Circulatory System Flashcards
Atria(Atrium)
reservoirs where blood collects from veins
Ventricles
Pump blood out of the heart at high pressures into the arteries
Inferior/Superior Vena Cava
large veins that pump deoxygenated blood into the right atrium
Do all of the arteries of the body carry oxygenated blood?
No, the pulmonary artery carries deoxygenated blood from the heart to the lungs.
Goals of the circulatory system
Distribution of nutrients, oxygen, metabolic waste products, hormones and homeostasis
Perfusion
Flow of blood through a tissue
Arteries
Vessels that carry blood away from the heart at high pressure
Veins
Vessels that carry blood toward the heart at low pressure
Arterioles
Increasingly smaller branches from arteries as the pressure of blood flow starts to decreases
Ischemia
inadequate blood flow
Hypoxia
Reduced supply of oxygen
What’s the difference between ischemia and hypoxia?
In hypoxia, wastes are adequately removed, but in ischemia they build up. Ischemia is worse.
If the arterioles constrict in a tissue, will material diffuse through the wall of the arterioles into the tissue?
No, all exchange of material between the blood and tissues must occur in capillaries. The walls of arterioles are too thick and muscular for exchange to occur.
Capillaries
Very small vessels where only a single/ few blood cells from the arterioles pass through and where exchange occurs between blood and tissues
Aorta
Single large artery where blood is pumped from the left ventricle
Inner lining of all blood vessels is formed by a thin layer of
Endothelial cells
Functions of endothelial cells
Vasodilation and vasoconstriction, inflammation, angiogenesis, thrombosis
Two main types of circulation of blood
Pulmonary (heart to lungs) and systemic circulation (heart to rest of the body)
Why have mammals evolved a separate circulation for the lungs in comparison to, for example fish?
Mammals need more pressure to reach both the body and lungs, so having two separate circulations solves this problem
Hepatic portal system
Blood passes through capillaries in the intestine > collects in veins to travel to the liver > blood once again passes through capillaries
Hypothalamic-hypophysial portal system
Blood passes through the capillaries in the hypothalamus > portal veins > capillaries in the pituitary gland
What are portal systems and why did the evolve?
They are direct transport systems where nutrients can be directly passed from the intestine to the liver or hypothalamus to the pituitary without passing through the whole body
Coronary arteries
Branches from the aorta which supply blood to the wall of the heart
“Coronary”
encircle the heart
Coronary veins
Deoxygenated blood from the heart travels through this and combine to form the coronary sinus (directly drains into the right atrium)
The two atrioventricular valves are
Bicuspid valve (between the left atrium and left ventricle) and the tricuspid valve (between the right atrium and right ventricle)
the two semilunar valves
The pulmonary (between right ventricle and pulmonary artery) and aortic semilunar valve (between left ventricle and the aorta)
How does blood in veins travel back to the heart when there is low pressure?
Contraction of skeletal muscles and the venous valves which prevent back flow
What is the result of venous valve failure?
Varicose veins - veins where venous pressure increases in the legs
Diastole
Relaxation of ventricles of ventricles and contraction of atriums to propel the blood into the ventricles
Systole
Contraction of ventricles and closing of AV valves to increase the pressure in the ventricles to ultimately open the semilunar valves; when the ventricle is nearly empty, there is less pressure so the semilunar valves close
How strong is atrial compared to ventricular contraction?
Much weaker, the muscular walls of atria are much thinner, the ventricles need more muscle to pump blood into capillaries throughout the body
Cardiac output equation
CO = SV * HR
Cardiac output (L/min) = Stroke volume (L/beat) x Heart rate (beats/minute)
Is diastole or systole longer?
Diastole, as it is the time between the lub-dup
