lecture 4 Flashcards
(86 cards)
1
Q
What does muscle tissue consist of
A
Elongated cells (muscle cells or muscle fibres or myocytes that use energy from the hydrolysis of ATP to generate force
2
Q
As a result of contraction, muscle tissue produces
A
Body movement, maintains posture and generates heat
3
Q
How many types of muscle
A
3
4
Q
Name the three types of muscle
A
Skeletal
Cardiac
Smooth
5
Q
Attachment of skeletal muscles
A
Attached to bones via tendons
6
Q
How do skeletal muscles appear under microscope
A
Striated
7
Q
Contraction of skeletal muscle is
A
Voluntary and usually under conscious control eg posture
8
Q
Shape of fibres (cells) in skeletal muscle
A
Cylindrical
9
Q
Smallest skeletal muscle
A
Stapedius
10
Q
What does the stapedius do
A
Smallest skeletal muscle and it stabilises the smallest human bone the stapes in the ear and prevents hyperacusis - damage to stapedius by extra loud sound perception- and tymapnic reflex by controlling the tension on bones to prevent becoming deaf when hearing loud noises and bells palsy which is caused by paralysis of facial nerve
11
Q
How small is the stapedius
A
1.25mm
12
Q
How long is the sartorius
A
60cm
13
Q
What is the name of the longest skeletal muscle
A
Sartorius
14
Q
How to look underneath sartorius
A
Twist foot and rotate leg
15
Q
Hip functions
A
Flexor, abductor, lateral rotator
16
Q
Functions of knee
A
Flexor
17
Q
How far does sartorius extend
A
Hip to just above knee tibia
18
Q
Structure of skeletal muscle
A
Long and can be up to 30cm
Striated
Multinucleated with many peripheral nuclei pushed to the sides so hard to tell which part of the cell is controlled by which nucleus
19
Q
Control of skeletal muscle
A
Voluntary
20
Q
Function of skeletal muscle
A
Motion posture heat and protection
21
Q
What causes skeletal muscle fibre striations
A
Due to highly organised arrangement of myofibrils within cells
22
Q
Cytoplasm if muscle fibre is called
A
Sarcoplasm
23
Q
What are myofibrils and what do they do
A
They are 2 micrometers diameter and more or less fill the sarcoplasm of muscle fibre and extend its entire length within the cell
24
Q
Skeletal muscle cell membrane
A
Sarcolemma
25
Name the two types of myofilaments that myofibrils are composed of
Thin filaments and thick filament
26
What are thin filaments made of
Mostly actin protein and are 8nm diameters in length which is half of the thick filaments and they are 1-2 micrometers long
27
What are thick filaments made of
Myosin and are 16nm diameter with 1-2 micrometer length
28
Myofilaments do not extend the length of the muscle fibre but
Are arranged in compartments known as sarcomeres
29
What is a sarcomere
Basic functional unit of a myofibril and sarcomeres are seperated by zig zag z discs or z lines
Sarcomeres are segmental batches of ordered blocks of filaments
30
What do z lines di
Seperate sarcomeres and define the end point of a sarcomere where some proteins lock into it
31
Line of order of ct of skeletal muscles
Epimysium
Perimysium
Endomysium
Sarcolemma
Sarcoplasm
32
Line of order of fascicle
Endomysium
Muscle fibre with striations
Sarcolemma and sarcoplasm
Myofibril inside sarcoplasm
Filament inside myofibril
33
How are striations produced
Thick and thin myofilaments overlap to produce the striations in the myofibril
34
What is the A band
Dark middle part which contains all the thick filaments and therefore is the length of the thick filament
Contractile length
35
I band
Thin filaments but no thick filaments - spans between and straddles sarcomeres
36
H zone
Thick filaments but no thin filaments - decreases distance when muscle contracts
Dynamic space and end of overlap between thick and thin filaments
37
M line
Middle of sarcomere and holds thick filaments together
38
Z disk
Passes through centre of I band between sarcomeres in zigzag and is made up of actinins that link filaments of adjacent sarcomeres
39
What and where is titin filament
Squiggly molecular spring shaped - links z disk to m line and provides resting tension in I bandfound between thin filaments
40
What is thin filament made of
Actin
41
What is thick filament made of
Myosin
42
Features of cardiac muscle
Striated and branched
Single central nucleus
Fibres join end to end through junction comprised of intercalated disks
Sequential contraction for muscle coordination
43
Intercalated disks contain
Desmosomes which bind intermediate filaments and provide adhesion in contraction
And gap junctions for communication which are coordinated for rapid conduction
44
What are parkinje fibres
Specialised muscle cells which conduct electrical activity around the heart. They have less myofibrils and more specialised connexins from gap junction
45
Increased coordinated contractions through
Fibres going in lots of different direction so when heart contracts it contracts effectively and layers are different in this
46
Control of cardiac muscle tissue
Involuntary
47
Smooth muscle features
Short spindle shaped and about 30-200 micrometers long with 3-8 micrometer thickest in middle
Non striated
Single central nucleus
48
Smooth muscle movement
Involuntary
49
Where is smooth muscle tissue located
Walls of hollow internal structures and organs
Intestines for peristalsis
Blood vessels walls for change of shape and constriction - needs to change diameter to control and direct blood flow
Also iris of eye
Reproductive and digestive and respiratory urinary system and skin erector pili
50
Shape of smooth muscle tissue allows
Packing efficiency for muscle around cell
51
Thin filaments in smooth muscle tissue
Actin and attached to dense bodies - similar function to z discs and in the dense body the main protein is actinin
52
Intermediate filaments in smooth muscle tissue
Non contractile element and are also connected to dense body
Strong
Dont bend as much
53
What happens during smooth muscle tissue contraction
Tension transmitted to intermediate filaments which dont contract and the cell twists
The dense bodies provide structural connections during contractions
