Card Set Information
the composition of dry air (numbers for O2, N, CO2)
O2 = 20.95%
N = 78.09%
CO2 = 0.03% - treat basically as zero
torr = ?
1 kpa = _ mmHg
as you go up in altitude, pressure ___
PO2 = ?
PO2 = FO2 x (Patm - r.h. (PsH2O))
PsH20 = water vapor pressure at certain temps
what determines the amount of gas dissolved in fluid? and Henry's law
: [gas] = solubility constant x Pgas
Henry's law coefficient for different gases - O2, CO2, N2
solubility for O2 is very low - not much oxygen is dissolved in liquid (.003 ml/100ml - mmHg)
CO2 solubility is much higher (.071 ml/100 ml-mmHg) -
the difference in O2 and CO2 solubility has consequences for their transport in the body
N2 - .0015 - also pretty low
at equilibrium, is pressure or concentration the same across phases? diffusion depends on....
so there is more O2 in air than in water and more CO2 in water than in air
average capillary PO2, and average brain/retinal tissue PO2
capillary = 30-40 mmHg
brain = 20 mmHg
what does solubility depend on?
Temperature and salinity
solubility decreases as T increases
solubility decreases as salinity incrases
solubility depends on temp and salinity so concentration does too
diffusion works for gases when? when it doesn't work anymore - what is used?
diffusion of gas is ok for short distances but too slow for long distances
use convection then!!! - how gases get around the body
to get gas into lungs use convection (inhale) - at alveoli you depend on diffusion, flow of blood = convection, rely on diffusion to get oxygen into mitochondria
difference between air and water as a respiratory medium
O2 is much more concentrated in oxygen
much higher viscosity of H2O than viscosity of air = much harder to move water over resp. passages
diffusion rate is MUCH higher in air than it is in water
diffusion rate equation
J = Dx (solubility coefficient) x A x (change in P/change in distance)
J = mass flow, D = diffusion coefficient, A = area
J is related to pressure gradient, but also related to diffusion coefficient
less important differences between air and water as a respiratory medium
thermal conductivity of water is much higher than air
heat capacity of water is much higher than air
these don't really have much of a role in gas transport though
how does PO2 vary with depth?
it should stay the same in a sterile lake b/c if there were changes diffusion would cause them to equal out
but in an unsterile lake - PO2 decreases with depth b/c of metabolism by animals and microorganisms
(the low diffusion coefficient and high viscosity of water keep downward movement of O2 slow so pressure differences remain)
concentration of O2 should be higher with increasing depth b/c of coldness if all other things were kept equal
mixed venous blood
blood that is returning to the heart
at different altitudes - ambient pressure is much different. is mixed venous blood pressure any different?
no - they are about the same - adaptations to have steeper slope for P changes in other parts of the blood (air to alveoli and artery to mixed venous)
want venous blood to have high enough PO2 so that is can still diffuse into the mitochondria
the two main categories of respiratory designs
invaginated - like lungs
evaginated - external or internal gills
usually lungs = air, gills = water
two categories of gas vs. blood flow (counter and con)
concurrent exchange - water and blood flow in same direction - worse - at some point there won't be a difference in gradient so not much will be transferred
countercurrent flow - flow in opposite directions - maintains a gradient across entire length of exchange surface - better
as medium flows across a respiratory surface, respiratory medium loses oxygen to blood
how do the gills work?
water is pumped across the gills by the mouth and opercular movements
blood flows through the arch vessels, along venuoles
the capillaries are in the lamellae (the offshoots from the arches) - blood flow is countercurrent to water flow
distance between RBC and water in gills
3-8 umeters - much bigger than in us
the gills must have water flow to keep them open - will collapse in air
two other categories of gas vs. blood flow for when the medium is air
cross-current - intermediate effectiveness between counter and concurrent exchange
cross - air flow is to the right, and blood flow goes across - what birds have
tidal - is the most inefficient - relies on diffusion at the bottom --> no uniform flow of respiratory medium - air goes down and gets stuck in chambers
these two designs are for when the medium is air
characteristics of mammalian lungs
LOTS of surface area
several layers of respiratory membrane (epithelium for alveoli, basement membrane, capillary basement membrane, and endothelial cell in capillaries)
this is less than 1 micron thick
BUT still not all the air gets exchanged - 150 ml of dead space
is respiratory surface area vs. body weight an allometric function?
