Cardiovascular system- The vessels Flashcards
Name the five main types of blood vessel
Arteries, arterioles, capillaries, venules and veins.
Are arterioles and venules smaller or bigger than arteries and veins?
Smaller
Name some arteries
radial, carotid, femoral, aorta, brachial.
Name some veins
jugular, vena cava, hepatic, popliteal, renal
Name the layers of a blood vessel
Tunica intima, tunica media, tunica externa.
Is tunica intima made of smooth muscle?
Yes
Is the tunica media made of smooth muscle?
Yes and elastic fibres.
Is tunica externa made of smooth muscle?
No, its made of collagen.
Do arteries carry oxygenated or deoxygenated blood?
oxygenated (except pulmonary artery)
Do arteries or veins have more elastic/smooth muscle?
arteries.
Do arteries or veins carry blood away from heart?
arteries.
Do arteries or veins have valves?
veins
do arteries or veins have larger lumens?
veins
Do arteries or veins have higher pressure?
arteries
Do big arteries have more elastic or smooth muscle?
elastic
What is anastomoses?
where arteries in a main area link.
What are end arteries
nothing beyond them so if blocked there is no blood supply distally.
2/3 of blood at any one time is held in…
The venous system.
What are the valves in some veins called?
semilunar valves.
do arteries or veins tend to spurt when cut?
arteries with the exception of varicose veins
How thick are capillaries?
one cell thick- semi permeable membrane
Why do capillaries have a semi permeable membrane?
to allow for gaseous exchange
What is the lumen size of a capillary?
diameter of an erythrocyte (red blood cell)
What do pre-capillary sphincters do?
direct blood flow
When do capillaries have an increased blood flow?
during hypoxia or higher waste
What are sinusoids?
smaller than capillaries with thinner walls and separate blood from neighbouring cells.
What is the ideal capillary refill time?
2 seconds
What gases are exchanged between alveoli and capillaries?
O2 and CO2. CO2 goes from red blood cells to alveoli and O2 goes from alveoli to red blood cells
what is gas exchange also known as?
Internal respiration
What is osmosis?
The movement of water from a lower concentration to a higher concentration of solute.
What is hydrostatic pressure?
blood pressure pushing fluid from blood in to tissues
What is osmotic pressure?
pulling fluid back into the blood stream.
during blood supply to vessels thick walled vessels do what?
receive their own blood supply
during blood supply thinner walled vessels and endothelium receive nutrients through what?
diffusion of blood flowing through them.
What controls the diameter of a blood vessel?
exercise, illness/tissue damage, heat, blood volume, peripheral vascular resistance, excess waste products/hypoxia
dilate vs constrict
open vs close
vaso- dilate/constrict is in relation to…
the vessels
will vessels dilate or constrict when blood volume is low?
constrict to increase blood pressure.
Most blood vessels except capillaries are serves by nerves in the…
autonomic nervous system (ANS)
nerves in the ANS are controlled by the…
vasomotor centre in the medulla oblongata.
baroreceptors control vasodilation/constriction in…
large arteries.
vasoconstriction/dilation in arterioles/arteries respond purely to…
nerve stimulation.
decreased nervous stimulation causes…
relaxation- vasodilation
increased nervous stimulation causes
contract- vasoconstriction
vascular resistance is caused by what 3 factors?
diameter of vessel, length of vessel and blood viscosity
peripheral vascular resistance and vascular resistance relies on…
vasodilation/constriction.
blood pressure is…
the force of blood that exerts vessel walls
Blood pressure equation
cardiac output x peripheral resistance
systolic blood pressure is what?
when blood forced into aorta exerts pressure on arteries. 120mmHg
diastolic blood pressure
resting blood pressure during cardiac diastole. 80mmHg
mmHg
millimetres of mercury (traditional way of measuring BP)
short term control of BP is through
baroreceptors, chemoreceptors, higher centres brain.
What are the 5 stages of blood pressure rising to homeostasis?
- stimulus
- baroreceptors in carotid arch and aortic arch are stimulated.
- impulses from baroreceptors stimulate cardioinhibitory centre and inhibit vasomotor centre.
- sympathetic impulses to heart cause HR drop, CO drop and contractility drop. Rate of vasomotor impulses causes vasodilation and lower resistance.
- CO and resistance drop returning blood pressure to normal.
Where is a pulse felt?
In the arteries. (expansion and recoil next to a bone)
Heart rate and pulse rate are normally…
the same
What information can be gathered from a pulse?
brady/tachycardia, heart malfunctions, possible medications.
What affects a pulse?
Age, injury, exercise, emotion, heart problems, temperature
