Anatomy Flashcards
Where is the heart located?
middle mediastinum
What is the mediastinum?
the area that lies between the lungs
What is the pericardium?
the sac surrounding the heart
What are the 2 layers of the pericardium?
outer fibrous
inner serous
Describe the fibrous pericardium
tough, thick, protective layer
prevents overfilling and protects from penetrating injuries
What happens if the pericardial cavity fills with blood?
haemopericardium can cause an increase in pressure that prevents cardiac contraction
–> cardiac tamponade
Describe the serous pericardium
lines heart surface
secreted serous fluid
has visceral and parietal layer
What type of nerves supply the heart?
sensory nerves - visceral afferents
motor nerves - sympathetic and parasympathetic
What effect does parasympathetic stimulation have on the heart rate?
slows it down
What effect does sympathetic stimulation have on the heart ?
speeds up heart rate
increase force of contraction
What are the 3 layers of the heart?
epicardium
myocardium
endocardium
What is the epicardium?
the visceral serous pericardium
What is the myocardium?
layer of muscle
What is the endocardium?
internal lining that is continuous with the endothelium of blood vessels connecting with the heart
What does the inferior surface of the heart rest on?
the diaphragm
What forms the inferior surface of the heart?
both ventricles
What forms the anterior surface of the heart?
mainly the right ventricle
What blood goes into the right side of the heart? via what?
deoxygenated blood from the body tissues via the vena cava
Where does blood leave the right side of the heart?
via the pulmonary artery to the lungs
What blood goes into the left side of the heart? via what?
oxygenated blood from the lungs via the pulmonary veins
Where does blood leave the left side of the heart?
to the organs and tissues via the aorta
Describe the electrical pathway of the heart
starts at SA node
travels to AV node
travels down right and left bundles in septum
spreads out to myocardium
What part of the heart insulates the electrical signals?
fibrous skeleton (valves and septum)
Why is it important that there is only one point of electrical conduction between the atrial and ventricular myocardium?
to ensure that atrial contraction and therefore, ventricular filling can be completed before ventricular conctraction
What is fibrillation?
uncoordinated contraction of myocytes that results in inefficient pumping that can be fatal if it involves the ventricles
Which nerve puts a constant effect on SA node that dominates at rest?
vagus nerve (parasympathetic)
What is the neurotransmitter for the sympathetic supply to the heart?
noradrenaline in b1 adrenoceptors
What is the neurotransmitter for the parasympathetic supply to the heart?
acetyl-choline
What type of muscle is cardiac muscle?
striated
What are gap junctions?
protein channels that form low resistance communication to ensure each excitation reaches all the myocytes
How is cardiac muscle tension produced?
sliding of actin filaments on myocin filaments
shortening of muscle to produce force
Is
a) actin
b) myosin
the thick or thin filament?
a) thin
b) thick
What is the blood supply to the inferior heart?
right coronary artery and circumflex artery
What is the blood supply to the anterior heart and septum?
left anterior descending artery
What is the blood supply to the lateral heart?
obtuse marginal branch of the circumflex artery
diagonal branch of the left anterior descending artery
