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Physiology > QCM Type > Flashcards

QCM Type Flashcards

1
Q

What defines a eukaryotic cell ?

A

All cells which contain a nucleus are eukaryotic cells.

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2
Q

All eukaryotic cells have…..

A

a nucleus, genetic material, plasma membrane, ribosomes, cytoplasm and cytoskeleton.

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3
Q

What is the function of the nucleus ?

A

stores and protects DNA, holds nucleic acids and proteins and comunicates with the rest of the cell.
stores information for cell growth, cell reproduction and function.

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4
Q

What is the plasma membrane and what is its function ?

A

The plasma membrane seperates the outside of the cell from the inside of the cell.

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5
Q

What are ribosomes responsible for ?

A

Ribosomes are responsible for protein sythesis.

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6
Q

Where are mitochondria found and what is its function ?

A

Mitochondria are found within most of eukaryotic cells and they are responsible for producing energy (ATP).

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7
Q

What is the cytoplasm ?

A

The cytoplasm is a gel-like fluid inside the cell and all cellular components and organelles are suspended within this structure.

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8
Q

What function does the smooth endoplasmic reticulum have ?

A

It is involved in synthesis of lipids and steroids.

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9
Q

Lipids are combined with phosphorus in the smooth endoplasmic reticulum to produce what ?

A

Phospholipids.

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10
Q

What function does the rough endoplasmic reticulum have ?

A

It is involved in the synthesis of proteins.

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11
Q

Where is the golgi apparatus found and what is its function ?

A

It is found in most eukaryotic cells and it packs proteins, lipids and steroids into vesicles.

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12
Q

The golgi apparatus pack lipids and steroids into vesicles and sends them where in the cell and why ?

A

Lipids and steroids are sent to the end of the cell where they are used to build or repair the cell and organelle membranes.

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13
Q

What function does the flagella have and is it found in all eukaryotic cells ?

A

No it is not found in all eukaryotic cells. Its function is to move the cell around.

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14
Q

“act as short hairs moving back and forth across the outside of the cell. It moves matters past the cell” what organelle is this

A

Cilia

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15
Q

Most eukaryotic cells have….

A

Mitochondria, flagella, golgi apparatus, celia, endoplasmic reticulum and lysosomes.

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16
Q

“gel-like fluid inside the cell. All cellular components and organelles are suspended within this fluid” what substance is this ?

A

cytoplasm.

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17
Q

“separates the outside of the cell from the inside of the cell. It controlles what gets in and out of the cell and send and receives chemical signals from other cells” what component is this ?

A

plasma membrane

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18
Q

How much of the total body weight is body water ?

A

60%

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19
Q

how much of the body weight is in the intracellular fluid and where is the intracellular fluid found ?

A

The intracellular fluid is found inside the cell and makes up 40% of the body weight.

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20
Q

How much of the total body water is in the extracellular fluid and where is it found ?

A

The extracellular fluid makes up 20% of the body weight and it is found outside the cell.

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21
Q

The extracellular fluid is split into plasma and interstitial fluid. The interstitial fluid makes up how much of the body weight and where is it found ?

A

It makes up 15% of the body weight and it is found between the cells or surrounding the cells.

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22
Q

What is the principal intracellular cation ?

A

Potassium ions (K+)

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23
Q

what is the principal extracellular cation ?

A

sodium ions (Na+)

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24
Q

Is there more calcium found inside the cell or outside the cell ?

A

More outside the cell.

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25
Q

is there more magnesium found inside the cell or outside the cell ?

A

More outside the cell.

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26
Q

there are more potassium ions out side the cell than inside the cell.

A

False

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27
Q

There are no proteins found in the extra cellular fluid.

A

False

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28
Q

Proteins are found in the interstital fluid (of the ECF) and in the intracellular fluid.

A

True

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29
Q

In osmosis water moves in the direction where there is a lower concentration of solute and higher concentration of water.

A

False

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30
Q

What is osmosis ?

A

Osmosis is the diffusion of water from a high concentration of water to a low concentration of water.

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31
Q

What happens during osmosis ?

A

Water moves in the direction where there is a high concentration of solute and low concentration of water.

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32
Q

What is diffusion ?

A

The process by which molecules move from an area of high concentration to an area of low concentration.

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33
Q

What is equilibrium ?

A

When molecules are evenly spread out.

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34
Q

What type of transport is diffusion ?

A

Passive transport.

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35
Q

If energy is needed for transportation the transport is considered an/a….

A

Active transport.

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36
Q

What is a facilitated diffusion and is it an active transport ?

A

Diffusion of polar molecules across the membrane through protein channels. It is not an active transport.

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37
Q

“protein channels allow for the diffusion across a cell membrane from an area of high concentration to an area of low concentration”

A

Facilitated diffusion.

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38
Q

“movement of molecules across a cell membrane from an area of low concentration to an area of hight concentration” what type of transport is this ?

A

active tranport.

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39
Q

Active transport is a protein pump that needs ATP to function.

A

True

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40
Q

How does the sodium-potassium pump work ?

A

It pumps 3 sodium ions from inside the cell to the outside and 2 potassium ions from outside the cell to inside the cell using ATP.

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41
Q

“vesicles are formed in the golgi apparatus, filled with material and then they fuse with the cell membrane and relase their contents outside the cell” what type of transport is this ?

A

Extocytosis – active transport.

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42
Q

what are the 3 main types of active transport ?

A

Sodium-potassium pump, endocytosis and extocytosis.

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43
Q

what is an endocytosis and what is it used for ?

A

it is an active transport that transports large molicules inside the cell.

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44
Q

a secondary active transport does not use ATP.

A

False

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45
Q

When is ATP required for transporting molecules ?

A

When a molecule is going against the concentration gradient.

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46
Q

In an isotonic solution:

A

There is equal solute and equal water.

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47
Q

“there are more molecules outside the cell so water will move from inside the cell to outside the cell and the cell will shrink” what type of solution is this ?

A

Hypertonic.

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48
Q

What happens with a hypotonic solution ?

A

Water will move from outside the cell and into the cell. The cell will grow.

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49
Q

What happens with a hypertonic solution ?

A

Water will move from inside the cell to outside the cell. The cell will shrink.

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50
Q

What is osmolarity:

A

Osmolarity is the concentration of solute particles dissolved in the fluid.

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51
Q

What does increased osmolarity mean ?

A

There is a higher concentration of solute and less concentration of water.

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52
Q

What solute is responsible for ECF osmolarity ?