BUT also, homeotherms have higher exchange area b/c of higher metabolic rates
the ectotherms don't need as much oxygen - less surface area
fish use this to get air from the water
they open their mouth and swim to run liquid across their gills
good for high O2 demands - some use just ram ventilation, others use it when their swimming speed increases
more energy efficient than opercular pumping at higher speeds of swimming
another possibility besides lungs/gills
insects have these
trachae - tubes in which air diffuses through
pores in the surface are called spiracles
some insects even pump air into the trachea to boost diffusion with convection
another possibility to get air
gas transport through skin - no specialized respiratory organ
works well in amphibians especially
small for most reptiles, mammals, birds
why do reptiles have lower amount of gas transport through skin?
much lower permeability to water - b/c in terrestrial conditions
don't want to lose water and dry out!
the anatomy of the lungs/thorax - what helps quiet/heavy breathing
lungs are passive - no muscles to do with ventilation
lungs are encased in closed chamber - you move the wall of that chamber (the thorax)
lungs are connected to the thorax by a vacuum in the pleural space
the small negative pressure (relative to atmospheric) of the intrapleural space balances elastic recoil of lung and chest
during quiet breathing, just diaphragm
during heavy breathing - use thorax too
so how do we ventilate?
small pressure changes expand the lungs
when you breathe in, the interpleural space gets more negative
air flow is determined by difference between atmospheric and alveoli pressure (Palv goes neg when Pip goes neg)
BUT - at end of respiration, Pip is more negative, but alveoli pressure goes above zero
this is because air enters the lungs until the Patm-Palv difference is zero
what happens when you puncture the chest wall
you lose the negative pressure inside the intrapleural space
what is different about bird lungs?
they have other air sacs in the body
these sacs are connected to the lung for holding air
cross current gas flow - very efficient - good for high altitudes
the parabronchi are channels
non-tidal - one way flow
what is different about bird respiration?
breathes air through trachea
goes into posterior air sacs
expiration - air flows across the lungs
inspiration - air pulled from lungs into anterior air sacs
expiration - pushed out of sac and out of trachea
crosscurrent exchange in birds
blood flow in channels adjacent to parabronchus
more efficient than tidal
the fluid dynamics of air flow cause the air to go across parabronchi instead of back through trachea on first exhalation
how would you optimize the respiratory system?
max lung volume
max surface area between external medium and blood
minimize thickness of interface (easier to diffuse)
mas flow rate of fluids passing resp. surface (increase pressure difference across fluid space across long - lower IP pressure)
actively move fluid (not tracheas like insects)
optimize exchange geometry (countercurrent, crosscurrent, tidal)
minimize dead space
live in air not water
the similarities in the O2 cascade in water and air breathers and the differences
: stepwise gradient form medium to tissues
: the difference between lung PO2 and arterial PO2 is much smaller than gill PO2 to arterial PO2.
why? - diffusion across the respiratory membrane is faster in air breathing animals!
what is different about CO2 and O2 that will influence CO2 elimination form the body?
there is a lot less CO2 in the atmosphere -partial pressures will be different
solubilities will be different - CO2 much more soluble in liquid than O2
CO2 carried in blood in form of bicarbonate
CO2 doesn't really attach to the heme in hemoglobin
why is there a huge drop between alveoli and ambient air in the CO2 cascade for lungs?
because tidal exchange is really bad
CO2 must leave by diffusion - CO2 backs up in the system, increases PCO2 everywhere
what are the PO2 and PCO2 values for entering and leaving the lung?
PO2 entering = 40 mmHg
PO2 leaving = 100
PCO2 entering - 45
PCO2 leaving = 40
bigger difference in O2 across lung than CO2!
and what it is for carbs, amino acids, protein
CO2 produced/O2 used =respiratory quotient
1 for carbs
0.8 for amino acids
0.7 for proteins?
we produce about as much CO2 as we use O2!
what form of the gas contributes to partial pressure?
only the dissolved form!
