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NPB101 > MT2 > Flashcards

MT2 Flashcards

1
Q

how much of body is skeletal muscle

A

30-40% body weight

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2
Q

which type of muscle are striated muscle

A

skeletal and cardiac

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3
Q

which type are unstriated

A

smooth

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4
Q

voluntary muscle

A

skeletal muscle

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5
Q

involuntary msucle

A

cardiac and smooth

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6
Q

sarcomere

A

Functional unit of SHORTENING
interactions between myosin (thick) and actin filaments

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7
Q

thick filament

A

1 thick surrounded by 6 thin filaments
MYOSIN molecules: 2 golf-club shaped subunits
tails aligned toward middle
globular heads protrude out at regular intervals

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8
Q

thin filaments

A

joined at Z-line
helical actin molecules
each with a myosin binding site to allow for cross-bridge formation

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9
Q

t tubules

A

an extension of membrane through the muscle cell
allows for propagation of action potential
deep channel into the cell from the surface
the sarcoplasmic reticulum surrounds t-tubules and myofibrils

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10
Q

motor unit

A

motor NEURON and all the muscle FIBERS it innervates
vary in size- range of <10 to >1000 muscle fibers per unit; bigger can generate more force
each muscle fiber is innervated by just ONE AXON
each AXON BRANCHES to innervate all of the fibers in its UNIT

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11
Q

how are motor units intercalated in bulk muscle

A

can elicit a range of strengths from the SAME muscle
lots of motor units inside; each with a different strength

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12
Q

neural control with single action potential

A

has a reaction which causes muscle contraction but it will return to rest due to no new neural input (change in tension due to AP)

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13
Q

what happens to the lateral sac after the DHP activation by the AP

A

depolarization releases Ca2+ from lateral sac
DHP activation directly gate open ryanodine receptors on the SR membrane

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14
Q

what happens when the Ca2+ binds to the troponin

A

removes blocking action of tropomyosin
Ca2+ reflux from SR baths the myofibrils in Ca2+

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15
Q

what allows the muscles to relax

A

Ca2+ transported back into SR via ATP-dependent pump

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16
Q

what happens once Ca2+ is removed from cytoskeleton

A

troponin restores tropomyosin blocking action

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17
Q

low cytosolic Ca2+; relaxed muscle

A

actin binding sites are covered!
cross bridge is energized

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18
Q

high cytosolic Ca2+, activated muscle

A

Ca2+ uncovers binding sites
binding of activated cross bridge to actin generates force
conformational rearrangement occur so now the cross bridge can bind

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19
Q

myosin is

A

motor protein

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20
Q

actin is

A

highway

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21
Q

H zone

A

1 thin end to the end of another

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22
Q

start of power stroke

A

TROPOMYOSIN ropes covering ACTIN BINDING SITES
Ca2+ then RISES…
Cross bridge binds to actin
- ropes shifted and uncovered binding sites

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23
Q

how is the flex allowed (cross bridge)

A

Loses the ADP+Pi

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24
Q

how does the cross bridge detach from the binding sites

A

addition of ATP and its binding to myosin

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25
Q

how is cross bridge energized

A

hydrolysis of ATP

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26
Q

what happens if there is no ATP in the power stroke

A

cross bridge stays flexed and bound

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27
Q

muscle spindle is

A

proprioceptor; a sense organ that receives information from muscle, that senses STRETCH and the SPEED of the stretch

when you stretch and feel the message that you are at the ENDPOINT of your stretch, the spindle is sending a REFLEX ARC signal to your spinal column telling you to NOT STRETCH ANY FURTHER

PROTECTS from overstretching or stretching too fast and hurting yourself

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28
Q

golgi tendon organ is a proprioceptor…

A

sense organ that receives information from the tendon, that senses TENSION
when you lift weights, the golgi tendon organ is the sense organ that tells you how much tension the muscle is exerting

too much tension and the golgi organ will inhibit the muscle from creating any force, prevent injury

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29
Q

tension

A

force exerted on an object BY A CONTRACTING MUSCLE

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30
Q

load

A

force exerted on the muscle BY AN OBJECT

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31
Q

Isotonic contraction

A

muscle changes length while the load remains constant
concentric- SHORTENING
tension exceeds load
eccentric- LENGTHENING (extend)
load exceeds tension

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32
Q

isometric contraction

A

muscle develops tension but does NOT SHORTEN OR LENGTHEN

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33
Q

isotonic twitch

A

at heavier loads, latent period is longer
the shortening velocity (distance shortened per unit of time) is slower
distance shortened is less

