Muscle and nervous tissue Flashcards
What is the main purpose of muscle tissue?
To convert ATP into use movement
How much of the body is made of muscle?
~50% of mass
What are the functions of muscle tissue?
Produces body movement, maintains posture and generates heat
What are the red types of muscle tissue?
Skeletal, Cardiac, Smooth
How many name skeletal muscles are there?
~650
Where is skeletal muscle found and how is it attached?
Attached onto bones by tendons
What does skeletal muscle look like under a microscope?
Striated cylindrical long cells that are multi nucleated, nucleus is pushed to the side
Is skeletal muscles conscious or unconscious control? voluntary or involuntary? Give an example
It is voluntary but not always conscious, e.g. posture is voluntary but it is involuntary
What is the smallest and largest muscle in the body? What are their sizes?
Stapedius = 1.25mm Sartorius = 60cm
What is the function of the stapedius muscle? What can cause it to not work? What happens when it doesn’t work properly?
Adjusts the way sound travel into your ear,
A viral infection can cause Bell’s palsy when the muscle doesn’t work causing hyperacusis (everything sounds loud)
Where is the Sartorius and what motion does it control?
It is from the hip to the tibia across the front of the thigh
helps leg rotate inwards
What is the reason for the striation of skeletal muscle fibres?
Due ot eh highly organised arrangement of myofibrils within the cells
What are myofibrils?
Filaments that fill the sarcoplasm (cytoplasm of striated muscle cells)
What are the types of filaments that make up myofibrils? Describe them
Thin filaments: mostly actin, 8nm diameter, 1-2μm long
Thick filament: myosin, 16nm diam, 1-2μm long
How are myofilaments arranged?
In compartments of sarcomeres
What is a sarcomere?
The basic functional unit of a myofibril
What separates sarcomeres from each other?
Z discs
What is the organisational level of muscle tissue?
Many sarcomere make up myofibril, these myofibril are packed together into a sucre fibre/cell. These muscle fibres are bundled together to form a fascicle. Multiple fascicles are bound together to form skeletal muscle
What is the composition of a sarcomere?
Thick filaments are in the middle and thick filaments slide over these and are attached to Z discs. M line is in the middle of the sarcomere and holds the thick filaments together and attic filament runs through the sarcomere to and from the Z disc
What is the full structure of skeletal muscle?
Myofibril make up the muscle fibre/cells. Endomysium coasts the muscle fibre. Muscle fibres are bundled together to form a fascicle and is coated by perimysium. Fascicle’s are bundled together to form the skeletal muscle. These muscle tissue is bound by epimysium and this then attaches onto the bone with tendons
What is the purpose of outer sheaths on each organisational level of muscle tissue?
Separates them from each other (e.g. separates muscle tissue, different muscles from each other) so they can slide over each other
What are the different bands in a sarcomere?
A band I band H zone Z disc M line
What is the A band?
Dark middle park that contains full length of the the thick filament (therefore includes the overlapping thin filaments)
What is the I band?
thin filaments excluding the overlapping thick filaments
What is the H zone?
Central zone where there are only thick filaments and no overlapping thin filaments
What is the Z disc? What is its function?
Plat of dense material within the I band
separates the sarcomeres
Where is the M line? What is its function?
In the middle of the sarcomere
Holds the thick filaments together
Where is the cardiac muscle found?
Only in the heart
What would cardiac muscle look like under a microscope?
Striated and branched with a single central nucleus connected with intercalated discs
What do the intercalated discs contain? What are the functions of these components? What is the function of the intercalated discs?
Desmosomes: bind intermediate filaments and provide adhesion in contraction
Gap junctions: communication for co-ordiated rapid conduction
It is to provide rapid communication channels in the hearts for co-ordinated contractions
What other types of tissue other than cardiac tissue can you find intercalated discs?
You can’t, they’re only found in cardiac tissue
Where can you find smooth muscle tissue? Give examples
In the walls of hollow internal structure, e.g. blood vessels and intestines
What would smooth muscle tissue look like under a microscope?
no striations, single nucleus per fibre, short small and spindle shaped (30-200μm long, 3-8μm thick in middle)
What is the structure of a smooth muscle fibre?
Nucleus in the middle made of made of bundles of thick and thin filaments, however the outside of the fibre is bound by intermediate filaments which are connected to dense bodies
What is the function of dense bodies and intermediate filaments?
During contraction, tensions is transmitted to intermediate filament which are held together by dense bodies. This means cells rotate and twist therefore don’t collapse
What is a key function of the twisting motion of smooth muscle fibres?
Allows for the control of fluid/solid movement
What is a major protein in dense bodies? What are functionally similar to?
Actinin, similar to Z discs
What are the two subdivisions of nervous tissue?
The central nervous system (CNS) and peripheral nervous system (PNS)
What is apart of the CNS?
Brain and spinal cord
What is apart of the PNS?