Co2 in blood is carried in 3 ways (Hb, dissolved, and converted to HCO3
O2 in blood carried in 2 forms - dissolved and Hb
ventilation and equation for it
rate at which medium is made to flow across respiratory organ
= frequency of breathing x tidal volume
rate at which blood flows through respiratory organ
how do water breathers regulate ventilation?
monitor O2 concentration in incurrent water
CO2 concentration is usually too low to monitor (b/c its usually as HCO3 or other compounds, it diffuses away from gills too fast to monitor)
ventilation increases if O2 in water decreases b/c this decreases O2 in blood
regulation of ventilation for air breathers
control based on CO2 concentration b/c its closely linked to pH of blood
b/c so much O2 is stored in hemoglobin, we are less affected by the inspired O2 concentration
increase blood CO2 = more ventilation
decrease blood O2 = increased ventilation (takes bigger change in O2 than CO2 though)
no effect if more O2 than normal
sensors in mammals that regulate ventilation?
pulmonary stretch receptors
chemoreceptors in mammals
in the medulla of the brain
detect pH and/or CO2
very important for ventilation rate
small change in CO2 = big change in respiration
also in carotid and aortic bodies - they detect O2 in blood
pulmonary stretch receptors
these are called baroreceptors in the lung
help control breathing rhythm
mediated by skeletal muscle, but essentially all automatic and controlled by brain stem
increase of stretch = decrease in inhalation
2 alpha, 2 beta
4 globins each with a heme - iron atom
the heme is where the oxygen binds
so hemoglobin can bind 4 oxygen molecules
the 4 kinds of oxygen binding proteins
where are hemoglobins found?
protostome and deuterostome phyla
intracellular in muslce (myoglobin)
extracellular in blood (polymers)
intracellular in blood (RBC)
hemocyanins and where found
molluscs and arthropods
blue not red
extracellular in blood
heme based and similar to hemoglobin
only in a few annelids
extracellular in blood
iron based, but not heme based
in several phyla
intracellular in blood
why are the monomeric to tetrameric hemoglobins only intracellular and not extracellular?
if small ones were extracellular they would gum up the kidneys! - plug up glomerulus and kidney
there would be too high of an oncotic pressure in extracellular blood (pressure due to proteins in blood)
the polymers don't seem to cause this problem, are present in extracelular blood
equation for vol % and what the numbers are for at rest and heavy exercise
vol% = mlO2/100 ml blood
5 vol% is extracted at rest - so it goes from 20 to 15
15 vol % is extracted for exerise, so it goes from 20 to like 5
extraction = ?
the SaO2 - SvO2
mucher higher in exercise
QO2 = ?
the oxygen utilization/consumption (like metabolic rate)
= F (SaO2 - SvO2)
F = blood flow for organ or for whole body (for whole body F would be cardiac ouput!)
called the Fick principle
what 3 properties does O2 binding vary with?
P50 - affinity of hemoglobin for oxygen (partial pressure at which blood is half saturated with O2)
the lower the P50 = the higher the affinity
Cooperativity - how easy it is for 2nd, 3rd, etc. to bind after one or two is already attached
Total amount of pigment in blood - is the plateau
SO2 equation and what each variable means
SO2 = Smax (PO2^n / (P50^n + PO2^n))
Smax = total amount
P50 is affinity
n = cooperativity
gives s-shaped curve!
how do P50, cooperativity, smax vary the O2 concentration curve?
P50 - shifts curve left and right
smax - shifts curve up/down - same shape, same P50, just higher or lower
cooperativity - with more cooperativity the curve gets steeper!
how does pH and PCO2 and temperature affect affinity for O2
if gets more acidic (like during exercise) - no effect on smax or cooperativity, but P50 increases, graph shifts right = Bohr effect!
