Physiology -Chap 6.3- Outline

Bones and Homeostasis

• Bone Remodeling: Continuous replacement of old bone tissue
  
  • Involves bone resorption: Removal of minerals and collagen fibers from bone by osteoclasts
    
  • Involves bone
    deposition: Addition of minerals and collagen fibers to bone by osteoblasts
    
    • Resorption causes destruction of EC-M
      
    • Deposition causes formation of EC-M
      
  • Takes place at different rates in different regions
    
  • Benefits:
    
    • If new bone is placed under stress it thickness becoming stronger than old bone
      
    • Shape can be altered for proper support based on stress patterns
      
    • More resistant to fracture
      

  *Remodeling and Orthodontics*
  

• Orthodontics: Dentistry concerned with prevention and correction of poorly aligned teeth
  
• Braces
  
  • Places stress on bone that forms the sockets that anchor the teeth
    
  • In response the osteoclast/blasts remodel the sockets so the teeth align
    
    • Osteoclasts attach to bone surface at endosteum and forms a leak-proof seal
      
    • Releases lysosomal enzymes and acids
      
    • Osteoclasts carve a tunnel into bone
      
      • The minerals carved out are resorbed
        
    • Osteoclasts leave and osteoblasts come in and rebuild
      

  Factors Affecting Bone Growth and Bone Remodeling
  

• Factors in growth
  
  • Minerals: Calcium and phosphorus needed when bones are growing
    
  • Vitamins: Vitamin C in needed for synthesis of collagen and for differentiation of osteoblasts into osteocytes
    
    • Also needed: K, B12, and A
      
  • Hormones:
    
    • Childhood:
      
      • Insulin-like growth factors (IGF)
        
        • Produced by liver and bone tissue
          
        • Stimulate *blasts, promote cell division, and enhance synthesis of proteins
          
      • Thyroid hormones also promote bone growth by stimulating *blasts
        
    • Puberty:
      
      • Sex
        hormones:
        
        • Include: Estrogen and testosterone
          
        • Responsible for increased *blast activity and synthesis of bone EC-M and the 'growth spurt'
          
    • Adulthood:
      
      • Sex hormones:
        
        • Slow resorption of old bone and promotes deposition of new bone
          

  Fracture and Repair of Bone
  

• Fracture: Break in any bone
  
  • Named for sensitivity, shape, or position of line:
    
    • Open fracture: Broken ends protrude through skin
      
    • Comminuted fracture: Bone splinters at site of impact and smaller bone fragments lie between the two main fragment
      
    • Greenstick fracture: Partial fracture in which one side is broken and other bends
      
    • Impacted fracture: One end is forcefully driven into the interior of other
      
    • Pott's fracture: Fracture of the distal end of the lateral leg bone, with serious injury of the distal tibial articulation
      
    • Colles' Fracture: Fracture of the distal end of the lateral forearm bone in which the distal fragment is displaced posteriorly
      
  • Stress fracture: Series of microscopic fissures in bone that forms without any evidence of injury to other tissues
    
• Repairing a bone:
  
  • Formation of Fracture Hematoma
    
    • Blood vessels crossing the fracture line (FL) are broken
      
    • Clots are formed as blood leaks (Fracture hematoma)
      
    • Nearby bone cells die
      
      • Causes swelling and inflammation
        
  • Fibrocartilaginous Callus Formation
    
    • Fibroblasts invade fracture site and produce collagen
      
    • Cells from periosteum develop into chondroblasts and produce fibrocartilage
      
      • Lead to development of fibrocartilaginous
        callus
        
        • Repair tissue consisting of collagen that bridges broken ends
          
  • Bony Callus Formation
    
    • Osteogenic cells develop into osteoblasts which produce spongy bone trabeculae
      
    • Fibrocartilage is converted to spongy bone and callus referred to bony callus
      
  • Bone Remodeling
    
    • Dead portion of original fragment is resorbed
      
    • Compact replaces spongy around periphery of the fracture
      

  *Treatments for Fracture
  

• For bones to unite properly the ends must be brought to alignment
  
  • Called reduction
    
    • Closed reduction: Fractured ends of bone brought into alignment by manual manipulation
      
