http://highered.mcgraw-hill.com/sites/dl/free/ image from our text book powerpoint
11.1 Overview of Skeletal System
11.2 Bone Growth, Remodeling, and Repair
11.3 Bones of the Axial Skeleton
11.4 Bones of the Appendicular Skeleton
11.5 Articulations
11.1 Overview of Skeletal System
Skeletal system consists of bones, cartilage, and fibrous connective tissue, which occurs in ligaments and joints-
The skeleton supports the body-
The skeleton protects soft body parts-
The skeleton produces blood cells-
The skeleton stores minerals and fat-
The skeleton, along with muscles, permits flexible body movement-
Anatomy of a long bone:
Diaphysis (shaft) is main portion-
Diaphysis has medullary cavity (walls contain compact bone)-
Medullary cavity filled with yellow bone marrow that stores fat-
Compact bone is highly organized- bone cells are called osteocytes and the ostescytes are in lacunae-
Matrix fills lacunae spaces-
Spongy bone is “unorganized’ when compared to compact bone- spaces of spongy bone are filled with red bone marrow which produces al types of blood cells-
Cartilage is not as strong as bone- it is flexible due to gel like matrix-cells of cartilage- these cells are called chondrocytes and are found irregularly in lacunae-
Cartilage does not have blood vessels, and is slow healing-
Three types of cartilage:
1-hyaline cartilage is firm somewhat flexible
2-fibrocartilage is stronger and matrix contains collagen fibers
3- elastic cartilage is flexible and matrix contains mostly elastin fibers
Fibrous connective tissue makes up the ligaments that connect bone to bone and bone to joint-
11.2 Bone Growth, Remodeling, and Repair
Bones ability to respond to stress by changing size, shape, and strength is called remodeling-
When bones are fractured and they repair this is called bone repair-
Bones are composed of living tissue- they are composed of several different types of cells-
1- Osteoblasts are bone forming cells
2- Osteocytes are mature bone cells
3- Osteoclasts are bone absorbing cells
Osteoclasts are removing matrix’ and osteoblasts are building it up-
Ossification is the formation of bone-
Intramembranous bones are flat bones such as skull bones-
Intramembranous ossification is the formation of bone between sheets of fibrous connective tissue-
Endochondral Ossification - most of the human skeleton falls into this type of bone-
Bone replaces the cartilaginous models of the bones- calcified bone matrix makes it possible for the endochondral bones to hold and support weight-
This process from cartilage to most long bone is as follows:
Cartilage model into the bone collar into the primary ossification center into the medullary cavity and secondary ossification sites and finally into the epiphyseal (growth) plate-
The epiphyseal contains four layers:
1- resting zone is where cartilage remains
2-proliferating zone is where chondrocytes produce new cartilage cells
3- degenerating zone cartilage cells dying off
4- ossification zone is where bone is forming
Bone length growth is final once the epiphyseal plate closes- hormones control the activity of the epiphyseal plate-
Hormones affect bone growth
Hormones are chemical messengers made in one part of the body but used by the body in another part.
Vitamin D is an important vitamin for bone formation because it is converted into a hormone that works in the intestinal tract with the absorption of calcium-
Bone Remodeling and its Role in Homeostasis
Osteoclasts is the break down of bone and Osteoblasts is the reforming process that is continually taking place within the body- This process is called “Remodeling”
Paget’s Disease is where the new bone is generated too quickly, therefore softer and weaker than desired-
Bone recycling allows our bodies to regulate the amount of calcium in the blood- blood calcium is important for clotting to occur-bones are the storage site for calcium-blood calcium is regulate by two hormones:
1- parathyroid hormone accelerates recycling and increases blood calcium level-
2- calcitonin hormone acts opposite to parathyroid hormone
Bone remodeling is the reason why our bones can respond to stress- exercise is strongly recommended as this also keeps bones strong by stimulating the osteoblasts instead of the osteoclasts process-
Bone Repair
The four steps to bone repair:
1-hematoma- after a fracture, blood escapes from vessels to form a hematoma in space between broken bones (6-8 hours)
2- fibrocartilaginous callus- tissue repair starts when a fibrocartilaginous callus fills space between ends of broken bones (approx. 3 weeks)
3- bony callus- osteoblasts produce trabeculae of spongy bone and convert fibrocartilaginous callus to bony callus- joins broken bones together (3-4 months)
4- remodeling- osteoblasts build new compact bone, osteoclasts absorb spongy bone, new medullary cavity is formed
Science Focus page 215
Identifying skeletal remains is discussed. Age of the remains can be approximated by dentition, which is studying the structure of the teeth. Bone ossification also gives clues to the approximate age of the remains. Pelvic bones are the best indicator of the gender. Observed racial characteristics can sometimes help determine the ethnicity of the skeleton, however, it is difficult with all of the genetic blending.