A

Na+ because it is the main solute in ECF.

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53
Q

What solute is responsible for ICF osmolarity ?

A

K+ because it is the main solute in ICF.

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54
Q

ICF and ECF are normally isotonic because the total concentration of Na+ and other solutes in ECF are equal to the total concentration of K+ and other solutes in ICF.

A

True

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55
Q

If there is water loss from the ECF what will be the effect ?

A

ECF will become hypertonic as water moves from inside the cell to the outside of the cell and the cell will shrink.

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56
Q

What will happen if ECF becomes hypotonic ?

A

Water will move from outside the cell to the inside of the cell and the cell will grow.

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57
Q

What will happen if we give isotonic solution ?

A

ECF will remain isotonic and there will be no movement of water into or out of the cell.

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58
Q

What is the plasma membrane ?

A

It is a thin bilayerd structure that surrounds the whole cell.

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59
Q

The plasma membrane consists of what ?

A

Phospholipids.

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60
Q

What does the fluid mosaic model say about the plasma membrane ?

A

Phospholipids and proteins can move around freely within the plasma membrane.
The plasma membrane is a flexible boundary of cells.

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61
Q

Phospholipids are found within the…

A

Plasma membrane

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62
Q

Phospholipids consist of…

A

A hydophilic head and 2 hydrophobic tails.

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63
Q

What makes up the phospholipids ?

A

Fatty acids.

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64
Q

What is the most important function of the phospholipids?

A

Forming the phospholipid bilayer.

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65
Q

How are the phospholipids in the phospholipid bilayer arranged ?

A

The hydrophilic head is pointing outwards and the hydrophobic tails are pointing inwards.

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66
Q

Which of the following is true about integral membrane proteins?

A

They are weaker than integral membrane proteins and only have a temporary connection to the membrane.

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67
Q

Which of the following are functions of membrane proteins ?

A

They transfer particular solutes across the membrane.
They mediate communication between the cell and outside world.
They can destinguish a cell from another defined cell.

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68
Q

What are proteins made of ?

A

Amino acids.

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69
Q

What are amino acids and what are their functions ?

A

Amino acids are building blocks for protein and they help with transportation and storage of neutrients.

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70
Q

Which of the following is true about amino acids ?

A

Polar amino acids are hydrophilic.
Polar amino acids are responsible for cell structure.

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71
Q

Alanine, valine, leucine, isoleucine, phenyl, alanine, glycine, tryptophan, methionine and proline are part of what group of amino acids ?

A

Non polar amino acids.

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72
Q

Glutamine, aspargine and tyrosine have what in common ?

A

they are all part of the polar amino acid group.

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73
Q

Where are polar amino acids found and are they hydrophilic or hydrophobic ?

A

They are found in the outer surface of the membrane and are hydrophilic.

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74
Q

Where are non-polar amino acids found and are they hydrophilic or hydrophobic ?

A

They are found within the membrane and are hydrophobic.

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75
Q

Where are carbohydrates found ?

A

Attached to proteins and lipids only on the outer surface of the membrane.

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76
Q

What is the most important function of carbohydrates.

A

Cell-to-cell recognision.

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77
Q

The peripheral nervous system is divided into what parts ?

A

Somatic, entric and auonomic nervous system.

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78
Q

Which is part of the autonomic nervous system and is it voluntary or involuntary ?

A

Sympathetic and parasympathetic nervous system and it is involuntary.

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79
Q

What does the entric nervous system controll and is it voluntary or involuntary ?

A

The entric nervous system controlls the gastrointestinalsystem and it is involuntary.

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80
Q

“rest and digest” is the response of what nervous system ?

A

Parasympathetic nervous system.

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81
Q

“fight or flight” is the response of what nervous system and when is it activated ?

A

Part of the sympathetic nervous system and its activated in cases of emergency or stress.

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82
Q

What cells have a resting membrane potential ?

A

All cells.

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83
Q

Which of the following is closest to a resting membrane potential ?

A

Between -70mV and -90mV

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84
Q

When the neuron is at rest there are more sodium inside the neuron than outside the neuron.

A

False

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85
Q

Only excitable cells have an action potential (neurons, muscle cells).

A

True

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86
Q

An action potential goes from about -70mV to +40mV

A

True

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87
Q

Depolarization is when more sodium flows into the neuron.

A

True

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88
Q

Repolarization is when potassium leaves the cell and the cell goes back down towards its RMP.

A

True

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89
Q

What is a threshold and what is its mV level ?

A

A membrane potential that a neuron needs to pass to fire and action potential. Its about -55mV.

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90
Q

What causes and action potential ?

A

A high influx of Na+ which push the membrane potential past the threshold.

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91
Q

What is depolarization and repolarization ?

A

Everything up to the peak of an action potential is depolarization and everything from there is repolarization.

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92
Q

What causes the neuron to repolarize ?

A

An eflux of K+

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93
Q

What is hyperpolarization and why does it happen ?

A

Hyperpolarization is when the membrane potential goes past the RMP. It happens because K+ channels stay open too long.

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94
Q

During hyperpolarization the membrane potential goes past the RMP to about ?

A

-90mV

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95
Q

During an action potential when do the sodium channels close ?

A

They start closing when the potassium channels open.

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96
Q

Why does the neuron go to hyperpolarization ?

A

Because it prevents the neuron from receiving another stimulus during this time.

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97
Q

What happens at the neuromuscular junction ?

A

A motor neuron transmits a signal to a skeletal muscle.

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98
Q

NMJ is ?

A

It is a synapse.
It is where the motor neuron can transmit a signal to skeletal muscle.
It is only found in skeletal muscles.

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99
Q

Motor neuron ?

A

Motor neurons are efferent neurons.
Motor neurons receive signals from the CNS and transport it to the target organ.

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100
Q

What is a presynaptic cell ?

A

It is the neuron that is sending the transmission.

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101
Q

“the muscle is receiving the transmission and is therefore reffered to as the ….”

A

Postsynaptic cell.

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102
Q

The space between the presynaptic cell and the postsynaptic cell is known as what ?

A

Synaptic cleft

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103
Q

“molecules stored in the presynaptic cell which are then released into the synpatic cleft where they bind with the postsynaptic receptors” this is about what?

A

Neurotransmitters.

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104
Q

Neurotransmitters

A

Acetylcholine.
Norepinephrine.
Epinephrine.

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105
Q

What causes the synpatic vesicles to release acetylcholine into the synaptic cleft in the neuromuscular junction ?