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34
Q

what happens if you recruit more motor units

A

increases tension
more strength

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35
Q

tetanus

A

PERSISTENT firing of AP
Can’t relax bc the inhibitory pathways are inhibited ]
gets to a point where it can stay contracted so it fatigues out

the toxin from Clostridium tetani prevents inhibitory signals from reaching the motor neurons, causing them to fire action potentials continuously

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36
Q

length and tension

A

shortened muscle isnt capable of generating much more tension
there is an ideal resting muscle length in which the maximal tension is able to be produced

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37
Q

Sarcomeres WITHIN MUSCLE

A

if they are arranged SIDE BY SIDE- act very fast
or STACKED- very strong

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38
Q

Muscle hypertrophy

A

increase in muscle fiber size resulting from resistance training, where micro-tears in the fibers stimulate repair processes that add more protein filaments, leading to thicker and stronger muscles

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39
Q

why do kidneys receive the second most amount of blood??

A

Kidneys do FILTRATION

kidneys make sure ion balance of blood and liquid surrounding cells remains homeostatically regular

kidneys filter blood

kidney is able to clear large amount of blood volume from toxins
quickly adjust [sodium] and water volume of blood

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40
Q

kidneys are responsible for

A

maintaining stable volume, electrolyte composition, and osmolarity of the ECF

by controlling the [salt] of blood, automatically also controlling the [] of liquid around the organs

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41
Q

Nephron is…

A

the FUNCTIONAL UNIT of the kidney

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42
Q

juxtamedullary nephron

A

(20%) lie in the inner cortex layer
goes deep into renal medulla
long loop of henle

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43
Q

how many nephrons

A

approximately 1 million nephrons per kidney

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44
Q

Vascular component of the nephron

A

glomerus, afferent arterioles, efferent articles, and peritubular capillaries

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45
Q

tubular component of nephron

A

starts at Bowman’s capsule

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46
Q

why are the capillaries so close to the tubular system

A

there is constant exchange of water and ions so the capillaries and tubular system are close together
capillaries are wrapped tightly around

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47
Q

afferent arteriole

A

carries blood to the glomerulus

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48
Q

glomerulus

A

tuft of capillaries that filter a protein-free plasma into the tubular component

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49
Q

peritubular capillaries

A

supply the renal tissue; involved in exchanges with the fluid in the tubular lumen

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50
Q

what happens to the large amount of plasma that enters the capillaries

A

gets filtered out

majority plasma is NOT FILTERED OUT; it continues on into the venous system
if not we would be peeing all day

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51
Q

juxtaglomerular apparatus

A

produces substances involved in the control of kidney function

region where the ascending loop of henle passes through the fork formed by the afferent and efferent arteriole, close to the glomerulus

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52
Q

what helps determine how much filtrate is made

A

AFFERENT and EFFERENT articles can constrict and expand
process is regulated

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53
Q

when do hormones start to play a role

A

hormones begin to play a significant role in reabsorption after the loop of Henle, primarily in the distal convoluted tubule and collecting ducts

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54
Q

What is the daily volume of plasma that is filtered

A

Approx. p180 liters of filtrate is formed each day

average plasma volume (blood-blood cells)= 2.75 liters
entire plasma volume in our body is filtered 65 times every day
approx. 178.5 of 180 liters of filtrate are reabsorbed
1.5 liters are secreted as urine

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55
Q

Glomerular Filtration

A

push plasma out of glomerular to capsule
glomerular membrane is considerably more permeable than capillaries elsewhere
glomerular capillary wall consists of a single layer of flattened endothelial cells

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56
Q

major force for glomerular filtration

A

glomerular capillary BLOOD PRESSURE

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57
Q

to be filtered, must pass through

A

pore between endothelial cells of the glomerular capillary (100x more permeable to H2O and solutes than regular capillaries)

acellular basement membrane (collagen for structural strength, negatively charged glycoproteins to repel proteins

filtration slits between the foot processes of the podocytes in the inner layer of the Bowman’s capsule

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58
Q

what if there is no pressure or filtrate?

A

suffer in pH, toxins stay in, kidney failure
As long as there is pressure in the capillaries, some plasma will get filtered out

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59
Q

glomerular capillary blood pressure

A

favors filtration; typically 55 mm Hg; CAN VARY

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60
Q

plasma-colloid osmotic pressure

A

caused by unequal distribution of protein between plasma and glomerular filtrate (no protein)
CONSTANT
opposes filtration
water wants to move down osmotic gradient INTO GLOM

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61
Q

Bowman’s capsule hydrostatic pressure

A

fluid pressure by the filtrate in Bowman’s capsule
Opposes filtration from GLOM to bowmans capsule
CONSTANT