Root effect - max O2 saturation can also vary with CO2
an allosteric modulator of O2 affinity
if you increase amoutn of 2,3 DPG, you increase the P50 = lower the affinity of hemoglobin for O2
why are most organs in parallel in the mammalian circulatory plan?
allows each of them to have access to high pressure that comes out of the aorta
to drive the blood through the organs
the liver and kidney are not parallel though!
artery vs. vein
artery - flows away from the heart (oxygenated except pulmonary)
vein - flows toward the heart (partly deoxygenated except pulmonary)
the conduction system of the heart
heart must contract ALMOST as a single unit - starts at apex of heart and spreads downward
from SA node, to AV node (specialzied cardiac muscle - a myogenic heart)
then through bundles to bottom of heart
why is the left ventricle thinker than teh muscle of the right ventricle?
b/c the systemic resistance is much higher than pulmonary resistance!
what is the average presure of systemic circuit and pulmonary circuit at the arteries?
systemic - 90 mmHg
pulmonary - 20 mmHg
b/c resistance in pulmonary is much lower than in systemic
measure the activity of the heart
happens b/c a small amount of current flows out to the surface of the body
show where the heart depolarizes/repolarizes
ventrical depolarization = QRS wave
ventricle repolarization = T wave
P = atrial depolarization
the wall of the heart that has the coronary circulation (circulation to body of the heart muscle)
we have a compact myocardium with coronary arteries and veins
spongy myocardium - little/no coronary vessels - it perfuses as same time that ventricle perfuses - allows smaller enough distances between muscle and blood that diffusion of O2 works!
can also be a mixed structure - blood flows from lumen into coronary veins - vessels that emminate from the ventricle itself (invertebrates)
what are the heart valves mostly controlled by?
when blood flows from ventricle into the aorta, the aorta and arteries expand and store pressure in their elastic walls
during diastole, thw all of the aorta (muscular and springy) will contract and push blood through the circulation
how does total cross sectional area and average velocity of blood change over the circulation system
much larger cross sectional area in the smaller vessels (biggest in capillaries)
b/c of this velocity is lowest in capillaries
you want this slowing of blood so that there is time for oxygen to leave and pick up CO2!
you also want a ton of area so that they have enough area for oxygen to diffuse out into the tissue
Flow rate equations
F = change in P/R for each vessel
F = volume/time
R = resistance to flow
Fartery = all F in areriole = n(F arteriole) --> conservation of mass
F = V x A (v = velocity, A = cross sectional area)
the resistance of the group of arterioles is lower or higher than the resistance of each arteriole
with more arterioles = more paths - resistance is much lower than resistance of each one
more channels = easier for blood to get through!
how is resistance of the gorup (Rt) related to individual resistances? (Ri)
Rt = Ri/n
n = number of aterioles/capillaries, whatever it is
so Ri is bigger than Rt!
where is the largest presure drop in teh circulation?
at the arterioles! - have largest resistance in teh system
this is also the place hwere you can adjust resistance to lower or raise the blood flow
why is there resistance to blood flow?
b/c fluid is viscous - slipping past itself takes up some energy
laminar flow of blood vessels
highest velocity at center - velocity at walls = zero
for all circulation except capillaries! - b/c the RBC are larger than capillaries - can't have middle of RBC go faster than edges
RBC must move all at once
R = (8nl)/ (r^4 x pi)
n = viscosity
r = radius
how is resistance in the circulation regulated?
change diameter of arterioles - lots of smooth muscle around arterioles - none around capillaries
change number of capillaies that are open - change diameter of sphincter muscles
resistance controlled largely at arteriole level
autonomic control - smooth muscle - sympathetic for norepinephrine
metabolic local control - if more O2 used in tissues, vessels will dilate
chemical factors - drugs like histamine, angiotensin, nitric oxide
cardiac output and equation for it
flow through the whole circulation
the flow into each side
C.O. = (Pa - Pv) / TPR
TPR = total peripheral resistance
since Pv = o
Pa = C.O. x TPR
cardiac output equation involving heart rate and stroke volume
C.O. = HR x SV
HR = heart rate, frequency
SV = stroke volume - amount of blood pumped on individual beat
if you want to incrase CO you usually increase both HR and SV
TPR decreases so Pa stays the same
the two pressure components for capillaries
hydrostatic - usually forces fluid out of the capillary and into the blood
decreases as you go across the capillary
oncotic (pressure due to proteins in blood) - stays constant and wants water to be drawn into capillaries (Acts against hydrostatic pressure)
Net filtration = k ((Pcap-Pecf) - (picap - piecf)
k = filtration coefficient
fish circulatory plan
one pump not two
pump blood once - through gills and then through systemic circulation
pressure will be lower
lower cardiac output
low C.O. b/c MR is lower!