A

An influx of Ca++

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106
Q

Acetylcholine binds to receptors on the postsynaptic cell in the neuromuscular junction which causes what ?

A

Na+ channels open and sodium flows into the postsynaptic muscle fiber which causes a postsynaptic action potential.

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107
Q

In order for an action potential to occur what needs to happen ?

A

The influx of sodium into the cell must be great enough to get the membrane potential up to the threshold.

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108
Q

What happens to the acetylcholine after it binds to the postsynaptic receptors ?

A

Acetylcholine is broken down into acedic acid and choline by the enzyme acetylcholinesterase and choline is reabsorbed by the presynaptic cell.

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109
Q

What does the peripheral nervous system contain and what is its main function ?

A

Motor nerves that receive information from the body and deliver it to the CNS.
Sensory nerves that transfer signals from the CNS to the rest of the body.

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110
Q

Sensory nerves ?

A

They are a part of the peripheral nervous system.
They are afferent nerves.
They transfer signals from the body to the CNS.

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111
Q

What is the function of motor nerves ?

A

They transfer signals from the CNS to the body.

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112
Q

Most nerves in the peripheral nervous system are…

A

Mixed nerves – they serve both functions.

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113
Q

There are 2 types of acetylcholine receptors ?

A

Nicotinic and muscarinic receptors.

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114
Q

What is an ionotropic receptor ?

A

A receptor that opens ions channels when neurotransmitters bind to it.
They generate a fast response.

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115
Q

Nicotinic receptors are ionotropic receptors.

A

True

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116
Q

The neuromuscular junction uses what type of receptors ?

A

Nicotinic receptors.

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117
Q

How many types of nicotinic receptors are there ?

A

3

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118
Q

How many muscarinic receptors are there?

A

5

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119
Q

Muscarinic receptor ?

A

They use g-proteins to transport ions.
They are acetylcholine receptors.

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120
Q

Which nervous system produces voluntary movements ?

A

The somatic nervous system.

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121
Q

Somatic nervous system ?

A

The somatic nervous system uses only 1 neuron between the CNS and the target organ.
The somatic nervous system innervates skeletal muscles.
The somatic nervous system produces voluntary movements.

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122
Q

Autonomic nervous system ?

A

It functions involuntarily and reflexively.
It uses 2 neurons between the CNS and the target organ.
It controlls smooth muscles and glands.

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123
Q

The autonomic nervous system is only functioning during “flight or fight” or “rest and digest”

A

False

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124
Q

What is the difference between the somatic and autonomic nervous system ?

A

The somatic nervous system functions voluntarily and the autonomic system functions involuntarily.
The somatic nervous system uses 1 neuron between the CNS and the target organ but the autonomic nervous system uses 2 neurons between the CNS and target organ.

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125
Q

In the sympathetic nervous system the preganglionic neuron comes from where ?

A

The thoracic and lumbar spinal cord.

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126
Q

How does the sympathetic nervous system work ?

A

The preganglionic neuron projects to an autonomic ganglion. The postganglionic neuron then projects to the target organ.

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127
Q

What neurotransmitter does the preganglionic neuron in the sympathetic nervous system use ?

A

Acetylcholine.

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128
Q

What neurotransmitter does the postganglionic neuron in the sympathetic nervous system use ?

A

Norepinephrine/Acetylcholine

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129
Q

“it uses energy, blood pressure increases, heart beats faster and digestion slows down” this is the symptom of what nervous system respons and from what nervous system ?

A

“fight or flight” sympathetic nervous system.

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130
Q

How does the parasympathetic nervous system work ?

A

The preganglionic neuron projects to an autonomic ganglion. The postganglionic neuron then projects to the target organ.

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131
Q

In the parasympathetic nervous system the preganglionic neruon comes from where ?

A

The sacral spinal cord and the medulla.

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132
Q

What neurotransmitter does the preganglionic neuron in the parasympathetic nervous system use ?

A

Acetylcholine.

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133
Q

What is the sarcolemma ?

A

It is a plasma membrane that coveres each muscle fiber.

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134
Q

What function do the T-tubules have ?

A

They transmit action potential through the whole muscle fiber.

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135
Q

T-tubules ?

A

They pass through the whole muscle fiber.

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136
Q

A tirad is made up of T-tubules and 2 terminal cisterna. Where are the terminal cisterna found ?

A

They surround the sarcoplasmic reticulum.
They surround the T-tubules.

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137
Q

Muscle fibers ?

A

They can have multiple nuclei.

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138
Q

What is the sarcoplasm ?

A

It is the cytoplasm of the muscle.

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139
Q

Where is mitochondria found and what is its function ?

A

It is found in the sarcoplasm and it produces energy (ATP).

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140
Q

Where is myoglobin found and what is its function ?

A

It is found in the sarcoplasm and it stores oxygen.

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141
Q

skeletal muscles ?

A

They are under voluntary controll of the somatic nervous system.
They produce rapid contractions.
They consist of packages of muscle fibers called fasicles.
They are striated.
They can have many nuclei per cell.

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142
Q

What is the epimysium ?

A

A connective tissue that surrounds the whole muscle.

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143
Q

What are fasicles ?

A

A cluster of muscle fibers.

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144
Q

How many muscle fibers does each fascicle contain ?

A

Between 10 and 100.

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145
Q

What is the perimysium ?

A

A connective tissue that covers all fasicles.

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146
Q

What is the endomysium ?

A

A connective tissue that covers each individual fasicle.

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147
Q

Most external layer of skeletal connective tissue ?

A

Epimysium.

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148
Q

Where is the sarcoplasmic reticulum found and what is its function ?

A

It extends through the sarcoplasm and stores Ca++ until it is needed by the sarcomeres for muscle contraction.

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149
Q

What substance stores calcium ions in skeletal muscles ?

A

The sarcoplasmic reticulum.

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150
Q

Myofibrils consist of what and where are they found ?

A

Thin and thick filaments and it extends through the whole lenght of the muscle fiber.

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151
Q

What are sarcomeres ?

A

Thin and thick filaments that overlap in a structured way.

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152
Q

What are thick filaments made of ?

A

Only Myosin.

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153
Q

What are thin filaments made of ?

A

Actin, troponin and tropomyosin.

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154
Q

What are troponin and tropomyosin and where are they found ?

A

They are regulatory proteins found in the thin filaments.
Regulatory proteins which regulate interaction between actin and myosin.

