CFB L1 Flashcards
Structure of CV system
Closed organ system which circulates blood around the body in two circulations:
- Pulmonary circulation
- Systemic circulation
Consists of:
- Heart
- Blood vessels
Function of CV System
Circulates blood to lungs and to body
Structure of Heart
1.Hollow muscular organ
2.4 chambers, 2 atria (left + right), 2 ventricles (left + right)
3.Rests superior to diaghragm, anterior to veterbral column and posterior to sternum in the mediastinum
4.Positioned between the 2nd rib and 5th intercostal space.
5.Posterior + superior surface of heart = base. Flat surface + points towards right shoulder. POINT OF ATTATCHMENT OF MAJOR GREAT BLOOD VESSELS
6. Anterior + inferior surface of heart = apex towads left of heart. Tapers to a blunt joint
Left Side of Heart
- High Pressure Side
- Acts as pressure pump
- Pumps blood into systemic arteries at a sufficient pressure to alloow them to “drive” to body tissues
Right side of Heart
- Low pressure side
- Pumps blood into pulmonary arteries at a relatively lower pressure, “drives” blood into lungs
Structure of the Wall of Heart
Wall of heart has 3 layers, surronded by a 2 layer sac
Layer 1: Epicardium
Layer2: Myocardium
Layer3: Endocardium
Two layer sac: pericardium
Epicardium
Outer layer
Consists of
- Epithelial cells
- Connective tissue
Thin, transparent layer
Mycardium
M - MIDDLE
Middle layer, forms bulk of heart
Consists of
Cardiac myscle cells
Rich supply of blood vessels
Nerve fibres
Muscle pumping action
Endocardium
Inner layer
Consists of squamous epithelial cells which overly (spread across) layer of connective tissue therefore, allowing inner layer to join with myocardium.
Inner layer is continous with endothelium of blood vessels entering / leaving heart
Lines chambers of heart + valves
Cardiac Muscle Tissue - Myocardium
Consists of cardiomyocytes
Striated - tubular myofibrils with repeating sacomeres containing contractile filaments
Cardiomyocytes have 1 nucleus and many mitochondria, 40% of cell is mitochondria
Adjascent cardiomyocyte cells join together, end to end via interconnected disks (cross bands)
Interconnected disks allow exchange of ions + synchronised muscle contraction of myocardium
CARDIAC MUSCLE WORKS AS A SINGLE FUNCTIONAL SYNCYTIUM
Borders of the Heart
Four Borders of the Heart:
- Right Border - Formed by right atrium in line with superior + inferior vena cava
- Inferioir Border - formed mainly by right ventricle, slightly by right atrium, bear the apex
- Left Border - formed mainly by left ventricle, slightly by left atrium
- Superior Border - formed by left + righy atria
Structure of the Chambers of the Heart
Upper two are atria, lower two are ventricles
SEPTUM - Internal partition, separates atria and ventricles
Inter -atrial septum - separates left and right atria
Inter - ventricular septum - separates left and righy vetricles
The left ventricle is larger + stronger, therefore, dominates inferior posterior part, forms apex
Right ventricle dominates anterior surface
Blood flow to atria + ventricles is controlled by valves between atria + ventricles
DIAGRAM of heart chambers
LEFT ATRIUM
LEFT VENTRICLE
RIGHT ATRIUM
RIGHT VENTRICLE
SEPTUM
ATRIOVENTRICULAR VALVES
Right Atrium
Upper right chamber of heart
Recieves deoxygenated venous blood from rest of body
Ejects this blood into right ventricle through right atrioventricular opening which is guarded by right atrioventricular valve
Forms right border, superior border + base
Right Ventricle
Lower right chamber of heart
Recieves venous deoxygenated blood from the right atrium via tricuspid valve
Pumps this blood through semi lunar pulmonary valve into pulmonary trunk where it reaches the lungs for gas exhange
Makes up inferior border
Left Atrium
Upper Left Chamber of Heart
Recieves oxygenated blood from pulmonary veins (2 from each lung)
Ejects this blood into the left ventricle through left AV openings guarded via AV valves
Forms superior border
Left ventricle
Lower left chamber of heart
Recieves oxygenated blood from left atrium through bicuspid valve
Pumps this blood through semilunar aortic valve into aorta (aortic arch) to rest of body tissues at high pressure through
Makes inferior border + left border
THICKEST OF ALL CHAMBERS
Mitral Valve
- Bicuspid Valve / Left AV valve
Function of Valves
Control unidirectional blood flow
Prevent backflow of blood
Types of Valves in heart
Right atrioventricular valve: between the right atrium and right ventricle
Left atrioventricular Valve: Between left atrium and left ventricle
Semi-lunar aortic valve - at base of aortic branch
Semi-lunar pulmonary valve - at base of pulmonary trunk
AV valves attached firmly to ventricles like cord like tendons - chordae tendineae
Chordae tendineae attached to papillary muscles, when papillary muscles contract, they produce tension, preventing vavlves from inverting during systole.
