Week 9 (exam 3) Flashcards by MsBarb99 .

What are the 2 structures of the bone?

1) spongy or cancellous bone

2) compact bone

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What is spongy or cancellous bone made with?

Made with trabeculae (sg trabeculum)

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What is trabeculae?

Little struts that criss cross each other

If you take a strut and look under a microscope you will see lamella, lacunae, canaliculi in red bone marrow

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What is compact bone?

Thick and solid

Has a central canal or Haversian canal

Has many osteons or haversian systems

Waste goes in cell to central canal and nutrients from canal go outward through the cell

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Why do bones bleed?

Because of the central canal or Haversian canal

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How are bones formed?

1) dermal membrane or membrane bone or intramembranous bone

2) endochondrial (cartilage replacement bone)

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What is dermal bones or membrane bone or intramembranous bone?

CT membrane in fetus that is laid down

Osteoblasts in membrane starts to make bony matrix

Center of ossification or ossification system

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What is the dermis?

Lower layer of skin where bone initially develops

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What is the center of ossification or ossification center?

Where process of bone formation begins and where it spreads out

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What does ossification mean?

Bone formation

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What is endochondrial?

Begins as hyaline cartilage

Includes bones in limbs

Becomes bone over time

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What is an epiphyseal plate?

The cartilage that is left in bone when you’re a teenager

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What happens when epiphyseal plates go through closure?

The bone cannot grow anymore

Person is in their late teens

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What are epiphyseal lines?

Where the epiphyseal plates were

Happens in late teens

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What is the articular cartilage?

Only cartilage left in bone

Thin little layer at the joint

Late teens

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How is the medullary cavity or marrow cavity formed?

When the process of creating bone through endochondrial is done or almost done osteoclasts kick in and remove matrix inside bone

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What is a medullary cavity or marrow cavity and what is found in it?

Hollow space in bone where yellow marrow or white marrow is found (basically fat)

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What is remodeling in bone?

The constant dance between osteoclasts (breaking down matrix) and osteoblasts (building up matrix)

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Where can you take and store Ca if needed?

Skeleton

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What are the 2 major regulators of Ca?

1) parathyroid gland (4 of them in the back of thyroid glands)
2) thyroid gland

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What is secreted from the parathyroid gland and what does it do?

Parathyroid gland hormone

PTH increases osteoclasts activity
- breaks skeleton down and blood Ca levels rise

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What is secreted from the thyroid gland and what does it do?

Calcitonin hormone

Inhibits activity of osteoclasts
-blood Ca levels drop

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What kind of cells produce calcitonin?

Parafollicular cells or C cells

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What happens to the osteoblasts when a person gets older?

Bone becomes brittle lack of collagen

Osteopenia

Osteoporosis

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What is osteopenia?

Insufficient ossification (decrease in bone density and not strong enough)

What is osteoporosis?

Osteopenia to the extreme Extreme danger of fracture and breaks Pores appearance

What are Bisphosphonates?

Class of drugs to reduce osteoporosis Slows down osteoclasts and balances out osteoclasts with how slow osteoblasts are going

What are excited or irritability cells?

Cells that can alter a charge when stimulated Ex: neurons

How is alter in charge across cell membrane accomplished?

Ion channels Ionic players - Na+ - K+

Nerve or neurons that are at rest have what charge?

Slightly negative

What is a potential difference?

Difference of charge across cell membrane Negative on the inside Positive on the outside

What is the resting potential?

Difference in charge across the membrane when cell is resting

What is the resting potential number inside a cell membrane?

-70mV

What is an oscilloscope?

Used to measure electrical events

What is depolarization?

Heading toward positive territory from resting

What is hyperpolarization?

Heading toward more negative territory from resting

What is repolarization?

Depolarize and let it return to resting

What is graded potential?

Slight stimulate has gradual change in charge

What are the ions that voltage gated ion channels open for?

1) Na+ (they flood in) | 2) K+ (they flood out)

What is the action potential?

Threshold and on Basis of all nerve pulses All or none If you don’t depolarize and hit the threshold there is no action potential If you depolarize and hit the threshold you get action potential No action potentials are stronger than the others

After an action potential occurs what happens and explain

Refractory period- new action can not be stimulated 2 parts 1) absolute refractory period 2) relative refractory period

What is the absolute refractory period?

Occurs in the beginning Impossible to have another action potential Na+ and K+ ions are glued shut until end of absolute refractory period

What is the relative refractory period?

Can hit another action potential if hit with stronger than normal stimulation Not glued shit anymore

How are nerve signals transmitted? Step by step (from pictures from lecture)

1) neuron is at rest and has negative charges inside and positive charges outside 2) Na+ comes in at front of neuron 3) Na+ follows local current 4) Na+ moves to middle and K+ leaves from front of neuron 5) K+ leaves neuron as Na+ move to end and refractory period occurs from where Na+ started

What is the local current?

Movement of Na+ atoms moving down axon

What does the refractory period ensure?

Ensures action potential moves in one direction and doesn’t go backwards

What does propagation mean?

Action potential stimulates action potential stimulates action potential and continues to move like a WAVE down the axon

Is the strength of the action potential all in one lost or reduced?

What does myelin do?

Speeds up movement of action potential down an axon

What is an neurolemmocyte?

Schwanns cell Special kind of glial cell Wrapped around axon

What is the nodes of ranvier?

Parts of axon not covered by schwanns cells

What is saltatory propagation mean?

Nerve transmission has to skip down axis because of Schwanns cell

What are the 3 types of diameter the axon can have?

1) Type A fiber (Type A neuron/ axon) 2) Type B fiber 3) Type C fiber

What is type A fibers?

Largest diameter (thick) and fastest 300 miles per hour

What are type B fibers?

Intermediate diameter and moderate speed 40 miles per hour

What is type C fibers?

Thinnest diameter and slowest of the three 2 miles per hour

What is the connection between cells?

Synapse

Why do neurons connect to other cells?

To submit transmissions

What is the second cell CNS connects to?

Nerve cell Neuron to neuron

What is the 2nd cell PNS connects to?

Effector cells (muscle, organ, gland) or neurons

What does the axon communicate with on other cells?

Dendrites

What is a presynaptic neuron?

1st cell of sequence

What is a postsynaptic neuron?

2nd cell in sequence

What do the axon terminal branches do?

They have neurotransmitters at the end and release and stimulate postsynaptic neurons

What is at the end of each axon terminal branches?

Axon bulb or synaptic knob or terminal bouton

What is a synaptic cleft?

Space between dendrite and axon bulb

What does a synaptic vesicle contain?

Contains neurotransmitters

What is the ion channels in dendrites that begin to open?

Chemically regulates ion channel