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62
Q

Glomerular filtration rate (GFR); actual rate of filtrate depends on

A

net filtration pressure (major)
glomerular surface areas available for penetration (minor)
permeability of the glomerular membrane (minor)

controlled by glom capillary blood pressure

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63
Q

autoregulation

A

MYOGENIC, local response within arteriolar smooth muscle wall
tubuloglomerular feedback in response to salt concentration
vasoconstriction (decrease blood flow to GLOM) = reduce filtration
vasodilation (increases blood flow into GLOM)

REFERS TO THE COMBINED EFFECTS OF THE MYOGENIC RESPONSE AND TUBULOGLOMERULAR FEEDBACK

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64
Q

extrinsic sympathetic control

A
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65
Q

macula densa cells

A

detect and release paracrine factors that constrict the adjacent afferent arteriole in tubuloglomerular feedback

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66
Q

How would changes in blood pressure affect GFR ?

A

Increase blood pressure during exercise would increase GFR and lead to unnecessary loss of water and salts to urine
tubuloglomerular feedback prevents this

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67
Q

reabsorption allows

A

to reduce the ultimate filtrate amount to 0.5-1.5 liters

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68
Q

tubular reabsorption

A

selective movement of filtered substances from the TUBULAR LUMEN into the PERITUBULAR CAPILLARIES (e.g. H2O, Na+, Cl-)

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69
Q

tubular epithelium

A

entire length; tubule is ONE cell-layer thick
tubular epithelial cells have a luminal membrane and a basolateral membrane

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70
Q

adjacent tubular epithelial cells

A

form tight junctions (barrier; cant pass)

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71
Q

properties of capillary endothelium

A

through length; capillary is one very thin cell-layer thick
NO tight junction between endothelial cells (little barrier for water and solutes)

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72
Q

transepithelial transport requires substance cross 5 barriers

A
  1. luminal membrane of the tubular cell
  2. cytosol of tubular cell
  3. basolateral membrane of the tubular cell
  4. interstitial fluid
  5. capillary wall
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73
Q

two types of tubular reabsorption

A
  1. Passive reabsorption: movement down an osmotic or electrochemical gradient (e.g H2O)
    H2O absorbed back bc it follows absorpotion of Na+
  2. Active: requires energy (ATP), includes Na+, glucose, amino acids, other electrolytes
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74
Q

how much Na+ is reabsobred in proximal tubule

A

67%
2/3 reabsorbed before entering loop of henle

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75
Q

how much is reabsorbed in loop of henle

A

25%

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76
Q

how much is reabsorbed in distal and collecting tubules

A

8%

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77
Q

proximal tubule role in reabsorption

A

Na+ reabsorption plays a pivotal role in the reabsorption of glucose, amino acids, H2O, Cl-, and urea

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78
Q

loop of henle role in reabsorption

A

Na+ reabsorption plays a critical role in the kidney’s ability to produce urine of varying concentrations and volumes

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79
Q

distal tubule role in reabsorption

A

Na+ reabsorption is subject to hormonal control, important in the regulation of ECF volume

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80
Q

What does BILIRUBIN do?

A

If your urine is dark yellow, you are seeing secreted bilirubin
it gives urine its color
get it by taking hemoglobin and breaking it down

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81
Q

is Na+ reabsorption active or passive

A

really only one step in the 5 step process that requires ATP and therefore is ACTIVE
Transported by Na/K ATPase across the basolateral membrane
every other step is DIFFUSION

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82
Q

why does Na+ diffuse into pertitubular capillary

A

bc interstitial concentration of Na+ is high

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82
Q

why does Na+ diffuse into TUBULAR CELL

A

bc intracellular concentration of Na+ is low (ATPase)

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83
Q

why does reabsorption take place all the time

A

there is a CONSTANT number of sodium channels in the luminal membrane and Na/K ATPase pumps

proximal tubule and loop of Henle, a constant percentage of filtered Na+ is reabsorbed regardless of the amount of Na+ in the body fluids

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84
Q

extent of reabsorption in relation to the na+ in the body reabsorption is related to the magnitude of the Na+ load in the body

A

reabsorption is inversely related to the magnitude of the Na+ load in the body

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85
Q

aldosterone (hormone)

A

stimulates Na+ reabsorption

determine faith of final 8% Na+ of filtrate at end of loop of henle

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86
Q

atrial natriuretic peptide

A

inhibits Na+ reabsorption

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87
Q

what happens with water as Na+ is reabsorbed

A

As Na⁺ is reabsorbed, it creates an osmotic gradient because the reabsorption of solute (Na⁺) decreases the concentration of solutes in the tubular fluid
Following the reabsorption of Na⁺, water passively follows sodium due to this osmotic gradient. This occurs primarily through aquaporins (water channels) in the tubular epithelial cells