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155
Q

What happens when Ca+ binds to troponin and troponin changes shape ?

A

Tropomyosin rotates away from the myosin binding sites.

156
Q

What causes troponin to change shape ?

A

Calcium ions bind to troponin.

157
Q

What needs to happen so the myosin head becomes activated ?

A

ATP needs to bind with the myosin head and then be hydrolyzed into ADP and inorganic phosphate.

158
Q

What is the 1st step of a cross-bridge formation ?

A

The activated myosin head binds with actin and releases the inorganic phosphate which makes the bond stronger.

159
Q

In the 2nd step of a cross-bridge cycle what happens when ADP is released ?

A

The myosin head pivots, sliding the thin filament toward the center of the sarcomere.

160
Q

When does that head of the myosin detach from the actin ?

A

When a new ATP attaches to the myosin head

161
Q

When another ATP binds to the myosin head the myosin head detaches from the actin. What happens next ?

A

ATP is hydrolyzed into ADP and inorganic phosphate and the myosin head returns to the cocked position.

162
Q

What happens during the crossbridge cycle ?

A

The thin filaments are pulled towards each other and the sarcomere shortens which causes the whole muscle to contract.

163
Q

As long as the myosin binding sites remain exposed the crossbridge- cycle continues.

A

True

164
Q

What causes the crossbridge cycle to end ?

A

When calcium ions detach from the troponin and are transported back into the sarcoplasmic reticulum.

165
Q

When calcium ions detach from troponin, troponin changes shape and the tropomyosin rotates away from the myosin binding site.

A

False

166
Q

The sliding filament theory says what ?

A

The sliding of actin past myosin generates muscle tension/contraction.
That the thin filaments change length but the thick filaments stay constant in lenght.

167
Q

when the thin filaments change shape the z discs are pulled furhter apart causing muscle contraction.

A

False

168
Q

Sliding filament theory ?

A

Actin changes lenght along with the whole sarcomere but myosin stays constant in length.
When the thin filaments change shape the z discs are pulled closer together causing contraction.

169
Q

The thin filaments are only made of actin.

A

False

170
Q

How many heads does each myosin have and how many binding sites does each have ?

A

Each myosin has 2 heads and each head has 2 binding sites.

171
Q

What is muscle fatigue and why does it happen ?

A

It is the inability of muscles to contract strongly. It happens after a prolonged and intense activity.

172
Q

What is a concentric contraction ?

A

Its when the muscle length shortens.

173
Q

What is an eccentric contraction ?

A

Its when the muscle lengthens.

174
Q

What is an isometric contraction ?

A

Its when muscle tension changes but the length of the muscle stays the same.

175
Q

What is muscle tone ?

A

Its when motor units turn on and off alternatively to produce a constant and sustained contraction of muscle fibers.

176
Q

“the muscle tension changes but the muscle length stays the same” what is this ?

A

isometric contraction.

177
Q

“the muscle length shortens” what is this ?

A

Concentric contraction.

178
Q

What is a motor unit ?

A

A motor neuron + the skeletal muscle fibers inneravated by that neuron.

179
Q

What is a motor pool ?

A

A large number of motor units.

180
Q

Activating motor units alternatively allows the muscle to sustain contraction with minimal fatigue.

A

True

181
Q

Muscles that act on the largest body masses have motor units that contain many muscle fibers.

A

True

182
Q

Where are smooth muscles found ?

A

In the walls of hollow organs such as the stompach and in the walls of blood vessels.

183
Q

Smooth muscles are similar to which muscles ?

A

The smooth muscles are completely different from the other muscles.

184
Q

The smooth muscle generates its own action potential and it functions involuntarily.

A

False

185
Q

Smooth muscle ?

A

Smooth muscles produce wave-like contraction and contract as a whole muscle.
Smooth muscles are found in the walls of the blood vessels.
Smooth muscles are involuntary and controlled by the autonomic and endocrine nervous system.
Smooth muscles cells have a poorly developed sarcoplasmic reticulum.

186
Q

The smooth muscles are controlled by what nervous system ?

A

The endocrine nervous system.
The autonomic nervous system.

187
Q

How many nuclei do smooth muscle cells have and what is the location?

A

Only 1 nuclei located in the center of the cell.

188
Q

Smooth muscles are not striated and do not have sarcomores, myosin or actin.

A

False

189
Q

Which of the following do smooth muscles have ?

A

Dense bodies.
Gap junctions.

190
Q

Which of the following do smooth muscles NOT have ?

A

Z-discs.

191
Q

Smooth muscles have gap junctions.

A

True

192
Q

In smooth muscles where do the calcium ions come from ?

A

Mostly from the ECF but also from the sarcoplasmic reticulum.

193
Q

Which of the following do smooth muscles NOT have compare to skeletal muscle

A

Troponin.

194
Q

What are dense bodies and what is their function ?

A

The actin filaments attach to the dense bodies. They function as Z-discs.

195
Q

What are caveolae and what is its function ?

A

Caveolae function as T-tubules.

196
Q

There are 2 major types of smooth muscles, neurogenic and myogenic. What is the characteristic of neurogenic cells ?

A

The muscle contraction must be initiated by an autonomic neuron.
All the neurogenic cells behave independently and must be individually excited.
Action potentials do not occur in neurogenic smooth muscle cells.

197
Q

There are 2 major types of smooth muscles, neurogenic and myogenic. What is the characteristic of myogenic cells ?

A

All the myogenic cells behave as one unit and have gap junctions.

198
Q

Where are neurogenic smooth muscle cells found ?

A

In large blood vessels, large airways to lungs, ciliary muscle of the eye, iris of the eye and the piloerector muscle.

199
Q

What type of neuromuscular junction do neurogenic smooth muscles have ?

A

Contact junction – an autonomic nerve forms a junction with the muscle fiber and releases a neurotransmitter.

200
Q

How does depolarization happen in a neurogenic smooth muscle ?

A

Depolarization is caused by the rapid spread of the neurtransmitter over the surface of the smooth muscle cell.

201
Q

Why does an action potential not happen in neurogenic smooth muscle cells ?

A

Because a single fiber is too small to generate a self-propagating action potential.

202
Q

What does it mean for a cell to be myogenic ?

A

It can contract regularly without input from a motor neuron.
All the cells behave as one unit.
The cells use gap junctions to allow for electrical impulse between cells.
It is a functional syncytium.

203
Q

Which of the following is true about myogenic smooth muscle cells ?

A

The cells are electrically linked by gap junctions and therefore contract as a single unti.

