Quiz 2 Flashcards
What is the strongest type of cartilage?
Fibrocartilage
What is the weakest type of cartilage?
Hyaline cartilage
Fibrocartilage contains what type of collagen fibers?
Type I and II
Which cartilage lacks a perichondrium?
Fibrocartilage
Where would you likely find fibrocartilage?
Sites subject to pressure and stretch; menisci of knee, intervertebral discs, pubic symphysis
Which cartilage contains elastic fibers?
Elastic cartilage
Where would you find elastic cartilage?
external ear, epiglottis; in areas able to stand up to repeated bending and maintain shape.
Which cartilage types contain a perichondrium?
Hyaline, Elastic
The axial skeleton contains what skeletal elements?
Skull, vertebrae, ribs and sternum
Appendicular skeleton contains what skeletal elements?
Limbs and girdles (pelvic and pectoral girdle)
What are the functions of bone?
Support Protection Locomotion Hematopoiesis Mineral Homeostasis
What minerals is the bone responsible for maintaining at homeostatic levels?
Calcium, Phosphorus
Where do living cells in bone and cartilage occupy?
Lacunae
Bone is _________, and cartilage is _________. (Blood supply)
highly vascular, avascular
There is More/Less collagen found in bone than in cartilage?
more
Bone growth occurs by a process called what? And why is this needed?
Apposition, a deposition of bone on preexisting surfaces. Bone is heavily mineralized with calcium salts, and osteocytes are unable to divide due to lack of space.
Lamellae are arranged to form 2 types of architecture. What are these two types and what is the body’s composition of this?
Compact (cortical) Bone - outer layer of most bones, about 80% of bone in body
Traebecular (spongy) Bone - inside the cortical bone, about 20% of bone in body
The majority of collagen in bone is what type?
Type I
What type of collagen is in every type of cartilage?
Type II
Bone resorption is done by what cells?
Osteoclasts
Bone formation is done by what cells?
Osteoblasts
Mature bone cells are termed what?
Osteocytes
Osteoclasts attach to bone via what proteins?
Integrins
What are the areas called that osteoclasts attach to bone?
Sealing zones
What hormone regulates bone remodeling?
Parathyroid Hormone, as well as active vitamin D
What proteins are stimulated to activate osteoclasts?
RANKL (RANK ligand receptor)
List some important functions of Calcium
Second messenger for blood coaglulation, muscle contraction, nerve function
Bone calcium is available from two reservoirs, name them and identify the largest store
Exchangeable site
Stable site, where the majority of the bone is stowed
Parathyroid hormone is secreted by what?
Chief cells of the parathyroid glands
What is calcitonin and what does it do?
A blood calcium lowering hormone secreted primarily by the parafollicular cells in the thyroid gland
1, 25-dihydroxycholecalciferol is what?
A steroid hormone formed by vitamin D in skin via sun
How is 1, 25-dihydroxycholecalciferol formed?
Successive hydroxylations in the liver and kidneys
What hormoness interact to maintain calcium levels?
Parathyroid hormone and calcitonin
Defective bone matrix calcification due to vitamin D and/or calcium deficiency is what?
Rickets in children
Osteomalacia in adults - enamel hypoplasia and incomplete mineralization is commonly seen in dentition
Name some limitations to electrical signalling
Binary
Difficult to modify
Energy intensive
Microenvironment dependent
What is mainly responsible for the negative charge inside a cell membrane?
Negatively charged proteins
What are two important elements in maintaining resting membrane potential?
Ion transporters (Na/K ATPase pump) Ion Channels (K, Na, Ca, Cl)
The interior of the membrane is ________ charged
Negatively
At rest, a membrane is only permeable to what ion?
Potassium
The action potential is what?
A moving electrical event that propogates down an axon, changing the membrane potential.
The action potential is caused by what?
The sequential opening of Na and K channels in a voltage and time dependent manner, so a net flow of positive ions (Na) rush into the cell. K channels then open up and rapidly flow out of cell, leaving a negative charge in the cell once more.
What are some ion channels and functions?
Leakage - constant flow of ion along a gradient
Voltge gated - Respond to changes in membrane potential
Ligand gated - respond to ligand binding, (neurotransmitter, proteins, ions, lipids)
Physically gated - Respond to physical stimuli (mechanical, temp, light)
What are some ion transporters?
ATPase Pumps - Use ATP to move one or more substances against gradients
Ion Exchangers -
Co-Transporters -
Multiple transporter systems -
T/F: Voltage gated ion channels are time and charge dependent. Explain
True, as the membrane potential changes, there is a physical change associated with it. As membrane potential goes back to normal, channel will physically move to resting position.
What would happen if the slow leaking potassium channels in the membrane closed?
