Blood Vessels Flashcards
What vessels are part part of the pulmonary circulation?
Great veins, veins, venules
What blood vessels are part of the systemic circulation?
Aorta, arteries, arterioles
What vessels are part of both the pulmonary & systemic circulation?
Capillaries
What are the properties of the aorta?
Elastic artery, walls contain many many elastic fibres, elastic recoil during diastole helps to maintain high pressure during relaxation phase of cardiac cycle
What type of tissue are arteries made from?
Smooth muscle
What controls the arteries?
Autonomic nervous system
What do artery walls contain?
Thick layer of smooth muscle, small amount of elastic fibres
Arterioles are also muscular & are the principal site of what?
Vascular resistance
Arterioles are distribution vessels. What do they supply blood to?
Capillaries
What alters the diameter of the arterioles?
Autonomic nerves & hormones
What causes vasoconstriction in most arterioles?
Sympathetic stimulation & adrenaline
What are capillaries?
Exchange vessels running deep within tissues
What are capillaries often referred to as?
Capillary beds
What does the intricate network of capillaries provide?
Enormous surface area over which exchange can take place
Why is exchange possible in capillaries?
Walls are 1 cell thick
What is the purpose of the venous circulation?
Return blood to heart under low pressure
What are the properties of a vein?
Thin walls, wide lumen, some have valves to stop back flow
What aids venous return?
Locomotion (muscle pump) & breathing (respiratory pump)
What fibres are found in the pulmonary trunk & arteries?
Elastic
What fibres are found in the pulmonary arterioles?
Muscle
What are the pulmonary capillaries adapted for?
Exchange
What do the pulmonary venules do?
Collect blood from capillaries
What do pulmonary veins have?
Thin walls
Define blood pressure?
Blood pressure is the force exerted by the blood on the walls of the blood vessels.
Why do we measure blood pressure?
To check it is in the correct range for that person.
Establish a baseline against which to compare.
What should blood pressure be high enough to maintain?
Blood flow to brain. But not so high that vessels are damaged.
What generates blood pressure?
Pumping action of the heart.
Where are blood pressures highest?
Aorta & large arteries
What happens as blood flows around the circulation?
Pressure falls progressively
Where is blood pressure lowest?
Great veins as bod returns to right atrium
Where is blood pressure normally measured?
Systemic arteries
Where is bp most often measured clinically?
Brachial artery (large arteries)
Define systemic arterial blood pressure?
Systemic arterial blood pressure is the force exerted by the blood against the walls of the systemic arteries
In what fashion does blood flow in arteries?
Pulsatile
What causes fluctuations in arterial pressure?
Phase of the cardiac cycle
When is it called when bp at its highest?
Systolic pressure
What is it called when bp is at its lowest?
Diastolic pressure
Define systolic?
The force exerted by the blood on the walls of the systemic arteries during heart contraction
Define diastolic?
The force exerted by blood on the walls of the systemic arteries during heart relaxation
What is bp measured in?
mmHg (milimetres of mercury) / SI units (pascals/kilopascals)
How many mmHg is 1 kpa?
7.5mmHg
Define pulse pressure?
Difference between. Systolic & diastolic pressure ( systolic - diastolic)
What is a normal bp for a healthy adult?
120/80mmHg
What can influence bp?
Age, gender, genetics, diet, weight, stress, smoking etc…
What is hypertension?
High blood pressures & can damage vessells
What is hypotension?
Low pressures. Can cause dizziness
What characteristics of the cardiovascular system determine systemic arterial bp?
Cardiac output, resistance to blood through arteries
What is the equation for bp?
Blood pressure = cardiac output x pressure
What causes resistance to blood flow?
Diameter of blood vessels (influences by the autonomic nervous system & hormones).
Overall length of blood vessels.
Viscosity of blood.
Short term regulation of systemic arterial blood pressure is brought about by what?
Negative feedback loop
What receptors sense stretch/pressure in relation to bp?
Baroreceptors
Where are baroreceptors located?
Carotid sinus & aortic arch
What is the integrator related to bp?
Medulla oblongata
What are the effectors for bp?
Vasoconstriction/vasodilation, heart rate
