygenated blood from the superior and inferior vena cava arrive in the right atrium (3mm thick)
It pumps blood through tricuspid valve into the right ventricle (5mm thick)
Stage 2; Right ventricle contracts & pumps the deoxygenated blood through the pulmonary valve and into the pulmonary trunk (which divides the left & right pulmonary arteries)
Stage 3: The blood flows through the lungs where gas exchange occurs
Stage 4: Blood (now oxygenated) returns to the left atrium (3mm thick) via the pulmonary vein
Stage 5; The left atrium pumps oxygenated blood through the mitral / bicuspid valve into the left ventricle (10-15mm thick)
Stage 6: The left ventricle contracts & pumps oxygenated blood through the aortic valve into the ascending aorta. Some of the blood the aorta flows into the coronary arteries which carry blood to the heart wall
Cardiac output
The volume of blood being pumped out by the heart per minute. On average 5L per minute. Key definitions = systole, diastole, tachycardia, bradycardia
Cardiac output; blood pressure
The pressure exerted by circulating blood on the blood vessel walls.
Diastolic - Period of relaxation when the heart fills with blood
Systolic - The force that drives blood out of the heart (contraction)
Cardiac output; rate
Bradycardia; Resting heart rate under 60 bpm (brady = slow)
Tachycardia; Resting heart rate of over 100 bpm (tachy = rapid)
Cholesterol
A vital compound for cell structure and function. It is in every cell. Functions inc. cell membrane integrity, Vit D & calcium metabolism, sex hormone
Circulation
2 types of circulation; systemic circulation and pulmonary circulation;
Circulation (pulmonary)
Blood from the heart to the lungs and back to the heart (pulmonary = meaning lungs)
Circulation (systemic)
Blood from the heart is distributed around the body before returning to the heart (systemic = relating to body systems/entire body)
Conduction system of the heart
System of nerves that help the heart contract. 5 steps;
1) sinoatrial node (SA node),
2) Atrioventricular node (AV node),
3) Atrioventricular bundle (Bundle of His),
4) Right & left bundle branches,
5) Purkinje fibres
Step 1) Sinoatrial node (SA node);
The pacemaker of the heart – sets rate and rhythm. Initiates cardiac conduction in right atrial wall. Each nerve impulse from SA node propagates through each atrium causing atrial contraction
Step 2) Atrioventricular node (AV node); A relay station - conducts impulses at a slightly lower rate to allow atria to finish contracting. Located in the bottom right of intertribal septum
Step 3; Atrioventricular bundle (Bundle of His); Only site where nerve impulses can conduct from atria to ventricles
Step 4) Right & left bundle branches; From the bundle of his, the nerve impulse enters the left & right bundle branches, which extend the interventricular septum towards apex of the heart
Step 5) Purkinje fibres; The purkinje fibres conduct nerve impulse beginning at the apex of heart, up the remainder of ventricular myocardium = ventricular contraction
Contraction (of the heart)
The myocardium performs periodic contractions through a network of cardiac fibres that are self-excitable (autorhythmic)
Ductus arteriosum
A temporary blood vessel (during foetal life) called the ductus arteriosum shunts the blood from the pulmonary trunk to the aorta. Closes after birth to form ligamentum arteriosum (ductus = duct/tube, arteriosum = artery)
Foramen ovale
A depression called the fossa ovalis (within the interatrial septum is).Previously called foramen ovale in foetal development where it shunts blood from right atrium - left atrium, to bypass lungs (foramen=hole, fossa=shallow depression)
Heart layers
Fist sized muscular organ that contracts to pump blood around the body. Has three layers; endocardium, myocardium, pericardium
Layers; Endocardium
Innermost layer, thin layer of endothelium overlying a thin layer of connective tissue. Provides a smooth lining for the heart chambers & covers heart valves
Layers; Myocardium
Middle & thickest layer, autorhythmic cardiac muscle (striated & involuntary), makes up 95% of the heart. Functions to pump blood out of the heart
Layers; Pericardium
Outer layer of heart, thin double layered membrane. Contains fibrous pericardium that attaches to the diaphragm & inner serous pericardium. Functions to keep heart in position within the thorax & allow free movement during contractions
Lipoproteins;
LDL & HDL
Low density lipoproteins (LDL). Carry 75% total cholesterol in blood, carrying it from the liver to cells of the body. In excess can deposit cholesterol in arteries
High density lipoproteins (HDL). Remove excess cholesterol from body cells & blood & transport it to the liver. Prevent accumulation of cholesterol in blood
Myocardial metabolism
Fatty acids (50-70%) & glucose (30%) = predominant fuel in cardiac muscle. Cardiac is aerobic & heart consumes 10% of the total body O2 consumption
Nervous system; Parasympathetic
Rest and digest. Decrease rate and strength of contraction (via vagus nerve). Little influence on blood vessels
Nervous system; Sympathetic
Fight & flight. Increases rate and strength of contraction = vasoconstriction
Portal circulation
Venous blood passes from the digestive tract, spleen and pancreas directly to the liver, known as the hepatic first pass (hepatic = liver)
Portal vein
The vessel that carries the absorbed substances through the hepatic first pass
Pulse rate
A blood pressure wave originating from the heart. Varies depending on stage of life
Structure of the heart; chambers
The heart is divided into 4 chambers; right atrium, right ventricle, left atrium, left ventricle
Structure of heart; Atria
Receiving chambers of the heart (receive venous blood) & pump blood into ventricles. Separated by the interatrial septum.