Diagram showing Chordae Tendineae and Papillary Muscles
Left Atrium
Left Ventricle
Mitral Valve
Chordae Tendineae
Papillary Muscles
Right AV Valve
Tricuspid Valve
3 Cusps / leaflets (triangular folds of valve)
Controls blood flow between right atrium and right ventricle
Left AV Valve
Mitral / Bicuspid Valve
2 Cusps / Leaflets (triangular folds of valve)
Controls blood flow between left atrium and left ventricle
Opening / Closing of AV Valves
Open when pressure in ventricles lower than pressure in atria - ventricular diastole
Close at same time, which causes first heart sound, S1 LUB
Semi-lunar valves
Semi-lunar: shaped like a crescent
The 2 semilunar valves are: semilunar aortic valce and semilunar pulmonary valve
Located at base of aorta and pulmonary trunk
Both have 3 cusps
Open when intraventricular pressure is higher than arteriole pressure - ventricular systole
Close when arteriole pressure is higher than intraventricular pressure to prevent backflow of blood from arteries into ventricles - ventricular diastole
When semilunar valves close simultaneously, produces S2, second hear sound “dub”
Diagram showing valves
- Think about the direction of blood flow through the heart
- Mitral Valve
- Tricuspid Valve
- Pulmonary valve
- Aortic Valve
Cusps of Heart Valves
DIAGRAM CFB L1
Pulmonary Valve:
- Anterior semi-lunar cusp
- Left semi-lunar cusp
- Right semi-lunar cusp
Aortic Valve:
- Left semi-lunar cusp
- Right semi-lunar cusp
- Posterior semi-lunar cusp
Mitral Valve / Bicuspid Valve:
Anterior cusp
Posterior cusp
Tricuspid Valve:
Anterior cusp
Posterior cusp
Septal cusp
Types of blood vessels
3 types of blood vessels - based on structure and function which are then divided into 3 sub types:
- Arterial blood vessels ( Elastic arteries, muscular arteries, arterioles)
- Venous blood vessels (veins, venules, venous sinuses)
- Capillaries (continuous, fenestrated, sinusoids)
Blood vessels have 3 layers surrounding the lumen. What are these 3 layers?
Tunica interna - inner most layer
ENDOTHELIAL CELLS
Tunica media - medium layer TUNICA INTIMA
SMOOTH MUSCLE CELLS
Tunica externa - outermost layer TUNICA ADVENTITIA
COLLAGEN FIBRES + FIBROBLASTS
Structure of blood vessels
Recognise on DIAGRAM
- Tunica interna
- Tunica media
- Tunica externa
Look at these layers in both, arteries + veins and see the difference in thickness and proportion of the layers.
Pay attention to the capillary at the bottom, it does not have any of these layers surrounding the vessel lumen. It only has:
Single layer of endothelial cells
Pay attention to endothelial cell nucleus
General function of arterial blood vessels
To carry oxygenated blood from heart to body tissues.
To carry poorly oxygenated blood from heart to lungs so it can get oxygenated
Elastic arteries
Elastic Fibres:
-More elastic fibres than any other blood vessel
-Elastic fibres found in tunica media
-Allow artery to stretch / expand + recoil. Expand when blood is ejected from the heart into artery + recoil to push blood forward to other ateries, therefore, aka conducting artery
Large Diamater Lumen
-Low resistance for blood flowing that is pumped by the heart
Large + thick walls, close to the heart
Examples of elastic arteries
- Aorta
- Common Carotid
- Vertebral
- Pulmonary
Muscular arteries
Smooth Muscle
- More smooth muscle than any other vessel
- Lots of smooth muscle in tunica media
- Smooth muscle allows vasodilation + vasocontriction of arteries which helps control rate of blood flow - important for blood pressure control
- aka delivering arteries as they carry blood to different parts of body
Medium sized arteries + Thick walls 1mm
Examples of muscular arteries
- Splenic
-Brachial
-Radial
Arterioles
Control blood flow from arteries to capillaries - connect arteries to capillaries
Vasoconstrictions + vasodilations allow arterioles to control rate of blood flow to capillaries - also this helps control blood pressure
Arterioles near arteries consist of 3 layers. They have more smooth muscle than elastic fibre in their tunica media
Arterioles near capillaries only consist of a single layer of endothelial cells with a few surronding muscle fibres
Structure of arteriole
- Endothelium
- Smooth Muscle
- Elastic fibres
- Fibroblasts
RECOGNISE ON DIAGRAM!!!!!!
General Function Venous Blood Vessels
Carry oxygenated blood from lungs back to heart
Carry poorly oxygenated blood from body tissues to heart
Veins
Have the 3 layers, tunica interna, tunica media, tunica externa
Tunica interna thinner than arteries
Tunica media thinner than arteries. Less smooth muscle. Therefore, less vasodilations + vasocontrictions
Thickest layer - tunica externa - lots of collagen fibres + elastic fibres
Some veins contain valves to prevent backflow of blood
State examples of veins which do not contain valves
- Batson venous plexus
- Thebesian veins
- Coronary sinus
State the function of venules
CONNECT VEINS TO CAPILLARIES
Therefore, allow return of blood from capillary bed into vein
State the function of venous sinuses
-Thin wall, 1 layer of endothelium
-NO SMOOTH MUSCLE, ELASTIC FIBRES
-Located in BRAIN: Carry deoxyganetd blood from cerebral veins to jugular vein
State functions of capillaries
Exchange of oxygen, nutrients + waste between blood + cells
What is microcirculation?
Blood circulation from arterioles to venules through capillaries
How are capillaries adapted to their function?
Thin walls - single layer endothelium
Distroubted all over body, close to every cell
Higher number in tissues with high metabolic activity as they need more oxygen + nutrients
(e.g. kidney, liver, muscle)
State two body tissues which have no capillaries
Cornea
Lens
State 3 types of capillaries
- Continuous
- Fenestrated
- Sinusoid
Compare the 3 types of capillaries
Continuos - Endothelium + basement membrane continuous - found in skeletal muscle, connective tissue, lungs
Fenestrated - endothelium has small gaps (fenestrations) (kidneys, villi, choroid plexi)
-Sinusoids - endothelium has large gaps, incomplete basement membrne, liver, bone marrow, spleen, anterioir pituitary, parathyroid
Diagram comparing 3 types of capillaries
LECTURE 1