11.3 Bones of the Axial Skeleton
There are 206 bones of the skeleton.
Axial skeleton lies in the midline of body- consists of skull, hyoid bone, vertebral column, and rib cage-
The skull formed by cranium and facial bones-
The cranium protects the brain- adults have 8 bones tightly joined together to form cranium- sinuses are contained in the cranium- major bones of the cranium are named like the lobes of the brain: frontal, parietal, occipital, temporal-
Facial bones mainly consist of the;
Mandible- lower jaw
Maxillae- bones that form upper jaw and hard palate
Zeugmatic- cheekbone prominences
Nasal bones- bridge of nose
The hyoid bone is the only skeletal bone that does not articulate with any other bone- it is attached to the temporal bones by muscles and ligaments and the larynx by a membrane-
The vertebral column consists of 33 vertebrae- it has four curvatures- when the vertebrae join this is how the column is formed- there are different types of vertebrae- they are named according to their location-
Cervical vertebrae are located in the neck (7)
Atlas is the name of the first vertebrae and is so named for the Greek god “Atlas”
Axis is number two and is named because it allows some rotation.
Thoracic vertebrae (12)
Ribs attach here
Lumbar (5)
These are the vertebrae in the small of the back.
Sacrum (5)
Fused vertebrae-form pelvic curvature
Coccyx (3-5)
Fused- form the tail bone
The rib cage is called the thoracic cage- composed of thoracic vertebrae- rib cage is part of the axial skeleton- rib cage is protective but flexible-rib is a flattened bone- there are 12 pairs of ribs- helps protect the heart and lungs-
The Sternum lies midline of the body- helps protect the heart and lungs- also called the breast bone- it is composed of three bones:
1-manubrium (the handle)
2- body (the blade)
3- xiphoid process (the point of blade)
11.4 Bones of the Appendicular Skeleton
Appendicular Skeleton consists of the bones within the pectoral and pelvic girdles and the attached limbs- pectoral girdle are specialized for flexibility and the pelvic girdle are specialized for strength-
The Pectoral Girdle and Upper Limb
The body has left and right pectoral girdles-
Each consist of:
scapula (shoulder blade)
clavicle (collar bone)
Glenoid cavity (allows arm to move in almost any direction)
Rotator cuff (tendons extend to humerous from four muscles on scalpula)
Humerous (long bone in the arm)
Radius (capitulum)
Ulna (trochlea)
Carpal (wrist consists of eight) look like small pebbles
Metacarpal (bones that fan out to form hand framework)
Digits (fingers or toes)
Phalanges (bones of fingers and thumbs)
The Pelvic Girdle and Lower Limb
The body has a left and right pelvic girdle
Pelvic girdle (hip girdle) has two heavy large coxal bones (hip bones)
Pelvis is a basin made of the pelvic girdle, sacrum, and coccyx-
Pelvis bears the body weight, protects organs within pelvic cavity, and is the place of attachment for legs-
Coxal bone (has three parts) 1-ilium 2-ischium 3-pubis- these are fused in adults
Hip socket (acetabulum) forms where three bones meet-
Femur )longest and strongest bone in the body)
Tibia
Patella (knee cap)
Fibula (slender bone of the leg)
Foot (each foot has ankle, instep, and five toes)
Ankle (consists of seven tarsal bones)
Instep has five elongated metatarsal bones
Phalanges (toe bones)
11.5 Articulations
Bones are joined at joints-
Joints are fibrous-
Suture are fibrous joints between the cranial bones and they are immovable-
Cartilaginous joints are connected by hyaline cartilage or fibro cartilage-
