8 Special Circulations Flashcards
What are the diastolic and systolic pressures in the right ventricle?
Diastolic: 0-8mmHg
Systolic: 15-30mmHg
What are the diastolic and systolic pressures in the aorta?
Diastolic: 60-90mmHg
Systolic: 100-140mmHg
What are the diastolic and systolic pressures in the left ventricle?
Diastolic: 1-10mmHg
Systolic: 100-140mmHg
What is the mean:
i. ) Arterial pressure
ii. ) Capillary pressure
iii. ) Venous pressure
i. ) 12-15mmHg
ii. ) 9-12mmHg
iii. ) 5mmHg
What are the diastolic and systolic pressures in the pulmonary artery?
Diastolic: 4-12mmHg
Systolic: 15-30mmHg
How is ventilation of the alveoli matched to the perfusion of the alveoli?
Blood is diverted away from alveoli that are not well ventilated to maintain the V/Q ratio.
What is the optimum V/Q ratio?
0.8
What can chronic hypoxic vasoconstriction cause?
Ventricular failure in the right heart
In the upright position, where is the most pressure experienced in the lung?
Lower part
What pressure forces fluid OUT of the capillaries?
Hydrostatic pressure
What pressure pulls fluid back INTO the capillaries?
Oncotic pressure
What drugs are given to treat oedema?
Diuretics
What blood vessel adaptations are present in the brain?
High capillary density
Reduced diffusion distance
High basal flow rate
High O2 extraction
How long does it take for a neurone to be irreversibly damaged when no oxygen is supplied?
4 minutes
How is blood supply to the brain secured structurally?
Anastomoses between the basilar and internal carotid arteries
What molecule are cerebral vessels very sensitive to?
CO2
What do the vessel muscles do when the PCO2 is increased?
Vasodilation
What is the Cushing’s reflex?
The rigid cranium protects the brain but also does not allow for expansion. Increases in intracranial pressure result in haemorrhaging or tumours.
When does blood flow in the left coronary artery usually occur?
Diastole
Which circulation has an important role in regulating arterial blood pressure?
Skeletal muscle circulation
How is heat loss via the skin regulated?
Cutaneous circulation
What does a decreased temperature induce in the cutaneous circulation?
Increases sympathetic tone in the anastomoses.
What does a increased temperature induce in the cutaneous circulation?
Allows the anastomoses to dilate so heat is dissipated.
