Physiology of Sensations and Reflexes

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Questions and Answers

Which sensation is primarily responsible for alerts regarding temperature changes inside the body?

Superficial receptors

Central temperature receptors (correct)

Nociceptors

Hypothermia sensitivity

Which type of sensation can result from overextension of the urinary bladder?

Tactile sensation

Pressure sensation

Visceral sensation (correct)

Temperature sensation

What is the role of nociceptors in the body?

Detect pain stimuli (correct)

Regulate temperature

Perceive touch sensations

Sense pressure changes

Which of the following is NOT a type of sensation that can be detected by superficial temperature receptors?

Deep pressure Signup and view all the answers

Which physiological response is primarily triggered by increases in the body's core temperature?

Sweating Signup and view all the answers

What is the primary function of a somatic reflex?

To contract or inhibit skeletal muscle Signup and view all the answers

Which of the following best describes the stretch reflex?

A monosynaptic reflex involving only one synapse Signup and view all the answers

Which neuron is directly responsible for sending an integrated response to target organs in the reflex arc?

Motor neuron Signup and view all the answers

What structure initiates the reflex arc?

Sensory receptor Signup and view all the answers

What is the role of autonomic reflexes?

To regulate smooth muscle and cardiac muscle activity Signup and view all the answers

Which type of neuron synapses with the motor neuron in the reflex arc?

Interneuron Signup and view all the answers

What is the significance of the patellar reflex in clinical practice?

It is useful for diagnosing spinal cord trauma Signup and view all the answers

During a stretch reflex, what happens when the muscle spindle stretches?

It sends a signal via the somatic sensory neuron Signup and view all the answers

What is the purpose of pain receptors?

To protect the body from injury Signup and view all the answers

What is the first step in the nociception process?

Transduction Signup and view all the answers

Which type of pain primarily affects muscles and joints?

Deep pain Signup and view all the answers

What is 'wind-up pain'?

Pain that is amplified by the spinal cord Signup and view all the answers

What challenge is commonly faced when assessing pain in animals?

Animals tend to hide pain due to survival instincts Signup and view all the answers

Which statement is false regarding pain management?

Old methods of 'masking' pain are considered ethical. Signup and view all the answers

During which process does conscious perception of pain occur?

Perception Signup and view all the answers

What characterizes acute pain?

Sharp and intense feeling Signup and view all the answers

What is the term for an excessively strong reflex?

Hyperreflexive Signup and view all the answers

If a dog has a spinal cord injury at L2-L4, what reflex response should be expected?

Hyporeflexive patellar reflex Signup and view all the answers

What is being evaluated when testing the palpebral reflex?

Sensory neurons in CN V Signup and view all the answers

Which of the following describes the normal response to the pupillary light reflex (PLR)?

Both eyes constrict simultaneously Signup and view all the answers

What condition is characterized by a bulging or ruptured intervertebral disc?

Intervertebral Disc Disease (IVDD) Signup and view all the answers

What is the role of the quadriceps femoris during the patellar reflex?

It contracts upon triggering of the reflex arc. Signup and view all the answers

What is a clinical sign of Intervertebral Disc Disease (IVDD)?

Decreased pain sensitivity Signup and view all the answers

What would be a likely intervention for managing Intervertebral Disc Disease (IVDD)?

Surgical intervention or medical management Signup and view all the answers

What happens to opposing muscles during the stretch reflex?

They are relaxed to allow smooth movement. Signup and view all the answers

Which of the following is NOT included in the general senses?

Vision Signup and view all the answers

Which statement is true regarding the withdrawal reflex?

It activates muscles in response to a painful stimulus. Signup and view all the answers

What characterizes the crossed extensor reflex?

It prevents falling by extending muscles on the opposite limb. Signup and view all the answers

How does the brain influence the strength of reflexes?

It dampens the intensity of reflex responses. Signup and view all the answers

What is a notable feature of the stretch reflex in comparison to other reflexes?

It is an ipsilateral reflex. Signup and view all the answers

What happens when the spinal cord is injured above the reflex area?

Reflexes occur normally without modulation. Signup and view all the answers

How do afferent sensory neurons contribute to muscle relaxation during the reflex?

They inhibit the motor neuron of opposing muscles. Signup and view all the answers

Study Notes

Neurology: Reflexes, Senses & Pain

This presentation covers spinal reflexes, how they work, brain modulation, general senses, and pain.
Three main topics will be discussed: spinal reflexes, how the brain controls them, and the general senses, including pain.

Reflexes

Reflexes are rapid, automatic responses to stimuli.
There are three types:
- Reflex: a rapid, automatic response to a stimulus.
- Somatic reflex: involves contraction of skeletal muscles (e.g., knee-jerk).
- Autonomic reflex: involves smooth muscle, cardiac muscle, and endocrine glands (e.g., digestion).

The Reflex Arc

A reflex arc describes the pathway a nerve impulse takes from stimulus to response.
Sensory receptor → Sensory neuron → Interneuron → Motor neuron → Effector (muscle or gland).
Interneurons integrate sensory input with other signals, creating the appropriate response.

Motor Neuron Target

Somatic motor neurons control skeletal muscles.
Autonomic motor neurons control organs, blood vessels, cardiac muscle, and endocrine glands.