      • Skin remains intact
        
    • Open reduction: Brought together during a surgery
      

  Bone's Role in Calcium Homeostasis
  

• Small changes in calcium concentration could be fatal
  
  • High=Heart may stop
    
  • Low=Breathing may stop
    
• Bone buffers the calcium level
  
  • Releasing when too low
    
  • Absorbing when too high
    
• Regulated by hormones:
  
  • Parathyroid
    hormone (PTH)
    
    • Secreted by parathyroid glands
      
    • Increases blood calcium level
      
    • Operates with a negative feedback system
      
    • Acts on kidneys to decrease loss calcium in urine so more stays in the blood
      
    • Stimulates formation of calcitriol
      
      • Inhibits activity of osteoclasts
        
      • Speeds blood calcium uptake by bone
        
      • Accelerates calcium deposits
        

  Exercise and Bone Tissue
  

• When placed under stress bone tissue becomes stronger through increased deposition of mineral salts
  
• Without mechanical stress bone does not remodel normally
  
  • Resorption occurs more quickly than formation
    
• Walking and weight lifting (weight bearing activities) build and retain bone mass
  

  Aging and Bone Tissue
  

• More bone tissue is produced than lost
  
• As levels of sex hormones decrease there is a decrease in bone mass
  
  • Because bone resorption by osteoblasts outpaces deposition of osteoblasts
    
• Two aging effects
  
  • Loss of bone mass:
    
    • Results from demineralization
      
  • Brittleness
    
    • Results from decreased rate of protein synthesis
      

Physiology -Chap 6.2- Outline

Bone Scan

• A diagnostic procedure
  
  • Takes advantage that bone is living tissue
    
  • Radioactive tracer is absorbed by bone is injected
    
  • Measures radiation emitted by bone
    
    • X-Ray
      
• Normally appear as gray
  
  • Darker-hot spot-increased metabolism
    
  • Lighter-cold spot-decreased metabolism
    

  Bone and Nerve Supple of Bone
  

• Blood vessels pass into bone from periosteum
  
• Arteries
  
  • Periosteal
    
    • Enter the diaphysis through perforating canals
      
    • Supply periosteum and outer part of compact bone
      
  • Nutrient
    
    • Passes through hole in compact bone called nutrient foramen
      
    • Divides into proximal and distal branches
      
    • Supply the inner part of compact bone tissue and spongy bone tissue and red marrow
      

  (Long bones supplied by matephyseal plate and epiphyseal arteries
  

  Arise from arteries that supply the associated joint)
  

  • Metaphyseal
    
    • Enter the metaphyses with nutrient artery
      
    • Supply RBM and bone tissue of metaphyses
      
• Veins
  
  • Nutrient Veins
    
    • Accompany nutrient artery in the diaphysis
      
  • Epiphyseal & Metaphyseal
    
    • Exit in epiphyses
      
  • Periosteal
    
    • Exit with respective arteries in the periosteum
      
• Periosteum
  
  • Rich in sensory nerves
    
    • Carry pain sensations
      
    • Sensitive to tearing or tension
      

      
      

  Bone Formation
  

• Ossifacation/ Osteogensis
  
  • Formation of bone
    
• Skeleton of embryo
  
  • Composed of loose mesechymal cells
    
    • Shaped like bones
      
    • Provide template for subsequent ossifacation
      
• Methods of ossifacation
  
  • Intramembranous
    
    • Bone forms directly within mesenchyme arrange in sheet-like layers
      
      • Resembles membranes
        
  • Endochondral
    
    • Bone forms within hyaline cartilage that develops from mesenchyme
      

  Intramembranous Ossification
  

• Simpler
  
• Skull and jaw formed this way
  
• Hardening of fetal skull:
  
  • Development of ossifacation center
    
    • Chemical message causes mesenchymal cells to cluster and differentiate
      
    • Osteoblasts secrete organic EC-M until they are surrounded
      
  • Calcification
    
    • Secretion of EC-M stops and osteocytes lie in lacunae and extend cytoplasmic processes into canaliculi that radiate in all directions
      
    • In a few days it all hardens
      
  • Formation of Trabeculae
    
    • EC-M develops into trabeculae
      
      • Fuses with one another to form spongy bone
        
  • Development of the Periosteum
    
    • Mesenchyme condenses and develops into periosteum
      
    • Thing layer of compact bone replaces surface of spongy bone
      
    • Much of newly formed bone is remodeled as bone is transformed into its adult size and shape
      

  Endochondral Ossifacation
  

• Replacement of cartilage by bone
  
• Process:
  
