Muscle & Nervous Tissue Flashcards
There are three types of muscle
comprising ~50% of the body tissue
mass:
i. Skeletal Muscle
ii. Cardiac Muscle
iii. Smooth Muscle
Muscle Tissue
Consists of what type of elongated cells
muscle
fibres or myocytes
As a result of contraction, muscle tissue …
produces body
movements, maintains posture and generates heat.
There are ____named skeletal muscles in the
body
Appear _____under the microscope.
~650
striated
Fibres (remember = cells) are what shape
cylindrical
Smallest: 1.25 mm _____ (in the ear; prevent
“hyperacusis”loud sound perception.
; tympanic reflex; Bell’s Palsy )
stapedius
Longest: up to the 60 cm __________(“Checking for
gum!” : hip: flexor, abductor, lateral rotator; knee: flexor).
sartorius
Skeletal Muscle Tissue structure:
cylindrical cells Striated; Multinucleate (many peripheral nuclei pushed to side)
Attached to bones by
tendons are _______ control
Voluntary
The striations of skeletal muscle fibres (cells) are due to the
highly organised arrangement of
myofibrils within the cells
Myofibrils (2 µm diam) fill the sarcoplasm
of the muscle fibre
Myofibrils are composed of two types of filaments (myofilaments):
Thin filaments: mostly actin; 8 nm diam; 1-2 µm long
– Thick filaments: myosin; 16 nm diam; 1-2 µm long
The _______is the basic
functional unit of a myofibril
separated by_____
sarcomere
Z discs/lines
3 types of Connective tissue of skeletal
muscle
Epimysium: surrounds anatomical muscle Perimysium: fascicles Endomysium: muscle fibres (“cell”)
Cardiac Muscle structure?
What control?
Striated; branched; single
central nucleus; intercalated
discs
involuntry
Intercalated discs contain:
- Desmosomes (bind intermediate filaments)
Provide adhesion in contraction - Gap junctions (communication)
(co ordinated; rapid conduction)
Smooth Muscle structure?
What control?
Non-striated (smooth);Short, Small, spindle-shaped, single, central nucleus Involuntary
The thick and thin filaments overlap to produce the striations in sacromeres in skeletal mucle:
A band: dark, middle ; contains all thickfilaments
I band: thin filaments, no thick filaments
H zone: thickfilaments, no thin filaments
M line:middle (holds thick filaments together)
Z disc: through centre of I band (between sarcomeres) made up of “actinins” –link filaments of adjacent sarcomeres
Smooth Muscle is
Located where?
walls ofhollow internal structures
e.g. intestines (peristalsis); blood vessel walls (constriction);
also : Iris of eye, reproductive; digestive; respiratory; urinary; skin erector pili
Smooth muscle fibres have bundles of thin (e.g. actin) and thick (e.g myosin) filaments.
Thin and intermediate (non-contracting) attach to what?
dense bodies,
functionally similar to Z discs. (Dense body: a major protein is Actinin).
The nervous system has two main subdivisions:
Central nervous system (CNS): brain and spinal cord
–
Peripheral nervous system (PNS): all nervous tissue outside CNS
The nervous system helps to:
maintain homeostasis(along with the endocrine system),
initiates voluntary movements
responsible for perception, behaviour and memory.
nervous system Activities grouped under three major functions:
i.
Sensory: Detection of internal and external stimuli and transfer to CNS
ii.
Integrative: analysis and storing of information
iii.
Motor: stimulation of effectors (e.g. muscle and glands) through PNS i.e. motor here means “effector”
18
Nervous tissue consists of two types of cells:
neurons(nerve cells that can be very large)
•neuroglia (supportive cells–usually small).
Neurons are longest cells in body (up to 1m –spinal cord to toe)
Conscious and unconscious control
Neurons
Have a cell body into which short, branched ____convey nerve impulses (action potentials) and from which a longer, single ____conducts ____impulses to another neuron or tissue.
dendrites
axon
nerve
Multipolar Neurons have_____
dendrites and a ____axon
multiple(2 or more)
single
Most common neurons in CNS
Unipolar Neuron
•The dendrites and axon are______
•Cell body is________________
continuous
off to one side
Most sensory nerves are
unipolar
Has cell body between
_____and ______
axon , dendrite Special sense organs (sight, smell, hearing) relay information from receptor to neurons
what is? • Rare and function poorly understood • Anatomy cannot distinguish dendrites from axons • Found in brain and special sense organs
Anaxonic neuron
what is?
• Found in both CNS and PNS
Make up ~50% the volume of the CNS (“glue”).
• Smaller than neurons but more numerous (5-50x)
• Do not propagate action potentials, but can communicate.
• Can divide within the mature nervous system
Neuroglia
Functions of Neuroglia?
- Physical structure of nervous tissue
- Repair framework of nervous tissue
- Undertake phagocytosis
- Nutrient supply to Neurons
- Regulate interstitial fluid in neural tissue
Classification of Neuroglia
1. CNS Neuroglia
i. Astrocytes: a. Star-shaped
ii. Oligodendrocytes. multilayered
iii. Microglia: Phagocytic
Ependymal cells: Produce cerebrospinal fluid (CSF). Line the (CSF)-filled ventricles in \_\_\_\_ and the central canal of \_\_\_\_ These single layer of predominantly cuboidal cells have \_\_\_\_\_(flow) and \_\_\_\_\_\_\_ (sampling). CSF \_\_\_\_\_\_\_buffer; moves nutrients and waste
brain .spinal cord.
cilia . microvilli.
mechanical
2 cells of Peripheral Nervous System Neuroglia?
i. Schwann cells
ii. Satellite cells:
Schwann cells (“PNS version of CNS oligodendrocyte”) form:
form insulating
myelin sheath around axons or just support and surround several nonmyelinated
axons. (Note: One Schwann cell per axon for myelination but
more axons/cell if just support).
ii. Satellite cells surround______ ___ _______
Support and fluid exchange
neuron cell bodies.
