Circulatory System III Flashcards
where is the heart located?
the heart lies in the thoracic cavity between the lungs, it has a base, apex and it lies obliquely
what organs are associated with the heart?
- diaphragm
- esophagus
- trachea
- L & R bronchus
- vertebrae
- ribs
- intercostal muscles
what are the 3 layers of tissue which the heart is composed of?
- pericardium
- myocardium
- endocardium
Describe the structure of the pericardium?
the pericardium has 2 sacs, an outer sac and an inner sac
What is the structure & function of the pericardium’s outer sac?
the outer sac consists of fibrous tissue- preventing over distension of the heart
What is the structure & function of the pericardium’s inner sac?
the inner sac is a double serous membrane, allowing smooth movement between layers when the heart beats
Describe the structure and function of the myocardium?
myocardium is composed of specialised cardiac muscle, it is a sheet of muscle rather than individual cells as impulses spread across whole sheet, causing contraction
Describe the structure of the Endocardium?
Endocardium consists of flattened epithelial cells, continuous with endothelium lining blood vessels
What is the function of the Endocardium?
Endocardium lines chambers and valves of the heart, it is a smooth membrane allowing smooth flow of blood through the heart
What is the top part of the heart called?
Atriums
What is the bottom half of the heart called?
Ventricle
How many semi lunar cusps does the right valve have?
The right valve has 3 semi lunar cusps
How many semi lunar cusps does the left AV valve have?
The left AV valve has 2 cusps
What are the 2 largest veins?
Superior and inferior vena cava
What is the function of the superior and inferior vena cava?
They empty deoxygenated blood into the right atrium
What is the movement of deoxygenated blood once it has entered the right atrium?
- It then travels via the right AV tricuspid valve into right ventricle
- its then pumped from here into the pulmonary artery
What happens to the pulmonary artery once it leaves the heart?
it divides into L & R pulmonary artery which carries venous blood to lungs where gas exchange takes place
what is the function of a pulmonary vein?
carries oxygenated blood back to the left atrium
What is the movement of oxygenated blood once it has entered the left atrium?
- blood then passes through the left AV valve into left ventricle
- from here it is pumped into the aorta
what is pulmonary circulation?
when blood passes from the RHS of the heart to the LHS via the lungs
what are the branches of the ascending aorta?
right and left coronary arteries
what is the function of the left and right coronary arteries?
supplies tissues of the heart with oxygenated blood
what does the left and right coronary arteries form?
a network of capillaries which enclose the heart
what are the 3 branches of the arch of the aorta?
- left common carotid artery
- left subclavian artery
- brachiocephalic artery
what is the function of the sinoatrial node?
it emits impulses which cause the heart to contract, each heartbeat is known as a cardiac cycle
what is contraction known as?
systole
what is the relaxed state of the heart called?
diastole
what does the cardiac cycle range form in terms of BPM?
60-80 BPM
how long does each cardiac cycle last?
0.8 seconds
what is atrial systole?
contraction of atria
what is ventricular systole?
contraction of ventricles
what is complete cardiac diastole?
relaxation of atria and ventricles
what nervous system controls the cardiac cycle?
autonomic nervous system (parasympathetic and sympathetic)
what is the function of the parasympathetic nervous system in terms of cardiac cycle?
it slows HR and force of contraction
what is the function of the sympathetic nervous system in terms of cardiac cycle?
it increases HR and force of contraction
what is the nerve supply for the cardiac system?
vagus- 10th cranial nerve, arises in cardiac center of the medulla
what is the function of the left pulmonary artery?
left PA runs into the left lung and divides into 2, one passing into each lobe
what is the function of the right pulmonary artery?
right PA passes into the right lung and divides into 2, the larger branch carrying blood to middle and lower lobes, and the smaller branch to the upper lobe
within each lung, what do arteries divide into?
arterioles and capillaries
what does the brachiocephalic artery supply?
supplies right arm and right side of head and neck
what does the left common carotid artery supply?
supplies left side of head and neck
what does the left subclavian artery supply?
supplies left arm, part of head and neck
what supplies most of the lower limbs with blood?
right and left common iliac arteries
describe internal respiration?
- oxygen is carried from lungs to tissues in hemoglobin as oxyhemoglobin
- interchange if gasses between capillaries
- carbon dioxide is removed
describe portal circulation?
- blood circulating in stomach and intestines is conveyed to liver via portal vein
- blood with high concentration of nutrients goes to liver first where modifications of nutrients takes place before supplying the rest of the body
