Chapter 6- Basic Blood Vessels Flashcards
What are the 2 types of blood circulation?
The systemic circulation and the pulmonary circulation
What are the 5 types of blood vessels ?
Arteries-Arterioles- capillaries-Venules-Veins
What are the 3 types of layers forming the arteries aterioles veins and Venules ?
The tunica intima, the tunica media and the tunica externa
Is the endothelium continuous with the endocardium ?
Yes surrounding the lumen
What about the structure of the capillaries?
They are formed with one layer : the endothelium
What constitutes the tunica intima ?
The endothelium, the sub endothelium layer and the internal elastic membrane
What constitutes the tunica media?
Smooth muscle and elastic fibres and an external elastic membrane. Elastic fibres allow the vessels to distend and retract and smooth muscle to contract. The constriction of a vessel leads to a narrowest lumen.Vasocontriction and vasodilation of those vessels are then possible.
The tunica media also contains the sympathetic nervous system.
What constitutes the tunica externa ?
Collagen fibres and the vasa vasorum
What do the kind of arteries that are closest to the heart contain more in the tunica media and how are they called?
The elastic arteries, they contain more elastic fibres in the tunica media allowing then to retract or dilate
What happens with atherosclerosis or arteriosclerosis vascular disease ?
The arteries will be less elastic
Why are the muscular arteries called so ?
Because the tunica media contains more smooth muscle than others arteries allowing constriction or dilation
Arterioles carry blood into ?
Capillary beds
The wall of veins or Venules is always thiner than corresponding arteries or Arterioles true or false ?
True
The lumen of veins or Venules is always larger than the corresponding lumen of arteries or Arterioles, true or false?
True
What blood flow refers to ?
The volume of blood that moves to an organ or through a blood vessel or in the entire circulation per unit of time ( minutes); cardiac output= blood flow
The blood goes down through a pressure gradient, from high to low pressure regions
What is the definition of blood pressure ?
The force that is exerted per unit of surface area against the inner wall of blood vessel in millimetres of mercury (mmHg). Resistance to blood flow creates blood pressure.
What is resistance ?
Anything that opposes blood flow or makes It difficult for blood to flow through the system. Vascular resistance = peripheral resistance
What are the factors of vascular resistance?
Diameter of vessels, blood viscosity ( eg polycythemia or anaemia), the length of the vessels.
When do we generate systolic pressure in the blood vessels ?
During contraction of the left ventricle at the end of systole the highest pressure is generated in the aorta and arteries
When does diastolic pressure occur ?
During ventricular diastole, at the end of diastole the diastolic pressure in the large arteries is achieved
What are the 2 anatomical factors in the venous systemic circulation helping the blood flow towards the right atrium ?
The venous valves and the contraction of skeletal muscles on venous walls. Also when you inhale pressure in your thoracic cavity falls and helps the return of venous blood flow
What is the normal blood pressure in a resting adult ( non pregnant) ?
Systolic blood pressure < ~120 mmHg
Diastolic blood pressure<~ 80 mmHg
What factors influence mean arterial pressure ?
Cardiac output and resistance
Which vessels are the one creating the more resistance ?
Arterioles
Which blood vessels are the major determinant of peripheral resistance?
Arterioles
Is blood pressure lowest in large veins or Venules?
Large veins
Is resistance to blood flow highest in Arterioles or large arteries?
Arterioles
Is blood pressure highest in Arterioles or in large arteries?
Large arteries
Which layer of an arterial wall is most responsible for maintaining blood pressure and the continuous flow of blood through the circulation?
Tunica media
Is it blood vessel length, blood vessel diameter or blood viscosity the factor that has the biggest impact on peripheral resistance?
Blood Vessel diameter
When practitioners assess blood pressure, they listen carefully for the first Korotkoff sound, what does this sound correspond to ?
Systolic blood pressure
Hypertension is defined as a blood pressure of greater than what numbers ?
Systolic pressure > 140 mmHg and diastolic pressure > 90 mmHg
What are the 3 primary factors determining hight blood pressure?
Peripheral resistance, blood volume and cardiac output