can have ABO's
air breathing organs
puts circulatory plan into parallel instead of series
mouth, gut, swim bladder
swim bladder also used for buoyancy control
circulatory plan of lungfish!
don't use gills for oxygen transport
blood goes into pulmonary circulation to get oxygenated - not gills
1 atrium 1 ventricle
have two auxilary chambers to help with pumping tho
before atrium there is the sinus venosus
bulbus arteriosis (conus in tuna b/c its contractile)
2 atria, 1 ventricle
frog - has a conus with two outlets - not as much mixing between deoxygenated oxygenated blood
non crocodillian reptile hearts
2 atria, 1 divided ventricle
many inlets and outlets - no auxillary things
effective separation between pulmonary and systemic in ventricle
2 atria - 2 ventricles, but not totally parallel system
completely separated ventricles
when submerged tho - they can direct blood away form pulmonary circulation (can't get air so why?)
mammal and bird heart
2 atria, 2 ventricles
they have a single pump, but the gills come after the tissues
lack of vessels by tissues - no endothelialized channels
blood perfuses tissues - collects in sinuses
distributino of circulation is not as finely tunable as ours
blood gets back to heart by muscular contraction
open circulation heart
heart is refilled by elastic recoil
blood enters via ostia openings
electrogenic heart vs. myogenic
electrogenic - pacemaker is neural not muscular like myogenic
one neuron is pacemaker
what is different about octopus circulation?
its a double circuit
two branchial hearts that are separate from systemic heart
how much of us is water?
2/3 of it is intracellular
1/3 of it is extracellular (interstitial fluid and plasma)
water only moves if there is a ____ gradient
what ions dominate in seawater?
Na and Cl
lots of Mg and SO4 also
much higher osmolarity than seawater!!
freshwater fish - problems
they are hyperosmotic
so they gain water by osmosis and lose ions by diffusion
therefore they must excrete lots of urine that is hypoosmotic
AND actively take up Na and Cl (in food and through gills)
marine teleost fish - problems
they are hypoosmotic - bigger difference than in freshwater fish too
so they gain ions by diffusion and lose water by osmosis
must have concentrated urine - but they can't do this (isoosmotic)
urine has high concentrations of Mg and SO4 though
need to actively pump salt across their gills
marine elasmobranchs - problems
they are slightly hyperosmotic but they are hypoionic!
this is because of the concentration of urea and TMAO in their bodies
they gain some water by osmosis
and they also gain salt by diffusion
so they must excrete concentrated stuff --> do this with their rectal gland secretions (rich in salts)
counteracting solute and an example
a solute, in which you have a high concentration of to activate enzymes that balance the effect of urea inactivating them
TMAO is sharks
also could be other methylamines
compatible solutes - do humans use them?
they can raise osmolarity and have no effect on enzymes
glycerol, glycine, arginine, proline, serine (amino acids)
humans use them in cells in renal medulla where osmolarity is high
how freshwater fish regulate salt
use the gills
there is a Na/K pump at the basal membrane
Na will then cross passively across apical membrane
to get chloride across apical membrane - you have counter transport with HCO3 gradient to have energy for Cl transport
marine fish salt regulation
must secrete Na and Cl
at basal, Cl is transported by secondary active transport with K and Na
Cl across apical is then passive
at basal, Na comes in coupled with K and Cl
but no way for Na to go out at apical - b/c of negativity outside cell - it gets pulled out paracellularly between the gill epithelial cells
the pumping cells
in marine fish - there are tons of mitochondira in it and pavement cells almost completley cover ti
in freshwater fish - the pavement cells just surround the chloride cell
gas transporting cell
salt gland and how it is controlled
used by reptiles and birds in their heads
there are lobes full of epithelial cells that allow for this
controlled by high blood osmolarity - parasympathetic stimulation of the gland (AcH?) and then salt is secreted.
drying out - because skin and other surface allows for evaporation
a problem for terrestrial animals!
evaporation and body weight
dessication is an allometric function
the smaller animals have a larger rate of evaporation because of body surface area!!
relationship between size and urine concentrating ability
smaller animals have higher max urine osmolarity
this partially compensates for the greater rate of evaporation in smaller animals
what regulates thirst?
