Physiology Exam 4 (Chapters 14 and 15)

Flow Equation

change in pressure over resistance

Pressure

Force exerted by blood

If radius of bv is decreased(vasoconstriction)

resistance is increased

Flow is

Directly related to change in pressure

Resistance is

indirectly related to flow

While pressure is different

flow is constant

Systemic has a higher change in pressure, but,

flow is equal in both systemic and pulmonary circuits

Systemic change in pressure

is created than pulmonary change in pressure

Systemic circuit resistance is greater than pulmonary but why?

resistance is not equal

Factors affecting resistance to flow

*length of vessel, vasoconstriction/vasodilation,

Higher viscosity means

higher resistance

Viscosity

thickness of blood, thicker the viscosity, the lower the flow

Vasoconstriction

decreased radius and higher resistance

Vasodilation

higher radius and lower resistance

What is different between the two circuits?

length of blood vessels

TPR

combined resistance of all bvs in the systemic circuit

Microcirculation bus

arterioles, capillaries, venues

Capillaries

site of exchange, low velocity, blood moves slower

Components of bv walls

smooth muscle, fibrous CT(collagen), Elastic CT(elastin), varies by type of vessel

Elastic arteries

large diameter and lower resistance, walls contain elastin and fibrous tissue, high pressure, closer to heart, thick elastic walls, low compliance, storage site for pressure, expand as blood enters during systole, recoil during diastole

Muscular arteries

small, little elastin and have smooth muscle, smooth muscle regulates vasoconstriction and dilation, further from heart

Low compliance

doesn’t expand easily, small increase causes large increase in pressure

High compliance

expand easily, large increase needed to produce large increase in pressure

Measuring bp w a compressed artery

turbulent flow produced Korotkoff sound

Pressure at first Korotkoff sound is

systolic bp

Measuring bp w uncompressed artery

no sound bc laminar flow, pressure when sound disappears, shows diastolic bp

Pulse pressure

systolic minus diastolic

Where does the body spend most time?

diastole

How is bp shown?

systolic over diastolic

What bv has the highest resistance?

arterioles

Capillaries

have the greatest cross-sectional area, have slowest velocity of blood flow

Continuous capillaries have

intercellular clefts, small water soluble molecules move thru

Fenestrated capillaries have

pores or fenestrations, proteins can move thru, rapid met

Discontinuous capillaries

large gaps, sinusoids are spaces lined with endothelium, proteins can pass

Diffusion w caps

lipid soluble solutes diffuse thru plasma membrane

Metarterioles

between caps and arterioles, directly connect arterioles to venules

Precapillary sphincters

rings of smooth muscle that surround caps on arteriole end, metabolites(o2) cause relaxation

Movement across cap walls

exchange bw blood and cells, normal distribution of ECF

Diffusion

most common mechanism for exchange across cap walls

Lipophilic

across membrane, easy

Lipophobic

thru channels

Transcytosis

exchangeable proteins, endo and exocytosis

Mediated transport

BBB

Filtration

movement out of capillary into interstitial space

Absorption

movement into capillary from interstitial space

Edema

collection of fluid outside capillary, tells you where problem is, fluid out of blood in interstitial space but not reabsorbing it

Hydrostatic

force due to fluid, PUSHING

Osmotic pressure(oncotic - proteins)

osmotic force exerted on water by non permeable solutes, PULLING

P_cap

capillary hydrostatic pressure, capillary bp: favors filtration

P_if

interstitial hydrostatic pressure: favors reabsorption

N_cap

capillary osmotic pressure: favors reabsorption

N_if

interstitial fluid oncotic osmotic pressure: favors filtration

Net Filtration pressure

filtration pressure - absorption pressure

Factors affecting filtration and absorption

standing, injury, liver disease, kidney disease, heart disease

Standing

gravity increases hydrostatic pressure in lower extremities

Injuries

caps damaged they leak proteins and fluid, histamine increases permeability to proteins(they are large), affects N_it and swelling happens

Liver Disease

decreases plasma proteins

Kidney Disease

increases bv and bp, decreases plasma proteins, consequence is edema

Heart Disease

L failure - pulmonary edema

R failure - systemic edema

affecting P_cap edema around ankles(R) or lungs(L)

Determinants of MAP

heart rate, stroke volume, TPR

Regulation of MAP

neural(faster) and hormonal(slower)

MAP is

directly related to heart rate, stroke volume, and TPR

MAP

driving force for blood flow

Hypotension

MAP is less than normal, inadequate blood flow to tissues

Hypertension

MAP is greater than normal, stressor for heart and blood(over perfusing tissues)

Short term MAP regulation

neural control, regulates CO and TPR, involves heart and bus

Long term MAP regulation

regulates bvs, involves kidneys, hormonal control

Sensory receptors of neural control of MAP

baroreceptors(detects change in bp, aorta and carotid), pressure receptors, sometimes called stretch receptors

integration center of neural control of MAP

cardio centers in brainstem, medulla oblongata

Neural control of MAP effectors

heart, arterioles, and veins

Neural control center input

Neural control output

sympathetic(heart and bvs) and parasympathetic(heart nodes)

Baroreceptor reflex - hemorrhage

low bp=low MAP, increased SYM activity, decreased PS activity, greater resistance, less blood flow due to vasoconstriction, quick fix

Vasopressin

vasoconstrictor, kidney reabsorption of water

Angiotensin II

vasoconstrictor, stimulates thirst, stimulates release of aldosterone

Epinephrine

adrenergic receptors, acts on heart, increased SYM activity

Arrhythmia

irregular heart beat

Inspiration

decreased pressure in thoracic cavity, increased PS activity and heart rate

Expiration

increased pressure in thoracic cavity, increased PS activity, decreased heart rate

Chemoreceptors

respond to increases in CO2 levels in blood, regulate them

Thermoregulation

increased body temp, decreases SYM activity to skin, takes precedence over baroreceptor reflex, possible decreased TPR and MAP

Blood is what

55% plasma, 45% cellular components

What are some cellular components?

RBCs, WBCs, Platelets, proteins

Hematocrit

% of RBCs to rest of blood

Secondary polycythemia

hypoxia, decreased O2, kidneys release EPO to increase RBCs

Polycythemia vera

kidneys release EPO and RBCs

Relative polycythemia

malfunction of bone marrow, dehydration

Plasma is

mostly water, nutrient, wastes, gases, and electrolytes

Albumins

osmotic oncotic pressure, pulling force

Globulins

lipid transport, clot formation, and immunity

Fibrinogen

clot formation

Erythrocytes

RBCs, biconcave disk shape, no nucleus or organelles

Spectrin net

flexible membrane that allows RBCs to fit into capillaries

Erythrocyte function

transport O2 and CO2

Hemoglobin

iron and polypeptide chains

Heme

iron containing group that binds to O2 and CO

Globin

4 chains of polypeptides, binds to CO2

Carbonic Anhydrase equation

CO2+H2O←→H2CO3←→H+HCO3

Carbon Dioxide←→carbonic acid←→bicarbonate

How long to erythrocytes live?

120 days

Erythrocytes made in

red bone marrow through process of erythropoiesis