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ISCM > PHYSIOLOGY > Flashcards

PHYSIOLOGY Flashcards

1
Q

what are the three types of muscle

A

skeletal
cardiac
smooth

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2
Q

what is the function of each type

A

skeletal-attached to the bone, supports and moves the skeleton

cardiac-muscle of the heart, propels blood through the circulatory system

smooth-surrounds hollow organs of the body, controls the movement of contents through the organ

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3
Q

breakdown of the muscle structure

A

muscle ( epimysium )

fascicle (perimysium)

muscle fibre (plasma membrane -sarcolemma )

myofibril (sacromere)

myofilament (actin and myosin )

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4
Q

what are the two types of fibres

A

long fibre- large movements, high velocity eg hamstrings

short fibre- short movement, high force eg quadriceps

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5
Q

what is a motor unit

A

a single motor neurone and the muscle fibre it innervates

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6
Q

which chemical is used in contraction

A

ATP

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7
Q

what are three systems of generating ATP

A 
ATP phosphocreatine (PCr)
oxidative system (aerobic)
glycolytic system (anaerobic )
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8
Q

explain the need for ATP PCr system

A

ATP direct energy needs 2 seconds to exhaustion

PCr restores ATP level to 3-15 seconds to exhaustion ( as in it will be finished in about 15s)

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9
Q

explain the need for the glycolytic and oxidative system

A

they use aerobic and anaerobic methods to generate more ATP

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10
Q

what are the three types of muscle fibres

A

type I - slow twitch/oxidative
type IIa - fast twitch/oxidative
type IIb - fast twitch/glycolytic

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11
Q

are all muscle fibres of one motor unit the same type

A

yes

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12
Q

how to differentiate between the muscle fibre types

A

type I- dark
type IIa - lighter
type IIb - translucent

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13
Q

how to differentiate between muscle fibre types

A

type II stains metachromatic and type I stains dark blue

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14
Q

what is the function of a satellite cell

A

it is attached to the mature muscle fibre and it repairs it if its damaged

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15
Q

what are the functions of two regulatory proteins

A

tropomyosin-bocks myosin binding site

troponin-binds calcium

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16
Q

explain excitation contraction coupling

A

action potential in nerve-release of neurotransmitter at N/M junction-action potential in muscle-AP transferre to T tubule- SR releases calcium-muscle contracts

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17
Q

what holds the myosin and actin filaments together

A

titin filament

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18
Q

what is the function of nebulin

A

provides rigidity and ensures the actin filaments stay in place

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19
Q

what are the layers of cardiac muscle called

A

myocardium

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20
Q

what is the function of the sympatheitic system

A

releases noradrenaline

increases heart rate and force of contraction

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21
Q

what is the function of parasympathetic system

A

vagus nerve
releases acetylcholine
dominant effect at rest
depresses heart rate and force #

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22
Q

whats th structure of a cardiac muscle

A
  • striated muscle
  • uninucleate
  • cells act as a syncytium - connected in series with intercalated discs, which are gap juctions and desosomes
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23
Q

how does excitation-contraction coupling work

A

initial depolarisation in sinoatrial node- action potentialin muscle-AP transmitted to T tubule-calcium influx from extracellular space-SR releases calcium CICR(calcium induced calcium release)- muscle contracts

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24
Q

how to ensure that the cardiac muscles relax

A

an extended refractory period by the calcium VGC slowly opening which keeps the membrane depolarised for longer

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25
Q

what is the structure of smooth muscle cells

A

long spindle shaped cells
uninucleate
no neuromuscular junctions-it has nerve branches with small swellings called varicositites
it has no sarcomere

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26
Q

what are the functions of myosin filaments

A

site of ATPase activity but very slow rate
low energy consumption so very fatigue resistant
allows muscle tone eg bladder

