magma crystallization.
25,000 to 60,000 miles!
capillaries run into your fingers some end there but some turn around and go back down
There are valves in veins to prevent backflow. The blood pressure in veins is relatively low and, particularly in the legs and arms, can tend to pool if allowed to backflow. In contrast, there is relatively high blood pressure in the arteries, which prevents the need for valves to control backflow.
The veins act as a blood reservoir, because of the ease of distending them. 55-60% of blood is in systemic veins which is important for blood pressure. The volume of blood returned to the right atrium of the heart per minute is called the venous return. Generally venous return is equal to cardiac output, due to the closed system of the circulation, except for minor transient periods. A number of factors affecting the venous return are: Smooth muscle: Due to presence of smooth muscle, the diameter of the veins can be altered by sympathetic discharge(normally vasoconstrictive), adrenaline and angiotensin II (cause venoconstriction). But because the diameters of veins are large, venoconstriction has little effect on peripheral resistance. Elasticity of the heart: If the elasticity decreases, then the ability to fill the heart is reduced. valves: one way valves in the veins (not in large veins) ease blood flow to heart. Muscle pump: When muscles, particularly leg muscles contract, the thin walled veins are squeezed and the blood is forced towards heart, when muscles relax, blood enters the veins, but only from the arterial side. This is an important mechanism for facilitating venous return. Respiratory pump: Breathing in causes negative pressure in thorax causing a suction effect, i.e. the pressure gradient pushing blood towards the right atrium is increased, thus more blood returns to the heart, which means that inspiration leads to an increase in venous return. The opposite occurs with expiration, and venous return is decreased. Gravity: Opposes return of blood from the periphery during sitting or standing. The effect is lost when we lie down. Blood pressure at venous end of capillary: An increased pressure at the venule end of the capillary reduces venous return, because the pressure difference between the right atrium and the peripheral veins is reduced. Similarly a decrease in pressure at the venule end would increase venous return. Right atrial pressure: Is the inflow pressure for the heart. It is a function of the amount of blood returned to the heart and the pumping ability of the heart. Its value at rest is normally close to zero but can also become negative (between -4 to 5 mmHg). Its value is increased by blood volume, a weak heart, rapid increase in venous return. Its value is decreased by lower blood volume and a strong heart. The lower the pressure the greater the venous return (due to suction effect), but there is a limit to the increase in venous return because veins are collapsible.
In the body arteries are tubes that carry the blood from the heart out to the rest of the body, where nutrients are picked up by the cells. After all the nutrients are gone from the blood, veins are the tubes that carry the blood back to the lungs, where it gets more oxygen, and then on to the heart, where it gets pumped out again through the arteries. In geography, arteries are main highways that carry traffic to and from major population points, or main streets that carry people from one end of the city to the other.
magma crystallization
Saddle-reef gold is found in Hill End, New South Wales. This occurs in quartz veins.
It is released at the end of magma crystallization in a hot, mineral-rich fluid that fills cracks and voids in the surrounding rock. This fluid solidifies to form metal-rich quartz veins.by aidan
Quartz - metal band - ended in 1983.
plmonary veins begin as capillaries and end as capillaries
The distal end of the inferior vena cava is formed by the junction of the paired common iliac veins (Marieb, Elaine- A&P)
The most common end product of the chemical weathering of quartz is clay minerals. Clay minerals form due to the breakdown of the silicon and oxygen in quartz when exposed to water and carbon dioxide, leading to the transformation of quartz into the softer clay minerals.
The most common end product of chemical weathering of quartz is clay minerals. These clay minerals form from the breakdown of quartz due to exposure to water and other chemical elements over time.
At the end of Meiosis II, Spermatids are formed
Blood flows from arteries to veins or from arterioles (small arteries) to venules (small veins) in a capillary bed.
(3) Quartz
25,000 to 60,000 miles!