37 Questions
What is the main component of the H zone?
Thick filaments (myosin)
Which structure holds the thick filaments together in a sarcomere?
M Line
What is the function of the Z Disc?
Links filaments of adjacent sarcomeres
Which component acts like a molecular spring and provides resting tension in the I band?
Titin
In the sliding filament mechanism, what forms the basic units stacked throughout muscle tissue?
Sarcomeres
Which structure passes through the centre of the I band between sarcomeres?
Z Disc
What is the fundamental functional unit of a myofibril?
Sarcomere
Which type of filaments primarily consist of actin?
Thin filaments
What gives rise to the striations in the myofibril?
Overlap of thin and thick filaments
What is the composition of the A Band in a myofibril?
Contains all the thick filaments (made of myosin)
Which part of the myofibril is visualized as the 'chunky centre of a chocolate bar'?
A Band
Which type of filaments are organized into compartments called sarcomeres?
Myofilaments
What is the main difference between smooth muscle and skeletal muscle?
Smooth muscle has a non-striated appearance, while skeletal muscle has a striated appearance.
How are intermediate filaments involved in the function of smooth muscle cells?
Intermediate filaments serve as anchors connecting to dense bodies.
What distinguishes nervous tissue from other types of tissue in the body?
Nervous tissue forms the essential component of the nervous system.
Which part of the nervous system acts as the command center for overall coordination?
Central Nervous System (CNS)
How do smooth muscle cells differ from skeletal muscle cells in terms of striation?
Smooth muscle cells are striated, while skeletal muscle cells are non-striated.
What type of filaments attach to 'dense bodies' within smooth muscle cells?
Actin filaments
What is the role of intermediate filaments in smooth muscle contraction?
Intermediate filaments provide structural support by connecting to dense bodies.
What distinguishes the Central Nervous System (CNS) from the Peripheral Nervous System (PNS)?
The CNS acts as the command center, while the PNS transmits information to the brain.
In what way does smooth muscle differ from skeletal muscle cells regarding its appearance?
Smooth muscles lack stripes, unlike skeletal muscles which have a striated appearance.
What is the role of the axon in a neuron?
Transmitter cable
Where are bipolar neurons commonly found?
Retina, olfactory epithelium, cochlea
What distinguishes unipolar neurons from bipolar neurons?
Length of axon
What is a key feature of unipolar neurons?
Continuous dendrites and axon
Which type of neuron is mainly responsible for relaying sensory information to the central nervous system?
Unipolar neurons
What is the typical size of a bipolar neuron?
30 micrometres
Where can unipolar neurons be found in the body?
Skin, muscles, organs
What role do astrocytes play in the nervous system?
Structural support and repair of brain tissue
How do oligodendrocytes contribute to nerve function?
Wrap around CNS axons to form myelin sheath
What is the main function of microglia in the nervous system?
Protection as bodyguards of the nervous system
Which neuroglia cell type influences the permeability and maintenance of the blood-brain barrier?
Astrocytes
What distinguishes oligodendrocytes from Schwann cells in terms of myelination?
Oligodendrocytes myelinate multiple axons, while Schwann cells only myelinate one axon
Which neuroglia cell type resembles little stars and forms a syncytium network within the nervous system?
Astrocytes
How do astrocytes communicate with neurons?
Using special molecules like glutamate
What feature distinguishes astrocytes from other neuroglia in terms of numbers and size?
They are the largest and most numerous neuroglia in the nervous system
What is the role of oligodendrocytes in terms of nerve function?
Creating a multilayered myelin sheath around CNS axons to boost speed
Study Notes
Smooth Muscle
- Smooth muscle is involuntary, non-striated (no stripes), and found everywhere in the body, from intestines to blood vessels.
- Each smooth muscle cell has a single central nucleus, bundles of thin (actin) and thick (myosin) filaments, and intermediate filaments that connect to dense bodies.
- When smooth muscle contracts, it twists gently, with tension traveling to the intermediate filaments, which don't contract themselves.
Nervous Tissue
- Nervous tissue is the essential component of the nervous system, consisting of the central nervous system (CNS) and peripheral nervous system (PNS).
- The CNS is the command centre, including the brain and H zone.
Muscle Contraction
- The sliding filament mechanism helps understand how muscles contract, with sarcomeres as the basic units stacked throughout muscle tissue.
- Myofibrils are the contractile elements within muscle cells, composed of thin filaments (actin) and thick filaments (myosin).
- During muscle contraction, thin and thick filaments slide past each other, leading to muscle shortening.
Sarcomeres
- Sarcomeres are the fundamental functional units of a myofibril, consisting of overlapping thin and thick filaments.
- A band is the dark, middle part of the myofibril, containing thick filaments.
- I band is the lighter region between A bands, containing only thin filaments.
Neurons
- Neurons are the building blocks of the nervous system, consisting of dendrites, axon, and cell body.
- Dendrites are like the receiving antenna, axon is the transmitter cable, and cell body coordinates the neuron's activities.
Types of Neurons
- Bipolar neurons are small, rare, and found in special sense organs, relaying information from sensory receptors to other neurons.
- Unipolar neurons are long-distance runners, often sensory specialists, and can stretch up to 1 meter.
Neuroglia
- Neuroglia are like the support crew for neurons, providing structural support, repair, and maintenance of the brain's environment.
- Astrocytes are the largest and most numerous neuroglia, resembling little stars, and are involved in various functions like gliotransmitters, environment management, and blood-brain barrier maintenance.
- Oligodendrocytes are like the insulators for neurons, creating a myelin sheath around CNS axons to accelerate action potentials.
- Microglia are like the bodyguards of the nervous system.
Test your knowledge on the composition of myofibrils within muscle fibres, including thin filaments primarily composed of actin and thick filaments composed of myosin. Explore the structure and components of myofibrils found in muscle cells.
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