Left Atrium receives Oxygenated blood from the pulmonary veins and pumps it into the left ventricle via the bicuspid (mitral) valve
Right atrium recieves deoxygenated blood from the vena cava and pumps it into the right ventricle via the tricuspid valve
Structures of heart; ventricles
The lower chambers of the heart, which receive blood from the atria. The ventricles are separated by the interventricular septum. They pump blood into arteries (aorta and pulmonary arteries) via atrioventricular valves.
Left ventricle receives oxygenated blood via the bicuspid (mitral) valve from the left atrium. The ventricle pumps blood via the aortic valve into the aorta to be taken to the rest of the body. The left ventricle has the thickest wall as it needs to pump blood through the aorta to the whole body.
The right ventricle receives deoxygenated blood via the tricuspid valve from the right atrium. The ventricle pumps blood via the pulmonary valve into the pulmonary trunk and then arteries, to the lungs.
Structures of heart; Septum
Structure separating the left and right atrium and ventricles (atrioventricular and interventricular)
Structures of the heart;
Pulmonary veins
Part of the pulmonary circulation. Transport oxygenated blood from the lungs to the heart (into the left atrium).
Structures of the heart; Superior Vena cava
A large vein that carries deoxygenated blood to the heart from other areas of the body:
Superior Vena Cava – from the upper body
Inferior Vena Cava – from the lower body
Structures of the heart;
Pulmonary arteries
Part of pulmonary circulation. Transport deoxygenated blood from the right side of the heart to the lungs)
Structure of heart; Aorta
Main artery that carries Oxygenated blood away from your heart to the rest of your body.
Structures of heart; Tricuspid valve (atrioventricular)
Valve between right atrium & right ventricle. Ensure blood flow is one way
Structures of heart; Bicuspid (mitral) valve (atrioventricular)
Valve between left atrium & left ventricle. Ensure blood flow is one way
Structures of heart; Pulmonary valve
Valve between right ventricle & pulmonary trunk/arteries. Ensure blood flow is one way
Structures of heart; Aortic valve
Valve between left ventricle & aorta. Ensure blood flow is one way
Vasoconstriction
Smooth muscle is influence by the ANS – Vasoconstriction increases blood pressure, triggered by sympathetic nervous system stimulation
Vasodilation
Smooth muscle is influenced by the ANS – Vasodilation reduces blood pressure, triggered by the parasympathetic nervous system
Vessels: types and layers
Transport blood around the body. Three main types are arteries, veins and capillaries Small arteries are arterioles, small veins are venules. Most contain 3 layers; tunica intima, tunica media, tunica externa
Vessels; Arteries and arterioles
Vessels that carry oxygenated blood (except pulmonary and umbilical) away from the heart. High pressure, no valves, thicker / more muscular.
Vessels; Veins and venules
Vessels that carry de-oxygenated (except pulmonary and umbilical veins) blood towards the heart, low pressure with valves, thin walls.
Vessels; Capillaries
Small blood vessels connecting arterioles & venules. Specialise in the exchange of substances between blood & cells/tissues, contain only epithelium-thin walls.
Vessels; Capillary exchange
Keeps blood flowing through capillaries to allow exchange of water (osmosis), nutrients (facilitated diffusion & active transport), gases -CO2 & O2 (diffusion)
Vessel structures:
Tunica intima; Innermost layer made of epithelium (epithelial tissue); protects vessel wall and secretes chemicals.
Tunica media; middle layer. Layer of smooth muscle that controls blood vessel diameter
Tunica externa; Outermost layer made of elastic and collagen fibres
