4. Anatomy of the CVS 1 Flashcards
What is the function of arteries?
distribute blood AWAY from heart
What is the function of capillaries?
exchange of nutrients
What is the function of veins?
collect and return blood TOWARDS the heart
What is the function of the lymphatics?
drain excess extracellular fluid from tissues and plays a role in metastases
Where is the heart located in the thoracic chest?
middle mediastinum
Which region of the body doesn’t have blood vessels? How does it get its nutrient supply?
cartilage; gets its nutrients from diffusion from underlying connective tissue
Which 2 regions of the body doesn’t have lymphatics? How does it get its nutrient supply?
- brain
- eye
What are 2 main circulations in cardiovascular system?
- pulmonary (heart-lungs-heart)
2. systemic (heart-body-heart)
What are 2 additional important circulatory systems?
- hepatic portal circulation
2. lymphatic system
In which region is the apex of heart found?
l. ventricle ( left anterior side)
In which region is the base of the heart found?
l.atrium (posteriorly)
What is right border of heart formed by?
right atrium
What is the left border of the heart formed by?
l. ventricle
What is the function of the auricles in the heart?
- store blood
- increase capacity of the atrium (and the volume of blood it’s able to contain)
What veins drain coronary arteries?
Cardiac veins (wrapped around the heart)
Above which vertebral region does superior mediastinum lie?
above T4
Where does the inferior mediastinum start and end at?
Starts at T4 and ends at the diaphragm
What are mediastinum divided into?
- superior
- inferior; anterior, middle and posterior
What does anterior mediastinum contain?
fat, remnants of thymus gland (which disappears at puberty)
What is caused if thymus remnants spread into lungs and what surgical procedure is needed?
thymoma; thymectomy needed
Define mediastinum.
- central compartment of thoracic cavity surrounded by loose connective tissue
Where EXACTLY is the apex of the heart found?
5th left intercostal space in the midclavicular line
What is the difference in the position of the heart in children?
-positioned higher in children and lies more horizontal
If a person is standing up, what will happen to the heart?
May appear slightly lower than 5th left intercostal space in the midclavicular line
What is situs inversus?
condition where all organs lie on the opposite sides of the chest (swapped), people are asymptomatic (apex on right and aorta on left)
At what vertebral landmark is the sternal angle located?
T4
What is anterior to the heart? (4)
- sternum
- costal cartilages 4-7
- anterior edges lungs and pleurae
- thymic remnants
What is posterior to the heart? (3)
- oesophagus
- descending aorta
- thoracic vertebrae 5-8
What is lateral to the heart? (2)
- lungs
2. phrenic nerves (which also give sensory fibres to pericardium as much as to the diaphragm)
What is inferior to the heart? (1)
- central tendon of diaphragm
What 3 layers make up the heart wall?
- endocardium (innermost)
- myocardium (middle)
- epicardium (outermost)
What makes up the endocardium? (3)
- epithelium (flat simple squamous epithelial cells)
- basement membrane
- connective tissue
What makes up the myocardium? (1)
- muscle
What makes up the epicardium?
- connective tissue
- basement membrane
- epithelium (flat simple squamous epithelial cells)
What makes up the epithelium of epicardium?
visceral pericardium
What 2 layers are found above the visceral pericardium (epithelium of epicardium)
- parietal pericardium
- fibrous pericardium (outside)
What is found between visceral pericardium and parietal pericardium?
pericardial cavity
What are features of endocardium? (what does it line, what cells make it up and what does it sit on?)
- lines heart chambers
- simple squamous epithelium sitting on the BM
- sits on connective tissue
What does endocardium form?
forms valves (projections on it form valves)
What is myocardium made up of?
- cardiac (striated) muscle (myocytes)
- thick middle layer of heart wall
What do the myocyte cells look like?
- contain lots of mitochondria
- central rounded nuclei in myocardium
Is there a capillary bed in the myocardium?
Yes, a rich capillary bed
Why are muscle bundles in different planes in myocardium?
to close down chamber lumen
What are myocytes connected by?
intercalated discs (complex junctions that anchor structures containing gap junctions)
What do myocytes all connected together form as they synchronise?
a functional syncytium as they contract in unison
What two junctions make up the intercalated disc?
