Blood vessels and circulation Flashcards
Describe the structure of a blood vessel.
Tunica intima: (endothelium –> simple squamous epithelium): innermost layer, part that touches the blood as it flows.
-Tunica media: (mostly made of smooth muscle): the middle layer/tunic. Crucial in maintaining blood pressure, any change(s) in diameter of vessels impacts blood flow/blood pressure
-Tunica externa/adventitia (connective tissue): outermost layer; protect/reinforce the vessel, anchor it to surrounding structures
describe the types of arteries, capillaries, and veins
Arteries carry blood away from your heart.
Veins carry blood back toward your heart.
Capillaries, the smallest blood vessels, connect arteries and veins.
Trace the general route usually taken by the blood from the heart and back again; and
Heart > Arteries > Arterioles > Capillaries > Venules > Veins
Pulse pressure and mean arterial BP are formulated
BP (mL/min)
PP(difference between systolic and diastolic pressure)
MAP (DP + PP/3) = MAP
describe three factors that determine resistance to blood flow;
- Peripheral resistance (resistance to flow)
-blood viscosity
-vessel length
-vessel radius - Cardiac output
- Blood Volume: controlled by kidneys.
Explain how vessel diameter influences blood pressure and low.
Vessel radius is the best way to control resistance
-Vasoreflexes: changes in vessel radius
-Vasoconstriction: contraction of the smooth muscle of the tunica media
-Vasodilation: based on laminar flow
describe some local, neural, and hormonal influences on vessel diameter
Local:
-Autoregulation: the ability of tissues to regulate their own blood supply
Neural
-Sympathetic control over blood vessels
-Automatic, negative feedback response to change in blood pressure
-Automatic, negative feedback response to change in blood pressure.
Hormonal
-Hormones influence blood pressure through vasoactive means or by regulating water balance
describe how materials get from the blood into the surrounding tissues
Metabolic theory of autoregulation
-Tissue is inadequately perfused, wastes accumulate, stimulating vasodilation which increases perfusion.
-Bloodstream delivers oxygen and removes metabolites
-When wastes are removed, vessels constrict
Describe the transport and other forces that cause capillaries to release and reabsorb fluid from the ECF
Give Off: Fluid filters out of the arterial end of the capillary and osmotically reenters the venous end.
Reabsorbed
Opposing Forces:
-Hydrostatic pressure: physical force of a liquid against a surface Ex. Blood pressure.
-Colloid osmotic pressure (COP) draws fluid into capillary because plasma proteins (albumin) higher in blood.
explain how blood in the veins is returned to the heart
. Pressure Gradient
-Venules (12 to 18 mm Hg) to central venous pressure: point where the venae cavae enter the heart (~5 mm Hg)
- Gravity drains blood from head and neck
- Skeletal muscle pump in the limbs
- Thoracic (respiratory) pump
-Inhalation: thoracic pressure decreases & abdominal pressure increases forcing blood upward through the vena cava.
- Cardiac suction of expanding atrial space (tendinous chords)
Discuss the importance of physical activity in venous return.
- Pressure gradient
-Venules (12 to 18 mm Hg) to central venous pressure: point were the venae cavae enter the heart (~5mm Hg) - Gravity drains blood from head and neck
- Skeletal muscle pump in the limbs
- Thoracic (respiratory) pump
-Inhalation: thoracic pressure decreases & abdominal pressure increases forcing blood upward through the vena cava. - Cardiac suction of expanding atrial space (tendinous chords)
Explain how blood in the veins is returned to the heart.
As the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs, where it is oxygenated. The oxygenated blood then returns to the heart through the pulmonary veins. The pulmonary veins empty oxygen-rich blood from the lungs into the left atrium.
name and describe the stages of shock.
Initial stage (early stage)
2. Nonprogressive or Compensatory stage
3. Progressive stage
4. Progressive stage S&S
explain how the brain maintains stable perfusion
The cerebral arteries dilate when the systemic BP drops and constrict when it rises, thus minimizing fluctuations in cerebral BP.
trace the route of blood through the pulmonary circuit.
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