204
Q

Which smooth muscle cells are a functional syncytium ?

A

Only myogenic cells.

205
Q

What does it mean to be a multiunit smooth muscle ?

A

The muscle contraction must be initiated by an autonomic neuron.
All the neurogenic cells behave independently and must be individually excited.

206
Q

Which of the following is a characteristic of multiunit smooth muscles ?

A

The cells behave independently and must be individually excited.

207
Q

What does it mean to be a singleunit smooth muscle ?

A

It can contract regularly without input from a motor neuron.
All the smooth muscle cells in the organ behave as one unit.

208
Q

What type of neuromuscular junction do singleunit smooth muscles have ?

A

A diffuse junction – there is no contact with a nerve cell and the neurotransmitter is released near the muscle fiber.

209
Q

Where are myogenic singleunit smooth muscles found ?

A

In the walls of the GIT, in large blood vessels, ureter, bile duct and uterus.

210
Q

A single unit smooth muscle is myogenic which means it can contract regularly without input from a motor neuron.

A

True

211
Q

What is a diffuse junction ?

A

A junction where there is no contact between the neuron and the muscle.
A type of junction that is found in singleunit smooth muscles.

212
Q

Single unit smooth muscle cells have 3 specific membrane potential.

A

Spike potentials can be generated by an electrical stimulation, hormones, neurotransmitter or spontaneously.
It can last as long as a second and can account for prolonged contractions.

213
Q

Smooth muscle cells can be tonic or phasic. What does it mean to be tonic and what is an example of a tonic smooth muscle ?

A

Tonic smooth muscle cells produce a slow sustained contraction-relaxation and use little energy. The digestive and resperatory system.

214
Q

What does it mean to be phasic and what is an example of a phasic smooth muscle ?

A

Phasic smooth muscle cells produce rapid contraction-relaxation and contracts only periodically. Urinary bladder.

215
Q

Smooth muscles follow the sliding-filament theory.

A

True.

216
Q

In what way is a contraction of the smooth muscle different from a contraction of skeletal muscle ?

A

In skeletal muscle cells Ca++ enters the cell through the sarcoplasmic reticulum but in smooth muscle cells the Ca++ enters the cell mainly fromt he ECF.
In skeletal muscle cells calcium binds to troponin but in smooth muscle cells calcium binds to calmodulin.

217
Q

What is the enzyme that phosphorilates myosin in smooth muscle cells called ?

A

MCLK

218
Q

When do myosin become activated in smooth muscle cells ?

A

When the MLCK phosphorylates the myosin head.

219
Q

In order for a smooth muscle to contract the myosin head must be activated. The first step is an influx of calcium ions. Calcium ions than bind to what molecule ? to form what complex ?

A

Calmodulin to form the calcium-calmodulin complex.

220
Q

What is the final step in myosin activation in smooth muscle cells ?

A

Calcium-calmodulin complex binds with MLCK to activate it and the MLCK then phosphorylates the myosin head which activates the myosin head.

221
Q

The contraction of the thick and thin filaments in smooth muscles causes the dense bodies to move closer which causes what ?

A

Shortening of the intermediate filaments.

222
Q

What is the function of MLCK ?

A

It is an enzyme that phosphorylates other proteins.
It is an enzyme that activates the myosin head.

223
Q

myosin and actin bind for a long period of time in what type of muscle ?

A

Smooth muscles.

224
Q

to relax the smooth muscle, calcium must be pumped out of the cell. How is this done ? and where is the calcium returned to ?

A

By ATP pumps or calcium-sodium pumps. It is returned to the ECF and the sarcoplasmic reticulum.

225
Q

what happens after the calcium has been pumped out of the cell in smooth muscle cell relaxation ?

A

MLCP de-phosphorylates the myosin head so it becomes inactive.
Myosin phosphatase removes the phosphate from the myosin head so it becomes inactive.

226
Q

what causes the myosin to de-phosphylate in smooth muscle cells ? what happens after it de-phosphorylates ?

A

MLCP and myosin head detaches from the actin.

227
Q

A synapse is the area between the presynaptic and postsynaptic cell where transmission of information takes place.

A

True

228
Q

What is a chemical synapse ?

A

It is a biological junction through where the presynaptic neuron or cell can send a signal to the postsynapic neuron or cell.

229
Q

What is a neurotransmitter ?

A

Chemical messengers that enable neurotransmission.

230
Q

The motor end plate is a chemical synapse.

A

True

231
Q

What is a neurotransmission ?

A

The communication process by which neurotransmitters are released by a neuron and bind too and activate the receptors of another neuron or muscle cell.

232
Q

From where is the neurotransmitter released in a chemical synapse ? and into what is it released ?

A

It is released from the presynaptic neuron into the synaptic cleft.

233
Q

What happens after the neurtransmitters are released into the synpatic cleft in a chemical synapse ?

A

The neurotransmitters bind to the receptors on the postsynaptic cell.

234
Q

Both the preganglionic and the postganglionic neuron in the parasympathetic nervous system use acetylcholine as a neurotransmitter.

A

True

235
Q

the parasympathetic nervous system inneravtes all substance connected to what ?

A

cranial and sacral spinal cord.

236
Q

what are cholinergic neurons ?

A

neurons releasing acetylcholine.

237
Q

what are adrenergic neurons ?

A

neurons releasing acetylcholine.
Neurons releasing epinephrine.

238
Q

All postganglionic neurons of the sympathetic nervous system are cholinergic.

A

False

239
Q

Almost all postganglionic neurons of the sympathetic nervous system use what type of neurotransmitter ? and are therefore….

A

Norepineprhine and are therefore adrenergic.

240
Q

Almost all postganglionic neurons of the sympathetic nervous system are adrenergic but what are the exceptions ?

A

Neurons innervating the sweat glands and pilorector muscles.
Neurons innervating some muscular blood vessels.

241
Q

What is a neuron ganglion ?

A

A group of neurons located in the autonomic nervous system.

242
Q

Parts of the body that use or are affected by acetylcholine are referred to as adrenergic.

A

False

243
Q

What are the substances that interfere with acetylcholine activity called ?

A

Anticholinergic.

244
Q

Acetylcholine uses a cholinergic receptor. There are 2 broad classes of cholinergic receptors one of which is the nicotinic receptor. How many nicotinic receptor types are there and where are they found ?

A

There are 3 types of nicotinic receptors and they are found in the neuromuscular junction, autonomic ganglia, and in the CNS.

