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how is pressure lost from friction
friction within the blood, friction between blood and vessel walls
Flow
directly proportional to the pressure gradient and inversely proportional to resistance (Cardiac output)
what is blood flow through the circulatory system driven by
the pressure gradient which is generated by cardiac contraction
venous return (VR)
the flow of blood into the right atrium from the peripheral vessels
where is blood flow velocity slowest
capillaries, total cross-sectional area is large
precapillary schincters
open and close in response to local metabolic conditions
metarterioles
divert blood flow if sphincters are closed, also allow larger materials (WBC) to bypass narrow capillaries
capillaries
site of gas exchange, are leaky, density related to metabolic activity of cells, single layer of flattened epithelial cells
bulk fluid flow
3L/day of fluid through capillaries, excess picked up by lymphatic vessels
active hyperemia
increased blood flow accompanies increased metabolic activity
reactive hyperemia
increased tissue blood flow following period of low perfusion
orthostatic hypotension
decreased blood pressure that occurs upon standing up
Atherosclerosis
inflammatory condition in which fatty deposits called plaques develop in arteries
what are the pressure resevoir
arteries, are elastic and can stretch and recoil to maintain pressure
systemic pressure
highest in aorta; declines throughout pathway; 0 mm Hg in right atrium
pulse pressure
systolic pressure minus diastolic pressure (avg. 40mm Hg) force heart creates each contraction
Mean Artieral Pressure (MAP)
diastolic pressure + 1/3 (pulse pressure) = avg. 60mm Hg (driving pressure)
HR x SV =
CO
EDV - ESV =
SV
CO x R =
MAP (~93) min 60
how to quickly decrease BP
compensation by cardiovascular system (vasodilation, decrease CO)
how to slowly decrease BP
compensation by kidneys (excretion of fluid in urine decreases blood volume)
arteriole resistance by changing radius
local factors (myogenic or paracrine response, sympathetic NS regulation
local factors: myogenic autoregulation
reflexive constriction helps maintain constant blood flow despite changes in perfusion pressure
local factors: paracrines
active hyperemia will cause vasodilation (O2,CO2, H+), reactive hyperemia compensation after reduced blood flow
SNS effect: norepinephrine
a1-adrenergic receptors, increase constricts, decrease dilates, diverging mechanism
what type of control does SNS effect on arteriole resistance
tonic control on most arterioles
SNS effect: epinephrine
released from adrenal medulla, fight or flight, b2-adrenergic receptors, converging mechanism
Baroreceptors
pressure sensors in carotid and aortic arch, stretch-activated, tonically active, increased pressure opens more channels=more AP
Baroreceptor reflex
The primary reflex pathway for homeostatic control of blood pressure (decrease sympathetic output, increase parasympathetic output)
plasma proteins
albumins, globulins, fibrinogen
cellular elements of blood
erythrocytes (RBC), leukocytes (WBC), platelets (thrombocytes)
5 WBC
lymphocytes, monocytes, neutrophils, eosinophils, basophils
fibrinolysis
Plasmin dissolves fibrin in platelet plug + breaks down clot as damaged vessel is repaired
Prostacyclin
restricts platelet plugs to site of injury
anticoagulants
limit extent of blood clotting within a vessel
blood
7% of body weight, connective tissue, watery extracellular matrix (plasma 1/4 body ECF)
centrifugation
Separates components by density using high speed spinning
buffy layer
platelets and white cells between plasma and RBCs ~1%
hematocrit
% of total blood volume that is occupied by RBC ~42%
hematopoeisis
synthesis of blood cells occurs in the red bone marrow of long flat bones, 25% become RBC, 75% become WBC
cytokines
proteins release from 1 cell that affect the activity of another
Erythropoietin (EPO)
low RBC, produced in kidney cells
Thrombopoietin (TPO)
low platelets, produced in liver
hypoxia
low O2 levels in arterial blood, sensed by kidney stimulates EPO
hemoglobin
four protein globin chain, centered around a porphyrin heme group ring, iron atom in center
enemia
low RBC count, decreased hemoglobin content=reduced O2 carrying capacity