  • Development of the Cartilage Model
    
    • Chemical messages cause mesenchymal calls to crowd in the shape of the future bone
      
    • Develop into chondroblasts
      
      • Secrete EC-M
        
      • Produce cartilage model
        
      • Perichondrium membrane develops around it
        
  • Growth of the Cartilage Model
    
    • Model grows further by continual cell division of chondrocytes and further secretion of EC-M
      
      • Called interstitial growth
        
      • Results in an increase of length
        
    • Thickness due to addition of EC-M material
      
      • Appositional growth
        
    • Chondrocytes and surroundings EC-M calcifies
      
  • Development of the Primary Ossifacation Center
    
    • Proceeds inward from external surface of bone
      
    • Nutrient artery penetrates perichondrium, and cart. Model
      
      • Stimulates osteogenic cells to differentiate into osteoblasts
        
    • Once perichondrium starts of form the bone it's known as periosteum
      
    • Growth
      of primary ossifacation center
      
      • Where bone tissue replaces cart.
        
    • Start of formation of spongy bone tabeculae
      
  • Development of the Medullary Cavity
    
    • Osteoclasts break down newly formed spongy bone trabeculae
      
      • Leaves a cavity in the diaphysis
        
        • Eventually replaced by compact bone
          
  • Development of the Secondary Ossifacation Centers
    
    • Formed when epip. artery enter the epiphyses
      
    • Spongy bone remains in the interior
      
    • Proceeds outward
      
  • Formation the Articular Cartilage and the Epiphyseal Plate
    
    • Hyaline cart. that covers the epiphyses becomes the articular cart.
      
    • Epiphyseal plate=Responsible for lengthwise growth of long bones
      

  Bone Growth
  

  Growth in Length
  

• Epiphyseal contains for layers:
  
• Zone of Resting Cartilage
  
  • Consists of small scattered chodrocytes
    
  • Cells do not function in growth
    
    • Anchor to epiphyseal plate to the epiphyses of the bone
      
• Zone of Proliferating Cartilage
  
  • Chondrocytes arranged in stacks
    
    • They divide to replace those that die at the diaphyseal side
      
• Zone of Hypertrophic Cartilage
  
  • Consists of large maturing chondrocytes arranged in columns
    
• Zone of Calcified Cartilage
  
  • Only a few thick
    
  • Consists of dead chondrocytes
    
    • Dead by calcified EC-M
      
• At maturation plate fades leaving the bony structure called the epiphyseal
  line
  

  Growth in Thickness
  

• Appositional growth:
  
  • Cells in the periosteum differentiate into osteoblasts
    
    • Secrete collagen fibers and other molecules that form EC-M
      
    • Become surrounded by EC-m and turn into osteocytes
      
      • Forms ridges
        
  • Ridges fold together and fuse
    
    • Groove become tunnel that encloses blood vessel
      
    • Periosteum=endosteum
      
  • Osteoblasts deposit bone EC-M
    
    • Forms new concentric lamellae
      
      • Proceeds inward
        
  • Ostoblasts under periosteum deposit new outer circumferential lamellae
    

    
    

    
    

    
    

  
  

Art History -Chap 6 - Vocab.

Artium: Central courtyard

Round
Arch: Formed by wedge-shaped stones

Barrel
vault: Elongated vault shaped like a half-cylinder

Corbel
arch: Over hanging courses of masonry meet at top

Courses: Horizontal layer of stone used in building

Voussiors: wedge-shaped stones

Pilasters: column-like uprights

Podium: Platform on which Etruscan temples were built on

Ridgepole: Longitudinal timber at the apex of a roof that supports the upper ends of the rafters

Jambs: A supporting upright

Piers: A supporting upright

Buttressing: Added support for arches

Centering: Arches being held in place by wooden scaffolding until mortar dries

Intrados: Inside surface of arch

Extrados: Outside curve of arch

Springing: Points from which the curves of the arch rise

Imposts: Reinforcement for the springing

Spandrels: Wall areas adjacent to curves

Arcade: Succession of an arch

Bay: Space encompassed by each arch and it's support

Groin
vault: Intersection of two barrel vaults

Cross
Vault: See groin vault

Triumphal
arches: Part architecture part sculpture. Commemorates triumph or formal victory