Cartilaginous joints tend to be slightly movable-
Synovial joint is one filled where the cavity is filled with lubricating fluid called synovial fluid- ligaments connect bone to bone and support/strengthen joints. The fluid sacs (synovial) ease friction and make movement possible-
Different types of Synovial joint movement:
1- flexion/Extension
2- Adduction/Abduction
3-Rotation/Circumduction
4- Inversion/Eversion
When there is muscle contraction, one bone moves in relation to another bone-
Chapter 12/Muscular System
12.1 Overview of Muscular System
12.2 Skeletal Muscle Fiber Contraction
12.3 Whole Muscle Contraction
12.4 Muscular Disorders
12.5 Homeostasis
12.1 Overview of Muscular System
All muscles contract-
When a muscle contracts, some part of the body moves.
Humans have three types of muscle tissue:
(1) smooth- fibers are spindle shaped cells-single nucleus (uninucleated)-cells arranged in parallel lines-located in walls of hollow internal organs- causes contractions, which are involuntary-slow to contract but can sustain longer- does not fatigue easily-
(2) cardiac- heart wall-fibers are uninucleated, striated, tubular, and branched-fibers interlock at intercalated disks-relax completely between contractions which prevent fatigue-rhythmical-occurs without outside nervous stimulation-involuntary-
(3) skeletal- fibers are tubular, multinucleated, and striated-attached to the skeleton-run length of muscle- often quite long-voluntary muscle-
Skeletal muscles have many functions:
1- support the body
2- help maintain constant body temperature
3-contraction assists movement in cardiovascular and lymphatic vessels
4-help protect internal organs and stabilize joints
Skeletal muscles are well organized
Whole muscle is made up of bundles of skeletal muscle fibers called fascicles
Fascicles are strands
Each fiber is surrounded by connective tissue as is the entire fascicle
Muscles are covered with fascia (type of connective tissue that becomes a tendon)
Skeletal muscles usually function in groups
For movement a group of muscles is stimulated, not just a single muscle-
Muscles contract and they shorten- this means that muscles can only pull, they cannot push-
Human Muscle Groups from figure 12.4:
Front view-left side of picture
orbicular is oculi
orbicular is oris
Pectoralis major
Serratus anterior
External oblique
Quadriceps femoris
Tibialis anterior
Front view-right side of picture
Masseter
Deltoid
Biceps brachii
Rectus abdominis
Flexor carpi group
Adductor longus
Sartorius
Extensor digit rum longus
Trapezius
Lattisimus dorsi
Triceps brachii
Extensor carpi group
Extensordigitorum
Gluteus maximus
Biceps femoris
gastrocnemius
12.2 Skeletal Muscle Fiber
http://highered.mcgraw-hill.com/sites/dl/free image from out powerpoint presentation
Skeletal muscles have alternating light and dark bands giving striated appearance-
A muscle fiber is a cell containing cellular components-
Plasma membrane is called sarcolemma
Cytoplasm is the sarcoplasm
Endoplasmic reticulum is the sarcoplasmic reticulum
Muscle fiber has T transverse tubules that penetrate/dip down into cell so they come into contact, but do not fuse together-
Sarcoplasmic reticulum encases myofibrils (which are the contractors in the muscle fibers)
There are thick and thin Myofilaments
Thick filaments- made of several hundred molecules of protein myosin
Thin filaments-consists of two intertwining strands of protein actin- two other proteins are also involved at this point, they are tropomyosin and troponin.