blood osmolarity and angiotensin
which stimulate release of ADH - for water conservation
metabolic water production relation to body size
smaller animals produce more metabolic water b/c their metabolic rate is higher!
means we are ureotelic
medium amount of water needed to excrete it
medium cost of production
what do we make for nitrogen excretion?
excrete ammonia as nitrogen waste?
ammonotelic - mostly aquatic vertebrates
but highly toxic
low cost of making
must have a lot of water with it to excrete it
use uric acid for nitrogen excretion?
birds, many reptiles, sharks
high cost or metabolic production
small amounts of water required for excretion
low solubilty - precipitates out (bird poop)
urine vs feces wastes
urine - eliminates prety much everything made in teh body/absorbed into the blood (water, ions, amine groups, cellular metabolism products)
feces - eliminate components of food that could not be digested - are usually never actually inside the body
path of circulation in the kidney
renal artery --> afferent arteriole --> glomerular capillaries --> efferent arteriole --> paritubular capillaies or vasa recta --> renal vein
equation for E =
which parts are not included for water, Na, and H
E (extraction) = F - R + S
water - no secretion
Na - no secretion
H - no reabsorption usually
what determines GFR?
the amoutn of fluid filtered
Hydrostatic pressure (Pgc - Pbc)
Oncotic pressure which opposes filtration -
Filtration coefficient K
GFR = k x glomerular filtration pressure
what is much of reabsorption driven by?
active Na reabsorption in proximal tubule!
about 75% of total water and Na reabsorption occur in proximal tubule!
all of glucose is reabsorbed in proximal tubule too!
why do we secrete things if we filter so much? (2 reasons)
1 - sometimes we need regulatory adjustments for secretion late in the tubule
2 - sometimes you don't filter enough! like H+
how is osmotic gradient created in extracellular fluid in medulla?
partially by active ion pumping from thick ascending limb of Loop of Henle (pumps out ions) whereas descending limb is permeable to water so it flows out
causes insertion of aquaporin 2 water channels in apicla membrane
at basal - the aquaporins are already present and open!
how does relative medullary thickness relate to body weight?
decreases as animals get bigger - more able to concentrate their urine
increased ADH secretion with increase in blood osmolarity and decrease in ECF volume
causes ADH release from hypothalamus which allows for water reabsorption in CT
acts on distal tubule
increases Na reabsorption
increases K secretion
its a steroid so it makes more Na/K pumps at basal and more apical K channels
regulation of aldosterone
more release from adrenal cortex when increase in K concentration in plasma or when blood pressure decreases
it eventually causes more water reabsorption!
the primitive organization for nervous systems
no organized groups of neurons
contacts are pretty random at crossing points
like our enteric nervous system
what do bilateral animals show for their nervous systems?
centralization (into ganglia)
cephalizatoin (ganglion in head)
cerebrum, thalamus, hypothalamus
what does the cerebrum include?
cerebral cortex (outer covering)
like eye movements
pons, medulla, cerebellum
motor learning and feedback to control motor function
group of cells in CNS
bundles of axons within ganglia in CNS
smooth muscle, cardiac muscle, some endocrin/exocrine glands
what parts of the brain control autonomic function?
hypothalamus and hindbrain
which function has no autonomic component?
which part is only autonomic?
what are the 3 types of neurons?
about a day
exist without environmental information
a biological clock controls these rhythms
the main biological clock in mammals
its in the hypothalamus
like the pineal gland for birds
what is the cellular unit of vertebrate striated muscles? and description of it
the muscle fiber
its functional unit is the myofibril that runs parallel in it
purpose of T-tubules
carries the excitation of the plasma mebrane due to acetylcholine releasing Na
how much of the muscle mass is due to the myofibrils?
what does calcium due to actin/myosin binding in skeletal muscle?
Ca binds to troponin complex - moves tropomyosin!
allows for them to bind!
a molecule that goes from Z line (by actins) to the M line (by mysoins)
helps with elastic recoil of stretched muscles
anchors the actin
is inelastic unlike titin
motor unit definition
a motor neuron and the fibers it innervates
the receptors in skeletal muscle in excitation-contraction
Dihydropryidine receptor (DHPR) on t-tubule and Ryanodine receptor (Ryr) on SR
action potential opens them!
allows Ca to be released from SR
how does Ca get back into SR?
what are ATP's three main jobs in skeletal muscle excitation contraction?
disconnects the actin-myosin bond
the myosin head moves
pumps the Ca back into SR
useful tension of a skeletal muscle?
