Lecture 11: Circulatory System Flashcards
What is hematocrit?
-Defined as the measure of the fractional volume of erythrocytes
-representation of the oxygen carrying capacity of blood (1 molecule hemoglobin can transport 4 molecules of oxygen)
-normal values: men-40-45
Women: 36-45
Hematocrit reduced by over-hydration, blood loss, anaemia
Increased by dehydration, increased production of red blood cells
What are the components of the blood?
Plasma: water, protein, electrolytes, gases, by products (non living) 55%
Buffy coat: Leukocytes and platelets 1%
Erythrocytes: red blood cells (45%)
Be able to label the main blood vessels on pg 6
Big one bebe
Why is there 80% in venous circulation most of the time?
Because of the size of the lumen, they can expand further and carry more blood
Types of arteries.
Large elastic arteries: tunica media has bulk elastic fibres➡ allows expansion eg aorta
Medium muscular arteries: tunica media mostly smooth muscle fibres➡ regulation of vascular tone by para and Symp fibres eg coronary arteries, axillary arteries, intercostal arteries
Small arteries and arterioles
End arteries: end terminal artery➡ ie don’t anastomoses with adjacent arteries = only supply of oxygenated blood eg central artery of retina. If they get occluded blood supply gone forever
Functional end arteries: form INEFFECTIVE anastomoses. So if they were occluded wouldn’t keep tissue Alice eg coronary artery = myocardial infarction
Anastomoses. Why are they important?
In vital tissues vulnerable to ischemia. Collateral arteries will provide an alternative supply of blood
Eg brain or crucial joints in body like hip, knew, ankle, knee etc otherwise we would loose ability to run from lions
What are the 3 branches of the aortic arch?
Brachiocephalic artery -right subclavian, and right common carotid
Left common carotid artery
Left subclavian artery
Slide 17
Tell some stuff about the brachiocephalic trunk.
- Originates behind the manubrium for protection
- at superior edge of right sternoclavicular joint it divides into right common carotid and (supplied right side of head and neck) and right subclavian artery (supplied limb)
Tell me about the left common carotid
- slightly posterior to brachiocephalic trunk
- ascends through superior mediastinum along left side of trachea
- supplies left side of head and neck
Left subclavian
- ascends through superior mediastinum along left side of trachea
- major blood supply to left upper limb
As the aorta goes down through the thorax, what arteries branch of it?
Pericardial Bronchioles Oesophageal Mediastinal Posterior intercostal arteries Superior phrenic armies Subcostal arteries Slide 21
Thoracic arteries
Label slide 22
Comes of subclavian arteries➡ internal thoracic artery➡ superior epigastric artery.
Anterior perforating branches come of it.
Anterior intercostal arteries come from it also
Tell me about the intercostal arteries
Posterior intercostals: They arise from the descending thoracic aorta ➡ posterior intercostal arteries (except 1st and 2nd space)
Anterior internal thoracic arteries come from internal thoracic arteries (1st-6th space)
Slide 23
Tell me about the internal thoracic arteries
They arise from subclavian
- paired
- deep to ribs
- 1cm lateral to sternum
- supplies anterior chest wall and breasts
- birficates into the superior epigastric and musculophrenic artery at 6th intercostal space
Perfusion (delivery of blood to a capillary bed) of anterior thoracic and abdominal wall.
Slide 26
There is anastomosis formed between descending superior epigastric and musculophrenic arteries (from the internal thoracic artery) and ascending inferior epigastric artery from the external iliac artery.