*See figure 12.5 page 233 for diagram
Sliding filaments- muscles are stimulated- impulses travel down T tubule- calcium is release- muscle fiber contracts as sarcomeres shorten-actin filaments slide past myosin (thick filament) and approach one another-band then shortens causing Z line to move inward- H zone almost completely disappears-
Movement of actin filaments in relation to myosin filaments is “sliding filament model”
Control of Muscle Fiber Contraction
Muscle fibers contract because they are stimulated by motor neurons with axons in the nerves-
Each axon has several branches-
Each branch ends in a terminal-
http://www.islandcounty.net/health/images/PhyAct1.jpg ( pyramid picture)
personal photo of the 2008 Whiskey Row Marathon in Prescott
Slow-twitch fibers have steadier tug, more endurance, small number of fibers- helpful in some sports (long distance running, biking, jogging, and swimming) energy is produced aerobically, they tire only when they are out of fuel- have many mitochondria- dark in color-contain myoglobin-surrounded by dense capillary beds and draw blood and oxygen from fast-twitch fibers-low maximum tension- highly resistant to fatigue- they have a substantial reserve of glycogen and fat, along with high mitochondria, help maintain and produce ATP when oxygen is available-
Chapter 11/Skeletal System
11.1 Overview of Skeletal System
11.2 Bone Growth, Remodeling, and Repair
11.3 Bones of the Axial Skeleton
11.4 Bones of the Appendicular Skeleton
11.5 Articulations
11.1 Overview of Skeletal System
Skeletal system consists of bones, cartilage, and fibrous connective tissue, which occurs in ligaments and joints-
The skeleton supports the body-
The skeleton protects soft body parts-
The skeleton produces blood cells-
The skeleton stores minerals and fat-
The skeleton, along with muscles, permits flexible body movement-
Anatomy of a long bone:
Diaphysis (shaft) is main portion-
Diaphysis has medullary cavity (walls contain compact bone)-
Medullary cavity filled with yellow bone marrow that stores fat-
Compact bone is highly organized- bone cells are called osteocytes and the ostescytes are in lacunae-
Matrix fills lacunae spaces-
Spongy bone is “unorganized’ when compared to compact bone- spaces of spongy bone are filled with red bone marrow which produces al types of blood cells-
Cartilage is not as strong as bone- it is flexible due to gel like matrix-cells of cartilage- these cells are called chondrocytes and are found irregularly in lacunae-
Cartilage does not have blood vessels, and is slow healing-
Three types of cartilage:
1-hyaline cartilage is firm somewhat flexible
2-fibrocartilage is stronger and matrix contains collagen fibers
3- elastic cartilage is flexible and matrix contains mostly elastin fibers
Fibrous connective tissue makes up the ligaments that connect bone to bone and bone to joint-
11.2 Bone Growth, Remodeling, and Repair
Bones ability to respond to stress by changing size, shape, and strength is called remodeling-
When bones are fractured and they repair this is called bone repair-
Bones are composed of living tissue- they are composed of several different types of cells-
1- Osteoblasts are bone forming cells
2- Osteocytes are mature bone cells
3- Osteoclasts are bone absorbing cells
Osteoclasts are removing matrix’ and osteoblasts are building it up-
Ossification is the formation of bone-
Intramembranous bones are flat bones such as skull bones-
Intramembranous ossification is the formation of bone between sheets of fibrous connective tissue-
Endochondral Ossification - most of the human skeleton falls into this type of bone-
Bone replaces the cartilaginous models of the bones- calcified bone matrix makes it possible for the endochondral bones to hold and support weight-
This process from cartilage to most long bone is as follows:
Cartilage model into the bone collar into the primary ossification center into the medullary cavity and secondary ossification sites and finally into the epiphyseal (growth) plate-
The epiphyseal contains four layers:
1- resting zone is where cartilage remains
2-proliferating zone is where chondrocytes produce new cartilage cells
3- degenerating zone cartilage cells dying off
4- ossification zone is where bone is forming
Bone length growth is final once the epiphyseal plate closes- hormones control the activity of the epiphyseal plate-
Hormones affect bone growth
Hormones are chemical messengers made in one part of the body but used by the body in another part.
