Physiology

Question 1

You encounter a patient with a rare viral disorder that erodes the cartilage from the long bones especially of the distal femur and proximal tibia. The bodies repairing of this structure would most likely convert which type of cartilage into which new material? A) fibrocartillage into elastic cartilage B) Hyline cartilage into fibrocartillage C) Hyline cartilage into elastic cartilage D) Periosteum into hyline cartilage The early stages of this condition leading to inflammation and pain and increased friction would be called what?

Answer 1

B) The cartilage of long bone is hyline cartilage and when repaired becomes fibrocartilage, which has more type 1 collagen making it stronger but also doesn’t bear weight well at the joint due to its rigidity. Initially this would be considered osteomalacia and later athritis.

Question 2

A patient presents with stiffness of the back and a PE reveals a fairly healthy 5’2” 14 y/o girl. After viewing an x-ray of the back you discover some suspicious finding in her inter-vertebral disks, which appear more dense than usual; though she has no signs of tumor. How would you generally classify her condition? A) Achondroplasia B) Arthritis C) Chondrodystrophy D) osteosarcoma

Answer 2

C. Chondrodystrophies are a group of disorders in which cartilage is ossified into bone. The problem is with the fibrous cartilage of the inter-vertebral disk. This is a cartilage issue and the only one that fits. Her height is not an issue due to her age, and arthritis isn’t a good fit.

Question 3

What is a precursor to a fibroblast? Hematopoetic stem cell Fibrocyte Chondrocyte Messenchymal cell Osteoclast precursor?

Answer 3

Messenchymal cell Monocyte

Question 4

What general process causes the circular formations of lamelae?

Answer 4

Bone remodeling

Question 5

What is endochondral ossification?

Answer 5

In conjunction with intramembranous ossificiation it is one of two essential processes during fetal development by which bone tissue is created; cartilage is present in this process. The formation and growth of long bones as well as the healing of bone is what defines this process.

Question 6

WHAT DO YOU THINK IS HIGH YIELD FOR THIS LECTURE?

Answer 6

PRECURSOR CELLS TISSUE ID

Question 7

What is marfan’s syndrome?

Answer 7

Defect in fibrillin 1 which is the primary component in microfibrils which attach to elastin. It is essential for the proper formation of ECM, including the formation of elastic fibers. Can lead to aortic aneurysm Increased TGF-B activity: neg affects vascular smooth muscle development Inflammation

Question 8

Connectve tissue proper is of two types. What are they and which tissue compose them?

Answer 8

Dense and loose connective tissue Dense- regular (tendons, ligaments) irregular- skin, dermis, periosteum/chondrium Elastic- EEEE + aorta, vocal cords, epiglottis, eustacian tubes Loose- areolar, adipose, and reticular

Question 9

What is syndesmosis, synchondrosis, and diarthrosis?

Answer 9

Syndesmosis- Bone united by the same ligament (interosseus membrane of the tibia and fibula) Synchondrosi- same cartillage- cartilage joints, like costal cartilage Diathrosis is the same thing as a synovial joint.

Question 10

When a joint is injured and hyline cartilage is replaced with fibrous cartilage how does the collagen content differ in the newly repaired joint?

Answer 10

Fibrocartilage has more collagen Type I, so its stronger, but less flexible.

Question 11

How is osteoblast formation different from osteoclast?

Answer 11

Mesenchymal stem cell–> osteoprogenitor cell–> osteoblast–> osteoclast Hematopoietic stem cell–> myeloid stem cell-> monocyte–> osteoclast precursor–> osteoclast

Question 12

Pain sensation has what four qualities?

Answer 12

Location

Modality-type or quality

Intensity-sharp or dull

Duration/Frequency

Question 13

What is a receptive field? What type of neurons innervate it, and how many neurons can innervate it?

Answer 13

Is a area sensitive to stimuli such as touch temperature pressure pain etc.

First order neurons innervate it and can be either inhibitory or excitatory; one or many.

Question 14

Which type of first order neuron utilizes an interneuron as an intermediate to the second order neuron?

A) Excitatory first order neuron

B) motor neuron

C) Inhibitory first order neuron

D) Inhibitory motor neuron

Answer 14

C) inhibitory first order neuron

The excitatory first order neuron acts directly on the second order neuron and motor neurons don’t make sense in this sensory contex.

Question 15

How does a sensory neuron compare to a motor neuron, or a projection interneuron?

Answer 15

The sensory neurons soma is between the free nerve ending on one end and the terminal buttons on the other. This is contrasted with both the motor neuron and the projection interneuron and others whose soma are surrounded by dendrites receiving signals from other neurons.

Question 16

You’re on your way back to town after a long camping trip with your friends when you decide to stop and eat and a mexican restarant known for its habenaro peppers. How does your body interpret the capsaicin in your mouth as spicy? What type of nociceptor is involved and what fiber type does it utilize to process this information?

Answer 16

Your body has Transient receptor potential (TRP) channels that respond to different modalities: hot, cold, chem, mechanical. When activated the channel opens and ions flow into the nociceptor causing depolarization of the membrane potential.

