EK B2 Ch6 Musculoskeletal system Flashcards
Bone, Skin, Muscle
Bone marrow
where stem cells are born
bone
think of it as living tissue interacting with other phsyiological systems, responding to hormones dynamic rather than scaffolding inside the body that is static!
skeleton anatomy 1
- Vertebrate skeleton has two divisions
- Axial skeleton: skull, vertebral column, ribs, sternum
- Appendicular skeleton: bones in limbs, shoulders (pectoral girdle), hips (pelvic girdle)
skeleton anatomy 2
- Vertebral column has vertebrae, sacrum, and coccyx
- Vertebrae are cervical (neck), thoracic (chest), lumbar (back) and sacral (pelvic)
- Ribcage has 12 ribs, most fused to sternum, a few attached to cartilage or free floating
Gross bone structure
- Periosteum is membrane of connective tissue that covers bone
- Compact bone is outer layer, hard and dense
- Spongy bone is inner layer, more porous and less dense
- Diaphysis is long shaft portion of bone
- Epiphysis is bulbous end of bone
- Long bones contain marrow
- Yellow marrow is fatty tissue (in hollow of bone)
- Red marrow is source of blood cells (in spongy bone)
metaphysis and epiphysical line
• Metaphysis is cartilaginous growth zone, between diaphysis and epiphysis (in children) transition area, caritlage converted to bone when long bones grow, how kids get taller cartiaginous region where more bone cells get added! SO IT is sometimes referred to as the growth plate!
There is a line where metaphysis meets epiphysis labeled epiphysis line which shows how far bone growth has gotten, doctor can tell how much more likely they will grow -position of epiphysisal line gives read on how much cartiglate has been pushed into bone
compact bone vs spongy bone
all around parameter of diaphysis is compact bone, hard bone which is really what is responsible for anomotical support, hard part marrow is not compact bone inside of the compact bone surroundings spongy bone, called spongy because pourus so a lot of holes in it, not as strong
Bone marrow in center…
Bone marrow all through center of bone
red bone marrow gives rise to blood cells
yellow marrow which is fatty deposits, so a lot of fat in bone
periosteum
thin membrane around outside of bone called periosteum
cartilage
- Cartilage is an elastic connective tissue, provides joint cushioning
- Cartilage contains chrondrocyte cells and extracellular collagen
- Embryonic skeleton is cartilaginous, becomes bone (ossification)- process still going on in long bones when kid is growing, happens early in skull, carilaginous skeleton gives way to skeleton, but in long bones to get kid to keep going remains carilaginous until bone growth is finished
- Metaphysis is cartilaginous, permits bone elongation
- Adult cartilage in ear, nose, ribcage, between spinal vertebrae, and in joints as fully grown adults have bits of cartilage in ears, verebtrates other joints because it provides really good cushioning* really really painful when two bones rub directly together in a joint so having cartilage there to cushion that keeps it comfortable for people
what kind of cells make up cartilage
chrondrocyte cells
osteon
= Haversion system what looks like if have cross section osteocytes are bone cells
canal in middle of one of these systems called Haversion canal where blood vessels and nerves are found, the osteocytes bone is hard as it grows and gets stronger it creates this hard extracellular matrix around itself, but osteocytes are living cells in bone, problem for evolution to solve to keep these cells alive in bone even when building fortress around themselves so bone would be strong, system of canals and little passages haversian canal is where blood vessels are, like Venice, so oxygen nutrients move out through that canal system diffuse out and reach osteocyte, then carbon dioxide and waste go back through center and enter blood supply, without it osteocytes would not be able to stay alive
Osteoblasts
Osteoblasts build up bone (ossification) BLASTS BUILD BONE UP
Osteoclasts
Osteoclasts break down bone (resorption) BREAK DOWN BONE. CHEW BONE UP *not to be confused with reabsoprtion
Bone remolding
Bone constantly beign adjusted, broken down or built up, can change shape, its an active tissue, as bone is developing osteoblasts, the bone building cells are what is really active
Osteoblasts secrete collagen* collagen forms a web on that web there are these crystals called hydroxy appetite crystals that get deposited on the collagen that makes bone hard and what gives bone its strength, made of calcium, phosphate and hydroxide ions*
crystals deposited on collagen
hydroxyapatite, but if unpack what is in a hydroxyapatiate crystal made of= it is made of calcium, phosphate and hydroxide ions to make hard crystal structure what gives bone its strength
osteocytes
trapped in extracellular matrix with hydroxyapatite crystals, older cells so need whole osteon system set up to nurish those cells!
Osteocytes are the longest living bone cell, making up 90–95% of cells in bone tissue in contrast to osteoclasts and osteoblasts making up ~5% (40). Osteocytes form when osteoblasts become buried in the mineral matrix of bone and develop distinct features.
