Chapter 17 - Vascular System Flashcards
Distinguish the structures and functions of various blood vessels
The blood vessels constrict, relax, and pulsate as they conduct blood and other substances to the body tissues.
although the two heart ventricles have uneven workloads, equal volumes of blood are pumped to the pulmonary and systemic circuits simultaneously.
The five general classes of blood vessels in the cardiovascular system are the arteries, arterioles, capillaries, venues, and veins.
in total, the blood vessels of an average age human adult, if stretched out, are about 60,000 miles in length.
Arteries are very strong elastic vessels that are able to carry blood away from the heart under high-pressure. They subdivided into thin arteries that give rise to the branched, finer arterioles.
In the systemic circuit, the arteries carry only oxygenated blood, whereas the veins carry only deoxygenated blood. In the pulmonary circuit, the reverse is true.
The only blood vessels that closely contact tissue cells and serve the needs of the cells are the capillaries.
The extremely thin capillary walls allow most exchanges that occur between blood and tissue cells.
blood vessel structure: arteries
Outer coat - Tunica externa/tunica adventitia
Muscle coat - Tunica media - thick in arteries, thin in veins
Elastic white fibrous tissue
Lining - Tunica intima of endothelium
and artery’s wall consists of three distinct layers and a blood containing space known as the lumen.
The innermost tunica intima is made up of a layer of simple squamous epithelium known as the endothelium. it rests on a connective tissue membrane with many elastic, collagenous fibres.
The endothelium helps prevent blood clotting and may also help in regulating blood flow. It releases nitric oxide to relax smooth-muscle of the vessel.
In arteries, the outer margin has a thick layer of elastic fibres known as the internal elastic membrane.
vasa vasorum
The vasa vasorum is a network of small blood vessels that supply the walls of large blood vessels, such as elastic arteries (e.g. aorta) and large veins (e.g. venae cavae). The name derives from Latin, meaning ‘the vessels of the vessels’.
Explain the difference between pulmonary and systemic vessels.
The systemic circuit has a long pathway through all of the body and is powered by the left ventricle. Along the circuit, there is about five times more resistance to bloodflow then in the pulmonary circuit.
The systemic circuit is served by the left ventricle of the heart.
Equal volumes of blood pumped to the pulmonary and systemic circuits simultaneously.
The pulmonary circuit is a short, low-pressure circulation. It is served by the right ventricle of the heart. In the systemic circuit the arteries carry only oxygenated blood, where as the veins carry only deoxygenated blood. In the pulmonary circuit, the reverse is true.
Define blood flow, blood pressure and resistance
Bloodflow is the amount of volume of blood that flows through blood vessels, organs, or the systemic circulation, in millimetres per minute (mL/min)
Blood pressure is the force the blood exert against the inner walls of blood vessels.
Resistance is the friction between blood and blood vessel walls.
Describe the effects of the sympathetic and parasympathetic nervous system is on blood vessels
Generally, sympathetic stimulation, which releases epinephrine, causes vasoconstriction and therefore increased blood pressure.
However, the parasympathetic nervous system has the opposite effect and generally causes vasodilation and decreased blood pressure.
Describe the factors that influence blood pressure and explain how blood pressure is regulated
The factors that influence blood pressure include homoeostatic mechanisms such as cardiac output, peripheral resistance, blood pressure, and lumen size of the arteries and arterioles.
Blood pressure is regulated by the regulation of cardiac output with peripheral resistance. Changes in the diameters of arterioles regulate peripheral resistance, which is controlled by the vasomotor centre of the medulla oblongata.
Peripheral resistance is also influenced by carbon dioxide, oxygen, and hydrogen ions.
Arterial blood pressure rises and falls according to cardiac cycle phases.
The control of blood vessel size, and therefore blood pressure, is also related to normal activities via reflex arcs, baroreceptors, related afferent fibres, chemo receptors, high brain centre influences, hormonal controls, and renal controls.
Cardiac cycle
A heartbeat. It consists of a complete series of systolic and diastolic events
Peripheral resistance
A force produced by friction between blood and blood vessel walls
Vasomotor Centre
The part of the medulla oblongata that controls blood vessel diameter and peripheral resistance
Homoeostatic mechanisms
Effectors, receptors, and the body’s set point, which act together to maintain homoeostasis
Epinephrine
Adrenaline.
A hormone and neurotransmitter important for the bodies fight or flight response
Pulmonary circuit
The bloodflow and blood vessels within the lungs and between the lungs and the heart
Systemic circuit
The general blood circulation of the body, not including the lungs. It is also called the greater circulation.
