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Blood vessel concept map, Blood vessels:
how the blood circulates…
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Blood vessels:
- how the blood circulates through the body
Arteries:
- conducts blood away from the heart; however, it can be both a conducting and distributing vessel (Key term)
- has thicker walls because they are closer to the heart and receive its blood at a much higher pressure. (20.1)
- has a narrow Lumen that help maintain blood pressure while it moves through the body. (20.1)
Veins:
- Conducts blood toward the heart and are low-pressure vessels (20.1)
- thin walled vessels with large and irregular lumens (20.1)
- Larger veins have valves to promote unidirectional flow of blood toward the heart, preventing backflow toward capillaries (20.1)
Capillaries:
- The smallest blood vessel; physical exchange of nutrients and waste are exchanged here. (Key terms)
- has a lumen of 5-10 micrometers, the flow through a capillary is considered microcirculation (20.1)
- The walls of capillaries are "leaky" so substances can pass through (20.1)
Blood vessel wall structure:
- Blood vessels share similar structures despite different lumen sizes and wall thickness. of the walls of the vessel, there are 3 components.
- from inner to outer: Intima, Media, Externa
Tunica Media:
- the thickest layer in arteries consisting of layers of smooth muscle supported by connective tissue made of elastic fibers. (20.1)
- the outer portion has longitudinal muscles that can contract and relax, decreasing and increasing lumen diameter (20.1)
- responsible for vasoconstriction (decrease in blood flow) and vasodilation (increase in blood flow) (20.1)
Tunica Intima:
- composed of epithelial and connective tissue layers (20.1)
- Endothelium lines the tunica intima (20.1)
- the endothelium of this wall is important because it helps regulate capillary exchange and blood flow alteration (20.1)
- next to the endothelium is the basement membrane, basal lamina, which provides strength while allowing flexibility and permeability (20.1)
Tunica Externa:
- a substantial sheath of connective tissue composed of collagenous fibers. (20.1)
- the thickest tunic in veins (20.1)
- it blends with surrounding connective tissue outside the vessel, helping it hold its position (20.1)
Arteries:
- a blood vessel that conducts blood away from the heart generally having a thick wall to withstand pressure from the blood ejected from the heart (20.1)
Muscular:
- has an increased amount of smooth muscle in the tunica media and a decrease in elastic fibers in the tunica intima. (20.1)
- the thick tunica media allows this artery to perform vasoconstriction, but its decreased elastic fibers limits its expandability (20.1)
- begins to branch to distribute blood to arterioles; the reason it is also called the distributing artery (20.1)
Elastic:
- the closest to the heart, containing a high percentage of elastic fibers in all the tunics. (20.1)
- allows for expansion and recoil after blood is pumped from the ventricles (20.1)
- its elasticity helps maintain the pressure gradient that drives blood trough the arterial system (20.1)
Arterioles:
- a very small artery leading to a capillary (20.1)
- critical for slowing down, or resisting, blood flow; it causes a major drop in blood pressure. (20.1)
- usually has a consistent muscle tone because its muscle fibers are slightly contracted (20.1)
- primary site for resistance and regulation of blood pressure (20.1)
Capillaries:
- a microscopic channel that supplies blood to the tissues (20.1)
- has a lumen diameter of 5-10 micrometers (20.1)
Fenestrated:
- has pores and tight junctions in the endothelial lining (20.1)
- commonly found in the small intestine, kidneys, choroid plexus of the brain, and many endocrine structures (20.1)
- allows for rapid passage of certain small materials (Key Terms)
sinusoidal:
- least common type of capillary; they are flattened and have extensive intercellular gaps and incomplete basement membranes (20.1)
- Swiss cheese appearance, allowing the passage of large molecules such as plasma proteins and even cells. (20.1)
- blood flows slowly here, allowing for more time of molecule exchanges (20.1)
- often found in the liver, spleen, bone marrow, lymph nodes, and many endocrine glands (20.1)
Continuous:
- the most common capillary type (20.1)