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27
Q

what are the functions of actin filaments

A

consists of actin molecules but longer

no troponin- function replaced by calmodulin in cytoplasm

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28
Q

what are the functions of calmodulin

A

involved in calcium binding

activates contraction

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29
Q

where does the actin bind insmooth muscle

A

to dense bodies

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30
Q

what is another word for transverse tubules in the smooth muscle

A

caveolae

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31
Q

what does smooth muscle respond to

A 
neurotransmitters 
hormones 
local chemical changes eg pH 
stretch 
spontaneous electrical activity
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32
Q

what are the two types of smooth muscle

A

multiunit- discreet cells, richly innervated by nerves, contract indpendently of neighbour

single unit/visceral - cells linked by gap junctions, respond to a variety of signals, many cells respond as a single unit, spontaneously active

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33
Q

what is the excitation contraction coupling

A

stimulus-muscle membrane depolarises-calcium influx from extracellular space CICR-calcium binds to calmodulin- ATPase activated- muscle contracts

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34
Q

what are the different charcaterisitics of smooth muscle

A 
very versatile
very fatigue resistant
low energy consumption
allows muscle tone 
contract over much greater lengths
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35
Q

what are the main functions of the skeletal system

A 
support-provides rigid structure 
protection of internal organs 
reservoir for calcium,, inorganic phosphate and other minerals 
storage of lipids (yellow marrow)
blood cell production (red marrow)
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36
Q

what is the end of bone/growth plate called

A

epiphysis

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37
Q

what is the bone shaft called

A

diaphysis

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38
Q

what is the yellow marrow called

A

medullary (triglyceride store)

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39
Q

what is the red marrow called

A

spongy/cancellous bone (blood cell production)

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40
Q

what is the membrane with osteoblasts and osteoclasts on inner layer called

A

periosteum/ endosteum

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41
Q

what is the lamellae

A

rings of hard calcified bone matrix

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42
Q

what is lacunae

A

spaces which hold osteocytes

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43
Q

what is osteon

A

circular column of concentric lamellae

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44
Q

what is Haversian canal

A

central space containing blood vessels and nerves

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45
Q

what is canaliculi

A

small channel with osteocyte processes

46
Q

what are osteoprogenitor cells

A
  • mesenchymal bone stem cells
  • produce osteoblasts
  • proliferative, involved in growth and repair
47
Q

what do osteoblasts do

A

secrete collagen to create a matrix (scaffold) which will become calcifies (osteogenesis )
-mature into osteocytes when surrounded by calcified matrix

48
Q

what are osteocytes

A
  • do not divide
  • help maintain protein and mineral content of the matrix
  • help repair damaged bone
49
Q

what are osteoclasts

A
  • giant multi nucleated cells
  • secrete acids and proteases to dissolve bone (osteolysis)
  • come from the same lineage as white blood cells
50
Q

where are osteoclasts, osteoblasts and osteoprogenitor cells found

A

osteoblasts- lacunae
osteoclasts -line medullary cavity
osteoprogenitor-on the inside of the periosteum

51
Q

what is bone composed of (organic matrix)

A
  • collagen matrix(osteoid), gives elasticity and resistance-95%
  • ground substance, extracellular fluid and proteoglycans chondroitin sulfate and hyaluronic acid
  • mineral deposited on matrix (calcification), contributes strength and resistance
52
Q

what is the formula for hydroxyapatite

A

calcium phosphate+calcium hydroxide

Ca3(PO4)2+Ca(OH)2 –>Ca10(PO4)6(OH)2

53
Q

what stops the hydroxyapatite from forming

A

inhibitors such as pyrophosphate

54
Q

what regulates pyrophosphateand how

A

alkaline phosphatase

  • breaks down pyrophosphates
  • collagen fibres then develop hydroxyapatite crystals for calcification
55
Q

where does alkaline phosphatase come from

A

released by osteoblasts

56
Q

what happens as a result o deficiency in alkaline phosphatase

A

soft bones

57
Q

how does calcium level disruption lead neuromuscular excitability (twitching)