245
Q

How many muscarinic receptor types are there and where are they found ?

A

There are 5 types of muscarinic receptors and they are found on the myocardial muscle, certain smooth muscles and in the CNS.

246
Q

Acetylcholine ?

A

Acetylcholine is the neurotransmitter of all preganglionic neurons in the autonomic nervous system.
Acetylcholine is the neurotransmitter of the sweat glands, pilorector muscle and of some blood vessels.

247
Q

epinephrine ?

A

It is both a neurotransmitter and hormone.

248
Q

norepinephrine ?

A

Norepinephrine uses an adrenergic receptor.
It functions as a neurotransmitter and a hormone.
Norepinephrine along with epinephrine cause the “fight or flight” response.

249
Q

Which of the following is the “fight-or-flight” hormone ?

A

Both epinephrine and norepinephrine.

250
Q

What is a metabotropic receptor ?

A

A type of receptor that uses G proteins to deliver secondary messages.

251
Q

muscarinic receptors ?

A

They are metabotropic receptors.
Sweat glands use muscarinic receptors.

252
Q

nicotinic receptors ?

A

They are ionotropic receptors.
They are cholinergic receptors.

253
Q

The sympathetic nervous system is responsible for the “fight or flight” response. But what does that response include ?

A

Dialating the pupils, increasing heart rate, mobilizing energy and diverting blood flow from non-essential organs to skeletal muscles.

254
Q

Adrenergic receptors can be split into two groups. What are those receptors and what are they responsible for ?

A

Alpha receptors that cause contraction of vascular smooth muscle and beta receptors that cause relaxation of vascular smooth muscle and increase heart rate and force of cardiac contraction.

255
Q

Adrenergic receptors can be split into two groups, the alpha receptors and the beta receptors. How many alpha receptors are there and what are they responsible for ?

A

There are 2 types and they are responsible for contraction of vascular smooth muscle.

256
Q

Alpha and beta receptors ?

A

There are 2 types of alpha receptors and 2 types of beta receptors.

257
Q

Epinephrine bonds with…

A

Both alpha and both beta receptors.

258
Q

Norepineprhine bonds with…

A

both alpha receptors and one beta receptor.

259
Q

What is a preganglionic neuron ?

A

The nerve fibers that connect the CNS to the ganglia.

260
Q

What is a postganglionic neuron ?

A

The nerve fibers that project form the autonomic ganglion to the target organ.

261
Q

Why is the autonomic nervous system unique ?

A

Because it needs 2 neurons to get to the target organ.

262
Q

What is the presynaptic membrane ?

A

The membrane portion of the neuron that sends information.

263
Q

What is the postsynaptic membrane ?

A

The membrane portion of the cell that receives information.

264
Q

What is an electrical synapse ?

A

It is a junction between neurons or cell that serve as a bridge between their cytoplasm.
A current injected into the presynaptic cell flows into the postsynaptic gap junctions.
It is unidirectional – it goes in both ways.

265
Q

A gap junction is an electrical synapse.

A

True

266
Q

Metabotropic receptors

A

They generate slow responses.

267
Q

what happens during an inhibitory postsynaptic potential (PIPS) and what does it cause ?

A

Potassium flows out of the cell and the cell becomes hyperpolarized.
Chloride flows into the cell and the cell becomes hypropolarized.

268
Q

what happens during an excitatory postsynaptic potential and what does it cause ?

A

There is a sodium influx and a potassium eflux and the cell depolarizes.

269
Q

During a fast excitatory postsynaptic potential what type of transmitter is used ?

A

Ionotropic receptors.

270
Q

during a slow excitatory postsynaptic potential what type of transmitter is used ?

A

Metabotropic receptors.

271
Q

what type of transmitters do inhibitory postsynaptic potentials use and why ?

A

They use ionotropic receptors because they use fast channels.

272
Q

during a fast excitatory postsynaptic potential there is an influx of what and and eflux of what ?

A

There is an influx of sodium and eflux of potassium.

273
Q

inhibitory postsynaptic potentials hyperpolarize the cell. They do this by either using potassium or chloride. How does it happen with potassium ?

A

A neurotransmitter binds to the ionotropic receptor, potassium channels open and potassium flows out of the cell.

274
Q

inhibitory postsynaptic potentials hyperpolarize the cell. They do this by either using potassium or chloride. How does it happen with chloride ?

A

A chloride pump pumps chloride ions from a low concentration to a high concentration which creates a gradient, this gradient opens chloride channels and chloride moves into the cell.

275
Q

There are 2 types of postsynaptic potentials. One of which is the excitatory postsynaptic potential or PEPS.

A

True

276
Q

Would a G-protein be involved in an inhibitory postsynaptic potential ?

A

No

277
Q

There are 5 different types of muscarinic receptors. What are the most common muscarinic receptors in the secretory glands

A

M1

278
Q

There are 5 different types of muscarinic receptors. Where are M2 receptors found ?

A

In cardiac tissue.

279
Q

There are 5 different types of muscarinic receptors. Where are M3 receptors found ?

A

In smooth muscles and in secretion glands.

280
Q

The synaptic integration is the term used to describe how neurons “add up” excitatory postsynaptic potentials and inhibitory postsynaptic potentials to determine if an action potential should be fired.

A

True

281
Q

Is a single excitatory postsynaptic potential enough to reach the threshold and fire an action potential ?

A

No

282
Q

In order for the postsynaptic membrane to fire an action potential the excitatory postsynaptic potential must overcome the inhibitory action potential as well.

A

True

283
Q

For an ecxitatory postsynaptic potential to reach the threshold it can use either temporal summation or spatial summation. What happens with a spatial summation ?

A

Its when the inputs from several presynaptic neurons acting on different areas combine to from an action potential.

284
Q

For an ecxitatory postsynaptic potential to reach the threshold it can use either temporal summation or spatial summation. What happens with a temporal summation ?

A

Occurs when excitatory postsynaptic potentials occur one after another at the same time, therby combining the potential in the postsynaptic terminal.

285
Q

Epineprhine takes part in controllin what ?

A

Sleep.
The adrenal glands.
The “fight or flight” response.

286
Q

The GABA neurotransmitter is used where ?

A

In fast inhibitory synapses in the brain.

287
Q

Neuromuscular disease is a medical condition where the normal conduction through the neuromuscular junction fails to function correctly.

A

True

288
Q

What is myasthenia gravis ?

A

A disease that blocks acetylcholine receptors.