70%-140% because of sliding filament theory
you want as many crossbridges in right orientation as possible!
don't want too scrunched but also dont want to lengthened
what are the series elements in muscles? parallel elements?
series - tendons
parallel - titin, SR membrane, blood vessels
most normal contractions start isometric/isotonic and go isometric/isotonic?
go to isotonic
do sarcomeres in parallel or series exert more force?
larger diameter = larger force!
velocity-load curve for skeletal muscles
if no load - velocity of contraction is fast
if max load - no movement - contraction is isometric - velocity is zero
much less prevalent than twitch muscles
no action potentials in teh muscle membrane!
innervated at several points
slower contraction but more efficient
mammals = only in muscle spindles, extraocular muscles
lower vertebrates - in postural
what is different about invertebrate muscle?
more than one neuron per muscle fiber (motor units overlap)
fewer total neurons per muscle than in vertebrates
also have inhibitory motor neurons (we just inhibit in CNS)
smooth muscle characteristics
lots more actin than in striated
actin attaches to membrane at dense body
slow but efficient
chemical/neural signals but also spontaneously
related to intracellular Ca but a lot comes from extracellular
large contractile range
single unit smooth msucle
acts like a big single cell b/c of all the gap jnctions
more hormonal control, some neural control
can spontaneously depolarize
in small blood vessels, late in the uterus contractions
mutliunit smooth muscle
few gap junctions - acts as separate cells
more neural control
rarely sponteaneously depolarizes
in large blood vessels, in early uterus contractions, in hair follicles
how is Calcium different in smooth muscle?
must be extracellular too
Ca binds to CaM - which activates MLCK - phosphorylates myosin - allows binding to actin
homing vs migration
: return to starting point (usually more frequent than migration)
: seasonal/life-cycle movement - over a longer distance than homing
the reliable cues from environment for navigation
sun - light and polarization
how to use the sun position for navigation
sun always moves 15 degrees per hour (from E to W)
seen in bees - there little dance
polarization of the sun for navigation
sunlight is unpolarized
90 degrees to sun is max polarization
it reflects off atmospheric water and dust particles
must know degree of polarization and time of day to determine where sun is - determine where you are
must have an oritentation of photopigment to do this (arthropods and birds)
using star position for navigation
stars rotate around Polaris in the North
its a learned behavior!
use magnetic cues for navigation
either the magnetic field (weak but reliable) or dip angles
magnetic cues mechanisms?
particles of magnetic materials (like in nose of trout)
electroreceptors in lateral line in Sharks to detect magnetism
light induced electron transfer between photopigments?
track direction changes/distances to make direct path back to home
no map though - can get displaced
1a afferent neuron
used in stretch/myotactic spinal reflexes
are sensory axons associated with muscle spindles
simple, graded response to a specific stimulus
the working fibers - generate the load
gamma motor neurons
involved in stretch reflex
innervate the intrafusal fibers --> if you increase their activity you increase the muscle spindle activity
allwos for load compensation - maintains sensitivity of the reflex
make indirect connections with motor neurons - for protection
like stepping on a tack
twitch and its 3 periods
response to single action potential - normally an all or none thing
when the muscle does not shorten much as it exerts a tension on a force it cannot move
pulls on the elastic elements
the muscle changes its length as it exerts a tension on a load
tension = constant
concentric (shortens) or eccentric (lengthens)
slow oxidative muscles
slow at rate of cross-bridging (300 ATP/myosin-sec)
smaller diameter = less force over all
lots of blood capillaries
slow to fatigue
posture, slow movements
fast oxidative muscles
fast at cross-bridging (600 ATP/myosin-sec)
lots of capillaries
slow to fatigue
fast glycolytic muscles
fast at cross-bridging (600 ATP/myosin-sec)
fast to fatigue
large diameter = large force!
quick, fast movements, jumps
in a motor unit - are all the muscles fibers of 1 type or more?
map sense for navigation
have some sort of representation of position and goal position
landmarks, smell, magnetic cues?
turtles use different cues for different parts of travel!