Lecture Exam 3 Flashcards
Functions of muscle tissue
Movement stability control of openings and passageways heat production glycemic control
-600 human skeletal muscles
-3 kinds of muscle tissue: skeletal, cardiac, smooth
specialized to convert chemical energy of ATP into motion
Describe connective tissue components of muscle
endomysium perimysium fascicles epimysium fascia
Name the types of muscle bone attachments
Muscle indirectly attaches to bone
-tendons connect muscle to bone; collagen fibers in endo, peri, and epimysium that form the tendon connects directly to periosteum
Muscle force and strength come from fascicle arrangement
fusiform- biceps brachii parallel- rectus abdominis triangular- pectoralis major unipennate- palmar interosseous bipennate- rectus femoris multipennate- deltoid circular- orbicularis oculi
Observe how muscles are organized into compartments
- in a transverse sectionlike arms and legs, there are connective tissues that organizes muscles into compartments
- in compartment syndrome, muscle damage is permanent and will not grow back after 6 hours
Structural components of muscle fiber
sarcolemma
sarcoplasm
sarcoplasmic reticulum
T tubules
Components of sarcomere
-sarcomere is a segment of muscle fiber from z-disc to z-disc with an m-line
-myosin thick filament
actin thin filament with tropomyosin and troponin
-striations from organization of actin and myosin
Major proteins of muscle fiber
myosin- protein with 2 globular heads that contain actin and ATP binding sites
actin- thin filament that binds myosin
tropomyosin- block myosin binding when muscle is relaxed
troponin- bind actin, bind tropomyosin, binds calcium
Motor units and muscle contraction
- the motor neuron and muscle cell it touches is the motor unit.
- muscle fibers of one motor unit contract weakly in unison
- average motor unit contains 200 muscle fibers
- small motor units=fine motor control with 3-6 muscle fibers per neuron like eye and hand movements
- large motor units=more strength than control
- powerful contractions caused by 1,000 of muscle fibers per neuron in gastrocnemius in calf
Isometric vs Isotonic movements
Isometric: muscle produces internal tension but external resistance causes it to stay the same length
ex) postural muscles
Isotonic: muscle changes in lenght with no change in tension
Concentric vs Eccentric contractions
concentric: muscle shortens as it maintains tension
ex) lifting weight
eccentric: muscle lengthens as it maintains tension
ex) slowly lowering weight
Why is extra oxygen needed after exercise is over?
- oxygen debt needs to be filled so muscles can return to resting state
- aerobically replenish ATP, regenerates creatine phosphate
- replace O2 for myoglobin
- provides O2 for liver to break down lactate
- provide O2 to cells with high metabolic rates after exercise
Slow Twitch and Fast twitch muscle fibers
Slow(red):
- endurance, resists fatigue
- important for posture muscles
- thin fibers, small motor units for precise movements
Fast(white)
- quick and powerful muscles (eye, hand, gastrocnemius and biceps brachii)
- utilizes glycolysis and anaerobic fermentation
- no myoglobin=white
- large motor units controlled by less excited neurons.
Functions of nervous system
- endocrine and nervous systems maintain internal coordination
- endocrine: releases hormones in blood (slow act, long duration)
- nervous: uses electrical and chemical signals to send cells info (fast acting, short duration)
- sense organs receive info; transmits coded info to brain and spinal cord
- CNS processes info, relates to past experience, and determines response
- CNS issues commands to muscles and glands to carry out a response
CNS vs PNS
Central nervous system: brain and spinal cord
Peripheral nervous system: all nervous system except brain and spinal cord
-sensory (afferent) division: carries signals from receptors to CNS
-motor (efferent) division: carries signals from CNS to gland or muscle, effectors
-visceral motor division (autonomic)
>sympathetic: arouses body for action, accelerates heartbeat and breathing
>parasympathetic: calms body, slows heartbeat and breathing, stimulates digestion and urinary tract
Properties of neurons
Excitability (irritability)
Conductivity
Secretion
Categories of neurons
Sensory (afferent): detect stimuli and transmit info to CNS
Interneurons: in CNS that connects motor and sensory pathways (90% of neurons). Receives many signals from neurons and decides a response
Motor (effferent): send signals to effectors, glands and muscles
Parts of neuron
Dendrites neurosoma axon hillock axon axon terminal
Types of neurons
multipolar: one axon, multiple dendrites (most common in CNS)
bipolar: one axon, one dendrite (olfactory cells, retina, inner ear)
unipolar: one process leading away from neurosoma (skin/organ sensory cells to spinal cord)
Neuroglia in CNS
oligodendrocyte
ependymal
microglia
astrocyte
Neuroglia in PNS
schwann
satellite
Myelin sheath and conduction
myelin sheath created by schwann cells and oligodendrocytes, begins at week 14 of fetal development, and requires a lot of dietary fats
-segmented with nodes of ranvier and internodes
Larger fibers=more surface area=conducts signals faster
-myelin speeds up signal conduction since it can jump between internodes
Under what conditions can nervous tissue regenerate?
- it is in the PNS
- neurosoma is intact
- the cell membrane, nuerilemma remains
How does nervous tissue regenerate?
- fiber distal to injury dies, degenerates, macrophages clean debris
- neurosoma swells, ER breaks up, nucleus moves offcenter
- axon stump sprouts mutliple growth processes as severed distal end degenerates
- schwann cells, basal lamina, and neurilemma form a regeneration tube which helps neuron to grow to original destination and reestablish synaptic connection
- slow growth = 2 years
- nerve fibers may connect to wrong muscle fibers or die