289
Q

“Muscle weakness and fatigue that increase with activity and decrease with rest. Difficulty swallowing and chewing.” These are symptoms of what neuromuscular dissease ?

A

myasthenia gravis

290
Q

What causes Mysthenia gravis ?

A

Antibodies block acetylcholine receptors on the postsynaptic membrane of the neuromuscular junction.

291
Q

“its an intoxication characterized by muscle spasms. It affects only skeletal muscle” what neuromuscular disease does this describe ?

A

tetanus.

292
Q

What causes tetanus ?

A

A toxin blocks the release of glycine and GABA neurotransmitters.

293
Q

What are the symptoms of tetanus ?

A

Muscle spasms, fever, sweating, headache, trouble swallowing and fast heart rate.

294
Q

How is tetanus spread ?

A

Through a break or cut in the skin.

295
Q

“autoimmune disease which results from antibodies that block acetylcholine receptors at the junction between the nerve and the muscle. This prevents nerve impulses from triggering muscle contractions. There is also a decrease of nicotinic receptors” what disease is this ?

A

Myasthenia gravis.

296
Q

“its a rare but potentially fatal illness caused by a neurotoxin produced by the barteria clostridium botulinum” what neuromuscular disease is this discribing ?

A

botulism.

297
Q

What disease is brought on by the same bacteria that is used to produce botox ?

A

Botulism.

298
Q

“this toxin causes flaccid paralysis by blocking acetylcholine, necessary for muscle contraction” what neuromuscular disease is this describing ?

A

Botulism.

299
Q

What are the symptoms of botulism ?

A

Weakness, trouble seeing, feeling tired, trouble speaking, weakness of the arms, chest muscles and legs.

300
Q

What is an anticholinergic agent ?

A

Substance that blocks the neurotransmitter acetylcholine.

301
Q

How are anticholinergic agents classified and what are their names ?

A

According to the receptors that are affected. Antimuscarinic and antinicotinc.

302
Q

Majority of anticholinergic drugs are…

A

Antimuscarinic drugs.

303
Q

The majority of antinicotinic drugs are….

A

Non-depolarizing skeletal muscle relaxants.

304
Q

What effect do antimuscarinic agents have ?

A

They block the muscarinic receptors.
They do not have any affect on the nicotinic receptors.

305
Q

Which of the following are antimuscarinic agents ?

A

Scopolamine.
Atropine.

306
Q

Muscles that act on the largest body masses have motor units that contain many muscle fibers.

A

True

307
Q

Cardiac muscle do not contain

A

many motor units.

308
Q

Cardiac muscle are

A

They are involuntary.
Found only in the heart.
All the cardiac muscle fibers are connected to one another by intercalated discs.
They have autorythmic cells that generate an action potential.

309
Q

Cardiac muscle cells are connected to each other by intercalated discs.

A

True

310
Q

Some of the cardiac muscle cells produce their own action potential – it is not generated by a motor neuron.

A

True.

311
Q

What does autorythmic mean ?

A

The action potential is not generated by a motor neuron but by autorhythmic cells.

312
Q

What cells in the cardiac muscles can produce their own action potential with out a motor neuron ?

A

Only autorhythmic cells.

313
Q

The cardiac muscles produce a short action potential.

A

False.

314
Q

What is the adipose tissue ?

A

The outermost layer of the heart.

315
Q

What is the pericardium ?

A

A connective tissue layer that surrounds the whole heart and lies underneath the adipose tissue.

316
Q

What is the epicardium ?

A

A layer of muscle found covering the external surface of the heart and it lies under the pericardium.

317
Q

Which of the following is true about the pericardium ?

A

The pericardium has an inner and outer layer and inbetween those layers is the pericardial sac which contrains pericardial fluid.

318
Q

Which of the following is NOT true about the pericardium ?

A

The pericardium is located between the endocardium and the epicardium.

319
Q

“it is directly fused with the myocardium internally and is in contact with the serous layer of the pericardium” what cardiac muscle structure is this ?

A

Epicardium.

320
Q

what is the function of the myocardium and where is it found ?

A

It is found between the epicardium and the endocardium and it assists in contraction and relaxation of the cardiac walls so blood can pass between the heart chambers.

321
Q

what does the endocardium form and what does it controll ?

A

it is the innermost layer and it forms the 4 heart chambers.

322
Q

Cardiac and skeletal muscle cells are completely the same.

A

False.

323
Q

What do cardiac and skeletal muscle fiber cells have in common ?

A

They both depend on calcium ions for contraction.
They both have sarcomeres.

324
Q

What is the difference between cardiac and skeletal muscle cells ?

A

Skeletal muscle cells need a stimulus from a motor nerve to produce an action potential but cardiac muscle cells produce spontaneous action potential.

325
Q

From where do the calcium ions in cardiac muscles come from ?

A

The sarcoplasmic reticulum.
The extracellular fluid.

326
Q

Cardiac muscle cells contain more mitochondria than skeletal muscle cells and produce more ATP.

A

True.

327
Q

The T-tubules are better developed and bigger in cardiac muscle cells than in skeletal muscle cells.

A

True.

328
Q

Which of the following is true ?

A

Cardiac muscle cells are connected together by intercalated discs.
Cardiac muscle cells have the same type of sarcomeres as the skeletal muscle cells.

329
Q

Cardiac muscle cells contain how many nuclei ?

A

1 or 2 nuclei.

330
Q

What are intercalated discs and where are they found ?

A

Intercalated discs connect cardiac muscle cells together and are found only between adjacent cardiac muscle cells.

331
Q

The intercalated discs form 2 important structures what are those structures and what are their functions?

A

Gap junctions that form channels between the cardiac cells and desmosomes that keep the cells well connected during a contraction.

332
Q

What is the function of a gap junction and where is it found ?

A

The gap junction is found between the cardiac cells and it forms channels between the cardiac cells.

333
Q

Intercalated discs are structures that are found in the end of each cardiac muscle cell. They are structures that are only found in cardiac muscle cells.

A

True.

334
Q

What is the function of desmosomes and where are they found ?

A

Desmosomes hold the connecting cardiac cells tightly together.

335
Q

How many of the hearts cells are autorhythmic and what function do autorhythmic cells have ?

A

1% of the cardiac cells are autorhythmic and their function is to produce their own action potential without a stimulus from a neuron.

336
Q

How many of the hearts cells are contractile and from where do they receive an action potential ?

A

99% of the cardiac cells are contractile cells and they receive an action potential from the autorhythmic cells via a gap junction.

