Blood vessels and Hemodynamics part 3

the volume of blood flowing back to the heart through the systemic veins, occurs due to pressure generated by contractions of the left ventricles.

at rest, the venous valves in the lower limbs are open and blood flows towards the heart.  Contraction of the leg muscles pushes the blood through the proximal valve while closing the distal. As the leg relaxes the proximal valve closes and the distal valve opens

during inhalation the diaphragm moves downwards which causes a decrease in pressure in the thoracic cavity and an increase in pressure in the abdominal cavity. As a result abdominal veins are compressed and a greater volume of blood moves into the thoracic veins and into the right atrium

is the time required for a drop of blood to pass from the right atrium, through the pulmonary circulation, back to the left atrium through the systemic circulation down to the foot and back to the right atrium

how sympathetic impulses reach the heart from the CV centre in the medulla oblongata. Increase heart rate and contractility

parasympathetic nerve that carries impulses from the CV centre decrease the heart rate and contractility.

the CV centre also continually sends impulses to smooth muscle in blood vessels via this nerve.

the vasomotor region of the cardiovascular centre continually sends impulses over these routes to arterioles throughout the body.  The result is a moderate state of tonic contraction or vasoconstriction

pressure sensitive sensory recepters are located in the aorta, internal carotid arteries. They send impulses to the CV centre to help regulate blood pressure.

this helps regulate blood pressure in the brain

which regulates systemic blood pressure.  nerve impulses from aortic baroreceptors reach the cv centre via sensory axons of the Vagus X nerves

sensory receptors that monitor the chemical composition of blood.  They detect changes in blood level of O2 CO2 and H+

when blood volume drops or flow to kidneys decreases, renin is secreted into the blood stream.  In sequence the renin and angiotensin converting enzymes act on their substrates to produce the active hormone angiotensin 2, which raises blood pressure

in response to sympathetic stimulation the adrenal medulla secretes these. These hormones increase cardiac output by increasing the rate and force of heart contractions.  They also cause vasoconstriction of arterioles and veins and vasodilation of arterioles in cardiac and skeletal muscle

is produced by the hypothalamus and is released by the posterior pituitary gland in response to dehydration or decreased blood volume.  It causes vasoconstriction.

released from cells in the atria of the heart, ANP lowers blood pressure by causing vasodilation and by promoting loss of salt and water in urin which reduces blood volume

the ability of tissue to automatically adjust its blood flow to match its metabolic demandes

the alternating expansion and recoiling of elastic arteries after each systole of the left ventricle creates a traveling pressure wave

the device used to measure blood pressure

the force of blood pressure on arterial walls just after ventricular contraction

represents the force exerted by the blood remaining in the arteries during ventricular relaxation

the sounds heard while taking blood pressure

the difference between systolic and diastolic pressure, usually 40 mmHg

is a failure of the cardiovascular system to deliver enough oxygen and nutrients to meet cellular metabolic needs

due to decreased blood volume. A common cause is acute (sudden) hemorrhage.  It may be external or internal.  Loss of other body fluids may also cause this

due to poor heart function. The heart fails to pump adequately.  Most often because of a myocardial infarction (heart attack)

due to inappropriate vasodilation

due to obstruction of blood flow

blood vessels are organized into these and carry blood to specific organs in the body.

need not be pumped as far as in the systemic routes. They carry blood to and from the lungs. These arteries are larger, with thinner walls and less elastic tissue.  The resistance is very low meaning it requires very low pressure

carries venous blood from the gastrointestinal organs and the spleen to the liver.

persistently high blood pressure.  it is the most common disorder affecting the heart and blood vessels and is the major cause of heart failure, kidney disease and stroke

a thin, weakened section of the wall of an artery or a vein that bulges outward, forming a balloon like sac .  Common causes are syphilis, artherosclerosis, congenital blood defects and trauma

the presence of a thrombus (blood clot)in a deep vein of the lower limbs

low blood pressure, most commonly used to describe an acute drop in blood pressure, as occurs during excessive blood loss

the closure or obstruction of the lumen of a structure such as a blood vessel

inflammation of a vein involving clot formation

inflammation of a vein involving clot formation