Vitamin D is an important vitamin for bone formation because it is converted into a hormone that works in the intestinal tract with the absorption of calcium-
Bone Remodeling and its Role in Homeostasis
Osteoclasts is the break down of bone and Osteoblasts is the reforming process that is continually taking place within the body- This process is called “Remodeling”
Paget’s Disease is where the new bone is generated too quickly, therefore softer and weaker than desired-
Bone recycling allows our bodies to regulate the amount of calcium in the blood- blood calcium is important for clotting to occur-bones are the storage site for calcium-blood calcium is regulate by two hormones:
1- parathyroid hormone accelerates recycling and increases blood calcium level-
2- calcitonin hormone acts opposite to parathyroid hormone
Bone remodeling is the reason why our bones can respond to stress- exercise is strongly recommended as this also keeps bones strong by stimulating the osteoblasts instead of the osteoclasts process-
Bone Repair
The four steps to bone repair:
1-hematoma- after a fracture, blood escapes from vessels to form a hematoma in space between broken bones (6-8 hours)
2- fibrocartilaginous callus- tissue repair starts when a fibrocartilaginous callus fills space between ends of broken bones (approx. 3 weeks)
3- bony callus- osteoblasts produce trabeculae of spongy bone and convert fibrocartilaginous callus to bony callus- joins broken bones together (3-4 months)
4- remodeling- osteoblasts build new compact bone, osteoclasts absorb spongy bone, new medullary cavity is formed
Science Focus page 215
Identifying skeletal remains is discussed. Age of the remains can be approximated by dentition, which is studying the structure of the teeth. Bone ossification also gives clues to the approximate age of the remains. Pelvic bones are the best indicator of the gender. Observed racial characteristics can sometimes help determine the ethnicity of the skeleton, however, it is difficult with all of the genetic blending.
11.3 Bones of the Axial Skeleton
There are 206 bones of the skeleton.
Axial skeleton lies in the midline of body- consists of skull, hyoid bone, vertebral column, and rib cage-
The skull formed by cranium and facial bones-
The cranium protects the brain- adults have 8 bones tightly joined together to form cranium- sinuses are contained in the cranium- major bones of the cranium are named like the lobes of the brain: frontal, parietal, occipital, temporal-
Facial bones mainly consist of the;
Mandible- lower jaw
Maxillae- bones that form upper jaw and hard palate
Zeugmatic- cheekbone prominences
Nasal bones- bridge of nose
The hyoid bone is the only skeletal bone that does not articulate with any other bone- it is attached to the temporal bones by muscles and ligaments and the larynx by a membrane-
The vertebral column consists of 33 vertebrae- it has four curvatures- when the vertebrae join this is how the column is formed- there are different types of vertebrae- they are named according to their location-
Cervical vertebrae are located in the neck (7)
Atlas is the name of the first vertebrae and is so named for the Greek god “Atlas”
Axis is number two and is named because it allows some rotation.
Thoracic vertebrae (12)
Ribs attach here
Lumbar (5)
These are the vertebrae in the small of the back.