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88
Q

Na+ reabsorption is followed by passive reabsorption

A

h2o down osmotic grad
Cl- down its electrochemical gradient
urea (waste product of protein breakdown); diffusion is not very effective

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89
Q

Aldosterone increases Na+ reabsorption in the distal and collecting tubules by

A

inserting additional Na+ leak channels in the luminal membrane
inserting additional Na/K ATPase in the basolateral membrane
BASICALLY increase the capacity of Na/K pumping & Na leaking in tubular cells
release controlled by RAAS system

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89
Q

aquaporins

A

proximal tubules express AQP1 (ALWAYS OPEN)
distal and collecting tubules express AQP2 (regulated by VASOPRESSIN)

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90
Q

aldosterone and RAAs; low BP

A

want to retain H2O: by retaining Na+ you also retain H2O;
preserve volume and NOT make more urine

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91
Q

angiotensinogen

A

synthesized in liver, always present in plasma
When blood pressure drops or when there is a decrease in blood volume (such as during dehydration), the kidneys release an enzyme called renin.
Renin converts angiotensinogen into angiotensin I, which is an inactive form

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92
Q

renin

A

released from kidneys (granular cells) into plasma
activates/converts angiotensinogen (precursor) into angiotensin I (active hormone)
(BP drops)

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93
Q

Angiotensin-converting enzyme (ACE)

A

enzyme present in the lungs; converts angiotensin I into angiotensin II

94
Q

angiotensin II

A

has many effects (stimulates vasopressin, thirst, arteriolar vasoconstriction)
also stimulates the adrenal cortex to release aldosterone
travels to kidney ——- drives insertion of additional Na+ channels and ATPase ——-cause reabsorption
general constriction of arterioles in body helps to maintain BP (vasoconstriction)

95
Q

when is RAAS shut down

A

Shut down RAAS system once goal is reached; restored to normal levels

96
Q

treatments for hypertension

A

diuretics
counteracts vasopressin and prevents from reabsorbing all the water (you pee more)

ACE inhibitors
prevents kidneys from responding as effectively to RAAS = wont reabsorb as much H2O as kidneys otherwise do
pee out
counteract hypertension

97
Q

natriuretic peptides

A

atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)

inhibit Na+ reabsorption

98
Q

when are natriuretic peptides released

A

in response to high blood pressure/volume/NaCl load

99
Q

what do ANP/BNP inhibit

A

Na+ reabsorption
RAAS activity
smooth muscle of afferent arterioles —– increased GFR
inhibit sympathetic NS to reduce cardiac output and peripheral resistance
REDUCE BP!!!!!

100
Q

when do we use BNP/ANP

A

response to High BP

101
Q

reabsorption of glucose and amino acids

A

reabsorbed in PROXIMAL tubules by Na+ dependent specific symport carriers across tubular membrane into the cell (=secondary active transport)

102
Q

secondary active transport

A

ex. SGLT- influx of Na⁺ into the cell, driven by its concentration gradient (established by the Na⁺/K⁺ pump), is coupled with the transport of glucose into the cell against its concentration gradient

103
Q

glucose reabsorption

A

efficient and complete, number of sodium-glucose symporters is finite—- tubular maximum
excess glucose lost in urine

104
Q

Hydrogen ion secretion is important in acid-base balance…

A

tubular secretion of H+ happens mostly in distal tubules (key way by which kidneys help control pH)

renal H+ is secreted in the proximal tubules

renal H+ can be either secreted or reabsorbed by special “intercalated cells’ in the distal and collection tubules depending on the acid balance in the plasma (final pH determined by if the distal tubules secrete more protons)

105
Q

which way does K+ move

A

in opposite directions along tubules

106
Q

where is most of the K+ reabsorbed

A

in the PROXIMAL tubules via leak channels in the basolateral membrane, tubular reabsorption

107
Q

if there is K+ in the urine; what does that mean

A

tubular secretion at distal tubules
(have leak channels)

108
Q

what does high plasma K+ stimulate

A

directly stimulates aldosterone from the adrenal cortex

109
Q

vertical osmotic gradient

A

increasing osmolarity of the interstitial fluid in the renal medulla as you move from the outer region toward the inner region. This gradient is crucial for the kidney’s ability to concentrate urine and regulate water balance.