A

binding to plasma proteins acting as ion channels

low levels- hypocalcaemic tetany (muscle spasms)

high levels- hypercalcaemia and cardiac arrhythmia (rapid changes)

58
Q

what is bone resorption

A

breakdown of bone which results in the release of calcium into the bloodstream

59
Q

which hormones are responsible for increasing and inhibiting bone resorption

A

Parathyroid hormone (PTH) increases and Calcitonin inhibits controlled by negative feedback

60
Q

where is parathyroid hormone released from

A

by parathyroid gland

61
Q

where is calcitonin released from

A

by prarfollicular cells in the thyroid gland

62
Q

give an example of the negative feedback cycle in calcium homeostasis

A

calcitonin released- osteoclast activity decreases- ca+ in the bone increases- plasma ca+ decreases- calcitonin release decreases-plasma ca+ increases

63
Q

where is bone marrow found in infants and adults

A

infants-medullary cavity and all areas of spongy bone

adults-in the diploe of flat bones and the head of the femur and humerus

64
Q

what happens to the amount of yellow marrow in the bone as we age

A

increases starting at the centre of the bone

65
Q

function of red marrow

A

supplies nutrients to the osteocytes

forms red and white blood cells

66
Q

function of yellow bone marrow

A

stores fat

may convert back to red marrow if there is severe bleeding

67
Q

what is ossification/osteogenesis

A

process of bone formation

68
Q

when do bones form

A
  • during development
  • during childhood growth
  • to remodel bone e.g. response to stress
  • repair
69
Q

what does the bone replace

A

cartilage and chondrocytes deposition create a model which is replaced

70
Q

what are dietary requirements for bone growth

A
  • minerals such as calcium, phosphorus, magnesium, fluoride
  • vitamins D(collagen), A(osteoblast activity and K
  • protein
71
Q

what factors affect growth

A
  • sex-males taller than females
  • sex hormones- end of puberty ceases growth
  • stress- cortisol inhibits growth and increases breakdown
  • nutrition
72
Q

how does structure of the bone change as we age

A

deposition of bone by osteoblasts from the outside ( periosteal layer)

resorption of bone by osteoclasts on the inside ( endosteal layer)

73
Q

what does physical stress and illness do to bone structure

A

physical stress increases deposition and illness decreases deposition

74
Q

how do osteocytes regulate bone remodeling and repair

A
  • support osteoclastogenesis
  • secrete growth factors to support bone formation
  • secrete sclerostin to inhibit bone formation
75
Q

what happen during the breakdown of bone

A

osteoclasts form grooves called resorption bays as they break down bone matrix

hydrogen ions and hydrolytic enzymes are released to dissolve the bone ( osteolysis)

the products of bone breakdown end up in the blood plasma thus increasing plasma calcium levels

76
Q

what affects bone density

A

exercise can increase bone density

77
Q

what are the different types of fractures

A

open-skin is broken
greenstick-more common in children
comminuted-fracture splintering/ crushing
impacted-fracture pushes bone into interior

78
Q

what are the phases of bone healing

A

reactive, reparative, callus formation, bone remodeling

79
Q

what happens in the reactive phase of bone healing

A
  • blood vessels crossing the line of the fracture are broken
  • a blood clot (fracture hematoma) rapidly forms around the fracture site
  • surrounding bone cells die due o lack of vascularisation
  • cell death and inflammation
  • clean up operation-immune system
80
Q

what happens in the reparative phase of bone healing

A
  • vasculogenesis of the hematoma-removal of dead cells by phagocytes
  • fibroblasts move into the fracture site and start to build new collagen fibre
  • cells from the periosteum develop into chondroblasts and produce fibrocatilaginous callus
  • the ends of the bone are being to stabilize usually takes 3 weeks
81
Q

what happens during callus formation

A
  • osteoprogenitor cells from the periosteum develop into osteoblasts and produce spongy bone trabeculae
  • trabaculae join up living and dead bone fragments
  • fibrocartilage is converted to spongy bone, the callus is now a bony callus
  • the bony callus lasts 3-4 months
82
Q

what happens during bone remodeling

A
  • osteoclasts resorb dead bone
  • spongy bone is replaced by compact bone
  • a thickened area may remain on the surface of the bone
83
Q

what is the approximate blood pressure in the pulmonary circuit

A

28/8 mmHg

84
Q

what is the approximate blood pressure in the systemic circuit

A

120/80 mmHg

85
Q

what is heart failure

A

the pathological state in which the heart is unable to pump blood at a rate required by metabolizing tissues or can do so only with an elevated filling pressure

