Lecture 4: Muscle and nerve tissue Flashcards
What is muscle tissue
Consists of elongated muscle fibres that use energy from ATP to generate force.
By contraction, muscle tissue produces movement, holds posture and generates heat
What are the 3 types of muscle tisse
Skeletal muscle
Cardiac muscle
Smooth muscle
What are the features of skeletal muscle
Attached to bones via tendons
Striated
Very common throughout body
Multinucleate
Voluntary and involuntary (muscles related to posture)
Allow motion, hold posture, produce heat, and protection
What is stapedius?
The name of the smallest skeletal muscle located in the inner ear.
Helps prevent hearing disorders
What is sartorius?
Name of the longest skeletal muscle in the thigh
What are the parts of a muscle fibre
Also known as myocytes or muscle cells, muscle fibres are composed of:
Sarcolemma - cell membrane
Sarcoplasm - cell cytoplasm
Myofibrils
What are the two components of myofibrils?
Thin filament (Actin) and Thick filament (myosin)
What is a myofibril
Cynlindrical structures made of thick and thin filaments
What is epimysium
Surrounds the whole muscle
What is perimysium
Surrounds fascicles (bundles of muscle fibres)
What are fascicles
Bundles of muscle fibres
What is endomysium
Layer for capillaries and nerves around muscle fibres
What are the parts of myofibril?
A band I band H zone M line Z disc Sarcomere
What is the A band
middle, dark part of myofibril which has overlap of actin and myosin filaments
What is I band
part containing only thin filaments
What is H zone
part containing only thick filaments
What is M line
Middle of sarcomere holding thick filaments together
What is Z disc
Located through the center of the I band made up of actinins that link filaments of adjacent sarcomeres
What is a sarcomere
Basic functional units of myofibrils that are separated by Z discs
What are the features of cardiac muscle
Striated Branched Single nucleus Fibres join end to end through intercalated discs (contains desmosomes and gap junctions) Found in the heart Involuntary
What are purkinje fibers?
Specialised muscle cells that conduct electrical activity around heart
Less myofibrils and more specialised connexins (gap junctions)
What are the features of smooth muscle?
No striations
Found in the internal wall of hollow structures
Short, small, spindle-shaped
Involuntary
Can contain gap junctions (allowing peristalsis in small intestine for example)
What are dense bodies?
Dense bodies - made up of actinin - exist around the smooth muscle providing anchoring points for contractile elements to bind to allowing muscle contraction.
They connect intermediate filaments
What is the nervous system composed of
CNS : brain and spinal cord
PNS : all other nervous tissue
What are the two divisions of PNS
Sensory/afferent divison : carry information to CNS
Motor/efferent divison : carry information from CNS to effectors
What is the afferent divison
Sensory division of PNS which carry information to CNS
What is the efferent division
Motor division carrying information from CNS to effectors
What is the function of the nervous system
Sensory : detection of internal and external stimuli and transfer to CNS
Integrative : analysis and storing of information
Motor : stimulation of effectors (muscles and glands) through PNS
What are the two types of nervous tissue cells?
Neurons and neuroglia
What are features of neurons?
Longest cells in the body that make up nervous tissue
Involved in concious and unconscious control
Have a cell body
Have dendrites carrying information into neurons
Have axons carrying information from neuron to neuron
Do not divide
High metabolic rate
What are dendrites?
Short, branched extensions of neurons which allow input of electrical impulses
What are axons?
Long part of neuron that carries action potentials to adjacent neurons
What are the 4 types of neurones?
Multipolar
Bipolar
Unipolar
Anaxonic
What are multipolar neurons/
2 or more dendrites
1 axon
Most common
All motor neurons are multipolar
What are bipolar neurons?
2 distinct processes - 1 dendritic and 1 axon
Cell body between dendritic part and axon part
Rare and small
Special sense organs
What are unipolar neurons?
Dendrites and axons are continuous Cell body off to one side Point where dendrites converge is axon Most sensory nerves are unipolar Long
What are anaxonic neurons?
Rare
Function idk?
Cannot distinguish between axon and dendrite
Found in brain and sense organs
What are neuroglia?
Cells of nervous tissue
A sort of glue that holds nervous tissue together
Found in CNS and PNS
Do not propagate action potentials, but can communicate
Can divide
What are functions of neuroglia (nervous cells)?
Hold physical structure of nervous tissue
Repair framework of nervous tissue
Undertake phagocytosis
Nutrient supply to neurons
Regulate interstitial fluid in neural tissue
What are the types of neuroglia?
CNS - astrocytes - oligodendrocytes - microglia - ependymal cells PNS - schwann cells - satellite cells
What are astrocytes
Type of neuroglia cells found in CNS
Star shaped and large
Numerous
Form syncytium (large co-ordinated network of cells)
Function in supporting tissue and repairing
Communicate with neurons via gliotransmitters (glutamate)
Maintain environment around neuron
Maintain blood-barrier via endothelium (can alter permeability of endothelium in blood vessels)
What are gliotransmitters?
Structures which allow astrocytes to communicate with neurons
What are oligodendrocytes?
Type of neuroglia cells found in CNS
Form insulating myelin-sheath (protein-lipid layer) around CNS axons
Can myelinate more than one neuron cell’s axon
What is the myelin sheath?
Lipid-protein layer around axons that accelerate action potentials
Secreted by oligodendrocytes in CNS and made up of schwann cells in PNS
What are microglia?
Type of neuroglia cells found in CNS
Phagocytic cells of the nervous tissue
What are ependymal cells
Type of neuroglia cells found in CNS
Produce cerebrospinal fluid (CSF)
Have cilia and microvilli
Cilia allow movement of nutrients and waste materials
Microvilli allow scanning and control of composition of cerebrospinal fluid
What are schwann cells
Type of neuroglia found in PNS
Form insulating myelin sheath by wrapping around PNS axons
Support and surround non-myelinated axons also
What are satellite cells
Glue-like role holding PNS nervous tissue together
Provide support and allow fluid exchange of PNS nervous tissue
