Cells and Tissues: Muscle and Nerve Tissue Flashcards
three types of muscle that make up ~50% of body tissue mass
- skeletal
- cardiac
- smooth
Skeletal muscle facts
- appear stratified micro
- ~650 named muscles
- fibres/cells = cylindrical
Smallest muscle
Stapedius (stabilizes smallest bone - bells palsy hyperacusis
1.2mm
Longest muscle
Sartorius hip and knee flexor and lateral rotator
60cm
whats the point of skeletal muscle?
- motion, posture, heat, protection
Striation cause
arrangement of myofibrils within the cells
Myofibrils are composed of two…
Myofilaments
- thin filaments, actin, 8nm diam 1-2 long
- thick filaments, myosin, 16nm diam 1-2 long
What are sarcomeres
- basic functional unit of myofibril
- z discs (z lines) separate sarcomeres
where is epimysium
surrounding anatomical muscle
Where is Perimysium
around fascicles
where is endomysium
around muscle fibres (‘cell’) - layer for capillaries/nerves
where is sarcolemma
actual cell plasma membrane
where is sarcoplasm
cell cytoplasm
A band
Dark, middle part; contains all thick filaments
I band
thin filaments, no thick filaments
H zone
thick filaments, no thin filaments
M line
middle of sarcomere (holds thick filaments together)
Z disc
passes through center of I band (between sarcomeres) made up of actinins - link adjacent sarcomeres
Cardiac muscle
striated, branched, single central nucleas, fibres join end-to-end through intercalated discs
Intercalated discs contains (2 of)
- desmosomes (bind filaments) adhesion and contraction
2. Gap junctions (communication, coordinated)
Cardiac muscle tissue
striated and branched, single cell nuclear, intercalated discs, involuntary, heart
smooth muscle (no striation) location
walls of hollow internal structures - intestines, blood vessel walls
smooth muscle shape and function - is it voluntary?
- short, small, spindle-shaped
- Involuntary, non-striated, single central nucleus
Are skeletal muscles involuntary or voluntary
voluntary; sometimes not always - posture
how does a skeletal muscle cell maintain its size?
- multinucleate (peripheral nuclei pushed to side)
description of skeletal muscle cells?
- long, striated cells that are attached to bones via tendons
smooth muscle (no striation) structure
- non-striated
- single central nucleas
smooth muscle (no striation) control?
- involentary
two nervous system subdivisions?
- central nervous system
- peripheral nervous system
where is the CNS
brain and spinal cord (and optic nerve)
where is the PNS
all nervous tissue outside
what does the sensory/afferent division do?
information to the CNS
what does the motor/efferent division do?
Information from the CNS to the organs (muscles and glands)
Nervous system helps to:
- maintain homeostasis - along with endocrine
- initiates voluntary movements
- responsible for perception, behaviour and memory
three main nervous system functions
- sensory
- integrative
- motor
sensory function
detects internal and external stimuli and transfer
integrative function
analysis and storing info
Motor function
stimulation of effectors - muscle and glands - through PNS i.e. motor here means “effector”
Nervous tissue two types of cells
Neurons (big nerve cells) and neuroglia (small, supportive cells)
neurons control type and length
- both conscious and unconscious control
- longest cells in the body - up to 1m
name 4 of the components of a neuron
- cell body
- dendrites
- axon
Dendrites location and function
- branched from cell body
- recieving input part of the neuron
axon location and function
- carries nerve impulse away from the neuron
- output portion of neuron
- long stick thingy
4 different neuron types
- Multipolar neurons
- bipolar neurons
- unipolar neuron
- anaxonic neuron
three multipolar neurons fun facts
- most common neurons in CNS
- all motor neurons (control skeletal muscles) are in this class
- some of longest (spinal cord to toe muscles)
Bipolar Neurons structure and process
- has one dendritic process and one axon
- cell body between axon and dendrite
multipolar neurons structure
- have 2 or more dendrite and a single axon
bipolar neuron 2 facts
- rare and small (30μm)
- special sense organs (smell, sight, hearing) relay info receptor to neurons
Unipolar Neurons structure
- dendrites and axon are continuous
- cell body off to one side
Unipolar Neurons fun facts
- whole thing where dendrites converge called axon
- most sensory nerves are unipolar
- very long - like 1m motor nerves
anaxonic neuron function and location
- rare and function poorly understood
- found in brain and special sense organs
Anatomy of anaxonic neuron
anatomy cannot distinguish dendrites from axons
Neuroglia location and structure
- CNS and PNS
- make up ~50% of CNS glue
- more of them than neurons and smaller than neurons
can neuroglia propagate action potentials
- they cant propagate action potentials
- can communicate
5 functions of neuroglia
- physcial structure of nervous tissue
- repair framework of nervous tissue
- undertake phagocytosis
nutrient supply to neurons - regulate interstitial fluid in neural tissue
four CNS Neuroglia types
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
Astrocytes structure
- star-shaped
- largest
- most numerous neuroglia
- syncytium network
what do astrocytes use to communicate with neurons?
gilotransmitters e.g. glutamte
regulating ions are used to
maintain the environemnt around the neuron
why do astrocytes wrap around vessels and influence their permeability?
to maintain the blood-brain barrier via endothelium
Oligodendrocytes insulate via?
multilayered insulating sheath called a myelin sheath - a protective lipid layer) around CNS axon
can Oligodendrocytes myelinate more than one axon?
yes
microglia are….?
- phagocytic (resident macrophages)
- protection
what cells produce cerebrospinal fluid?
Ependymal cells
where are Ependymal cells found
- line CSF filled ventricles in brain
- central canal of spinal cord
- other places CSF is found
what kind of cells does Ependymal cells have
- single layer, mainly cuboidal
- have cilia (flow)
- have microvilli (sampling)
Whats Ependymal cells function
CSF mechanical buffer; moves nutrients and waste
two types of Peripheral Nervous System Neuroglia
- schwann cells
- satellite cells
Schwann cells are the PNS version of what?
- PNS version of the CNS Oligodendrocyte
whats the point of schwann cells
- form insulating myelin sheath round axon
- can support or just surround several non-myelinated axons
how many axons for myelination vs support of axon
- One schwann cell per axon for myelination
- more cell/axon if just support
what do Satellite cells do?
- surround neuron cell bodies
- support and fluid exchanges
- equiv astrocytes in CNS