The interaction between the descending and ascending limbs of the loop of Henle enhances the gradient

109
Q

aldosterone and K+

A

aldosterone stimulates the insertion of K+ leak channels in the luminal membrane of the distal and collecting tubules
almost all the K+ in urine is the result of secretion
promote excretion

110
Q

is 1200 mOsm/liter hyper or hypotonic

A

severely hypertonic; too little H2O relative to solute

111
Q

descending limb

A

Permeability: Highly permeable to water
Function: Water is reabsorbed into the interstitium due to the osmotic gradient
Transport Mechanisms: Primarily passive transport; water exits through aquaporin channels.

112
Q

ascending limb

A

permeability: Impermeable to water but permeable to sodium, potassium, and chloride
Function: Actively reabsorbs sodium, potassium, and chloride from the tubular fluid into the interstitium, which dilutes the tubular fluid as it ascends

113
Q

why is osmotic gradient essential for vasopressin

A

osmotic gradient is essential for the reabsorption of water in the collecting ducts; the insertion of AQP2

114
Q

net effect of countercurrent multiplication

A

ability to concentrate urine

115
Q

When the body needs to conserve water…

A

vasopressin enhances the permeability of the collecting ducts to water, allowing more water to be reabsorbed into the bloodstream, resulting in concentrated urine

116
Q

2 purposes of countercurrent multiplication

A

produces hypotonic urine that can be excreted if ECF within the body has too much H2O

est. vertical osmotic gradient (in interstitial fluid) that can be used by collecting ducts to concentrate urine if the ECF within the body doesnt have enough H2O

117
Q

where does vasopressin have an impact

A

vasopressin controls H2O reabsorption in the COLLECTING TUBULES

118
Q

water excess; no vasopressin

A

hypotonic urine; large volume of dilute urine

distal and collecting tubules are IMPERMEABLE to H2O

119
Q

in water deficit; vasopressin

A

leads to insertion of AQP2 in luminal membrane
water leaves the tube and goes to medulla; get very concentrated

distal and collecting tubules are PERMEABLE to H2O

120
Q

how does excess alcohol consumption interfere with kidney function

A

dehydrated… vasopressin release is impaired; more filtrate so urinate a lot

121
Q

vasa recta

A

hairpin loop of the vasa recta by passive countercurrent exchange preserves the vertical osmotic gradient while supplying blood to medulla

122
Q

relative amounts of sodium and water reabsorption in proximal tubule

A

equal amounts of each

123
Q

relative amounts of sodium and water reabsorption in loop of henle

A

more Na+ than water

124
Q

relative amounts of sodium and water reabsorption in distal and collecting tubules

A

more water than Na+

125
Q

micturation (urination)

A

process of emptying the bladder

126
Q

urine is transported…

A

from kidneys to the bladder via the ureters

127
Q

what propels the urine to the bladder

A

peristaltic contractions of smooth muscle within the uretal wall

128
Q

what prevents back flow of urine

A

as bladder fills pressure against the ureters prevents

129
Q

bladder smooth muscle

A

rich innervated by parasympathetic fibers
stimulation of the parasympathetic fibers causes bladder contraction

130
Q

what prevents the bladder from emptying continuously

A

internal and external sphincter

131
Q

which sphincter is under voluntary control

A

external urethral sphincter

132
Q

internal urethral sphincter

A

composed of SMOOTH muscle and NOT under voluntary control
when bladder is relaxed, CLOSES OUTLET of bladder

133
Q

external urethral sphincter

A

composed of SKELETAL muscle and under VOLUNTARY control
motor neurons continuosly firing unless they are inhibited

134
Q

micturation reflex (spinal cord reflex)

A

initiated when stretch receptors in bladder wall stimulate the parasympathetic supply to the bladder and inhibit the bladder motor neurons
prevented by tightening external sphincter,

135
Q

Three principal components that make up the circulatory system

A

the heart (the pump)
• the blood vessels (the pipes)
• the blood (the fluid to be moved)

136
Q

What is the circulatory system impacted by

A

The endocrine system, nervous system, and kidneys

137
Q

Overall function of the circulatory system

A

Move blood around the body!

Supply oxygen and nutrients
Remove “wastes”
Temperature regulation
Distribute hormones
Clotting of open wounds
Immuno-vigilance

138
Q

Components of blood

A

Cells, cell fragments, and plasma (55%)

Erythrocytes (45%); leukocytes and platelets; plasma (55%)

139
Q

Plasma

A

at least 90% water and carries electrolytes and nutrients (glucose, amino acids, vitamins)
as well as wastes (urea, creatinine, bilirubin)
gases (O2 and CO2)
hormones
proteins produced by the liver such as albumin and fibrinogen.