Membrane potential would go to 0. There needs to be movement of current in order to establish an electrical potential energy (Voltage)
Action potentials are initiated where in the neuron?
Axon Hillock
What is responsible for action potentials only moving unidirectional?
Refractory period of voltage gated sodium channels
What is the gap of time between action potentials?
5 - 10 milliseconds
What are the functions of cartilage?
Withstand tension and compression
Provide low friction surface at joints
Provide support to soft tissue
Provide framework for long bone osteogenesis (during development)
Cells that are main composition of cartilage are called what?
Chondrocytes
The fibrous connective tissue sheath around cartilage is called what?
perichondrium
How does cartilage receive nutrients?
Diffusion via the perichondrium
How is cartilage different than bone?
Cartilage is more flexible than bone, is avascular, is a less organized structure, has no nerve fibers present and is about 80% water
The meniscus of the knee, pubic symhosis, and intervertebral discs are what type of cartilage?
Fibrocartilage, strongest type of cartilage, containing both type 1 and 2 collagen (only type to contain both) giving it great compressive strength
Where is elastic cartilage found?
Epiglottis and the cartilage of the external ear
Where is hyaline cartilage found?
Articular joints, Nasal cartilages, respiratory cartilages, coastal cartilages.
In the embryo, bone begins as what type of cartilage?
Hyaline
Describe the resistance to compression mechanism of cartilage
The ground substance of cartilage contains proteoglycans which are contain aggregates of chondoitin sulfate and hyaluronic acid. The sulfate groups are highly charged and generate electrostatic repulsion, giving the tissue compressive strength. Osteoarthritis can occur from loss of chondoitin sulfate
Chondrocytes in a threadlike network of elastic fibers and type II collagen is what type of cartilage?
Elastic
Parallel layers of a matrix with few chondrocytes and a layer of thick Type I and Type II collagen fibers forms what cartilage?
Fibrocartilage
Spherical chondrocytes in perichondrium with only type II collagen forms what type of cartilage>
Hyaline cartilage
What are the benefits of electrical signaling?
Covers long distances with minimal loss o signal
Rapid
Quickly repeated
Info can be conveyed in patterns
What are some limitations to electrical signaling?
Binary
Difficult to modify
Energy intensive
Microenvironment dependent
How is the resting membrane potential formed?
By a separation o charge across a plasma membrane caused by opposition of electrical and concentration gradients; formation of K concentration gradient and permeability of the membrane to K
What would happen to membrane potential if all K channels were closed?
It would go to zero! Using Ohms law, a voltage must be established by flow! (current) and (resistance)
What is an electrochemical equilibrium?
when concentration and electrical gradients for an ion are in balance
What transporters / channels are permeable or active all the time?
Na K ATPase, K leakage channels
Which equation calculates equilibrium potential of an individual ion?
Nernst equation
Which equation will calculate the equilibrium potential of the entire plasma membrane?
Goldman equation
What is the main difference between passive and active conduction?
In passive conduction, the current decays due to cytoplasmic resistance and distance, in active conduction the current is repropagated
What is something that the action potential requires?
Na and K gradients
What are 4 ion channels?
Leakage ion channels, voltage gated, ligand gated, and physically gated ion channels
What are some active transporters?
ATPase pumps, Ion exchangers, Co-transporters, Multiple transport systems
Is a voltage gated ion channel an active or passive transport?
passive, ions simply move down concentration gradients
Is a ligand gated ion channel passive or active transport?
passive, once the ligand is bound the ion moves via concentration gradients
During the resting phase of the membrane potential, what pumps and/or channels are open?
Na K ATPase pumps working, K leakage channels open
During the activation phase of an action potential, what pumps / channels are open?
Na K ATPase, K leakage, and Stimulus induced Na channels (stimulus gated - probable ligand gated)
During the rising phase of an action potential, what pumps and or channels are open?
Voltage gated Na channels are now open to depolarize the membrane heading toward the equilibrium membrane potential of Na
During the falling phase of an action potential, what gates and channels are open?
Voltage gated Na channels close, and now Voltage gated K channels open, to repolarize the membrane toward the equilibrium membrane potential of K
What happens at the end of the falling phase of an action potential?
Refractory period, a period in which the voltage gated Na channels cannot open, while the voltage gated K channels close after overshooting the resting membrane potential
What is happening in the recovery phase of an action potential?
All voltage gated channels are closed and K leakage channels restore the resting potential as well as Na K ATPase
Where are action potentials initiated?
At the axon hillock
Postsynaptic membrane potentials are summmated where?
Axon hillock
Why are action potentials anterograde and unidirectional?
Because of refractory periods, voltage gated Na channels cannot open and depolarize the membrane for some time once the AP has passed…
What are two ways of increasing action potential conductance?