Sacrum (5)
Fused vertebrae-form pelvic curvature
Coccyx (3-5)
Fused- form the tail bone
The rib cage is called the thoracic cage- composed of thoracic vertebrae- rib cage is part of the axial skeleton- rib cage is protective but flexible-rib is a flattened bone- there are 12 pairs of ribs- helps protect the heart and lungs-
The Sternum lies midline of the body- helps protect the heart and lungs- also called the breast bone- it is composed of three bones:
1-manubrium (the handle)
2- body (the blade)
3- xiphoid process (the point of blade)
11.4 Bones of the Appendicular Skeleton
Appendicular Skeleton consists of the bones within the pectoral and pelvic girdles and the attached limbs- pectoral girdle are specialized for flexibility and the pelvic girdle are specialized for strength-
The Pectoral Girdle and Upper Limb
The body has left and right pectoral girdles-
Each consist of:
scapula (shoulder blade)
clavicle (collar bone)
Glenoid cavity (allows arm to move in almost any direction)
Rotator cuff (tendons extend to humerous from four muscles on scalpula)
Humerous (long bone in the arm)
Radius (capitulum)
Ulna (trochlea)
Carpal (wrist consists of eight) look like small pebbles
Metacarpal (bones that fan out to form hand framework)
Digits (fingers or toes)
Phalanges (bones of fingers and thumbs)
The Pelvic Girdle and Lower Limb
The body has a left and right pelvic girdle
Pelvic girdle (hip girdle) has two heavy large coxal bones (hip bones)
Pelvis is a basin made of the pelvic girdle, sacrum, and coccyx-
Pelvis bears the body weight, protects organs within pelvic cavity, and is the place of attachment for legs-
Coxal bone (has three parts) 1-ilium 2-ischium 3-pubis- these are fused in adults
Hip socket (acetabulum) forms where three bones meet-
Femur )longest and strongest bone in the body)
Tibia
Patella (knee cap)
Fibula (slender bone of the leg)
Foot (each foot has ankle, instep, and five toes)
Ankle (consists of seven tarsal bones)
Instep has five elongated metatarsal bones
Phalanges (toe bones)
11.5 Articulations
Bones are joined at joints-
Joints are fibrous-
Suture are fibrous joints between the cranial bones and they are immovable-
Cartilaginous joints are connected by hyaline cartilage or fibro cartilage-
Cartilaginous joints tend to be slightly movable-
Synovial joint is one filled where the cavity is filled with lubricating fluid called synovial fluid- ligaments connect bone to bone and support/strengthen joints. The fluid sacs (synovial) ease friction and make movement possible-
Different types of Synovial joint movement:
1- flexion/Extension
2- Adduction/Abduction
3-Rotation/Circumduction
4- Inversion/Eversion
When there is muscle contraction, one bone moves in relation to another bone-
Chapter 12/Muscular System
12.1 Overview of Muscular System
12.2 Skeletal Muscle Fiber Contraction
12.3 Whole Muscle Contraction
12.4 Muscular Disorders
12.5 Homeostasis
12.1 Overview of Muscular System
All muscles contract-
When a muscle contracts, some part of the body moves.
Humans have three types of muscle tissue:
(1) smooth- fibers are spindle shaped cells-single nucleus (uninucleated)-cells arranged in parallel lines-located in walls of hollow internal organs- causes contractions, which are involuntary-slow to contract but can sustain longer- does not fatigue easily-
(2) cardiac- heart wall-fibers are uninucleated, striated, tubular, and branched-fibers interlock at intercalated disks-relax completely between contractions which prevent fatigue-rhythmical-occurs without outside nervous stimulation-involuntary-
(3) skeletal- fibers are tubular, multinucleated, and striated-attached to the skeleton-run length of muscle- often quite long-voluntary muscle-
Skeletal muscles have many functions:
1- support the body
2- help maintain constant body temperature
3-contraction assists movement in cardiovascular and lymphatic vessels
4-help protect internal organs and stabilize joints
Skeletal muscles are well organized
Whole muscle is made up of bundles of skeletal muscle fibers called fascicles
Fascicles are strands
Each fiber is surrounded by connective tissue as is the entire fascicle
Muscles are covered with fascia (type of connective tissue that becomes a tendon)
Skeletal muscles usually function in groups
For movement a group of muscles is stimulated, not just a single muscle-
Muscles contract and they shorten- this means that muscles can only pull, they cannot push-
Because of this muscles work in opposite pairs-
Human Muscle Groups from figure 12.4:
Front view-left side of picture
orbicular is oculi
orbicular is oris
Pectoralis major
Serratus anterior
External oblique
Quadriceps femoris
Tibialis anterior
Front view-right side of picture
Masseter
Deltoid
Biceps brachii
Rectus abdominis
Flexor carpi group
Adductor longus
Sartorius
Extensor digit rum longus
Back View:
Trapezius
Lattisimus dorsi
Triceps brachii
Extensor carpi group
Extensordigitorum
Gluteus maximus
Biceps femoris
gastrocnemius
12.2 Skeletal Muscle Fiber
http://highered.mcgraw-hill.com/sites/dl/free image from out powerpoint presentationSkeletal muscles have alternating light and dark bands giving striated appearance-
A muscle fiber is a cell containing cellular components-
Plasma membrane is called sarcolemma
Cytoplasm is the sarcoplasm
Endoplasmic reticulum is the sarcoplasmic reticulum
Muscle fiber has T transverse tubules that penetrate/dip down into cell so they come into contact, but do not fuse together-
Sarcoplasmic reticulum encases myofibrils (which are the contractors in the muscle fibers)
There are thick and thin Myofilaments
Thick filaments- made of several hundred molecules of protein myosin
Thin filaments-consists of two intertwining strands of protein actin- two other proteins are also involved at this point, they are tropomyosin and troponin.