All nervous tissue outside PNS
What are the three major functions of the nervous system? describe them
Sensory: detection of internal and external stimuli
Integrative: analysis and storing of info
Motor: stimulation of effectors (e.g. muscles and glands)
What are the types of cells apart of nervous tissue cells?
Neurons and neuroglia
What is special about neuron cells?
They are the longest cells in the body, up to a meter long
How can neurons be classified?
By structure or function
What are the structural classifications of neurons?
Multipolar
Bipolar
Unipolar
What is the function of a dendrite?
receives signals from other neurons to the cell body
What is the function of an axon?
transmit signals from the cell body to the cells in other tissue
What is the function of a cell body?
Control the neuron and re-directs nerve impulses as necessary
Describe a multipolar neuron
Has 2+ dendrites and a single axon with the cell body within the dendrites
All ____ are multipolar neurons and control ____
motor neurons, skeletal muscle
Describe a bipolar neuron
Lots of branched dendrites that convene into a single dendrite and 1 axon, cell body between axon and dendrite
What are bipolar neurons used for in particular?
Special sense organs (e.g. sight, smell, hearing) which relay information from receptor to neurons
Describe a unipolar neuron
Axons and dendrites are continuous which the cell body off to one side, has many branching axons and dendrites which converge into one branch
What are unipolar neurons commonly used in?
Most sensory nerves
Describe an anaxonic neuron
Cell body in middle and axons and dendrites are indistinguishable
Where are anaxonic neurons found and how common are they?
Found in the brain and special sense organs, however very rare and function poorly understood
What are the functional classifications of neurons?
Sensory, Motor, Interneurons
What kind of structural neurons are sensory neurons? How does the nerve impulse travel through it?
Mostly unipolar
Conveys impulse from a receptor into the CNS (afferent = into the CNS)
What kind of structural neurons are motor neurons? How does the nerve impulse travel through it?
Mostly multipolar
Convey impulse from CNS out to an effector (e.g. muscle or gland) (efferent = away CNS)
What kind of structural neurons are interneurons? Where are they located?
Mostly multipolar, found within CNS between sensory and motor neurons
What are neuroglia?
Another type of nervous tissue
How do neuroglia transmit information?
By chemical signals
Where are neuroglia found?
In both the CNS and PNS
What are the difference between neuroglia and neurons?
Neuroglia = chemical communication not electrical, can divide within mature nervous system, much smaller
What percent of the volume of the CNS do they make up? How much more numerous are they in the nervous tissue?
~50%, 5-50 times more numerous
What are the functions of neuroglia?
Provides physical structure of nervous tissue, repairs tissue, undertakes phagocytosis, provides nutrients to neurons and regulate interstitial fluid in neural tissue
What is neuroglia?
The connective tissue of the nervous tissue
What are the two types of neuroglia?
CNS and PNS neuroglia
What are the types of CNS neuroglia?
Astrocytes, Oligodendrocytes, Microglia and Eppendymal cells
What is the function of astrocytes?
Aids communication via gliotransmitters such as glutamate, maintain environment around neuron by regulating ions, repairs tissue (causes scarring), support nervous tissue (has microfilaments), maintain blood-brain barrier by wrapping around blood vessels and controlling permeability
What is the structure and arrangement of astrocytes?
Start shaped and in a syncytium network (where a multinucleate cell forms from the joining of multiple uni-nuclear cells????)
What is the function of the oligodendrocytes?
Form insulation multiplayer myelin sheath around CNS axons, by putting more myelin on axons increases the speed of the electrical impulse
What is the function of the microglia?
Performs phagocytic functions such as removing cell debris from damage, removes any bacteria that may have gotten through blood brain barrier
What is the function of the ependymal cells?
Produces cerebrospinal fluid (CSF)
Where are ependymal cells found?
They line the CSF filled ventricles in the brain and central canal of the spinal cord
What is the function of cerebrospinal fluid (CSF)? Where is it found?
It bathes the spinal cord and brain
Provides nutrition and provides a mechanical buffer for brain and spinal tissue
What kind of cell are ependymal cells? What is special about these cells? What does it allow them to do?
Cuboidal cells
They are ciliated and have microvilli on them
The cilia help move fluid around and the microvilli allow the the ependymal cells to sample the CSF to ensure it is the correct mixture for the brain and spinal cord
What is the difference between cilia and microvilli?
Cilia help to move things around, microvilli absorb nutrients
What are the types of PNS neuroglia?
Schwann cells, satellite cells
What is the function of schwann cells?
Form insulating myelin sheet around axons but can also just support non-myelinated axons
What are schwann cells similar to? What are key differences between these though?
similar to oligodendrocytes but for PNS
However they can only form an insulating sheath around one axon (oligodendrocytes can form myelin around multiple axons)
They are also dual functional (unlike oligodendrocytes) able to support several non-myelinated axons
How do schwann cells support multiple axons?
The axons get imbedded in the schwann cells
What is the function of satellite cells? What are they similar to in function?
Provide fluid exchange and alter the enviro and nutritional status of the neuron
Similar to astrocytes
Where are satellite cells found?
Sit around neuron cell bodies
