Chapter 45: Systems and Locomotion
What are the three things a skeleton provides structure for?
Support, Locomotion, and Protection
What are the two major types of skeletons?
Endoskeleton adn Exoskeleton
What does the exoskeleton surround and protect?
Internal organs, environment, and predators
What is the exoskeleton made of?
Chitin - polysaccharide (Some use calcium)
What is segmentation in the exoskeleton helpful for?
What is ecdysis?
Molting for growing
What organisms inhabits all ecological niches?
What are the differences in exoskeleton due to survival?
Flight and Protection
What is the endoskeleton function?
Internal support and protection
What is. bone?
Living, dynamic tissue with both organic and mineral components
What are the bone forming cells?
Osteoblasts and Osteocytes
What are Osteoblasts and osteocytes composed of providing strength and flexibility?
What are the cells that break down bone?
What are the two mineral ions provided through an animals diet?
Ca2+ and PO4 2-
What are the 3 functions of the vertebrate skeleton?
Support, Protection. of internal surfaces, and Movement
What are the two parts of the vertebrate skeleton?
Axial Skeleton and Appendicular skeleton
What is the axial skeleton?
Main longitudinal axis
What is the appendicular skeleton?
Limb bones and girdles
What is a joint?
Where two or more bones come together
What are three types of movement?
Pivot, Hinge, Ball and Socket
What is formed in marrow of bones?
Blood cells and platelets
When supply is low, what mineral do the bones supply for the body?
What do bones. provide?
Framework for skeletal muscles
How many types of muscle vertebrates have and how are they classified?
They a re classified according to structure, function, and control mechanisms
What are the three types of muscle and where are they located?
1. Cardiac Muscle - only found in the heart
2. Smooth muscle - surrounds. and forms part of the lining hollow organs and tubes
3. Skeletal muscle - directly involved in. locomotion
What kind of tissue bonds skeletal muscle together?
What are tendons?
Linkage of muscles to bones
As bone moves, muscle (shortens or extends)?
What happens. to the bones when a muscle is contracted?
Attached bones pulled toward or away from each other (ONLY a pulling force)
What is a flexor?
Bending a limb at a joint
What is an extensor?
Straightening of a limb
What are antagonists?
Groups of muscles that produce oppositely directed movements at a joint
Where do skeletal muscle fibers arise from?
Cells that fish to form a single cell with. multiple nuclei
What are myofibrils?
Cylinidrical bundles in. muscle fibers
What does each myofibril contain?
Repeating until of filaments (sarcomeres)
What are thick filaments made of?
What are thin filaments made of?
Actin and other proteins
What 2 types of bands on up a sarcomere?
A and I
What is the A band?
Wide. formed by thick filaments
What is the Z line?
Network of proteins to which thin filaments are attached
How many successive Z lines define a sarcomere?
What is the I band?
Contains portions of thing filaments that fo not overall thick filaments
What is the. H zone?
Narrow region in center of A band, space between the 2 sets of thin. filaments
What is M line?
In the center of H zone, proteins the think central regions of adjacent thick filaments
What are cross-bridges?
Spaces between overlapping thick and think filaments that are bridged together
What are thin filaments?
Actin molecules that form two intertwined helical chains
What two proteins are chains closely associated with? And, what are they important for regulation of?
Tropomyosin and Troponin
They are important in regulating contractions
What kind of structure does Myosin have and what does it mean?
Three domain structure
- Composed of two intertwined tails, two hinges, and two heads
What are thick filaments made of?
Many myosin proteins, with hinges and heads extending out to sides and forming cross-bridges
Each head of myosin contains bonding sites for ________ and _______?
Actin and ATP
When do sarcomeres shorten?
As thin filaments slide past stationary thick filaments (Z line towards the M line)
When myosin cross-bridges attach to thin filaments, what happens?
Thin filaments are formed toward center of sarcomere
What is the first step of the cross-bridge cycle?
Cross-bridge binds to actin in response to increase in Ca2+ concentration
What is the second step of the cross-bridge cycle?
Cross-Bridge and thin filaments move "power stroke"
What is the third step of the cross-bridge cycle?