140
Q

Erythrocytes (red blood cells)

A

Function in oxygen and carbon dioxide transport. Biconcave disk in shape with a flexible membrane. They have a large surface area which favors diffusion.
NO NUCLEUS/ORGANELLES
Limited lifetime; no division of mature RBC

141
Q

RBC enzymes

A

– Glycolytic enzymes
– Carbonic anhydrase

142
Q

Hemoglobin

A

Binds oxygen and carbon dioxide

143
Q

RBC life span

A

~ 120 days

144
Q

Synthesis of RBC

A

Synthesized in red bone marrow by the process called erythropoiesis

145
Q

What filters the RBC

A

Filtered by spleen and liver

146
Q

What triggers differentiation of stem cells to erythrocytes

A

Erythropoietin (hormone from the kidneys)

147
Q

Loops in cardiovascular system

A

2: systemic and pulmonary

148
Q

Pulmonary loop

A

carries oxygen- poor blood to the lungs and back to the heart.

149
Q

Systemic loop

A

carries blood from the heart to the rest of the body.

150
Q

Is the circulatory system closed or open

A

Closed system!

LEAKS WOULD BE BAD

151
Q

4 chambers

A

Left and right atria
Left and right ventricles

152
Q

Where do the chambers on the right pump to

A

Pump deoxygenated blood through the pulmonary circulation to the lungs

153
Q

Where do the chambers on the left pump oxygen-rich blood through

A

Systemic circulation to the body tissues
downnn

154
Q

Power of left ventricle

A

Most powerful pumping chamber of heart
Pumps throughout the entire body

155
Q

Right AV flows to

A

Right ventricle

156
Q

Right ventricle flows to

A

Pulmonary artery

157
Q

Left AV flows to

A

Left ventricle

158
Q

Left ventricle flows to

A

Aorta

159
Q

What do heart valves ensure

A

Ensure a one-way flow of blood

160
Q

Right AV valve

A

Tricuspid
Experience lower pressures

Flows “up” (lungs)

161
Q

Left AV valve

A

Bicuspid
Lower pressures
Up into aortic

162
Q

Aortic or pulmonary valve

A

Semilunar
Experience highest pressures
Aortic (down to body)
Pulmonary (pulmones!! Up)

163
Q

When will a valve open

A

When pressure is greater behind the valve

164
Q

When will valve close

A

When pressure is greater IN FRONT of the valve

165
Q

Endocardium

A

thin layer of endothelial tissue lining the interior of each chamber. It is continuous with the lining of the blood vessels entering and leaving the heart.

166
Q

Myocardium

A

Middle layer of the heart wall, composed of cardiac muscle

167
Q

Cardiac muscle cells connected end-to-end by

A

intercalated disks where two types of contacts are formed: desmosomes and gap-junctions

168
Q

Desmosomes

A

Mechanically hold the cells together

169
Q

Gap junctions

A

provide paths of low resistance to the flow of electrical current between muscle cells

enable the cardiac muscle to form a functional syncytium.

170
Q

Epicardium

A

is a thin external membrane covering the heart and is filled with a small volume of pericardial fluid.

171
Q

Cardiac cells

A

99% of cells are FORCE PRODUCING CELLS
• Called myocytes or contractile cells
• Contain striated muscle
• Muscle contraction follows a myosin/actin interaction.

1% of cells are the CONDUCTION SYSTEM
• Called pacemaker cells
• Do not have contractile components

172
Q

Pacemaker cells set

A

Rhythm of heart

Communicate to contractile cells that through the syncytium they are all electrically coupled together

173
Q

Autorhythmic

A

Heart muscle is capable of generating its own rhythmic electrical activity

174
Q

Pacemaker cells grouped together

A

specialized regions called nodes that together control the rate and coordination of cardiac contractions

175
Q

Do pacemakers initiate their own action potentials

A

Pacemaker cells intrinsically initiate their own action potentials at a regular frequency.

This process is referred to as pacemaker activity and is controlled by the generation of pacemaker potentials

176
Q

Pacemaker potential (in 1% of heart cells that do; pacemaker cells)

A

Oscillation of the membrane potential which causes the cell to reach threshold and generate an action potential at a regular interval

It involves changes in K+, Na+ and Ca2+.

177
Q

Do pacemaker potentials use different channels

A

There are 4 phases by 4 different channels

VG F-type Na Channel (F: funny)
• VG-T type Calcium Channel (T: transient)
• VG-L type Calcium Channel (aka DHP channel) (L: long-lasting)
• VG-Potassium Channels (several types)

178
Q

What does hyperpolarization in pacemaker potentials lead to

A

Transient increase in Na+ permeability (Na funny channels) which causes membrane potential to depolarize

179
Q

What does the membrane potential depolarization cause (pacemaker potential)

A

depolarization causes an increase in permeability to Ca++ (T-channel) that leads to further depolarization of the membrane potential and causes the cell to reach threshold.