*See figure 12.5 page 233 for diagram
Sliding filaments- muscles are stimulated- impulses travel down T tubule- calcium is release- muscle fiber contracts as sarcomeres shorten-actin filaments slide past myosin (thick filament) and approach one another-band then shortens causing Z line to move inward- H zone almost completely disappears-
Movement of actin filaments in relation to myosin filaments is “sliding filament model”
Control of Muscle Fiber Contraction
Muscle fibers contract because they are stimulated by motor neurons with axons in the nerves-
Each axon has several branches-
Each branch ends in a terminal-
Synaptic Cleft is a small gap that separates axon terminal from sarcolemma-
Axon terminals consist of synaptic vesicles filled with neurotransmitter acetylcholine (ACh)-
ACh is released when nerve impulse travel down motor neuron and arrive at axon terminal-
ACh is released and quickly diffuses across the synaptic cleft and binds to receptors in sarcolemma-
12.3 Whole Muscle Contraction
Muscles have Motor Units
Axons within a nerve stimulate muscle fibers-
“motor unit” is a nerve fiber along with all of the muscle fibers it innervates-
A motor unit obeys the “All or Nothing” law-This occurs because muscle fibers in motor unit are stimulated all at once, so they all either contract or do not contract-
Muscle Twitch refers to a single contraction that lasts only a fraction of a second-
When a “motor unit” is rapidly stimulated it can respond to the next signal prior to complete relaxation in between-
Whole muscles contain many motor units-
“Recruitment” is when the intensity of nervous stimulation increases more motor units in muscle are activated-
Muscle tone is dependent on contraction and occurs in a person’s body when the motor units are contracted but not enough to cause movement-
Energy for Muscle Contraction
There are four (4) sources a muscle can get its energy from-
Two of the sources are stored in muscle-they are glycogen and fat (triglycerides)
Two of the sources are stored in muscle-they are glycogen and fat (triglycerides)
Two are acquired from blood- muscles use “blood glucose” and “plasma fatty acids”
Muscle cells can store ATP but the amounts are limited.
There are three ways muscles can get more ATP
(1) produced by creatine phosphate (CP pathway) -ATP production by the CP pathway is the simplest and the fastest because it is only one reaction. The reaction occurs in the sliding filaments. Creatine Phosphate can ONLY be formed when a muscle cell is resting, and limited amount is stored.