- has a complete endothelial lining with tight junctions between endothelial cells (20.1)
- the tight junctions are incomplete which leave intercellular clefts that allow water exchange and small molecules between the blood plasma and interstitial fluid (20.1)
Blood Pressure Homeostatic Imbalances:
- the body fails to regulate blood pressure, leading to too high or too low of a blood pressure
Hypertension:
- chronically elevated blood pressure, if left untreated it can result in a heart attack or stroke (20.4)
- measures at 140/90mm HG or above (Key terms)
Circulatory shock:
- the loss of too much blood; the circulatory system fails to maintain proper blood flow to adequately supply sufficient oxygen and other nutrients to the tissues to maintain cellular metabolism (20.4)
- urine output falls substantially and the heart rate increases while blood pressure decreases (20.4)
Hypovolemic Shock:
- often caused by a hemorrhage in adults and can cause severe fluid loss in children (20.4)
- other causes include extensive burns, exposure to toxin, and excessive urine loss (20.4)
- symptoms include a fast but weak heart rate, cool clammy skin, shallow breathing, hypothermia, thirst, dry mouth (20.4)
- intravenous fluids are given to the patient to restore function and drugs such as dopamine, epinephrine, and norepinephrine are given to raise BP (20.4)
Cardiogenic Shock:
- the heart fails to maintain cardiac output, resulting from a infarction (heart attack) (20.4)
- can also be caused by arrhythmias, valve disorders, cardiomyopathies, cardiac failure, not enough flow of blood through cardiac vessels (20.4)
- for treatment, damage to the heart or its vessel are repaired to resolve an underlying issue (20.4)
Vascular shock:
- the arterioles lose their muscular tone and dilate dramatically (20.4)
- can happen for many causes, but treatment will always involve fluid replacement and medication to restore muscle tone in the vessels. (20.4)
Hypotension:
- low blood pressure, severe problems can include, confusion, a weak and rapid pulse, and pale skin.
- measures at 110/90mm HG
Blood Flow, Pressure and resistance
Pressure:
- The force exerted by the blood against the wall of a vessel or heart chamber (Key term)
- Typically refers to systemic arterial blood pressure; the pressure of blood flowing in the arteries of the systemic circulation (20.2)
Arterial blood pressure:
- the pressure of blood flowing in the arteries of systemic circulation and is measured in mm Hg and obtained using the brachial artery of the arm (20.2)
- expressed in 2 number i.e systolic pressure over diastolic pressure (20.2)
- The systolic pressure value results from the ejection of blood during systole (ventricular contraction), and the diastolic pressure comes come diastole (ventricular relaxation) (20.2)
Capillary blood pressure:
- drives fluids out of capillaries and into tissues (20.3)
- fluids generally move out and into the interstitial fluid; this is called filtration (20.3)
- Osmotic pressures cause the fluid from the interstitial fluid to move back into the capillaries (20.3)
Venous Blood Pressure:
- the pressure within the veins, crucial for getting blood back to the heart (20.2)
- for this to happen, pressure in the veins must be greater compared to the pressure in the atria. (20.2)
Flow:
- the movement of blood through a vessel, tissue, or organ. Often, it is expressed in terms of volume per unit of time (Key term)
- initiated by the contraction of the ventricles of the heart (20.2)
resistance:
- A factor which impedes or slows blood flow (20.2)
- blood viscosity, vessel length and diameter can effect blood resistance (20.2)
Veins:
- a blood vessel that conducts blood toward the heart (20.1)
Venules:
- an extremely small vein which join together to form a vein, ranging from 8-100 micrometers in diameter (20.1)
- Its walls consist of endothelium, a thin middle layer of muscles cells and elastic fibers, and an outer layer of connective tissue fibers, making a thin tunica externa (20.1)
- primary sites of emigration or diapedesis; the white blood cells adhere to the endothelial lining of the vessels and then squeeze through adjacent cells to enter the tissue fluid (20.1)
Veins:
- It has thin walls and large, irregular lumens (20.1)
- low-pressure vessels, commonly equipped with a valves to promote unidirectional flow of blood toward the heart and prevent backflow toward the capillaries (20.1)