cardovascular system Flashcards
location of the heart
between lungs, the sternum and thoracic vertebra;
surrounded by ribs in a space called mediastinum.
what tissue type is it made out of
dense fibrous connective tissue bag called the pericardial sac;
Pericardium
double walled sac enclosing the heart. It is anchored to the diaphragm
2 types of pericardium
1- fibrous
2- serous
coronary vessels
Left coronary artery gives rise to the anterior interventricular branch.
- Right coronary artery gives rise to the posterior interventricular branch
heart skeleton
- dense fibrous tissue with some fibrocartilage
- provides and anchor for the heart muscle
- provides electrical insulation
blood vessles (2 types)
Arteries carry blood away from the heart. Veins carry blood towards it.
3 layers of blood vessels
- Tunica interna: always has a layer of endothelium. May also have connective tissue and elastin.
• Tunica media: has smooth muscle, collagen and variable amount of elastic tissue (thicker in arteries).
• Tunica externa (adventitia): connective tissue and collagen fibres (thicker in veins).
3 different types of arterties
- conducting large arteries
- distrabuting musuclar arteries
- resistance with small arteries
3 different types of veins
- large veins
- medium veins
- venules
capillaries
Capillaries join arteries and veins. It is where the exchange between the tissues occurs
the cardiac cycle
- ventricular disatole
- isovolumetric contraction
- ventriciular ejection
- isvolumetric relaxation
control of the heart
- Cardiac muscle is involuntary. It has large amounts of mitochondria
- Cardiac muscle cells do not need stimulation for contraction, it works as single unit. The cells have a longer refractory period
contraction of the heart
- sinoatrial node cell depolarises
- The fibrous skeleton insulates the atria from the ventricles
- Purkinje fibres distribute the excitation through the
ventricular myocardium and into the papillary muscle which
contract - ventricles contract from the bottom up forcing blood
into the vessels
Electrocardiogram
finds the heart rate. Waves represent electrical activity
in the heart.
P wave
depolarisation of the atrium. Atria contracts after the P wave
QRS wave
depolarisation of the ventricles and atria. Ventricles contract after the QRS wave
T wave
repolarisation of ventricles. Ventricles relax after the T wave
Cardiac output
= stroke volume (volume of blood leaving the ventricle) x heart rate (beats per minute).
Respiratory pump
the diaphragm contracts, drops and squashes the veins in the abdomen pushing blood back up to the heart therefore increases venous return
Skeletal muscle pump
when skeletal muscles contract they get shorter and fatter causing squashing of the vein so blood is pushed back towards the heart. It ensure blood travels in one direction