180
Q

What happens when a second increase in permeability to Ca2+ occurs

A

cell generates an action potential when a second increase in permeability to Ca++ occurs (L- channel).

Note: spike itself does not involve voltage-gated Na+ channels.

181
Q

What happens as a result of depolarization from the action potential

A

causes an increase in K+ permeability
(K channels) and the membrane potential repolarizes.

182
Q

What happens once the cell repolarizes

A

cell repolarizes, the K+ permeability again decreases and the process starts over again.

183
Q

Sinoatrial (SA) node

A

Bundle of specialized cardiac pacemaker cells located in the wall of the right atrium near the opening of the superior vena cava.

exhibits an autorhythmicity of 70 action potentials per minute and leads the activity of the other pacemaker structures in the heart.

184
Q

Atrioventricular (AV) node

A

Bundle of specialized, cardiac pacemaker cells located at the base of the right atrium

exhibits an autorhythmicity of 50 action potentials per minute.

Under normal conditions, this node follows the faster SA node at 70 A.P./min.

185
Q

Bundle of His

A

A tract of specialized, cardiac pacemaker cells that originates at the AV node and divides and projects into the left and right ventricles.

186
Q

Purkinje fibers

A

Small terminal fibers of specialized, cardiac pacemaker cells that extend from the Bundle of His and spread throughout the ventricular myocardium.

Very fast conduction velocity.

exhibits an autorhythmicity of 30 action potentials per minute.

Under normal conditions, they follow the faster AV node which is following the faster AV node at 70 A.P./min.

187
Q

Interatrial pathway

A

pathway of specialized, cardiac cells that conducts pacemaker activity from the right atrium to the left atrium.

Fast conduction velocity.

188
Q

Intermodal pathway

A

a pathway of specialized, cardiac cells that conducts pacemaker activity from the SA node to the AV node

189
Q

AV Nodal Delay

A

Pacemaker activity is conducted relatively slowly through the AV node resulting in a delay of approximately 100 ms.

ensures that the ventricles contract after atrial contraction. Make sure ventricles are full and topped off

190
Q

Resting potential of cardiac action potential

A

Very negative : -90mV

191
Q

What causes the rising phase of the AP in cardiac AP

A

Fast Na+ influx; VG Na Channel

192
Q

Does the cardiac AP have a plateau phase

A

exhibits a plateau phase.
The plateau is due to an increase in membrane permeability to Ca2+ (L channel) and a decrease in membrane permeability to K+ (VG K channel).

193
Q

When does the falling phase of the cardiac AP occur

A

falling phase occurs when there is decrease in Ca2+ permeability and a rise in K+ permeability (VG K channel)

194
Q

Heart muscle contraction vs voluntary muscle

A

Longer action potentials
Plateau period
Does not require nerve stimulation (usually stimulated by either an autorhythmic cell or an adjacent myocyte)
Calcium enters through L-type calcium channels, which ‘triggers’ more calcium to be released from the SR.
Contraction occurs DURING the action potential!

195
Q

Refractory period of the heart

A

long twitch and the prolonged refractory period (that prevents tetanus) allow time for ventricles to fill with blood prior to pumping.

196
Q

Excitation contraction coupling in cardiac muscle

A
197
Q

Electrocardiogram

A

electrical currents generated by the coordinated action potentials of the heart muscle can reach the surface of the body and be detected as voltage differences between two points on the body surface.
The reading is a composite of the electrical activity, not a single action potential.

record resulting from measuring these voltage changes is referred to as the electrocardiogram or ECG. Disturbances in heart function can be detected as changes in the ECG.

198
Q

Electrocardiogram

A

electrical currents generated by the coordinated action potentials of the heart muscle can reach the surface of the body and be detected as voltage differences between two points on the body surface.
The reading is a composite of the electrical activity, not a single action potential.

record resulting from measuring these voltage changes is referred to as the electrocardiogram or ECG. Disturbances in heart function can be detected as changes in the ECG.

199
Q

P wave

A

component of the ECG represents depolarization of the atria.
Begin of next heartbeat

200
Q

QRS complex

A

represents depolarization of the ventricles.

Sharp spike

201
Q

T wave

A

repolarization of the ventricles.

Bigger hump

202
Q

Atrial excitation

A

Begin w SA node
Complete w AV node
Top off ventricles

203
Q

Ventricular excitation

A

Begin w atrial relaxation
Complete with contraction of ventricles

204
Q

End of sequence of EKG

A

Ventricular relaxation

205
Q

Tachycardia

A

Fast heartbeat
Lots of QRS spikes

206
Q

Cardiac cycle

A

all the events involved with blood flow through the heart during one heart beat.

