muscles & nerves

general features of muscle tissue

• elongated cells (muscle fibres/myocytes)

• use ATP to generate force

• contain actin and myosin filaments

types of muscle tissue

• skeletal

• cardiac

• smooth

skeletal muscle (location, structure, function)

• attached to bones via tendons;

• long cylindrical fibres, striated, multinucleated (peripheral nuclei).

• voluntary control

• functions: movement, posture, heat production, protection

internal structure of skeletal muscle (hierarchy)

• muscles

• fascicles

• myocyte (cell)

• myofibrils

• myofilaments (actin and myosin)

• sarcomeres

connective tissue of skeletal muscle (hierachy)

• epimysium (surrounds muscle)

• perimysium (around fascicles)

• endomysium (inside fascicle, wraps around sarcolemma)

• sarcolemma (actual cell membrane)

• sarcoplasm

key components of skeletal muscle

• sarcolemma (cell membrane)

• sarcoplasm (cytoplasm)

• actin (thin)

• myosin (thick)

myofibrils

• bundles of actin and myosin in sarcomeres

• causes striations

sarcomere structure
A band, I band, H zone, M line, Z disc

= contains thick and thin
= two at each end, thin only. (titin filament)
= middle, thick only
= centre
= boundary of sarcomere

sarcomere changes during contraction

I band shortens , H zone reduces, A band constant

function of fascicles

bundle of muscle fibres, coordinated contraction

titin filament

• located in I band of sarcomere

• stabilises & assists during contraction

cardiac muscle

• found in heart; striated, branched fibres

• single central nucleus

• coordinated pump

• intercalated discs

• purkinje fibres

intercalated discs

• junctions connecting cardiac cells

• contain desmosomes and gap junctions

purkinje fibres

• cardiac muscle cells for electrical conduction

• few myofibrils, more gap junctions

smooth muscle (location, structure, function)

• walls of hollow organs (intestines, blood vessels, uterus, bladder)

• non-striated, spindle-shaped cells

• single nucleus

• involuntary

• functions in movement of substances (peristalsis) and control of lumen

internal structure of smooth muscle

• actin and myosin

• no sacromeres

• filaments attach to dense bodies

general features of nervous tissue

• specialised for communication

• detects and responds to stimuli

• maintains homeostasis

divisions of nervous system

CNS - brain, spinal cord, optic nerve

PNS - all nervous tissue outside CNS

functional divisions of PNS

afferent (sensory) to PNS

efferent (motor) from CNS to effectors (muscles and glands)

Afferent arrives, efferent exits

cells in nervous tissuee

neurons (signal transmissions) neuroglia (support cells)

• large, excitable cells

• action potentials

• does not divide

• high metabolic rate

neurons

structure of neuron

• dendrites

• cell body (soma)

• trigger zone

• axon

• myelin sheath

• axon terminals

receive input in a neuron

dendrites

link together , form blood brain barrier

astrocytes

• form myelin sheath in CNS

• myelinate multiple axons

• increase action potential

oligodendrocytes

phagocytes of CNS

microglia

ependymal CELLS

line brain ventricle and spinal canal where cerebrospinal fluid circulates.

cilia for movement, microvilli samples fluid.

schwann cell

• pns neuroglia

• myelinates one axon at a time, supports others

satellite cells

• pns neuroglia

• like cns astrocytes

periastalsis

involuntary contractions that move food, liquids, waste through digestive tract