exam 2 class 11 Flashcards
distribution of blood to the tissues three things
- % of total flow
- Volume per 100 g of tissue per minute
- absolute rate of flow (L/min)
how is blood flow to all the individual tissues possible?
all of the arterioles in the body are in parallel
arterioles receive blood at the same time from the?
aorta
Flow through individual arterioles in a branching system of arterioles
depends on?
their resistance (R)
The higher the resistance in an arteriole, the _______the blood flow through it.
lower
Pressure-Volume relationships of _________ provide the basis for circulation
Boyle’s law
(1) blood flow increases in response to a pressure
gradient
(2) blood flow decreases as the resistance (R) of the system to flow increases
change in pressure/resistance
arteriolar resistance matches tissue blood flow to the metabolic needs of the tissue
Local control
the CNS maintain mean arterial pressure and determine blood distribution to various tissues to meet homeostatic needs, such as temperature regulation
Sympathetic reflexes
-particularly those that regulate salt and water excretion by the kidneys
-influence blood pressure by acting directly on the
arterioles and by altering autonomic reflex control
Hormones
help control involuntary body functions
Sympathetic neurons
facilitates the normal day-to-day functions
parasympathetic nervous
system
cell communication where a cell releases a signal to change the behavior of nearby cells
Paracrine signaling
when blood reaches the capillaries what happens
plasma and the cells exchange materials across the thin capillary walls
Most cells are located within ________ of the nearest capillary, and
diffusion over this short distance proceeds rapidly
0.1 mm
what has the most capillaries per unit area?
tissues
what has the lowest capillary density
subcutaneous tissue and cartilage
what has the highest capillary density?
muscles and glands
Adult human body has how many miles of capillaries
50,000 miles
thinnest walls of all the blood vessels, composed
of a single layer of flattened endothelial cells supported on a basal lamina
Capillaries
how much SA of capillaries do we have?
6300 m2 (two football fields)
diameter of a capillary is barely that of a red blood cell which forces?
RBCs to squeeze through in single file
Even though a single capillary has a tiny
diameter, when you put them all together,
their summed diameters cover an area much
larger than?
the total cross-sectional areas of all the arteries and veins combined
have a lining that contains pores that let only small molecules pass through. Nervous system, skin and lungs
Continuous capillaries
have larger openings
(fenestrations) between the cells that allow the quick
exchange of substances (nutrients and blood). Kidneys, small intestine and endocrine glands
Fenestrated capillaries
discontinuous, have even larger gaps and pores. Liver, spleen, lymph nodes, bone marrow and endocrine glands
Sinusoidal capillaries
Oxygen and carbon dioxide
diffuse freely across?
thin endothelium
In capillaries with leaky cell
junctions, most small dissolved solutes can diffuse freely between?
the cells or through the
fenestrations
mass movement of fluid as the result of hydrostatic
or osmotic pressure gradients
Bulk flow
If the direction of bulk flow is into the capillary
absorption
If the direction of flow is out of the capillary
filtration
kidneys?
filtration mostly
intestines?
absorption mostly
what regulates bulk flow in the capillaries
starling forces
lateral pressure component of blood flow that
pushes fluid out through the capillary pores
hydrostatic pressure
straling forces
- hydrostatic pressure
- osmotic pressure
determined by solute concentration of a
compartment
Osmotic pressure
what is the main solute difference between plasma and interstitial fluid?
proteins - present in the plasma but absent from interstitial fluid
the osmotic pressure created by the presence of these proteins
colloid osmotic pressure
also called oncotic pressure
A positive value for the net
pressure indicates ?
and a negative value indicates?
net filtration
net absorption
filtration is greater than?
absorption
how much bulk flow is there each day?
3 liters per day
allows the one-
way movement of interstitial fluid
from the tissues into the circulation
The lymphatic system
what physiological systems do the lymphatic system interact with?
cardiovascular system
digestive system
immune system
(1) returning fluid and proteins filtered to the circulatory system
(2) picking up fat absorbed at the small intestine and moves it to the circulatory system
(3) a filter to capture and destroy foreign pathogens
functions of the lymphatic system
accumulation of fluid in the
interstitial space, a condition called?
edema
(1) inadequate drainage of
lymph
(2) blood capillary filtration
that greatly exceeds capillary absorption
edema causes
-elevated venous pressure
e.g. during heart failure, a condition in which one ventricle loses pumping power and can no longer pump all the blood sent to it by the other ventricle
increase in capillary hydrostatic pressure
severe malnutrition or liver failure and these proteins are responsible for the colloid osmotic pressure component of the blood.
Decrease in plasma protein concentration
excessive leakage of proteins out of the blood decreases the colloid osmotic pressure gradient and increases net capillary filtration
Increase in interstitial proteins:
