exam 4- 25 + 26

what is the regulation of systemic blood flow: local control

systemic circulation

autoregulation artieroles

general rule: fresh blood reaching tissue can fix the local problem

what is the regulation of systemic blood flow: systemic control

system wide

neural arteries

hormonal

general rule: all blood needs to be cycled through the lungs

there are differences between pulmonary and systemic cirulation

what is autoregulation of blood flow

automatic adjustment of blood flow to each tissue relative to its varying requirements

Controlled by local signals that modify diameter of local arteries and precapillary sphinters feeding capillaries

independent of neuronal and hormonal control and MAP

what are the two types of short term auto regulation

metabolic controls

• local chemicals

myogenic controls

• local stretch

what are the two methods od metabolic controls

• vascodilation

• vasoconstriction

descide vasodilation

Increase local blood flow

• of arterioles and relaxation of precapillary sphincters occur in response to…

metabolically active tissues

• lower tissue O2

• higher tissue CO2, H, K, adenosine

some lead to realese of nitric oxide, a potent vasodilator

Nitrates increase NO for vasodilation

• nitroglycerin, viagra

inflammatory chemicals also cause vasodilation

• histamine, prostacyclins

descirbe vasoconstriction

decrease local blood flow

metabolically inactive tissues of hyperoxis

• high tissue O2

• lower tissue CO2, H, K

what is endothelins

Released from the endothelium are potent vasoconstrictors

NO and endothelins are balanced; unless blood flow is inadequate, then NO wins

what are myogenic controls

Myogenic responses keep tissue perfusion relatively constant despite most fluctuations in systemic pressure

Vascular smooth muscle responds to stretch

• Stretch increases intravascular pressure, promoting vasoconstriction and increased tone

• protects the weaker capillaries downstream

• Reduced stretch lowers pressure promote vasodilation and increased blood flow to the tissue

what happens to vasoconstrictors during metabolic and myogenic

metabolic

• increase O2

• decrease CO2 endothelins

• decrease H

myogenic

• increased stretch

what is angiogenesis

number of vessels to region increases and existing vessels enlarge

• Blood vessels grow into anoxic tissue (low 02)

also common in the heart when coronary vessels are occluded or throughout the body in people in high altitude areas

what is long term local auto regulation

occurs when short-term autoregulation cannot meet tissue nutrient requiremnts

1) too much 0 2 reduced retinal capillary growth

2) when high 02 was removed, the retina went anoxic and capillaries grew out into vitreous humor or detached the retina

what is perfusion

changes in Po2 in alveoli cuase changes in diameters of arterioles

what is ventilation

changes in Pco2 in alveoli changes in diameter of bronchioles

what happens to pulmonary blood flow if a lung collapses

pulmonary arteriole dilation directs most blood where alveolar O2 is high

Bronchial dilation allows more rapid elimination of CO2 from alveoli

what are short term neural controls of the systemic blood flow and pressure

counteract fluctuations in blood pressure by altering CO and PR

what are neural control of the systemic blood flow and pressure that are reflexes

baroreceptors (mechanical) located in

• carotid sinuses (divsion of external and internal carotid) and aortic arch

chemoreceptors (carotid bodies) located in

• aortic arch and large arteries of neck

what are the steps of homeostasis that keep blood pressure in normal rage

1) stimulus: decrease BP (arterial blood pressure falls below normal rage)

2) baroreceptors in the carotid sinus and aortic arch are inhibited

3) decreased impulses from baroreceptors activate the cardioacceleratory center (inhibiting the other) and stimulate the vasomotor center

4a) increased sympathetic impulses to heart cause increased HR, contractility, and CO

4b) vasomotor fibers stimulate vasoconstriction cuasing increased PR

5) increased CO and PR return blood pressure to the homeostatic range

what is hormonal control of systemic blood flow and pressure

long term regualtion via changes in blood volume (kidneys)

short term regualtion via changes in peripheral resistance and CO

what increased secretion increases blood pressure? hormonal control of systemic

Epinephrine and norepinephrine from the adrenal gland= increase CO and PR (vasoconstriction) almost everywhere

• except: heart, skeletal muscle, and liver (fight or flight)

ADH increases blood volume and causes vasoconstriction

Aldosterone increases Na and blood volume

Angiotensin II increases aldosterone release and vasoconstriction

what increased secretion lowers blood pressure? hormonal control of systemic

Atrial natriuretic peptide ANP causes vasodilation and decreases blood volume by

• lowering blood Na through kidney filtration

• inhibiting aldosterone and ADH

hogh blood pressure has what affect on the heart

stretches the heart and leads to ANP secretion

what are the three forms of capillary exchange

1) Diffusion through membranes

2) Movement through intercellular clefts and fenestrations

3) Transport via vesicles or caveolae (transcytosis)

explain capillary exchange through diffusion

high to low concentration

Hydrophobic substances cross the membrane (O2, CO2..)

hydrophilic substances pass through water filled pores in the endothelium

explain capillary exchange through vesicle transport

Small amounts of specific proteins (like hormones) are endocytosed on the luminal side and released on the opposite side (interstitial side) of the endothelium

explain capillary exchange via bulk flow

distribution of extracellular fluid volume

20L in bulk flow daily

what are three aspects of capillary permeability

most common= skin, skeletal muscle

1) continuous capillaries

2) fenestrated capillaries (kidney, SI)

3) sinusoidal capillaries

(liver, bone marrow, sleep)

what are fenesterated capillaries

capillaires are pressurized

• pores

what is capillary osmostiv pressure

OPc

created by large plasma proteins which draw water toward themselves

about 28 mm Hg

what is interstital fluid osmostic pressure

OPif

extracellular fluid around cells

low about 3 mm Hg due to low protein content

what is capillary hydrostatic pressure

HPc

capillary blood pressure

tends to force fluid through capillary walls

greater at arterial end (35 mm Hg) of the bed than at the venue end (15 mmHg)

what is intersistial fluid hydrostatic pressure

HP if

extraceullar fluid around cells

pressure that would push fluid into the blood vessel usuaully assumed to be zero mmHg because lymphatic vessels drain excess fluid

what is net filation pressure

Comprises all focres acting on the capillary bed

NFP= (HPc- HPif)-(OPc-OPif)

net fluid flow out at arterial end (hydrostatic> osmotic)

net fluid flow in at venous end (hydrostatic < osmotic)

how is excess fulid returned through the lympatic system

If more fluid leaves than is returned in the capillary it is returned to the heart via the lymphatic system

sturctual relationship between capillary bed of the blood vascular system and lymphatic capillaries

explain net filtration that occurs at the arteriolar end of a capillary

Hydrostatic pressure in the capillary pushes fluid out of the capillary

Osmotic pressure in the capillary pulls fluid into the capillary

Hydrostatic pressure in intersitiatl fluid has little effect on pushing fluid into the capillary

Osmotic pressure in interstitial fluid has little effect pulling flhid out of capillary

explain net reabsorpation that occurs at the venous end of a capillary

Hydrostatic pressure in capillary pushes fluid out of the capillary

Pressure has dropped due to resistance along capillaries

osmotic pressure in the capillary pulls fluid into capillary

Hydrostatic pressure in interstitial fluid had little effect on pushing fluid into the capillary

Osmotic pressure in interstitial fluid has little effect on pulling fluid out of the capillary

what are the major gunctions associated with cellulalr respiration

• supply cells with 02

• dispose of CO2

describe gas exchange that occurs at the alveoli

bronchi (1 degree, 2, 3), bronchioles, terminal bronchiole, respiratory bronchioles

Alveoli are like little stretchy balloons (elatin proteins)

alveoli surface area is 40-50 times greater than skin

what are three factors that hinder air passage and pulmonary ventilation

airway resistance

alveolar surface tension

lung compliance (ability to deform in shape)

what is anatomical dead space

No contribution to gas exchange

all airways above terminal bronchioles

air remaining in passageways about 150 mL

10% of the residual volume

what is alveolar dead space

non functional alveoli due to collapse, lack of capillaries or obstruction

what is total dead space

sun of anatomical and alveolar dead space

normally constant, difficult to measure

what is intrapulmonary pressure

insirpation

• less than atmospheric presure as lung volume increases

expiration

• greater than atrompheric pressure as lung volume decreases

what is intrapleural pressure

must remain lower than intrapulmonary pressure for lung to remain inflated

what is transpulmonary presure

must reamin positve for lung to remain inflated

what is volume of breath

pressure gradients move about 0.5L of air into and out of the lungs

tidal volume

what is atelectasis

lung collapse due to plugged bronchiles= collapse of alveoli

what is pneuothroax

air in pleural cavity

from either a wound in the parietal pleura (open pneumothorax) or reuptate of the visceral pleura (closed or tension pneumothorax)

treated by removing air with chest tubes

what is pulmonary ventrilation

exchange of air between the atmosphere and alveoli

air flow moves from high pressure to low pressure

air flow- pressure/ resistance

what is airway resistance

usually insignificant in large airways (large diameters)

Resistance is greatest in medium- sized bronchi

Progressive branching of airways as they get smaller increases total cross-sectional area and reduces total resistance

what are airway ressitance imbalences

airwyas resistance is most dependent on radiius

as airways resistance rises, breathing movements become more strenuous

what does sever constiction or obstuction of bronchioles cause

Can prevent life-sustaining ventilation

Can occur during acute asthema attacks; reduces ventilation

what are adrenergic and cholergic affect airway resistance imbalence

Adrenergic agonists minic epi

ACh constricts bronchioles

• blockers of Ach receptors (muscarinic) can relax the airways and reduce resistance

cholinergic antagonists inhbit Ach signaling

what is alveolar surface tension

attracts liquid molecules to one another at ga

what is alveolar surface tension: surfactant

what are lung compliance

explain negative pressure in terms of respiration

what is Boyles law

what are mechanical processes that lead to volume changes in thoratic cavity

explain aspects of pulmonary ventilation

what are the steps to inspiration

what are steps to expiration

what is intrapulmonary and intrapleural pressure at rest

how does intrapleural pressure keep lungs inflated

explain pressure relationships in the lungs