Spicey food would utilize a polymodal nociceptor with a nonmyelinated C fiber. This receptor handles high-intensity mech, chem, or thermal signals.

Question 17

As you continue to eat spicy peppers and the nociceptors activated stay above threshold how will this be interpreted by your body? Are there other ways to replicate this effect?

Answer 17

The result of multiple action potentials firing at a higher rate will be an increased intensity.

This can also be achieved by increasing the number of nociceptors involved, which results in a more intense signal being sent to the brain.

Question 18

You step into a walk in freezer at costco and the door accidentally closes behind you traping you inside. The temp is 23 deg. Assuming the range for your cold receptors is 7-43 deg and your cold-pain receptors initiate below 15 deg. How would you explain the firing rate for each at around 10 deg?

A) cold receptors are decreasing their firing rate and the cold pain receptors are increasing their firing rate

B) Cold-pain receptors are decresing their firing rate and the cold receptors are increasing their firing rate

C) Their are only a few cold receptors and cold pain receptors firing

D) Their are many cold receptors firing but only a few cold-pain receptors firing

Answer 18

A) is correct. According to the questions stem 10 degs is in the lower range for cold receptors, meaning they will be decreasing their firing rate. Conversely 10 degs is in the upper range for cold-pain receptors, meaning they will be starting to increase their firing rate.

B) opposite of A

C) It’s not the number of receptors firiing here that matters. It’s true that intensity of a signal can be increased with an increased rate of firing or with more receptors firing. If this was the case with the cold receptors though it wouldn’t translate to cold-pain. This is because Nociceptors respond to extreem temperatures (cold and heat) to signal pain, this is not the result of many “regular” cold or warm receptors having a additive effect.

Question 19

After being saved from a costco freezer entrapment you start to warm up to about 25 deg. What type of receptors facilitate this sensation and what is their fiber type?

A) Thermal nociceptors with A-delta fibers

B) Polymodal nociceptors with C-fibers

C) Regular warm receptors fiber type unknown

D) Mechanical nociceptors with A-delta fibers

Answer 19

C is correct

Unless the temp is extreem (>45 or <-5) you wont be utilizing thermal nociceptors (pain), just your regular warm receptors. Unless the stem explains that your set pt is decreased making you more sensitive to pain, you will not be using thermal nociceptors around room temperature 25 deg

Question 20

What is the pathway for pain sensation from nociceptor to the cortex and back to the NMJ?

Answer 20

Nociceptor

Peripheral nerve

(brachial plexus)

Spinal cord: relay neuron, dorsal horn.

Spinothalamic tract/Thalamus

Somatosensory cortex

THEN BACK

Motor cortex

Pyramidal tract

Spinal cord: motor neuron, anterior horn

(brachial plexus)

Peripheral nerve

Neuromuscular junction

Question 21

You decide to flip your tortillas by hand on the frying pan and accidentally burn your finger a bit. The nociceptors in your hand have various types of TRP channels, those with a majority of one type are named after that type. Which nociceptor type will signal the pain in your finger first, and which will come after? What is the name of this nociceptor type?

A) Thermal, Polymodal, Polymodal

B) Thermal, Polymodal, Thermal

C) Polymodal, Thermal, Polymodal

D) Polymodal, Thermal, Thermal

Answer 21

A is correct

Thermal nociceptors will send the pain signal first b/c they’re myelinated and polymodal will send signal after as it’s nonmyelinated. Both respond to thermal stimuli, but the receptor will be named after the polymodal nociceptor as it responds to high-intensity thermal stimuli (like heat from a frying pan).

Question 22

Describe the characteristics of thermal, mechanical, polymodal, and silent nociceptors

Answer 22

Thermal: (>45 deg C or <-5 deg C), small diameter, thinly myelinated A-delta (Aδ) fibers, 5-30 m/s

Mechanical: intense pressure to skin, A-delta (Aδ) fibers.

Polymodal: high-intensity mechanical, chemical, or thermal (both hot and cold stimuli), small diameter, nonmyelinated C fiber, slow (< 1.0 m/s).

Silent

Found in the viscera.

Not normally activated by noxious stimuli.

Inflammation and chemical agents can reduce their firing threshold.

Highly localized visceral damage (e.g. cutting the intestine in two) often does not cause pain but diffuse nociceptor activation (e.g. ischemia, spasm, chemical stimuli) can be severe.

Question 23

What are the classic chemical mediator that can activate or sensitize nociceptors? How can this effect be cyclic? How does this process usually begin? What would you call this decreased pain tolerance to noxious stimuli?

Answer 23

Prostaglandins and bradykinin can sensitize nociceptors.

Bradykinin activates Aδ and C fiber nociceptors directly

Increases the release and synthesis of prostaglandins from nearby cells.

This usually begins with injury-substance P release from neuron, vasodillation and histamine relase from mast cells= neurogenic inflammation. This leads to release of the above metabolites.

This decreased pain tolerance is termed Hyperalgesia-primary (increased sensitivity to damaged area), secondary (surrounding area).

