figure 46-19 sarcomere myofibril dark bandlight band relaxed contracted muscle tissue bundle of...
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Figure 46-19
Sarcomere
Myofibril
Dark band Light band
Relaxed
Contracted
Muscle tissue
Bundle of muscle fibers (many cells)
Muscles
Muscle fiber (one cell) contains many myofibrils
Figure 46-24a
Figure 46-20
Myofibril
Relaxed
Contracted
Thin filament (actin) Thick filament (myosin)
Z disk
A
A C
C D
DB
B
Figure 46-24b
Ryanodine receptors line on the sarcoplasmic reticulum
Voltage gated calcium channel in the T-Tubules
Figure 46-23
Myosin head
Troponin
Tropomyosin
Actin
Calcium ionsMyosin binding sites
Calcium ion Troponin-tropomyosin complex, moved
Figure 46-22
CHANGES IN THE CONFORMATION OF THE MYOSIN HEAD PRODUCE MOVEMENT.
1. ATP bound to myosin head. Head releases from thin filament.
2. ATP hydrolized. Head pivots, binds to new actin subunit.
3. Pi released. Head pivots, moves filament (power stroke).
4. ADP released. Cycle is ready to repeat.
Myosin head of thick filament
Actin in thin filament
Experimental evidenceIn vitro motility
Experimental evidenceOptical Tweezers
What stops muscle contraction?ATP is needed to (1) Induce the release of myosin crossbridges from actin.(2) Pump Ca++ back into the sarcoplasmic reticulum.
Forc
e
Time
http://www.dkimages.com/discover/previews/773/258319.JPG
Nerve nets, ganglia, cephalization
Midbrain: reflexive coord, tactile + auditory
Hindbrain: refined limb movement, resp., cardiac, gastric.
Forebrain Voluntary muscle, thought
Sulcus formation
Central Nervous system
Nervous Stysem Organization
Figure 45-19PARASYMPATHETIC NERVES
“Rest and digest”SYMPATHETIC NERVES
“Fight or flight”
Constrict pupils
Stimulate saliva
Slow heartbeat
Constrict airways
Stimulate activityof stomach
Inhibit release ofglucose; stimulategallbladder
Stimulate activityof intestines
Contract bladder
Promote erectionof genitals
Sacralnerves
Lumbarnerves
Thoracicnerves
Cervicalnerves
Cranialnerves
Dilate pupils
Inhibit salivation
Increase heartbeat
Relax airways
Inhibit activityof stomach
Stimulate releaseof glucose; inhibitgallbladder
Inhibit activityof intestines
Relax bladder
Promoteejaculation andvaginal contraction
Secreteepinephrine andnorepinephrine(hormones thatstimulate activity;see Chapter 47)
Figure 45-21b
Lefthemisphere
Intra-abdominal
Tongue
TeethJaw
Lips
NoseE
yeThum
bFingers
Hand
Arm
Head
Tru
nk
Hip
Leg
Gen
itals
How we study the brain:Electrically
Imaging
Lesions
Genetic maps
Figure 44-28
Sinoatrial node
Atrioventricular node
Purkinje fibers
Electrical control and conducting system
30
-30
-60
0
Phase 4
Phase 0
Phase 3
Cardiac pacemaker activity – The sinoatrial node
mV
0 100 200Time (ms)
Key Ion Currents
30
-30
-60
0
mV
0 100 200Time (ms)
Control of heart rateParasympathetic (Vagus nerve) Sympathetic
How do heart rate, vessel resistance and stroke volume help determine blood pressure?
Cardiac Output =heart rate(beats/min) * stroke volume (ml/beat)
Cardiac Output = PA-PV/R R = 8 L/ r4 (r is the “radius of arterioles” aka resistance vessels)
Stroke volume is determined, in part, by effective blood volume (EBV) returned to the heart. Constricting large veins increases EBV. (capacitance vessels). More than half of the blood volume is in veins.
Stand up quickly and feel dizzy?Giraffes? Fighter pilots? Tree-snakes versus land snakes?What organ are we worried about? Where (and how) do we sense blood pressure?
How do heart rate, vessel resistance and stroke volume help determine blood pressure?
Cardiac Output =heart rate(beats/min) * stroke volume (ml/beat)
Cardiac Output = PA-PV/R R = 8 L/ r4 (r is the “radius of arterioles” aka resistance vessels)
Blood pressure plummeting. Three mechanisms!
(1)Cardiac output(2)Diameter of resistance vessels(3)Diameter of capacitance vessels.
HeartHeart
What are directions of flow and the key events in the cardiac cycle?
Systole Diastole
Vena cava
Aorta artery
Pulmonary artery
Pulmonary vein
Conservation of mass: the total blood volume is constant (over minutes to hours).
That means all of the blood passing though the aorta has to equal all of the blood passing though the capillaries in every second!
AortaAorta
Cardiac Output = Area*Velocity = Total Area * Velocity
30
-30
-60
0
mV
0 100 200Time (ms)
Recap: Control of heart rateParasympathetic (Vagus nerve) SympatheticSlow heart rate Increase heart rateAch leads to lower Ica NE increases ICa,IF
Ca channel blockersDigitalis increases vagal activity
What would hyperkalemia (too much K) cause?
How do heart rate, vessel resistance and stroke volume help determine blood pressure?
Cardiac Output =heart rate(beats/min) * stroke volume (ml/beat)
Cardiac Output = PA-PV/R R = 8 L/ r4 (r is the “radius of arterioles” aka resistance vessels)
Stroke volume is determined, in part, by effective blood volume (EBV) returned to the heart. Constricting large veins increases EBV. (capacitance vessels). More than half of the blood volume is in veins.
Stand up quickly and feel dizzy?Giraffes? Fighter pilots? Tree-snakes versus land snakes?What organ are we worried about? Where (and how) do we sense blood pressure?
What are directions of flow and the key events in the cardiac cycle?
Systole Diastole
Vena cava
Aorta artery
Pulmonary artery
Pulmonary vein
Cardiac Output = PA-PV/R R = 8 L/ r4
What is blood?
40% RBC, 60% Plasma
How does the viscosity of blood vary with hematocrit (fraction rbc) or vessel diameter?
hematocrit Tube diameter m
1 10 100 10000 20 40 60 80
The Farheus-Lindvist Effect --- there are fewer red blood cells in the microcirculation because they move faster than all of the plasma!
Rouleaux formation
Faster RBC motion in middle of tube.
Equal areas – different velocities!
Other circulatory systems
Open versus closed
Figure 44-23
Interstitial fluid
Excess fluid in interstitialspace enters lymphatic duct Lymph leaves tissue
Blood enterscapillary fromarteriole (asmall artery)
Net pressure 10 mm Hg out
Osmoticpressure22 mm Hg
Blood pressure32 mm Hg
Capillary
Fluid leaves
Blood leavescapillary tovenule (asmall vein)
Net pressure 7 mm Hg in
Osmoticpressure22 mm Hg
Blood pressure15 mm Hg
Fluid returns
Lymphatic duct
Is it really “closed”?
Plasma and lymphatic exchange : a consequence of the balance of mechanical and osmotic pressures.