(2) fermentation- produces two ATP from breakdown of glucose to lactate anaeroically-This process usually begins with glycogen. Hormones signal muscles cells to break down glycogen, which makes glucose available to the muscle- fermentation is fast acting but builds up lactate-lactate build up causes short term muscle pain- oxygen debt (taking in of oxygen) helps break down the excess lactate-
(3) cellular respiration (CR)- A molecule called myoglobin is present in muscle cells- this molecule combines with /stores oxygen-
ATP is not immediately supplied for muscle contraction-
ATP is supplied when a person exercises - submaximal (less than at maximum output) with high intensity-
Aerobic exercise utilizes “CR” to make ATP for muscle contraction and burns body fat-
“CR” uses glucose from glycogen, also uses fatty acids-
“CR” uses glucose from glycogen, also uses fatty acids-
http://www.islandcounty.net/health/images/PhyAct1.jpg ( pyramid picture)Health Focus page 238
Exercise benefit’s the entire body! It improves muscle strength, cardio respiratory endurance, body composition, prevents certain kinds of cancer, and improve bone density. Exercise relieves depression. Studies show that even moderate exercise for just a few hours a week improves a persons mental and physical health. No body is too old to benefit from physical activity.
Fast-twitch fibers are anaerobic, designed for strength- there motor units contain many fibers-provide explosions of energy- helpful in sports activities (sprinting, weight lifting, golf club swings)-light in color because fewer mitochondria-they have little myoglobin- rapidly gains maximum tension- greater tension- accumulate lactate easily due to dependence on anaerobic energy-
Fast-twitch fibers are anaerobic, designed for strength- there motor units contain many fibers-provide explosions of energy- helpful in sports activities (sprinting, weight lifting, golf club swings)-light in color because fewer mitochondria-they have little myoglobin- rapidly gains maximum tension- greater tension- accumulate lactate easily due to dependence on anaerobic energy-
personal photo of the 2008 Whiskey Row Marathon in Prescott
Slow-twitch fibers have steadier tug, more endurance, small number of fibers- helpful in some sports (long distance running, biking, jogging, and swimming) energy is produced aerobically, they tire only when they are out of fuel- have many mitochondria- dark in color-contain myoglobin-surrounded by dense capillary beds and draw blood and oxygen from fast-twitch fibers-low maximum tension- highly resistant to fatigue- they have a substantial reserve of glycogen and fat, along with high mitochondria, help maintain and produce ATP when oxygen is available-
DOMS appears 24-48 hours after strenuous exercise -associated with activities where muscles contract while they are lengthening (walking down stairs, running down hill) prevention includes warm ups and cool downs, start new regimes slowly, don’t make huge changes in exercise program-
12.4 Muscular Disorders
Common Muscle Conditions
Spasms are sudden and involuntary
Strains are caused by stretching or tearing the muscle.
Tendinitis is when the tendon is impaired and inflamed.
Bursitis is the inflammation of the bursa.
Muscular Diseases
Myalgia means achy muscles usually caused by over-use or over-stretching.
Muscular Dystrophy is a progressive degeneration and weakening of the muscles.
Myasthenia gravis is an autoimmune disease of weakness in eye lids, face, neck, and extremities.
Amyotrophic Lateral Sclerosis (Lou Gehrig’s Disease) is gradual loss of abilities to walk, talk, chew, and swallow.
12.5 Homeostasis
Movement is essential in the maintaining of homeostasis. The skeletal and the muscular systems create movement by working together.
The skeletal and muscular systems work as a team with the following body systems to help maintain homeostasis:
(1)Cardiovascular system, (2)Urinary system,(3) Digestive system,(4) Nervous system, (5)Endocrine system,(6) Respiratory system, (7)Reproductive system.
The skeletal system protects soft organs of the body (1)brain (2)heart (3)lungs (4)spinal cord (5)kidneys (6)liver (7)endocrine glands
The muscular system pads bones and protects the abdominal organs-
Calcium homeostasis is over seen by the endocrine system as the skeletal system helps in the process.
Red bone marrow is where blood cells are produced.
Red blood cells are carriers of oxygen in blood.
Oxygen is necessary for production of ATP be aerobic CR. WBC originate in red bone marrow. White Blood Cells protect our bodies against pathogens. Bones have yellow and red marrow. Fat is stored in yellow bone marrow, that’s how and why its part of the bodies energy supply reserve.
Muscles Help Maintain Body Temperature
There are temperature sensitive neurons in the hypothalamus. ATP generates heat. Goose bumps are caused when arrector pili muscles contract.
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