86
Q

what is the relaxation of the atria and ventricles called

A

diastole

87
Q

what is the contraction of the atria and ventricles called

A

systole

88
Q

which node initiates the electrical signal

A

the SA node ( sinoatrial)

89
Q

what is atriole systole and what wave is it

A

when the atria contract and blood fills the ventricles and this is the P wave

90
Q

what is the first part ventricular systole and what part of the wave is it

A

when the ventricles contract and the AV valves close called the QRS complex

91
Q

what is the second part of systole and what part of the wave is it

A

semilunar valves open and blood is ejected this is the T wave

92
Q

what is the first part of ventricular diastole

A

the semilunar valves close and blood flows into the atria

93
Q

what is the second part of ventricular diastole

A

chambers relax and the blood refills the ventricles passively

94
Q

what is the function of desmosomes

A

hold the muscle cells together tightly

95
Q

what is the function of the intercalated disks

A

link muscle cells together and contain the desmosomes and gap junctions

96
Q

what is the function of gap junctions

A

allow passage of action potentials from one cell to the next very quickly

97
Q

what is a feature of myocardial cells

A

can simultaneously depolarize and this means an electric current can be automatically produced so the SAN cells dont need neighbor cells to depolarize first

98
Q

what is the importance of fibrous tissue between the atria and ventricles

A

it lacks gap junctions and electrically isolates atria from ventricles and so provides a border

99
Q

what is the transmembrane potential, TMP

A

the electrical potential difference between the inside and outside of a cell

100
Q

what is the difference between chemical and electrical potential

A

chemical is ions moving down its concentration gradient and electrical is ions moving away from ions/molecules of like charge

101
Q

what are cardiomyoctes

A

the cells responsible for generating contractile force in the intact heart.

102
Q

what are the properties of cardiac ion channels

A

selectivity- only permeable to a single type of ion based on their physical configuration

voltage-sensitive gating- dependent on a specific TMP range

time dependance- some are configured to close either slower or faster than others

103
Q

what is the pacemaker potential

A

when the cells of the SAN depolarize over time with the movement of ions causing the resting membrane potential to decrease

104
Q

what happens once the membrane potential exceeds the threshold and after how many seconds does this happen appproximately

A

an action potential is generated and this happens automatically every 0.8s

105
Q

why does AVN depolarize more slowly than the SAN and how slowly approximately

A

because this allows for a very short delay so that the blood can fill the ventricles before they contract usually about 0.09s

106
Q

what is excitation contraction coupling

A

the process by which an electrical action potential leads to contraction of cardiac muscle cells.

107
Q

how is excitation contraction coupling achieved

A

converting a chemical signal into mechanical energy via contractile proteins

108
Q

what mediator is important in convert the electrical excitation into physical contraction

A

calcium by cycling in and out of the monocytes cystol during an action potential

109
Q

what causes the pacemaker potential/ plateu in cardiac potential

A

funny channels in the SAN open and sodium ions enters which causes depolarization which opens gated calcium channels and they enter the membrane slowly and so it gradually depolarizes another type of voltage gated channel opens and calcium enters the cell rapidly and this leads to rapid depolarization which is the cardiac action potential

110
Q

what is an example of transient channel and at what potential does it open

A

T type Ca++ open briefly at -50mV

111
Q

what is an example of a long lasting channel and at what potential does it open

A

ca++ open at -40mv full depolarization

ISCM (19 decks)

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