207
Q

Systole

A

Ventricular contraction phase
- pressures start to rise; force semilunar valves open (blood can leave)
Volume: ventricle topped off; squeeze blood out and volume decrease

208
Q

Diastole

A

Ventricular RELAXATION PHASE

pressure falls bellow and valve snaps shut (no more pressure holding valves open)
Refill ventricular
Atria contracts and tops off to restart cycle

209
Q

Cardiac output

A

= heart rate x stroke volume.

210
Q

Heart rate is regulated by

A

both branches of the autonomic nervous system

211
Q

stroke volume is regulated extrinsically

A

by the sympathetic nervous system and intrinsically by the volume of venous return (Frank-Starling mechanism)

212
Q

The mechanisms (neurotransmitter, receptors, downstream effects on ion channels and
slop of AP) by which sympathetic and parasympathetic input speed and slow heart rate,
respectively.

A
213
Q

The influence of the sympathetic branch on ventricle contractility and stroke volume.

A
214
Q

The Frank-Starling mechanism

A

the greater the volume of blood filling the heart (preload), the stronger the heart’s contraction will be. This allows the heart to efficiently adjust its output to match the volume of blood returning to it, ensuring balanced circulation.

215
Q

aorta

A

largest artery in the body, responsible for carrying oxygen-rich blood from the heart to the rest of the body. It originates from the left ventricle and arches upward before descending

there ONE
2nd biggest internal radius

216
Q

arteries

A

blood vessels that carry oxygen-rich blood away from the heart to the body’s tissues and organs. They have thick, elastic walls to withstand high pressure as blood is pumped from the heart, and they branch into smaller arterioles

100s
.2 cm internal radius

217
Q

arterioles

A

small blood vessels that branch from arteries and lead to capillaries. They play a crucial role in regulating blood flow and pressure by constricting or dilating in response to various signals, helping to control the distribution of blood to different tissues in the body.

1/2 million
very very small internal radius .003

218
Q

capillaries

A

smallest blood vessels in the body, connecting arterioles to venules. They facilitate the exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues due to their thin walls and large surface area.

10 billion
EXTREMELY small internal radius .00035
largest cross sectional area

219
Q

inferior vena cava

A

large vein that carries deoxygenated blood from the lower half of the body back to the heart
1 of 2
biggest in internal radius

220
Q

superior vena cava

A

connects to right atrium
1 of 2
biggest internal radius

221
Q

Flow =

A

pressure gradient / resistance. While resistance is determined by several factors, the
main regulation is vessel radius. R is proportional to 1/r4 and therefore flow is proportional
to r4 . Thus, small changes in vessel radius can lead to large changes in local flow rate

222
Q

(smooth) muscular arteries constrict or dilate to change

A

relative blood flow to different
organs in a task-specific manner.

223
Q

Elastic arteries serve as pressure reservoirs to ensure

A

continuous blood flow

224
Q

sphygmomanometer

A

used to measure blood pressure

225
Q

intrinsic control of arteriole constriction/dilation

A

LOCAL
example
Myogenic Response: Arterioles can constrict or dilate in response to changes in internal blood pressure. An increase in pressure causes the smooth muscle in the vessel walls to stretch, leading to contraction, while a decrease in pressure results in relaxation.

226
Q

extrinsic control of arteriole constriction/dilation

A

mediated by the autonomic nervous system and hormones

Activation of the sympathetic nervous system leads to the release of norepinephrine, which typically causes vasoconstriction of arterioles, increasing blood pressure

Hormones such as epinephrine (adrenaline) can cause vasodilation in certain vascular beds while promoting vasoconstriction in others, depending on the type of adrenergic receptors present

227
Q

capillaries

A

extremely small blood vessels that serve to exchange materials between blood and tissues

SINGLE LAYER of endothelial cells

connections between endothelial cells form small water filled pores
LOOK SLIDES

228
Q

plasma carries

A

electrolytes, nutrients, wastes, gases and hormones for delivery to and from virtually all
cells in the body

229
Q

conduction through AV node

A

100ms delay ensures
that the ventricles contract only after the atria do

otherwise VERY FAST EVERYWHERE ELSE

230
Q

long twitch and prolonged refractory period of contractile cells

A

allow time for ventricles
to fill with blood prior to pumping

231
Q

read an ECG

A
232
Q

Note: these are bulk current source recordings, not intracellular
recordings, and therefore you cannot interpret upward and downward deflections as
depolarization and hyperpolarization

A
233
Q

cardiac cycle

A
234
Q

sounds/murmurs

A

pg 45

NPB101 (7 decks)

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