Increasing axon caliber - by reducing internal resistance
Insulate axons - to prevent current leakage
What cells insulate axons in the CNS? PNS?
CNS - oligodendrocytes
PNS - schwann cells
Compare the velocity of unmyelinate vs myelinated axons
Unmyelinated - 0.5 - 10 m/s
Myelinated - 150 m/s
What are the two types of neurotransmitters?
Small molecules and neuropeptides
What are some characteristics of small molecule neurotransmitters?
They are amino acids or derivatives
They are synthesized in the presynaptic terminal
Stored in small synaptic vesicles
Released from the presynaptic terminal
What are some characteristics of neuropeptides?
They are proteins
Synthesized in the cell body
Stored in large vesicles
Released both pre and postsynaptically
Glutamate and GABA have what functions as neurotransmitters?
Glutamate is a CNS excitatory NT
GABA is a CNS inhibitory NT
In the presynaptic terminal, what drives vesicle release?
Increased intracellular Calcium
In what order are the synaptic vesicles released?
1 - readily releasable pool
2 - recycling pool
3 - reserve pool
Which SNARE proteins are attached to the synaptic vesicle?
Synaptobrevin, synaptotagmin
Which SNARE proteins are attached to the presynaptic plasma membrane?
Syntaxin, SNAP 25
Which SNARE protein is Ca dependent?
Synaptotagmin
Which protein catalyzes vesicle membrane fusion with plasma membrane?
Synaptotagmin once Ca has bound to it
What happens after the synaptic vesicle has fused and the NT has been released?
NT binds to postsynaptic NT receptor, presynaptic ultra fast endocytosis to reform plasma membrane, and recycling of vesicle
What are the two NT receptor types? Decribe them
Ionotropic - Ligand gated ion channels
Metabotropic - G protein coupled receptors
With an inhibitory post synaptic potential, what may happen to hyperpolarize the postsynaptic terminal?
Chloride ions may enter the postsynaptic terminal, or Potassium ions may leave the PST
With an excitatory post synaptic potential, what may happen to depolarize the postsynaptic terminal?
Sodium ions may enter, or Calcium ions may enter the postsynaptic terminal
The total change n postsynaptic membrane potential based on the spatial and temporal aggregation of postsynaptic potentials is called what?
Summation
What are the two biggest factors in postsynaptic summation?
location (spatial) and frequency (temporal) of the sensory potentials
What is lamellae
Layers of mineralized bone matrix that make up mature bone
What are the nonessential amino acids?
Aspartate, Alanine, Asparagine, Serine, Glutamate
The cells in CNS that produce growth factor are what cells?
Astrocytes
The cells in the CNS that myelinate and insulate the axons are what? PNS?
CNS - oligodendrocytes
PNS - shwann cells / neurolemmocytes
The phagocytic cells in the CNS necessary for immune function and defense are what?
Microglial cells
What cells in the CNS produce CSF and line the ventricles of the brain and spinal cord?
ependymal cells
Type 1 integral proteins are arranged in what fashion? Type 2?
Type 1 - N terminus inside cell, C term outside
Type 2 - N terminus is outside the cell, C term in
Transbylayer diffusion is catalyzed or uncatalyzed?
Uncatalyzed
Flippase is uncatalyzed or catalyzed? What orientation does it change in the membrane lipid?
Flippase moves the lipid from outside the cell to inside the cell
Scramblase does what to membrane lipids?
Either direction the lipid is moved, in order to gain equilirbium
In simple diffusion, molecules move down what gradient?
concentration
In faciliatated diffusion, molecules move down what gradient?
electrochemical
Peripheral proteins can be isolated and removed how?
Adjusting pH, or use of a chelating agent
Integral proteins can be isolated and removed how?
Using a detergent
The C4 nerve is situated where?
Between C3 and C4
The ventral horn consists of what?
Somatic motor neurons
The lateral horn consists of what?
Visceral motor neurons
The dorsal horn consists of what?
Somatic and visceral sensory neurons
The C2 dermatome corresponds to where?
Occipital protruberance
C8 Dermatome corresponds to what location?
Pinky finger
C5 myotome corresponds to what movements?
Abduction of shoulder
C6 myotome corresponds to what movememnts?
Flexion of elbow, extension of wrist
T4 dermatome corresponds to what location?
Nipple
T7 dermatome corresponds to what location?
Xiphoid
Sympathetic nerves exist in what region of the spinal cord?
T1 - L1/L2
Parasympathetic nerves exist in what region of the spinal cord?
In brainstem and S2-S4
Sympathetic nerves run through which communicating ramus?
White communicans
Which hormones has a direct effect on osteoblast and osteoclast activity in regards to bone homeostasis?
Parathyroid Hormone, 1, 25(OH)2 VitD