Question 24

How do you get referred pain?

Answer 24

Nociceptors from different places on the body can converge on the same relay nerurons (AT THE DORSAL HORN) which can confuse the brain about the location of the pain. This can happen during MI when receptors on the skin of the left arm converge with receptors on the heart and is interpreted as arm pain which is more common in our everyday experience.

Question 25

You daughter falls down and hurts her knee and you tell her to rub it. Which nerve fibers will be used to transmit this signal? How will the signal be reduced?

Answer 25

A neuron with A-beta fibers will act on an inhibitory interneuron to reduce the stimulation sent to the projection neuron (up the spinal cord) from the polymodal neuron (C fibers)

Question 26

The **P**osterior column medial lemniscal path carries what type of sensory information? Where does it cross over? What direction is it traveling?

Answer 26

**p**roprioception, light touch, vibration medulla ascends along the spinal cord

Question 27

The Anterolateral pathway carries what type of signal information? Where does it cross over? What direction does it travel?

Answer 27

pain, temperature, and crude touch. spinal cord :synapses at the dorsal horn, then crosses to the opposite side of the spinal cord to the anterolateral tract ascends along the spinal cord

Question 28

The Lateral corticospinal tract is also known as what? What direction are signals flowing along this tract? Where is the cross-over point?

Answer 28

pyramidal tract The signals desends along the spinal cords lateral sides, and moves from the lateral corticospinal tract to the ventral horn to synapse with an effector motor neuron. The cross-over point is the pyramidal decussation at the inferior medulla

Question 29

What type of communicaiton takes place among longitudinal spinal cord neurons along spinal tracts, and what can affect this communication?

Answer 29

The cross talk among these neurons allows for the brain to make generalized demands whose specific signaling is mediated by these neurons, rather than the brain making all the decisions for each motion individually. The diffusion of neuropeptides can spread signals among these neurons (pain), also distal muscle function can be lost when these lines of communication are broken due to injury

Question 30

How is it that herniated disks in the lumbosacral region can have such widespread effects?

Answer 30

The arrangement of passing fibers in the cauda equina is such that many nerve fibers are passing by each intervertebral disk

Question 31

You have a patient complaining of low back pain that appears to have a herniated disk as seen on an MRI of the region, they want to treat it surgically. What should you do or recommend first? A) surgical intervention as it will totaly aleviate symptoms B) surgical intervention as it will aleviate some of the symptoms C) Treat the patient with non invasive manuvers first, then refer for surgery if that doesn't alleviate symptoms D) Discuss with the patient that surgical intervention may not do anything for relief of their symptoms

Answer 31

D) is correct herniated disk does not necessarily correlate with back pain. Studies have shown that 10 years after treatment for disk herniation, the outcome for patients did not relate to whether the herniation persisted or not. There is an estimate that up to one-third of asymptomatic adults have a lumbar disk protrusion detectable by CT or MRI scans.

Question 32

After bumping your knee on a chair you quickley feel pain and decide to sit down to study physiology and investigate the way in which this pain signal moves through your spinal cord and ascends into the somatosensory cortex of your brain. Along its path you notice: A) That your pain signal moves lateraly through the paleospinothalamic tract B) Medialy through the paleospinaothalamic tract C) Lateraly through the neospinothalamic tract D) Medialy through the neospinothalamic tract

Answer 32

C) The signal sent was along a fast pain fiber (alpha delta) which will enter the dorsal horn with a first order neuron, then synapse and a second order neuron will carry the signal across the spinal cord and acsend the anteriolateral spinal tract into the lateral neospinothalamic tract (b/c fast pain fiber) b) is the only other accurately described answer but is incorrect

Question 33

Identify the locations of the anterior cingulate cortex and the insula cortex and breifly describe their functions and how they behave when disfunctional

Answer 33

The cingulate cortex surrounds the corpus callosum and the insula cortex is lateromedially located deep to the temporal lobe in a lateral sulcus seen with a coronal section. Insular cortex process information on the internal state of the body. Lesions in this area allow pain sensation but incorrect interpritation, as well as, empathy loss. Anterior cingulate cortex-thunberg's illusion where a warm or cold non noxious stimulus are unable to signal pain, but together they can.

Question 34

Name some ways in which pain sensitivity can be changed begining with the periferal sensation of pain and moving to the CNS communication and feedback systems.

Answer 34

Periferal nociceptors can become sensitized Synapses in the dorsal horn of the spinal cord can be acted upon by endogenous opioids Natural analgesic pathways from the periaquaductal gray matter or along descending indirect pathways can be modified or damaged Drugs that mimic endogenous opioids can interfer with pain signaling.

Question 35

Under what conditions does wind-up occur and what is the mechanism of wind-up?

Answer 35

Wind-up is sensitivity to pain after experiencing a high level of pain. This modification takes place at the dorsal horn and begins with the release of glutamate (neurotransmiter) into the synapse and the activation NMDA receptors which allow the flow of Ca2+. Ca2= influx sensitizes the membrane activity of the postsynaptic neuron making it more sensitive to signaling.