PNB 2264 Exam 2

Bone stores what ions/salts

Ca (calcium) and P (phosphorus) salts

Hematopoiesis

making the cells of the blood

Hematopoietic stem cells

cells inside of bone

can differentiate between other cells (multipotent stem cells)

What type of bone is a patella

sesamoid bones

Structures of a long bone

Diaphysis = shaft

Metaphysis = neck

Epiphysis = end

Where is medullary/ marrow cavity located? what does it contain?

center of diaphysis, yellow bone marrow ( inactive bone marrow; cavity filled with fat)

Where is spongy bone located and what does it contain?

Epiphysis and contains red bone marrow (active bone marrow that contains hematopoietic stem cells)

Compact bone

contains osteons, lamellae, central canal

Spongy bone

lattice like network of trabeculae, lightens the weight of the bone

Periosteum

wrapping around the outside of the long bone, consists of fibrous layer (dense irregular connective tissue), and cellular layer (cells that can deposit calcium salts or take away)

Endosteum

inside the marrow cavity, contains osteoblasts (bone growth) and osteoclast (break bone)

Where in the long bone does bone grow?

metaphysis, at the epiphyseal/growth plate

Bone vessels enter compact bone through?

volkmann’s canals

Mesenchyme

connective tissue that forms the fetal skeleton

Intramembranous ossification 1

bone forms directly from mesenchyme, skull, clavicle, mandible

Osteoprogenitor cells

bone stem cells that give rise to osteoblasts

Cartilage proliferation

happens on epiphyseal side of epiphyseal plate, mitosis occurs

Ossification

occurs on diaphyseal side of the epiphyseal plate

Appositional growth

bone growth in width

Endochondral ossification

bone forming through hyaline cartilage

Intramembranous ossification

bone forming from mesenchyme

Primary ossification

part of endochondral ossification

As parathyroid hormone increases

increases blood calcium (stimulates osteoclasts; removal of calcium from bone)

Calcitonin

decreases blood calcium (prevents osteoclasts and stimulates osteoblasts)

Osteoporosis

compression fractures, loss of bone density, happens with age

Steps of Bone repair

Hematoma = blood clots to store the blood

Soft callus = forming of fibrocartilage

Bony callus = remodeling of the two calluses

Remodeling = bone is healed and placed back to the correct place

Range of Motion (ROM)

normal extent of mobility

Degrees of Freedom (DOF)

number of axes at which movement occurs (ex: 2 planes)

Classification by structural joint

• fibrous = sutures (skull)

• cartilaginous = symphysis (pubic symphysis)

• synovial = (bone/socket)

Classification by functional joint

• synarthrosis = immovable

• amphiarthrosis = slightly movable

• diarthrosis = freely movable

Synovial fluid helps?

cushion, lubricate and nourish in between bones, brings oxygen and nutrients

Axial skeleton consists of

Head, vertebral column (ribs and sternum)

TMJ (Temporal mandibular joint)

hinge joint between temporal bone and jaw

4 muscles to help move TMJ

• Digastric = opens jaws

• Temporalis = closes jaws

• Masseter = closes jaw

• pterygoids = allows jaw to move in vertical and horizontal direction

Total bones in Vertebral column and what it consists of?

26 total bones,

• 7 cervical

• 12 thoracic

• 5 lumbar

• sacrum (5 fused)

• coccyx (4 fused)

Intervertebral disk and what it consists of

connect the vertebral bodies,

• outer annulus fibrosus = fibrocartilage part

• inner nucleus pulposus = soft gelatinous that absorbs shock

Herniated disk

tear in annulus fibrosus, presses on spinal nerve = pain,

Atlas joint (C1)

no body , C1

Axis joint (C2)

C2, contains body

Atlanto axial joint

no-no movement of pivot joint (head)

Atlanto occipital joint

yes movement (head)

Sternocleidomastoid

tilts same side or opposite side of head

Rectus Abdominus

(ab muscles) flexes vertebral column

erector spinae

extend vertebral column (posterior side)

Thorax

protects heart and lungs

sternum, ribs, thoracic vertebrae

Costovertebral joint

2 joints head of rib w/vertebral body and tubercle of rib w/transverse process, gliding joints

Primary curves

convex faces backwards = thoracic, sacral

present at birth

Secondary curves

convex faces forwards = cervical, lumbar

Kyphosis

hunchback, common with osteoporosis

Lordosis

common in pregnancy, big belly

Muscle roles (3)

• agonist= directly performs the movement

• antagonist = opposes movement/ performs opposite action

• synergist = helper

Shoulder (pectoral) girdle consists of (3)

clavicle, sternum, scapula

Scapular muscles and actions

Trapezius = elevates, retracts and depresses

Shoulder (glenohumeral) joint

most freely movable,

bones : scapula and humerus

Excitability

membrane potential, basis of field of electrophysiology

Who is the father of electrophysiology?

Luigi Galvani (1700s)

What did Galvani discover?

Concluded that muscle had bioelectricity (the ability to pas an electrical current)

What did Galvani do?

• He connected a lightning rod on the roof of his lab to the sciatic nerve in the leg of a frog

• When lightening struck the rod, the electrical current passed through the wire into the frog leg, causing the leg to contract.

Attractive forces only work over a __________ distance.

short

If we want to keep opposite forces separate, it takes a lot of __________ ________________ to do so.

energy investment

Why are membranes semipermeable?

• plasma membrane is responsible for keeping charged particles separate from one another

• plasma membrane must compartmentalize ions and keep them at different concentrations on either side of the membrane (interstitial fluid has a different ion concentration than the cytosol)

• so ions can't freely pass the membrane (selective)

The plasma membrane can regulate the movement of ions (charged particles) and it can do that using _______________ ________________ ___________ such as ion channels and transporters.

