The Heart: Specialised striated pump in the vascular system

Right border: Right atrium, in line with super/infer VC

Inferior border: nearly horizontal, RV, slight contribution from LV @ apex

Left border: left ventricle + portion of left atrium

Superior border: both atria

Define the following:

Pericardium,

Fibrous Pericardium

Serous Pericardium

Pericardial Cavity

Pericardium: fibroserous sac enclosing the heart + roots of great vessels 2 layers: fibrous + serous

Fibrous Pericardium: superficial layer, tough inelastic, dense, irregular CT. Attaches to the central tendon of diaphragm + sternum.

Serious pericardium: double membrane, reflected on itself @ roots of vessels

parietal pericardium: Fused to fibrous pericardium

visceral serous pericardium: epicardium, adheres tightly to the heart surface

Pericardial Cavity: between serous pericardial layers, filled with pericardial fluid.

Epicardium: outer layer, CT, mesothelium. Protects inner structures of the heart

Myocardium: 95% heart, striated cardiac muscle, cardiac myocytes within supportive CT. Contracts to pump blood from ventricles, relaxes to allow atria to receive blood. Arranged in SPIRAL fashion, more effective 'wringing'. MI = no spiral = SHARP drop in output.

Endocardium: thin layer of endothelium overlying thin layer of CT. smooth lining for heart valves + chambers, continuous with endothelial lining of blood vessels. Minimises Friction

Define 'sulci':

Describe the two internal partitions and what arteries they contain.

Sulci: Surface grooves produced by internal partitions

Coronay Sulcus: circles heart, separates atria from ventricles. contains RCA, small cardiac vein, coronary sinus, circumflex branch.

IV sulci (anterior/posterior): separate two ventricles. Anterior IV sulcus contains anterior IV artery + great cardiac vein

posterior IV sulcus = diaphragmatic surface has PIVA + middle cardiac vein

Two continuous spaces, separated by the crista terminalis (smooth muscular ride) indicated by surface sulcus terminalis cordis

posterior to CT is the sinus of the venae cavae (smooth, thin walls)/(is where the veins empty)

anterior to the CT is the atrium proper

(has auricle) walls covered by pectinate muscle and coronary sinus

smallest cardiac veins: foramina:
scattered along the walls of the right atrium (drain myocardium directly)

Define:

interatrial septum

fossa ovalis

foramen ovale

interatrial septum: ridge, muscular, separates right/left atria. Faces forward to right. has muscular part (major part) and membranous part.

fossa ovalis: depression visible in the IA septum above inferior VC

foramen ovale: fetal, oxygenated blood from right atrium to left atrium to bypass lungs

Describe/define the structures of the Right Ventricle:

4-5mm in average thickness.

anterior surface of the heart. contains

trabeculae carnae: raised bundles of cardiac fibres (some are part of cardiac conduction system)

Chordeae tendineae: tendon-like structures, attach to cusps + papillary muscles.

Papillary muscles: cone-shaped trabeculae carnae 2 for each chordeae tendineae

Moderator band: specialised trabeculum, forms bridge between lower portion of IV septum and the papillary muscles.

Cons arteriosus (infundibulum): outflow tract of right ventricle

-forms the base/posterior surface of the heart

interatrial septum is part of the anterior wall

valve of the foramen ovale: opposite side of the foramen oval, may not be fused in some adults

10-15 mm thick, apex of the heart. posterior to the right ventricle (IV septum = anteiror wall)

ligamentum arteriosum: remnant.  of the ductus arteriosus from pulmonary trunk to the aorta.

Common structure of all valves:

commissures: sites in the fibrous ring where cusps are continuous 

Common to semilunar valves:

nodule of the semilunar valves: thickened middle portion at the free superior end. 

lunula of the semilunar cusp: thin lateral portion

Common to the AV valves:

Tricuspid Valve: between right atrium and ventricle, closed during ventricular valve.

Pulmonary valve: between pulmonary trunk and the right ventricle.

Mitral Valve: between left atrium and ventricle

aortic valve: you know wheree. projects into lumen of the aorta. right, left, posterior aortic sinuses are pocket like sinuses at the beginning of the aorta, right and left are where the coronary arteries leave. 

Fibres arranged spirally (wringing affect)

Ventricular muscle shortens, diameter of chamber is reduced

apex pulled upwards

therefore blood is more efficiently pressured

blood is directed towards the opening of the major arteries

1 central nucleaus

intercalated discs attach the ends of cardiac muscle fibres: contain gap junctions and desmosomes

gap junctions: allow action potentials to spread (therefore efficient contraction)

desmosomes: hold fibres together

DIFFERENCES BETWEEN IT AND SKELETAL

mitochondria: larger + more numerous than skeletal

actin/myosin/bands/zones/Z discs: the same

sarcoplasmic reticulum: smaller, therefore smaller muscle reserve of ca2+

Collection of dense, fibrous CT

anulus fibrosus: orificies between the chambers

maintains the integrity of the openings + attachment for the cusps. dense CT partition electrically isolates the atria from the ventricles. AV bundle passes between it, and is the only connection point

Left, Right branch come off the left, right coronary sinuses at the beginning of the aorta.

LCA: branches into the left circum flex and the anterior descending coronary branch

Anterior Descending Coronary Branch: anterior left ventricle and apex, anterior 2/3 of the interventricular septum, anterior right ventricle

Left circumflex branch: lateral part of the left ventricle, left atrium, 40% of the SA node

Right coronary artery:

Posterior Interventricular Branch:

Posterior left ventricle

Posteior 1/3 of IV septum

Posterior right ventricle

80% people have right dominance (regarding above)

Right marginal Branch:

Right Atrium

Lateral right atrium

60% of SA node

AV node (80%) people

Determined by the Starling forces

Hydrostatic forces describe physical pressure of blood within the vessels

Oncotic forces describe the concentration gradient developed by plasma proteins within the vessel, cannot move across capillary walls due to their size

filtration: from BHP and interstitial osmotic force

reabsorption: from oncotic force, more concentrated blood inside the capillaries. And high interstitial hydrostatic pressure

remaining fluid is drained into the capillaries

NFP: balance of filtation and absorption. net filtration = 11mgHg. net absorption = 9mmHg.

As EDV increases, so does the force of contraction.

EDV is determined by the duration of ventricular diastole

Venous Return: volume of blood that returns to the right ventricle.

The force EQUILISES output from both circulations.

What factors influence Fluid Movement?

How do hydrophilic/phobic molecules leave the capillaries?

Poiseuille's Law: Resistance to flow is proprotional to r^4

Tone of smooth muscles is controlled by local, exintrinsic and vasoactive substances.

local: histamine, pH, CO2, O2: DISTRIBUTION of cardiac output

Extrinsic: sympathetic nerves, circulatory hormones: Controlling BP

Vasoactive substances: released from the endothelial cells (NO, endothelin)

size of molecules: whether they can leave throguh the capillaires via simple diffusion: CO2, O2, glucose, amino acids and hormones

hydrophilic molecules pass through the intercellular clefts (fenestration)

hydrophobic molecules: leave through the lipid bilayer of endothelial cell plasma membranes