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BIOSCI 107 > (01) Muscle and Nervous Tissue > Flashcards

(01) Muscle and Nervous Tissue Flashcards

1
Q

functions of muscle tissue

A

uses energy from the hydrolysis of ATP to generate force
contract –> movements / maintain posture / generate heat

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2
Q

general structure of muscle tissue

A

consists of elongated cells - muscle cells / fibres or myocytes

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3
Q

what is a myocyte

A

the smallest subunit of all muscle tissue (cardiac and skeletal)

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4
Q

name the three types of muscle tissue

A

skeletal
cardiac
smooth

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5
Q

describe the appearance of skeletal muscle

A

striated (under microscope)
cylindrically shaped fibres
long cells
multinucleated (nuclei pushed to sides of cylindrical muscle fibres)

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6
Q

describe the functions and locations of skeletal muscle

A

voluntary / consciously controlled contractions

attached to bones by tendons

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7
Q

name the smallest skeletal muscle in the human body

A

Stapedius- 1.25mm

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8
Q

where is the stapedius located and what does it do?

A

in the ear
stabilises the stapes (smallest bone in the ear), keeps sound in comfortable range (prevents hyperacusis - loudness perception disorder)

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9
Q

name the longest skeletal muscle in the human body

A

sartorius - up to 60cm

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10
Q

where is the sartorius located

A

checking for gum - hip flexor, abductor, lateral rotator

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11
Q

meaning of prefix myo-

A

denotes muscle

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12
Q

meaning of prefix sarco-

A

denotes flesh

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13
Q

name the three main parts of a skeletal muscle fibre

A

sarcolemma = outside plasma membrane of muscle fibre
Sarcoplasm = inside part = cytoplasm
myofibrils = filaments

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14
Q

why are skeletal muscle fibres striated?

A

due to highly organised myofibrils within cells

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15
Q

name the two types of filaments in myofibrils

A

Myofilaments:
- THIN = actin
- THICK = myosin

8nm diam vs 16

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16
Q

what are sarcomeres

A

the basic functional unit of a myofibril

myofilaments are arranged in compartments called sarcomeres

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17
Q

name the bands producing striations

A

A band
I band
H zone
M line
Z disc

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18
Q

describe the A band

A

dark middle part of the sarcomere
contains ALL thick filaments

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19
Q

describe the I band

A

thin filaments, no thick filaments
the remaining part of the sarcomere not including A band

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20
Q

describe the H zone

A

thick filaments ONLY, no thin
within the A band

(think literally an H shape)

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21
Q

describe the M line

A

the middle of the sarcomere
Holds thick filaments together

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22
Q

describe the Z disc and what it’s made up of

A

between sarcomeres
links filaments to adjacent sarcomeres
passes through the centre of the I band

made up of ACTININS

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23
Q

describe contracted muscle in terms of bands / zones

A

relaxed muscle has both A / I band, and H zone
during contraction, H zone and I band shrink as thin and thick filaments overlap more
maximally contracted muscle has only A band

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24
Q

describe cardiac muscle (location, structure, appearance, function)

A

heart, involuntary

striated, branched
single central nucleus
intercalated discs - fibres joined end to end

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25
Q

what do intercalated discs contain?

A

desmosomes
gap junctions

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26
Q

what do desmosomes in intercalated discs do

A

heart must deal with FORCE:

they bind intermediate filaments
provide adhesion in contraction

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27
Q

what do gap junctions in intercalated discs do

A

heart must be COORDINATED:

important for communication
rapid conduction

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28
Q

describe the appearance / structure of smooth muscle

A

not striated, but still has bundles of thin (actin) and thick (myosin) filaments
short, small, spindle-shaped
single central nucleus
diamond layout of “dense bodies”

29
Q

function and location of smooth muscle

A

involuntary
in the walls of hollow internal structures
eg. blood vessels, intestines, skin

30
Q

what are dense bodies made up of and what do they do

A

functionally similar to Z discs
major protein is also actinin

connected to thin filaments and intermediate filaments, so during contraction tension is transmitted to intermediate filaments (don’t contract) and the cell twists

31
Q

roles of the nervous system

A

maintain homeostasis (with endocrine system)
initiates voluntary movements
perception, behaviour, memory

32
Q

three major functions of the nervous system

A
  1. sensory (detect external stimuli –> CNS)
  2. Integrative (analysis / store info)
  3. Motor (stimulation of effectors through PNS)
33
Q

two types of cells in nervous tissue

A

neurons (longest cells in the body!)
neuroglia

34
Q

name the main parts of a neutron

A

cell body (soma)
dendrites
axon

35
Q

describe dendrites

A

short, branched, attached to cell body
the receiving / input part

36
Q

describe the axon

A

longer, single axon attached to cell body
output - carries the nerve impulse away from the neuron