Integral membrane proteins

2 principles of membrane semi-permeability

1. Intact membranes do not allow ions to pass freely (separation of charge)

2. Ion channels and carriers permit the movement of ions across the membrane (change concentration gradient)

Membrane potential

• the uneven distribution of electrical charge across the membrane

• the movement of ions creates changes in membrane potential

• the potential energy to do work

Recording membrane potential (Vm)

• a recording lead is placed directly into the cell to measure the charge in that environment (intracellular fluid)

• a reference lead is placed into the surrounding interstitial fluid that measures the charge environment there

• see the magnitude of the difference between the two compartments

• when given a voltage, it ALWAYS describes the INside of the cell relative to the OUTside

What does a negative voltage tell you about a cell?

The inside of the cell close to the membrane is more negative than the outside

Vm is the potential __________ the cell relative to the potential ___________ the cell. It is expressed as a voltage.

inside; outside

How do cells create membrane potential?

• The plasma membrane is able to create compartmentalization, which allows us to have different concentrations of ions on either side.

Distribution of Important Ions (4)

4 biologically important ions: K+, Na+, Cl-, Ca2+

Interstitial fluid = ?

Cytosol = ?

extracellular

intracellular

Key contributions to Vm

1. Ions are not distributed equally across the cell membrane (unequal concentrations)

2. Membranes are unequally permeable to various ions (different permeability)

Without permeability, membrane potential _______________ exist because ions cannot move.

CAN'T

If Pion (permeability of an ion) increases,

Vm (membrane potential) moves towards Eion (equilibrium potential)

If Pion decreases,

Vm moves away from Eion

If Eion changes (concentration etc)

Vm moves in the same direction

If a number is higher than the original concentration gradient ( 95 to 100)

It is more negative

If a number is smaller than the original gradient (95 to 80)

It is more positive

K+ has how many mm inside and outside

100 inside and 5 outside

Na + has ___ inside and ___ outside

10 inside and 100 outside

Cl- has ___ inside and ___ outside

10 inside and 105 outside

Diffusion

Ions will move from high concentration to low concentration as long as concentration gradient exists

When the distributions of ions is equal on both sides of the membrane, does a concentration gradient still exist?

NO because the net charge cancels out

ex. net charge in intracellular and extracellular environment: 4 + and 4 - , so (+4) + (-4) = 0

If we don't have any difference in charge across the membrane, then the membrane potential is _______.

ZERO

Importance of selective permeability

If we had freely permeable membranes and ions could just move down their concentration gradients entirely, we would end up with equal concentrations of ions on both sides

• Everything would be balanced so membrane potential would not exist and excitable tissues like nerves and muscle would not function properly

Attractive forces

Attractive forces between charged particles kick in and influence the movement of ions

• Opposites attract, so some ions (depending on which ones the membrane is permeable to) will be pulled back into or out of the cell (depending on where the attractive force exists) because of this electrostatic force

Electrostatic force

There is electrostatic attraction between negative charges and positive charges

• The repulsive forces acting on like charges are attempting to push them away from the environment

Forces that set membrane potential

1. Concentration gradient (pushing ions towards chemical equilibrium).

CONCENTRATION = CHEMICAL

2. Electrical potential (pushing ions towards electrostatic equilibrium).

ELECTRICAL = ELECTROSTATIC

Vm is a balancing act between which two opposing forces?

concentration gradient AND electrical potential

when those two forces balance each other equal and opposite, what we end up with is MEMBRANE POTENTIAL.

Equilibrium potential (Ex)

potential at which electrical and concentration gradients are balanced in and out of cell, net flux is ZERO

Ions experience the effects of two different forces:

1. chemical driving force due to their concentration gradient

2. electrical driving force due to charge-charge interactions (electrical potential)

The equilibrium potential for an ion, Ex, is the membrane potential at which the _________________ _____________ and _____________ _______________ forces are EQUAL and OPPOSITE.

concentration gradient; electrical potential

How are cells in the body like the ocean?

The relative concentrations of ions almost NEVER change under normal circumstances inside your body, even when channels are open (unless in disease state or lab).

• When ions do move, they can create big changes in voltage BUT they don't create changes in voltage for the ENTIRE cell. They only change the voltage at the PLASMA MEMBRANE (right where the "food coloring" is dropped). That is the place where the ions are coming into or moving out of through channels.

• Why it's called membrane potential and not cell potential

Despite movement of ions, relative concentrations of ions __________ change.

DO NOT.

Small movements produce big changes in Vm.

Nernst equation

-used to calculate membrane potential if the cell is permeable to a single ion

-calculates equilibrium potential for a single ion

Nernst potential

Nernst potential = equilibrium potential = reversal potential

• unique to each ion b/c each ion has a unique concentration gradient and unique charge

Assumptions for Nernst equation

1. the ion is COMPLETELY permeable

2. the ion is the ONLY ion that's permeable

Nernst equation

E(ion)= equilibrium potential for ion

61= constant, temperature reference

z= valence charge = charges

log[out/in] = concentration gradient

If the ions have equal concentrations on the inside and outside of the cell, what is the equilibrium potential using Nernst equation?

log[3/3] = log[1] = 0

The Ex is zero because the log of one is zero.

The equilibrium potential for an ion is determined by _________ and __________________ _____________ (not constants).

charge; concentration gradients

Why is it difficult to change equilibrium potentials?

The only things that affect Ex are charge and concentrations gradients, which are factors that cannot be easily manipulated. You would need a nuclear reactor to change the charge, and homeostasis generally prevents major shifts in ion concentrations, which is why Ex remains the same for ions under normal circumstances.