Hyperactivity of osteoclasts →
Hyperactivity of osteoclasts → osteoporosis, which is when bone gets fragile and brittle and broken down, if osteoclasts are too active can weaken bone breaking down bone and making it less strong
parathyroid hormone and calcitonin
inc amount of calcium in blood
calcitonin dec amount of calcium in blood
so parathyroid hormone stimulates osteoclasts so if trying to release calcium from bone by breaking down bone, cells stimulated are osteoclasts break down bone
ex why bones broken down ballerinas not enough calcium, on flip side calcitonin trying to reduce amoutn of calcium in blood will stimulate other kind of cells to build bone, after age of 30 don’t build bone* so after that having enough calcium is about maintaining bone mass, which will then be there for a lifetime
bone mass and aging
- Bone mass is gained only until age 30
- After age 30, bone loss exceeds bone formation
- Very low bone mass → osteoporosis
- Postmenopausal women more susceptible to osteoporosis after menopasue when women have less estrogen much more susceptible to osteoporosis, why falls and hip fracture are such a big concern when taking care of elderly especially elderly women
Tendon
Tendon attaches muscle to bone
THINK:
“Tara must be a bully” tendons connect muscle to bone
joints are classified by
how much joints can move relative to each other
skull is a good example of that, we don’t want bones of cell skipping around, called immovable or fibrous joint btw bones
slightly movable joints- best example verbrate, move around a bit to absorb shock, fact can move a bit helps absorb shock
have the joint that can move the most bones can move the most, called free movable or synovial joints
synovial fluid
Freely movable/synovial joints = full movement (e.g., knee, elbow, shoulder)
Synovial joints have capsule with synovial fluid, are covered by connective tissue
can get infections, tares in ligaments connecting two bones at the knee, tons of conditions that involve these joints like knee or shoulder
cartilage critical in joints
muscles in the body
muscles in body come in pairs! one has to relax one has to work, agonist produces movement, antagonist one that if it contracted it would cause the opposite movement!
muscle class
• Abductor moves away from the midline (lifting arms, or moving away fingers)
“I have to move away from my diet to get abs”
• Adductor moves towards the midline (adding to center)
muscle
- Muscle generates force and permits movement
- Muscle contraction squeezes vessels, aiding in blood circulation and lymph movement
- Muscle contraction important for thermoregulation (shivering releases heat)
- All muscle contraction depends on Ca2+ skeletal muscle plays a really big role with circulatory system, keep blood moving through veins through action of skeletal muscle, need skeletal muscle movement to keep circulation normal, muscle contraction also important for thermoregulation, when get cold use our muscles to shiver and produce heat** in everything we say about muscle contraction Calcium plays a starring role, different muscle cells but all muscle cells involve calcium***
skeletal muscle
Skeletal is striated
voluntary
multinucleate
innervated by somatic nervous system
striated= means looks like it has stripes
voluntary= so we can decide to contract our skeletal muscle or we can decide to run or lift a cup or whatever
multinucelated= meaning really striking when look at skeletal muscle cells, sooo weird have 20 nuclei look like row of eyeballs but normal for skeletal muscle cells
innervated by somatic nervous system, called motor system or the somatic system, the nerves that give instructions for skeletal structures, these are the nerves somatic neurons that axons extend a great distance from spinal cord to big toe synapse with acetylcholine there is a neuromuscular junction there between neuron and skeletal muscle cell, when acetylcholine binds to its receptor in skeletal muscle cell the muscle cell contracts
Cardiac
cardiac muscle cell is striated, involuntary, 1 or 2 nuclei, innervated by autonomic nervous system
- 1 or 2 nuclei v important**
- Contracts and relaxes rhythmically, coordinated by a pacemaker
- Cardiac muscle fibers/cells are electrically coupled by gap junctions with structure called intercalated discs in thin heart muscle need free flow of ions from one to the next to get the whole heart to contract all together come back to this in circulatory chapter this is just a little preview
- Intercalated discs are physical and electrical junctions between muscle fibers
- Cardiac muscle fibers are branched, in a mesh
- Innervated by autonomic nervous system, which can influence contraction rate/strength
- Like skeletal muscle, cardiac muscle is striated, but unlike skeletal muscle, cardiac muscle cannot be consciously controlled and is called involuntary muscle. It has one nucleus per cell, is branched, and is distinguished by the presence of intercalated disks.
smooth muscle
- Smooth muscle is not striated, is involuntary
- Organization of muscle is less regular
- One nucleus per cell
- GI tract, blood vessels, arteries, bladder
- Smooth muscle fibers may be connected by gap junctions
- Contracts slowly and contraction is sustained
- Innervated by autonomic nervous system, meaning automatic not voluntary
Neurogenic =
Neurogenic = nerve impulse generates muscle contraction
-muscle cells must have an input from nervous system to contract
Myogenic =
• Myogenic = muscle generates its own contraction, able to generate own contractions, in petri dish and watch it beat cool and weird, can still be influenced by nervous system, have ability to contract on own but nervous system can tell them to contract faster or slower, still controlled by nervous system in ways that are really important, so skeletal muscle is neurogenic, it has to have input from nervous system, acetylcholine, nervous muscular junction
cardiac and smooth muscle are myogenic but nervous system still plays a role
When sarcometer contracts what changes?