Dome: Curved masonry vault consisting of arch rotated on its axis

Drum: Wall of dome

Oculus: Circular opening at top of dome

Iconographical:

Tuscan
order: Column order

Composite
order: Column order

Pedestals: Platform supporting sculpture or monument

Plinth: Slab-like base of column

Dado: Lower part of wall

Cornice: Uppermost section of Classical entablature. Horizontally projecting element of a building usually found on top of wall

Stucco: Slow-drying type of plaster

Sarcophagi: Coffins

Forums: Legal centers

Basilicas: Large rectangular building

Stadiums: A recreational facility

Aqueducts: Trough to carry water through gravity

Concrete: Consisted of powdered lime, sand, and rubble. At first used for poured foundations.

Veneer: facing of finer materials

Exedrae: Semi-circular niches

Arcades: Series of arches

Axial: Used to describe a plan or design that is based on a symmetrical arrangement of elements along a central axis

Peripteral: Term used to describe and building that is surrounded by a single row of columns

Cubicula: Small side of chambers

Necropolis: City of the dead

Verism: Convention of rendering accurate and faithful portraits of individuals

Apotheosis: Elevation to divine status:

Swags: Loops of flowers (garlands)

Molding: Shaped or sculpted strip with varying contours and patterns.

Meander: Continuous rectangular scroll used as decorative pattern

Cameo: Gemstone carved in low relief

Apse: Rounded extension

Nave: Large central area of the interior space

Clerestory: Upper nave wall with window

Broken
pediment: Consists of two ends of triangular pediment without middle section

Attic
Story: Top story of a building

Coffers: Sunken panels the create pattern in inner dome

Menorah: Seven branched lamp holder

Egg-and-dart: Decorative molding made of alternating pattern of round (eggs) and downward pointing tapered (darts) elements

Syncretic: Union of different ideas

Tablinum: Reception room

Tesserae: Cubes of glass or stone used for mosaics

Emblemata: panels from floor mosaic

Foreshortening: Three-dimensional shading

Intuitive
Perspective: Represents 3D space on 2D surface through use of formal elements

Atmospheric
perspective: Colors become grayer near horizon

Still
Lifes: Compositions of inanimate objects

Dado: Lower part of wall

Tondo: Circular panel

Diptych: Pair of panels attached with hinges

Econ -Unit 3- Chap 12 Questions

1. What is the central thrust of the Employment Act of 1946? What is the role of Council of Economic Advisers in response to this law?

Commits the Federal government to use all practicable means, consistent with the market system, it commits the Federal government to take action through momentary and fiscal policy to maintain economic stability. The council assisted and advised the president on economic matters.

2. Assume that a hypothetical economy with a MPC of .8 is experiencing a severe recession. By how much would government spending have to increase to shift the aggregate demand curve rightward by $25 billion? How large a tax cut would be needed to achieve the same increase in aggregate demand? Why the difference? Determine one possible combination of government spending increases and tax decreases that would accomplish the same goal.

Government spending would have to increase by $6.25 billion. A tax cut would need to be $7.81 for the same effect. There's a difference because with a tax cut there will be an increase in saving, so you have to cut it by more than your aim. A possible combination to reach the same goal would be a tax cut of $7 billion and an increase in government spending by $.65.

3. What are government's fiscal policy options for ending severe demand-pull inflation? Use the aggregate demand-aggregate supply model to show the impact of these fiscal policies on the price level. Which of these fiscal options do you thin might be favored by a person who wants to preserve the size of the government? A person who thinks the public sector is too large?

Options:
Decrease government spending: Preferred by those who want to preserver the size of the government
Increased taxes: Preferred by those who believe the public sector is too large


6. Explain how built-in (or automatic) stabilizers work. What are the differences between proportional, progressive, and regressive tax systems as they relate to an economy's built-in stability?

A built-in stabilizer is anything that increases the government’s budget deficit during a recession and increases its budget surplus during inflation without requiring explicit action by policy makers. Which means that to some degree, government tax revenues change automatically over the course of the business cycle and in ways that stabilize the economy.

9. Some politicians have suggested that the US enact a constitutional amendment requiring that the Federal government balance its budget annually. Explain why such an amendment, if strictly enforced, would force the government to enact the contractionary fiscal policy whenever the economy experienced a severe recession.

If we went into a recession, they'd have to try to stop it with contrfactionary fiscal policy to keep the budget around what it was