hemolytic anemia
accelerated RBC loss, genetic (sickle cell), acquired (malaria)
aplastic anemia
decreased RBC production, from drugs or radiation, dietary insufficiencies
hemorrhage
loss of blood from the vessels
hemostasis
keeping blood inside the blood vessels
4 steps to hemostasis in response to damage
vasoconstriction, platelet plug formation, coagulation, dissolution of clot
the coagulation cascade
The series of steps beginning with the intrinsic (collagen) or extrinsic (tissue factor) pathways of coagulation and proceeding through the formation of a fibrin clot
Fibrinolysis
tissue is repaired and clot dissolves due to actions of enzyme plasmin
A+ blood type
A flag, + Rh
A- blood type
A flag, no Rh
universal acceptor
AB (Rh+)
universal donor
O (Rh-)
hemolytic disease of the newborn
anti-Rh antibodies will cross the placenta and damage fetal RBC
air flow
nasal cavity, pharynx, larynx, trachea, primary bronchi, smaller bronchi, bronchioles, alveoli
functions of respiratory system
gas exchange, regulation of pH, conditioning inspired air, protection, vocalization
inspiration
air moves into lungs
expiration
air moves out of lungs
ventilation
air in and out
pleural membranes
fluid filled balloon that wraps around lungs so ribs and lungs move together
cardiac notch
A concave space on the left lung in which the heart lies
muscles used for quiet breathing
external intercostals, diaphram
muscles used for forceful breathing
sternocleidomastoids, scalenes
muscles used for forceful exhalation
internal intercostals, abdominal muscles
visceral pleural membrane
surrounds the lungs
parietal pleural membrane
surrounds intrapleural fluid and attaches to chest wall
pleural sac
protects lungs, lubricated membranes to slide, sticks lungs to thoracic wall, keeps lungs inflated
main role of airways
filter out foreign substances, warm air, add water vapor
watery saline layer of respiratory tract
allows cilia to push mucus toward pharynx (cystic fibrosis missing this layer)
bronchodilation
decreased resistance, paracrine response to CO2, SNS response nore/epinephrine bind to B2-receptor, Gs pathway
bronchoconstriction
increased resistance, paracrine response to histamine, PNS response ACh binds to (M3) muscarinic receptors, Gq pathway
alveoli
site of gas exchange, make up most of lung tissure, one layer epitheliaal cells,
type 1 alveolar cells
gas exchange, 95% alveolar space, squamous
type 2 alveolar cells
make and secrete surfactant
Surfactant
fluid that lines all the alveoli making them easier to expand and prevent from collapsing, decreases SA and tension
transpulmonary pressure
force inflating the lungs (Palv - Pip = 4mm Hg)
Functional Residual Capacity (FRC)
volume of air remaining in the lungs after a normal tidal volume expiration (ERV + RV)
pneumothorax
air in the pleural cavity caused by a puncture of the lung or chest wall
compliance
ability of the lung to stretch, decreased in restrictive pulmonary disease (fibrosis-espestos)
elastance
ability of the lung to spring back after being stretched, decreased in emphysema, loss of elastin
boyle's Law
P1V1 = P2V2
what does air sucked in do
lung volume increases, pressure in lungs decrease, inspiratory muscles contract
what does blowing air out do
lung volume decreases, pressure inside lungs increase, inspiratory muscles relax
spirometry
to measure changes in lung volumes during ventilation
tidal volume (Vt)
normal in and out ~500ml
Inspiratory reserve volume (IRV)
can pull in but usually dont
Expiratory Reserve Volume (ERV)
can push out but usually dont
Residual Volume (RV)
cant push out-lungs are inflated
inspiratory capacity
Vt + IRV, total capacity
Vital Capacity (VC)
TV + IRV + ERV, normal working range
Total Lung Capacity (TLC)
Vt + IRV + ERV + RV, everything
Dalton's law
Total pressure exerted by a mixture of gases is the sum of pressures exerted by all individual gases
what is rate of diffusion directly proportional to
SA, membrane permeability (D), conc. gradient
what is rate of diffusion inversely proportional to
diffusion distance (membrane thickness, interstitial fluid)
Hemoglobin
Found in RBC, reversibly binds to 4 O2, increases blood O2 carrying capacity, HbO2=oxyhemoglobin