Lecture 4: Muscle and Nervous tissue Flashcards
Describe the general features of muscle tissue and have an understanding of the three types of muscle, their location, structure and functional control Describe the general features of nervous tissue and have an understanding of the function of the different components
Definition of Muscle tissue and what system is it part of
elongated cells that use energy from hydrolysis of ATP to generate force. It is part of the Muscular system.
Muscle cells also called
myocyte, muscle fibre
What is the main purposes of Muscular tissue
To produce body movements, maintain posture, generate heat and provide protection.
3 types of Muscle tissue
Skeletal, cardiac, smooth
Skeletal muscle : basic structure, function and location
Structure: striated, multinucleated cells that are long. They are found attached to bones by tendons (CT) and functions are motion, heat, posture and protection.
Out of the three types of skeletal muscle which is under voluntary control.
Skeletal muscle. Cardiac and smooth muscle is under involuntary control.
Smallest skeletal muscle is the: … It is found in the: …. and is responsible for…
Stapedius, ear, stabilizes the stapes, prevents hyperacusis
Longest skeletal muscle is the: … It is found in the: …. and is responsible for…
Sartorius, hip , rotating the foot
List the layers of structure from biggest to smallest in what actually makes the skeletal muscle tissue. (> = made of)
Skeletal muscle tissue > bundles of muscle fibres called fascicles. One muscle fibre> myofibrils within the sarcoplasm> myofilaments
Tendon: what type of CT and where is it found
Dense regular CT. found attaching muscle to bone.
myofibrils are made of two types of myofilaments
Thin filaments - actin and thick filaments - myosin
In the microscopic anatomy of muscle fibre, which component fills the sarcoplasm of the muscle fibre and which component is arranged in compartments called sarcomeres
Myofibrils fill the sarcoplasm. Myofilaments are arranged in sarcomeres.
Epimysium: what type of CT and where is it found
Dense irregular CT. surrounds anatomical muscle at the biggest level.
Perimysium : what type of CT and where is it found
Dense irregular CT. surrounds the fascicles (bundles of muscle fibres)
Endomysium : what type of CT and where is it found
Areolar CT. surrounds each muscle fibres (in between cells)- the layer where the capillaries and nerves are passing through
What is the Sarcolemma
cell membrane of the muscle cell/ muscle fibre.
Which sections of the myofibril look smaller when the muscle contracts
the H zone, and the I band. The dark bands of the muscle look bigger (A band)
A band: dark What is it and where is it
The middle 3/4 of the sarcomere that has all thick filaments. It also includes any overlapping thin filaments that happen to be there and the H zone.
I band : What is it and where is it
The last 1/8 of the sarcomere and a 1/8 section after the Z disc where there are only thin filaments
H zone : What is it and where is it
It is a zone around the M line where there are are only thick filaments in the middle. (no thin filaments)
M line: What is it and where is it
a disc that holds the thick filaments together in the Middle of the sarcomere
Z disc/line : Where is it and what is it.
It is a dense plate of material that passes through the centre of the I band separating sarcomeres. It is made of actinins that link the filaments of adjacent sarcomeres
Cardiac muscle : basic structure, function and location
Striated, branched cells with single central nucleus. Fibres join end to end by intercalated discs. Found in the heart wall and used to pump blood.
Intercalated discs contain what two things. What do those two things do?
Desmosomes that bind intermediate filaments to give adhesion during contraction.
Gap junctions for rapid conduction of contraction stimulus.
What is the one muscle cell that is not striated
smooth muscle; cardiac and skeletal is striated.
What are Purkinje fibres
specialised muscle cells that conduct electrical signals around the heart so have less myofibrils and special connexins.
Smooth muscle: deep structure
Spindle shaped cells with intermediate filaments strapping diamonds across the surface, the corners are dense bodies, with thin filaments connecting vertically down the diamond with a band of thick filaments in middle of these thin filaments.
