Lecture 4 Anatomy of Heart Flashcards
• Describe the general organization of the cardiovascular system. • Orientate the heart within the thorax. • Describe the chambered structure of the heart and related this to the pumping action of the organ. • Name the layers of the heart wall.
Cardiovascular system organs. (incl what it does)
Heart (pump), Arteries (supply), Veins/Lymphatics (drainage), Capillaries (Exchange)
what are organs made up of?
Vascular tissue
What is Vascular tissue made up of?
Connective tissue
Cells
Epithelia
What do cells consist of in the cardiovascular system?
Epithelia
Muscle
Blood Vascular System
A closed supply and drainage system.
- a continuous loop
2 loops
1 loop from heart to lungs then to heart.
Another loop from heart going to all other tissues then back to heart.
Supplying and draining capillary beds in the body.
Lymphatic (Vascular) System
- An open-entry drainage system.
- a one-way system
Organisation of the cardiovascular system
Supply side
Exchange network
Heart
Pump
Centre
drives blood through body
Arteries
Supply network - pipes
Capillaries
Exchange surfaces -
bring nutrients, gases in, and wastes out
Veins Lymphatics
Drainage
Epithelial cells
Barriers between environments - barrier between one surface and another
Muscle
Cardiac
Smooth
Blood flow
on right side of heart there is a tubular structure going from capillaries to lungs for gas exchange and going to the left side of the heart.
Pulmonary circulation -
Sending deoxygenated blood from right side of heart to lungs (reoxygenated). The reoxygenated blood returns in veins to the left side of the heart.
Supply side
Organization of the cardiovascular system
(incl what the supply side does, what will happen if damaged?, where situated?)
- Only arteries in supply path
- Major arteries are situated to avoid damage (eg: deep in the trunk; on flexor aspect of limbs).
- Carries blood under high pressure and high velocity, if artery severed you will lose a lot of blood quickly
- Important structures receive blood from two arteriol sources (two separate arteries).
- Arteries change their name at each major branch.
Exchange network - types of capillaries
Organization of the cardiovascular system
Continuous (controlled ~ tight)
Fenestrated (leaky)
Sinusoidal (very leaky)
Exchange network - 3 different types of capillaries with varying degrees of permeability
(How easy to leave the lumen where the blood cells are and cross into the interstitial space surrounding the capillary)
3 pathways for drainage
- Deep veins (Venous)- next to deep supply arteries draining in opposite direction
- Superficial veins (venous) blood loss is less significant and blood travels slower at lower pressure
- Lymphatics
why is Cross-sectional area of veins is at least twice that of arteries?
to shift the same volume of blood / second.
otherwise all peripheral tissues (eg hand) would swell because supply of the arteries wouldn’t match the drainage of the veins.
How do we balance when the supply is under high pressure and velocity, and the drainage is under low pressure and low velocity?
Increase the CSA of the drainage channels to get the same number of ml / second draining back towards the heart as pumping towards the tissue.
Heart shape
Blunt, cone shaped
Pointed end- Apex
Broad end - Base
Rotation and tilt brings ⅔ of heart to the left
PMI
point of maximal impulse
loudest beat
where does the heart sit?
within chest, laterally, behind sternum,
⅔ to left
size of loosely closed fist. Between 2 & 3 ribs is superior aspect of heart,
Midclavicular line of left clavicle between 5 & 6 ribs is the intercostal space Apex beat PMI (point of maximal impulse) against anterior chest wall.
Right ventricle of heart most anterior chamber towards sternum
Left atrium towards posterior towards thoracic vertebrae
Space/Cavity where heart sits is mediastinum
*don’t think I need to know
- most anterior chamber towards sternum
- posterior towards thoracic vertebrae
- heart sits is mediastinum
Right atrium -
Right ventricle -
- receives deoxygentaed blood from body and is drained to right ventricle.
- Delivers deoxygenated blood from right atrium into the pulmonary artery to be reoxygenated in lungs.
Left atrium -
Left ventricle -
- receives oxygenated blood via 2 left lung veins and is drained to left ventricle
- oxygenated blood is pumped through a valve into the aorta.
Interventricular septum -
septal structures which separates the left and right ventricles.
Atrium
left and right. thin walled (receiving) chambers
Right atrium receives blood from:
- superior vena cava, (all the blood draining back from the head, neck,chest and upper limbs)
- inferior vena cava, (below diaphragm, draining back towards the right side of the heart.
- coronary sinus. (Venous drainage of the heart. The blood supply to the heart drains back into the sinus structure posterior to the heart and drains back into the right atrium
Left atrium receives blood from
- 4 pulmonary veins
(bringing oxygenated blood from lungs back towards the left side of heart for distribution into systemic circuit
Layers of the heart wall
Endocardium, - inner most, chamber (ventricle), thin layer
Myocardium, - middle, cardiac muscle layer, thickest
Epicardium, - outer
Pericardium - protective sac that the heart sits within
Endocardium the thin delicate layer that faces onto the chamber. consists of…
- Endothelium (forms a non stick surface) it’s Simple squamous epithelium (barrier between the wall and lumen or chamber of heart).
- Loose irregular fibrous connective tissue (FCT)
(irregular orientated, support epithelial cells) - Small blood vessels
- Purkinje fibres (specialised conduction pathways which use the endocardium layer to run around the heart)
If there was no endothelium the blood will
clot inside the pipes, chambers of heart
Myocardium thickness in
right ventricle
left ventricle
- 0.5cm thick
- 1.5cm thick
Why is the muscle thicker?
Need a lot of muscle as The systemic circuit (Aorta) has to generate a lot of pressure to push the blood around the body. Overcome gravity.
Need less muscle as the Pulmonary circuit (Lungs) blood travels a short journey to the lungs from the right side of heart and requires less pressure.
Epicardium consists of
- visceral serous pericardium (membrane that sits against organ)
- Blood vessels (artery & vein)
- Loose irregular FCT
- Adipose (soft padding around the structures)
Pericardium membrane has 2 different names
visceral (membrane that sits against organ)
parietal (faces away from organ)
Pericardium
- Fibrous Pericardium
- Parietal serous pericardium
- Pericardial cavity
Pericardial cavity -
lubricant space where the heart lies, and allows the heart to beat in a lubricated environment. reduce friction.
Deep veins (Venous)
- next to deep supply arteries draining in opposite direction
Superficial veins (venous)
blood loss is less significant and blood travels slower at lower pressure
Superior vena cava,
All the blood draining back from the head, neck,chest and upper limbs
Inferior vena cava
Below diaphragm, draining back towards the right side of the heart.
Coronary sinus.
Venous drainage of the heart.
The blood supply to the heart drains back into the sinus structure posterior to the heart and drains back into the right atrium.
Endothelium
forms a non stick surface
Simple squamous epithelium (barrier between the wall and lumen or chamber of heart).
makes up endocardium
Loose irregular fibrous connective tissue (FCT)
irregular orientated, support epithelial cells
makes up endocardium
Purkinje fibres
Specialised conduction pathways which use the endocardium layer to run around the heart.