37
Q

for our purposes, neurons…

A

do not divide
have high metabolic rate (die rapidly without O2)

38
Q

name four types of neurons

A

multipolar
bipolar
unipolar
anaxonic

39
Q

name the most common type of neurons in the CNS

A

multipolar neurons

40
Q

structural features of multipolar neurons

A

hace 2+ dendrites
a single axon
some of the longest (spinal cord to toe)

41
Q

what are motor neurons

A

they control skeletal muscles
all multipolar neurons

42
Q

structural features of bipolar neurons

A

two distinct processes: 1 dendritic process (can branch at tip but not at cell body) and 1 axon
cell body is between axon and dendrite

small and rare

43
Q

function of bipolar neurons

A

special sense organs (sight / smell / hearing)
relay info from receptor to neurons

44
Q

structure of unipolar neurons

A

CONTINUOUS dendrites and axon
cell body off to one side
very long

45
Q

function of unipolar neurons

A

most sensory nerves

46
Q

structure of anaxonic neurons

A

cannot distinguish dendrites from axons
(looks kinda like a starfish)

47
Q

function of anaxonic neurons

A

rare, function poorly understood
found in brain and special sense organs

48
Q

where are neuroglia found

A

both the CNS and PNS
makes up about 50% volume of CNS

49
Q

neuroglia vs neurons relative size

A

neuroglia are smaller than neurons but more numerous

50
Q

neuroglia vs neurons action potentials

A

neuroglia do NOT propagate action potentials, but they can communicate (chemically)

51
Q

neuroglia vs neurons cell division

A

unlike neurons, neuroglia continually divide throughout an individual’s lifetime, even within a mature nervous system

52
Q

functions of neuroglia

A

“-glia” = glue
physical structure of nervous tissue
repair framework of NT
undertake phagocytosis
nutrient supply to neurons
regulate interstitial fluid in neural tissue

53
Q

name four types of neuroglia in the CNS

A

Astrocytes
oligodendrocytes
microglia
ependymal cells

54
Q

describe the structure of astrocytes

A

star-shaped
largest and most numerous of the neuroglia - wrapped around capillaries
has microfilaments

55
Q

key functions of astrocytes

A

maintain (chemical) environment around neuron - blood-brain barrier via endothelium
support and repair
communicate with neurons via gliotransmitters (eg. glutamate)

56
Q

structure of oligodendrocytes

A

they resemble astrocytes (star shaped) but are smaller and contain fewer processes

57
Q

function of oligodendrocytes

A

forms insulating multilayered myelin sheath around CNS axons to accelerate action potential
(increases speed of nerve impulse conduction)

can mylenate more than one neuron cell’s axon

58
Q

what is the myelin sheath around CNS axons made of

A

a protein lipid layer

59
Q

describe the appearance of microglia

A

smaller cells with slender processes that give off numerous spine-like projections

60
Q

function of microglia

A

phagocytic – remove cellular debris
phagocytise microbes and damaged nervous tissue

61
Q

structure of ependymal cells

A

single layer of cuboidal (sometimes columnar) cells with both cilia and microvilli

62
Q

location of ependymal cells

A

lines ventricles of the brain and central canal of the spinal cord (and other locations where CSF is found)

63
Q

role of ependymal cells

A

produce and circulate cerebrospinal fluid (CSF)

CSF mechanical buffer - moves nutrients and waste

64
Q

Name the two types of neuroglia in the PNS

A

Schwann cells
Satellite cells

65
Q

what is the function of Schwann cells

A

the PNS equivalent of CNS oligodendrocytes -
forms insulating myelin sheath around axons (1 per axon)
OR supports several non-myelinated axons (multiple per axon)

66
Q

location and function of satellite cells

A

PNS equivalent of CNS astrocytes -
surrounds neuron cell bodies + regulate environment
support + fluid exchange

67
Q

myelinating Schwann structure

A

forms sheath around peripheral axons
outer surface of Schwann cell = neurilemma
single Schwann cell myelinated one INTERNODE of one axon

68
Q

non-myelinating Schwann cell structure and function

A

neurilemma (outer surface) wraps around multiple axons
forms internode of many unmyelinated axons
so that axons are arranged around the Schwann cell nucleus

stabilises positions of axons + isolates them from chemicals in interstitial fluid

BIOSCI 107 (22 decks)

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