- desmosomes
2. gap junctions
How do desmosomes connect and what is their function in cardiac cells?
- connect at horizonatal interface
- bind myocytes together
How do gap junctions connect and what is their function in cardiac cells?
- connect at vertical interface
- electrical communication
- essential to coordinated cardiac cycle
What is the epithelium of the epicardium the same as?
same as the visceral layer of serous pericardium
What tissue may be found in the epicardium?
fatty tissue
What features branch out from the epicardium?
contains main branches of coronary arteries
What are the 4 heart chambers?
- right atrium
- left atrium
- right ventricle
- left ventricle
What is the direction of blood flow controlled by?
valves (which prevent backflow)
What are the 4 heart borders?
- left border
- right border
- superior border
- inferior border
What makes up the left border of the heart?
mainly by l. ventricle (but a little bit by l.atrium also)
What makes up the right border of the heart?
mainly by r. atrium (and r. ventricle below)
What is the function of valves?
control direction of blood flow by preventing back flow
Where are cusps on valves derived from?
thin structures derived from endocardium
How do valves work?
passively
What 2 structures prevent valve failure and their prolapse?
- chordae tendinae
2. papillary muscles
What are the most common abnormalities in heart valves? (2)
- incompetence; widening of valve
2. stenosis; narrowing of valve
What is the most common infection of the heart valves?
bacterial endocarditis
What are the 4 heart valves?
- Tricuspid valve
- Mitral valve
- Pulmonary valve
- Aortic valve
What is another name for tricuspid and mitral valves?
AV valves
What is another name for pulmonary and aortic valves?
semi-lunar valves
What is the number of papillary muscles related to?
number of cusps on the valve it’s attached to
How many cusps does each valve have?
- tricuspid; 3
- pulmonary; 3
- aortic; 3
- mitral/bicuspid; 2
What is the cardiac skeleton made up of?
connective tissue
What are 2 main functions of the cardiac skeleton?
- structural support
2. electrical insulation
What is included in the structural support of the cardiac skeleton? (4)
- atrioventricular septum
- roots of great vessels
- anchorage for valves
- myoctes/ capillary network
What is included in the electrical insulation of the cardiac skeleton? (2)
- atria from ventricles
2. myocardium from great vessels
What are SIN and AV nodes externally modulated by?
- vagus nerve (keeps it at 70beats/min)
- sympathetic chain
How many major coronary arteries are there?
2: right and left
What is an aortic sinus?
- anatomic dilation of ascending aorta which occurs just above aortic valve
- widenings between wall of aorta and each of the 3 cusps of the aortic valve
- found just above coronary arteries branching
What occurs at systole to coronary arteries blood flow?
- openings in aortic sinuses are SHIELDED by aortic valve cusps which open to let blood through aorta
- no blood gets into coronary arteries
What occurs at diastole to coronary arteries blood flow?
- recoil of the aorta closes aortic valve revealing the aortic sinuses
- blood then FLOWS into coronary arteries at distole
On which cardiac layer are coronary arteries located?
in the epicardium
What happens to myocardium during diastole?
It RELAXES; blood can flow into capillaries
What can blockage/occlusion of coronary arteries lead to?
heart attack (myocardial infarction)
What does right coronary artery branch off into around the heart? (2)
- posterior descending artery
2. right marginal artery
What does left coronary artery branch off into around the heart? (2)
- anterior interventricular artery (left anterior descending; LAD)
- left cirumflex artery
What can be done to branches of coronary arteries in patients with coronary heart disease?
Branches can be anastomosed (joined together)
What holds the heart in place? (3)
- hangs by great vessels within fibrous pericardium
- dense connective tissue bag
- attachments
What are some of the attachments which hold the heart in place? (3)
- central tendon of diaphragm
- sternum
- roots of great vessels
What is the heart lined with?
serous pericardium
What fluid is secreted from the heart epithelium (visceral layer)?
pericardial fluid (lubricant)
What is visceral layer bound to?
bound to he heart (epithelium of the epicardium)
What is the parietal layer bound to?
bound to fibrous pericardium
Are visceral and parietal layers continous around the heart?
Yes; like a closed bag around the heart
What does the serous pericardium ensure the heart is able to do?
allows freedom of movement during cardiac cycle