Types of Somatic Reflexes

Stretch reflex: maintains muscle tone.
Withdrawal reflex: protects from harmful stimuli.
Extensor reflex: maintains balance during withdrawal.

Stretch Reflex

A simple, monosynaptic or two-neuron reflex arc.
It has one synapse between sensory and motor neurons.
The stretch receptor is a muscle spindle, sending signals to the spinal cord, then back to the muscle.
Prevents overstretching and maintains muscle tone.

Patellar Reflex

Commonly in neuro exams, it helps diagnose spinal cord trauma, peripheral nerve damage, or muscle disease.
The reflex hammer taps the patellar ligament, stretching the quadriceps femoris; triggering a contraction and the leg extending.

Stretch + Relaxation

The stretch reflex also causes opposing muscles to relax.
Afferent sensory neurons synapse with inhibitory interneurons in the spinal cord.
Inhibitory neurotransmitters are released.
This prevents opposing muscles from working against the other, allowing one to contract freely.

Withdrawal Reflex

Occurs when a harmful stimulus is received.
The hand is pulled away from the source of heat in a classic example.
The reflex involves several interneurons and synapses with motor neurons that contract muscles and opposing muscles that release inhibitory neurotransmitters

Crossed Extensor Reflex

If a painful stimulus is applied, the opposite leg extends to maintain balance and prevent a fall.
Afferent sensory impulses cross to the opposite side of the spinal cord.

Brain's Role in Moderating Reflexes

The brain can modify the intensity of reflex responses.
The brain does not dampen the reflex if the spinal cord is injured above the reflex area.
The response is stronger (hyperreflexive) in this instance.

Spinal Injury at the Level of the Reflex

An injury at the level of the spinal reflex may cause absence or decreased intensity of reflex response (hyporeflexive).
If the injury is above the reflex (L2, L3, L4) the reflex is hyperreflexive
If the injury is below L2-L4, the reflex is normal

Other Reflexes (Palpebral, Pupillary Light Reflex)

Palpebral reflex: a response to tapping the inner eyelid causing blinking.
Pupillary light reflex (PLR): the eye constricting simultaneously in response to shining light into the eye.

Clinical Case: Intervertebral Disc Disease (IVDD)

This is a neurologic condition resulting from spinal disc bulges or ruptures causing swelling around the spinal cord.
Signs include ataxia (lack of coordination), paralysis, or decreased pain.
Diagnoses are made through radiographs, MRI or CT to detect the exact segment with injured disc.
Treatment for IVDD depends on the severity, but mostly involves surgical decompression or/and medical management.

General Senses

General senses provide information about the body's environment (both internal and external).
Includes visceral sensations (internal organs), touch, temperature, and proprioception (body position).

Visceral Sensations

These inform the brain about the status of internal organs.
Includes sensations like hunger, thirst, pain from stretch, gas in the GI tract, kidney stones and urinary bladder.
Inflammation of peritoneum or pleura also causes pain.

Touch

The sensation of something being in contact with the body.
Includes light touch, deep pressure, vibration, and hair movement.

Temperature

Temperature receptors detect changes in body temperature (hypothermia, hyperthermia).
Superficial receptors (skin) detect skin temperature changes.
Central receptors (hypothalamus) monitor core temperature.
Responses to temperature variations include blood flow to the skin, sweating, piloerection, shivering, and thyroid hormone production

Pain (Nociception)

Nociceptors are pain receptors found throughout the body (except the brain).
They are simple, free nerve endings sensitive to mechanical force, temperature, and chemicals.
Nociception is the complex process of perceiving pain.
The steps involved in nociception include transduction, transmission, modulation, and perception.

Classifications of Pain

Categorized as superficial (skin, SQ tissue), deep (muscles, joints), or visceral (organs).
Pain can also be acute (sharp, intense) or chronic (dull, aching).

Wind-Up Pain

Spinal cord amplifies pain signals resulting in increased pain even when under anesthesia.
Multimodal pain control with medications can help to block pain perception at different parts of the pain pathway (transduction, transmission, modulation, and perception).

Challenges with Assessing Pain in Animals

Hiding pain is a survival mechanism for animals.
Animals less likely to complain about pain compared to people.

Pain Scales (canine and feline)

Pain scales provide tools for measuring and evaluating animal pain. (Specific scales mentioned are not part of this broad summary bullet formation requirement without additional detail, however the concepts of their use is important and a part of this study summary).

Proprioception

The sense of body position and movement in space.
Involves stretch receptors in muscles, tendons, and ligaments.
Used to evaluate neurological function.

Clinical Scenario: Old Dog Vestibular Disease

Vestibular system involves brain and inner ears.
Symptoms are rolling, nystagmus (eye movements), ataxia, vomiting, anorexia, and drooling.
Diagnoses often use labs, radiographs, BP, ear exam, and cytology.
Treatment generally involves hospitalization, IV fluids, and motion-sickness medications.

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Description

Test your knowledge on the physiological mechanisms of sensations and reflexes in the human body. This quiz covers key concepts such as temperature changes, reflex arcs, and the roles of nociceptors. Perfect for students in anatomy and physiology courses.