337
Q

Which of the following is true about autorhythmic cells ?

A

They have no resting membrane potential.
They generate all the action potential for the heart.

338
Q

Autorhythmic cells possess 4 properties, one of which is autorhythmicity. What does that intail ?

A

They have the ability to spontaneously genrate and discharge an action potential without external stimulation.

339
Q

Autorhythmic cells possess 4 properties, one of which is refractority. What does that intail ?

A

They are unable to generate another action potential for a duration of time.

340
Q

Autorhythmic cells possess 4 properties, one of which is conductivity. What does that intail ?

A

They have the ability to transmit an electrical impusle from one cell to the next one.

341
Q

Autorhythmic cells of the cardiac muscles are unable to generate another action potential for a duration of time.

A

True

342
Q

Which of the following membrane potentials are closest to the cardiac contractile cell resting membrane potential ?

A

-90mV

343
Q

Contractile cells make up the muscular walls of the atrium and ventricles.

A

True

344
Q

Contractile cells of the cardiac muscle possess 2 specific properties, one of which is contractility. What does that intail ?

A

They are able to contract in response to a stimulus.

345
Q

Which of the following membrane potentials is closest to the threshold of cardiac contractile cells ?

A

contractile cells dont have a threshold.

346
Q

What is a syncytium ?

A

Many uninuclear cells that connect together making a multinucleated cell.

347
Q

How many syncytiums are found in the heart and what are their names ?

A

There are 2. The atrial syncytium and the ventricular syncytium.

348
Q

Is there a gap junction between the atria and the ventricles of the heart ? what separates those two structures ?

A

No. A fibrous tissue separates them.

349
Q

The all or nothing principle says that the stimulation of any atrial muscle fiber causes the action potential to travel over the entrie ventricular mass.

A

True

350
Q

One atria never contracts. Either both do or both do not contract at all.

A

True

351
Q

Ventricles dont have to both contract. One can contract and the other not.

A

False

352
Q

Which contracts first, the atria or the ventricles ?

A

The atria

353
Q

The division of the muscle of the heart into 2 syncytiums allows the ventricles to contract a short time ahead of the atria.

A

False

354
Q

What is the function of the sinotrial node and where is it found ?

A

It is found in the right atrium. It acts as the pacemaker of the heart because it has the fastest rate of generating an action potential.

355
Q

Where is the atrioventricular node and what is its function ?

A

It is found on the opposite side of the SA node in the right atrium. It serves as an electrical gateway to the ventricles.

356
Q

Where is the bundle of HIS found ?

A

In both the left and right ventricles.

357
Q

What is the fastest autorhythmic tissue ?

A

The SA node.

358
Q

What autorhythmic tissue acts as th pacemaker of the heart ?

A

The SA node.

359
Q

In the conduction system of the heart electrical impulses from the SA node spread through out what ?

A

Both atria.

360
Q

In the conduction system of the heart, what happens right before the AV node receives signals from the SA node ?

A

Both atria eject all the blood into the ventricles.

361
Q

After the AV node receives the signals from the SA node where is the signal sent next ?

A

To the bundle of his.

362
Q

autorhythmic cells depolarize spontaniously without nervous system stimulation.

A

True

363
Q

The heart contracts as a single unit. What allows this to happen ?

A

The autorhythmic cell generates and sends an impulse to all the contractile cells through gap junctions, Allowing the heart to contract as a whole.

364
Q

How do the spontanious impuslses genreated by the autorhythmic cells travel to the other surrounding contractile cells ?

A

Through gap junctions.

365
Q

Which of the following is closes to the threshold of an autorhythmic cell ?

A

-40mV

366
Q

Autorhythmic cells have what type of leaky channels and what do they leak more ?

A

Sodium-potassium channels that leak more sodium.

367
Q

When do autorhythmic cells fire an action potential ?

A

When they reach the threshold.
When they reach -40mV.

368
Q

When the threshold is reached in cardiac autorhythmic cells what channels open and depolarize the cell ?

A

Calcium channels.

369
Q

What causes the depolarization of an autorhythmic cell ?

A

An influx of calcium.

370
Q

What causes the repolarization of an autorhythmic cell ?

A

Potassium eflux.

371
Q

Which of the follow membrane potentials are closest to the peak of depolarization in cardiac autorhythmic cells ?

A

10mV

372
Q

The “resting membrane potential” or the start point of an autorhythmic cell is closest to which of the following ?

A

-60mV

373
Q

hyperpolarization only happens in skeletal muscles.

A

False.

374
Q

When calcium voltage gated channels in an autorhythmic cell close what channels open and what happens ?

A

Potassium channels open and the cell repolarizes.

375
Q

Which cardiac cells are excitable ?

A

All cardiac cells.

376
Q

What does it mean that a cell is excitable ?

A

They are able to respond to an external stimulus.

377
Q

How does the electrical signal travel through the heart ?

A

From the SA node to the AV node to the Bundle of HIS and finally to the purkinje fibers.

378
Q

When an action potential comes into the contractile cell from the autorhythmic cell through gap junctions, what happens ?

A

Fast sodium channels open and sodium rushes out of the cell. This causes a depolarization.

379
Q

What is a plateu in contractile cells and what causes it ?

A

A plateu is a period of time where the cell can not be re-stimulated. Ca2+ rushing into the cell causes a this.

380
Q

When an action potential from the autorhythmic cell reaches the contractile cell sodium channels open which causes a rapid depolarization. What happens next ?

A

Sodium channels close and fast potassium channels open and potassium flows out of the cell.

381
Q

When depolarization of a contractile cell happens, potassium channels open next. What channels open next and what do those channels cause ?

A

Calcium channels open and calcium flows into the cell which causes a plateau.

382
Q

A contractile cell has 2 potassium channels, a fast one and a slow one. Which opens last and what does it cause ?

A

Slow potassium channels. Repolarization.

383
Q

Is repolarization slower or faster in cardiac cells than in skeletal cells ?

A

It is slower in cardiac muscle cells.

384
Q

Repolarization in cardiac cells is relatively slower than in skeletal cells. Why is this ?

A

Because cardiac cells have a plateau where the cell can not be re-stimulated for a period of time.

385
Q

What is the refractory period ?

A

During the refractory period the cell is not able to produce another action potential.

386
Q

Is the refractory period longer in cardiac or skeltal muscle cells ?

A

It is longer in cardiac muscles cells.

Physiology (1 decks)

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