Smooth muscle : basic structure, function and location
Non striated, spindle cells with a single central nucleus. Function is in constriction and propulsion. Its found in the walls of hollow internal structures- eg blood vessels. intestines, skin, iris.
What muscle cells have centrally located nucleus
only smooth and cardiac muscle . skeletal muscle has peripheral multinucleated cells.
Where does the smooth muscle cell have lots of gap junctions and no gap junctions
Lots: gut. No gap junctions: Iris
Describe the mechanism of contraction in a smooth muscle cell
During contraction, tension is transmitted to the intermediate filaments and the cell twists as it contracts about these “stable rods.”
Nervous tissue is part of the Nervous system. What are the two subdivisions of the nervous system
Central Nervous System which includes the Brain, spinal cord and optic nerve.
Peripheral Nervous System which includes all other nervous tissue
What are the two categories of Nervous tissue
neurons ( longest cells) , neuroglia (short supportive cells)
Multipolar neurons : structure and functional classification
2 or more dendrites and a single axon. Convey action potential from CNS to an effector (muscle or gland) as a motor neuron or be a interneuron between sensory and motor neurons.
Bipolar neurons - structure and functional classification
Has cell body between one distinct dendrite and one axon. Rare, Found in special sense organs relaying information from receptor to neurons.
Unipolar Neuron -structure and functional classification
continuous dendrite to axon (part after dendrites converge) process with cell body off to the side.
Sensory neuron that conveys action potential from a receptor into the CNS.
Anaxonic neuron- brain
Can’t tell dendrites from axons, found in brain and special sense organs but functions not well understood.
Neuroglia function
physical structure of nervous tissue, repair framework, phagocytosis, nutrient supply to neurons, regulate environment
What is the network of astrocytes
Syncytium
Astrocytes : 4 functions
- Maintain the blood brain barrier by wrapping around bV.
- Have microfilaments that support neurons and repair neurons (scar)
- Maintain the chemical environment
- Communicate with neurons via gliotransmitters.
Oligodendrocytes (few tree cells) function
Form insulating multilayered myelin sheath around CNS axons. Can myelinate more than one neuron, accelerate the action potential.
Microglia function
Resident macrophage that eats microbes and damaged tissue. It can be inactive and active.
Ependymal cells found
Lining the Cerebrospinal fluid filled ventricles of the brain and central canal of spinal cord
Ependymal cells function
producing cerebrospinal fluid protects the brain as a mechanical buffer. They also assist circulation of CSF which moves nutrients and wastes.
Ependymal cell structure
single layer of cuboidal cells that have cillia for flow and microvilli for sampling
Schwann cells function: myelinating and non myelinating
1 schwann cell per axon can form insulating myelin sheath for PNS neuron for M.
For nM it can just support several non myelinated axons
Are actin and myosin filaments found in all muscle cell types
yes
What are dense bodies
Made of protein actinin, and functionally similar to z discs.
What are the three things that nervous system helps us to do
maintain homoestasis, voluntary movements, perception, behaviour and memory.
What are the main structural features of neurons
has a Cell body (soma) into which short branched dendrites convey action potentials and from which a longer single axon conducts nerve impulses to another neuron or tissue.
What is the metabolic and mitotic rate of neurons
High metabolic rate (die rapidly w/out O2) and do not divide.
What are the 4 types of neurons
Multipolar, bipolar, unipolar and anaxonic
What are the types of neuroglia in the PNS
Myelinating and non myelinating Schwann cells, Satellite
What are the types of neuroglia in the CNS
Astrocytes, ogliodendrocytes, ependymal, microglia
What is the difference between afferent and efferent
afferent is directed in (of CNS) and efferent is directed out (of CNS)
Satellite cells function
Provide structural support around cell bodies of PNS neurons. regulates fluid exchange between cell bodies and interstitial fluid.
What are the sensory, integrative and motor functions of the nervous system
- detection of internal/external stimuli and transfer to CNS
- Analysis and storing of information
- Stimulation of effectors.