H and I change, ones that spell Hi go away
SR
stores a lot of calcium, lot in SR, as action potentials go down through its tubules they trigger voltage gated calcium channels on the membrane of the SR
- so when the action potential gets there calcium channels open in the membrane of the SR, and we said that the Ca concentration in SR is much greater and Ca concentration is lower in cytoplasm, means calcium is going to go out into cytoplasm, also said calcium is crucial for muscle contractions
MOVES DOWN ITS CONCENTRATON GRADIENT*
Calcium greater in SR and less in cytoplasm, so going down gradient!!! Why want this!
Synaptic terminal of motor neuron
acetylcholine binds to muscle cell, get action potentials, action potentals go deeper into cell cause calcium to be released into cytoplasm
head of myosin
The head of myosin has to bind to actin, don’t want myosin binding all the time or contracting all the time, see how it is regulated, if look closely on lefthand side of figure, if you see how look at orange beads of actin and grey rope wound around them, little holes in beads being covered up by grey rope –>what that is showing is that the little holes represent binding sites where myosin can attach to actin
Grey rope is a protein called tropomyosin
And at rest tropomyosin is covering the binding sites where myosin would bind to actin, and then there are also these purple proteins called troposin
Role of Ca2+ in muscle contraction
binds to troponin, troponin protein changes shape, pushes tryopomosin out of the way and exposes the sites on actin where myosin can bind
point of diagram when calcium binds to purple tropoin protein causes this shift so actin grey stuff moves and myosin can actually bind to actin*
trypomosin= grey rope
protein troponin= purple thing, Ca2+ ions bind to troponin protein on actin filament
power stroke cycle
trying to understand how action potential, signal from neuron causing action potential makes sacromere go in and shorten how myosin binding to actin can pull actin so more overlap between the two kinds of protein and that is what this image is about
calcium makes actin available to be bound to myosin but actual contraction is powered by ATP*** how exactly does ATP cause actin and myosin to move, kinda of weird mechanism
- myosin head low energy confirmation bound by ATP, not hydrolyzed or used yet
- ATP is hydrolyzed to ADP and Pi. The potential energy from ATP is transferred to myosin head, so what we are suppose to see is that the myosin head is in a different position in its high energy confirmation
- when myosin is in its high energy confirmation across bridge forms, so that just means myosin actually binds to actin
- ADP and phosphate group are released, potential energy stored in myosin is being used or converted to kinetic energy to push the actin push the thin filament moves toward center of sacromere
- Then returns to low energy confirmation, attached to actin takes ATP coming in in step five to release the myosin from the actin, ATP needed to detach from actin, pushing actin more and more but every time and cycle requires another ATP
why need atp for myosin….
idea need atp for myosin to let go of actin helps explain rigermortis, bodies stifen after they die is becuase not producing atp anymore and so all through the body myosin gets stuck to actin in a rigid state*
power stroke cycle 2
- if do muscle contraction and then really relax way to stop this is to pump calcium out of cytoplasm
- another thing ATP is important for in muscle cells is to sequester and pump ATP back into sacroplasmic reticulm, then if you remember that mechanism with tropomyosin, if calcium is not present then the binding sites on actin for myosin will get covered up again* so then myosin cannot bind to actin and muscle contraction cannot occur* how we would relax at the end of all of this
muscles, atp and energy
Muscle needs lots of ATP and is rich in mitochondria
- Rigor mortis is ATP depletion, can’t release myosin cross bridges
- Second storage compound is creatine phosphate
- Creatine phosphate + ADP → creatine + ATP
- Third storage compound is glycogen → breakdown to glucose → ATP
- Repeated contraction causes O2 debt and ATP depletion
- During O2 debt, anaerobic glycolysis produces lactic acid
Creatine phosphate
Create a little of atp through substrate level phospholraytion
More creatine in muscle cells can make more atp
Muscle cells can make some small additional amount og ATP from creatine phosphate and that gives them extra atp, another way can boost their atp ability*
when exercising hard
can do anerobic respiration and fermentation, causes lactic acid to build up in cells what is the muscle burn you get when exercising really hard
temperature and muscles
when muscles contract a lot of atp energy is released as heat, why get pretty hot when exercise but can harness that when cold by shivering