ATP binds to myosin, and cross-bridge detaches
What is the fourth, and final step of the cross-bridge cycle?
ATP hydrolysis reenergizes and resets the cross-bridge
How is Tropomyosin arranged?
Rod-shaped molecule composed of two intertwined proteins
Arranged. along length of actin thin filament
What happens with tropomyosin in the absence of Ca2+?
It covers myosin-binding sites and prevents cross-bridges from making contact with actin
What is the structure of troponin?
Smaller protein bound to tropomyosin and actin
Binds Ca2+ and moves tropomyosin off of myosin-binding site - permits cross-bridge cycling to occur
What happens with Troponin when Ca2+ is removed?
The process is reversed and contraction stops
What do skeletal muscle cell action potentials cause rises in and releases from?
They cause rises in cytosolic Ca2+ and is released from sarcoplasmic reticulum
What are invaginations of the plasma membrane?
Transverse (T-tubles) Tubules
What is the role of ion pumped in the excitation and coupling of skeletal muscle cells?
They return calcium to the sarcoplasmic reticulum, resulting in muscle relaxation
What is the neuromuscular junction?
Junction of motor neuron's axons and muscle fibers
The axon divides into terminals containing vesicles of what?
What is the region of muscle fiber under an axon terminal called?
Motor end plate (It is folded into junctional folds to increase surface area)
What Na+ flows into a muscle cell, what happens?
Depolarization and an action potential travels through T-tubles
Overstimulation of muscle fiber is prevented by?
Acetylcholinesterase (which removes acetylcholine)
What are slow fibers?
Have myosin with a low ATPase activity
What are fast fibers?
Contain myosin with higher ATPase activity
If the maximal force produced by each kind of fiber is the same, what varies (making them different)?
The rate of cross-bridge cycling
What are oxidative fibers?
Contain numerous mitochondria and have a high capacity for oxidative phosphorylation
What do oxidative fibers contain large amounts of?
Myoglobin as an intracellular reservoir of oxygen
What are glycolic fibers?
Few mitochondria but a high concentration of glycolic enzymes and large stores of glycogen
Why are glycolic fibers pale or white?
They contain little myoglobin
What are the three major types of skeletal muscle fibers?
Slow-oxidative, Fast-oxidative, and Fast-glycotic
What are slow-oxidative fibers?
Low rates of myosin ATP hydrolysis but makes large amounts of ATP
What are slow-oxidative fibers used for?
Prolonged, regular activity (Posture, flight)
What are fast-oxidative fibers?
High myosin activity, makes large amounts of ATP
What are fast-oxidative fibers used for?
Suited for rapid actions (Bird song, rattlesnake tail)
What are fast-glycotic fibers?
High myosin activity but cannot make as much ATP
What are fast-glycotic fibers used for?
Suited for rapid, intense actions but fatigue quickly (Cheetah sprints)
An increased amount of exercise can produce an increase in what?
The size of muscle fibers and their capacity for ATP production
What is Atrophy?
Reduction in size of a muscle
When does Atrophy occur?
As a result of decline or cessation of muscular activity
What are two constraints to animal locomotion?
Must overcome drag
Energy is required for thrust and/or lift
What does locomotion result from?
Muscular contractions exerting force on the skeleton
What is the greatest challenge for locomotion in water?
The density of water
What is an energetic advantage of locomotion in water?
Do not need to overcome gravity
What is the main way aquatic animals produce locomotion?
What is the most energetically cost way of locomotion?
Locomotion on land
What must be overcome at every step when moving on land?
Most animals limit ground contact to reduce what?
What are the only four occasions where locomotion is involved in air?
Ptersosaurs, insects, birds, and mammals (bats)
What are the numerous advantages of locomotion in air?
Escape, scan large areas, inhabit inaccessible ares
What are two things you must overcome when flying?
Gravity and air resistance
What is the lift and thrust in vertebrates provided by?
Pectoral and back muscles
What are rickets?
Improper mineral deposition (Vitamin D)
What is Osteoporosis?
Occurs when normal balance between bone formation and breakdown is disrupted
What is muscular dystrophy?
Progressive degeneration of skeletal and cardiac muscles, ultimately leading to death