Dense bodies come closer together whereas intermediate filaments dont really move and when tissue encircles another tube it shortens during contraction to change diameter of hollow tube
54
For smooth muscle tissue where are lots of gap junctions and where are few
Gut - lots
Iris - few
55
What system is the nervous tissue a part of
Nervous system
56
Name the two subdivisions of the nervous system
Central nervous system and peripheral nervous system
57
What does the central nervous system consist of
Brain and spinal cord and optic nerve
58
Subdivisions of pns
Sensory/afferent division and motor/efferent division
59
Sensory/afferent sends info to the
Cns
60
Motor/efferent sends
Info from cns to organs (muscles and glands)
61
What does pns consist of
All nervous tissue outside cns
62
Three things nervous system helps with
Maintains homeostasis (along with endocrine system)
Initiates voluntary movements
Responsible for perception, behaviour and memory
63
What are the three major functions that are grouped under activities
- sensory which is detection of internal and external stimuli and transfer it to cns
- integrative - the analysis of storing information and assembling so we can initiate action
- motor - stimulation of effectors like muscle and glands through the pns - motor means effector (doing)
64
Two types of cells in nervous tissue
Neurons - nerve cells that can be very large
Neuroglia - supportive cells of neurons and very small
65
Size of neuron
Longest cell in body up to 1m from spinal cord to toe
66
Control of neurons
Conscious and unconscious
67
What is a dendrite
It is the receiving input part of the neuron and brings impulses into the cell body. Branched dendrites convey nerve impulses (action potential)
68
What does an axon do
Carries nerve impulses away from the neurons cell body. It is the output portion of the neuron. Conducts nerve impulses to another neuron or tissue
69
For our purposes neurons..
Dont divide and have a high metabolic rate meaning they die rapidly without O2.
70
Myelin sheath
Waxy substance coating which helps with conduction
71
Multipolar neuron
2 or more dendrites = multiple areas of info and a single axon leaving
Most common neurons in cns
All motor neurons (control skeletal muscle) are in this class
Some of the longest (spinal cord to toe muscles)
72
Bipolar neurons
Two distinct processes
- 1 dendritic process (can branch at tip but not at cell body)
- 1 axon so info goes downwards
Has cell body between dendrite and axon
- small 30 micrometers
Special sense organs like sight smell hearing relay info from receptor to neuron
You see this type of neuron branching between neurons or involved in special sensory sight smell and hearing
73
Unipolar neurons
Sensory nervous system - most sensory neurons are unipolar
Cell body is off to one side so dendrites and axon are connected and continuous
Very long 1m like motor nerves from cns to toe
Whole thing from where dendrites converge is axon
74
Anaxonic neuron
Rare and function is poorly understood
Anatomy cannot distinguish axons from dendrites
Found in brain and special sense organs
75
Neuroglia
Found in both cns and pns and makes a lot of tissue in cns
Makes up 50% of volume of cns glue
Smaller than neurons but more numerous 5-50x
Do not propogate action potentials but can communicate biochemically
Can divide within the mature nervous system
76
Functions of neuroglia
Makes Physical structure if nervous tissue
Repairs the framework of nervous tissue by walling off damaged areas to enable scarring and prevents cavities from forming
Undertakes phagocytosis
Nutrient supply to neurons
Regulates intertitial fluid which is the environment in pns and cns in neural tissue
77
Four classifications of cns Neuroglia
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
78
5 functions and processes of astrocytes
- star shaped and largest - most numerous of Neuroglia and has syncytium network which often links to itself via lots of different connections
- support (have microfilaments) and repair by scarring
- communicate with neurons via gliotransmitters like glutamate
- maintain environment around neuron such as ion regulation
- maintain blood brain barrier via the endothelium and wraps around vessels to influence permeability preventing some things from blood seeping into the brain
79
Oligodendrocytes functions
- form insulating multilayered myelin sheath which is a protein lipid layer) around cns axons which helps neurons conduct better and faster and less prone to interference - also can put out processes to make more than one neuron
- can myelinate more than one neuron cells axon to accelerate action potential
80
Function of microglia
Phagocytic (resident macrophages) for protection - engulfs materials
Removes damaged tissue of cns and is activated during infection
81
Ependymal cells functions and processes
- produce cerebrospinal fluid which bathes brain and spinal cord and provides nutrients and protection
- line the cfs filled ventricles in brain and central canal of spinal cord
- located in ventricles and in other locations where csf is found
- csf mechanical buffer which moves nutrients and waste
- single layer of predominately cuboidal cells have cilia flow and microvilli sampling
82
Purpose of microvilli in ependymal cells
Make sure csf is in right conditions all the time and maintain composition
83
Purpose of cilia flow in Ependymal cells
Need to move csf around openings in brain and spinal cord called ventricals which is where csf flows
84
Two types of pns neuroglia
Schwann cells and satellite cells
85
What are schwann cells
They are the pns version of cns Oligodendrocytes- they form insulating myelin sheath around axons or can support and surround several non myelinated axons
Note - one schwann cell per axon/neuron for myelination but more axons/cells if just support
86
Purpose and function of satellite cells
- surrounds neuron cell bodies and supports fluid - equivalent to astrocytes in cns
