New Nervous System Lecture

Main functions of the Nervous System

• Provide communication between tissues

• Integrate and process info from environment (external) and body (internal)

• Control movement and physiological processes

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Synapse

• Chemical transmission occurs across this

• Polysynaptic element

What chemically transmits across the synapse

Neurotransmitters (e. acetylcholine, norepinephrine)

Polysynaptic element can be either

• Another neuron (dendrites or cell body)

• Innervated tissue (e. muscle)

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Central Nervous System (CNS)

Brain amd spinal cord

Different parts of brain

Brainstem + Cerebral hemispheres + Cerebellum

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Peripheral Nervous System (PNS)

Neurons and other neural structures oustide of CNS

PNS parts

• Cranial nerves

• Motor nerves

• Parasympathetic nerves

• Sympathetic nerves

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Nerve

A gross structure of a bundle of axons usually surrounded by connective tissue and blood vessels

• Travels in the PNS

• Does NOT contain cell bodies

___ nerves exit out of brain stem, but ______ does not.

11, olfactory

Afferent/sensory

Neurons or the pathway involved in carrying info to the CNS

Sensory stimuli

Skin, muscle, joints, bones, organs/viscera

Specialzed dendrites

• Nociceptors

• Proprioceptors

• Mechanoreceptors

__________ for most neuron type in afferent/sensory pathway.

Pseudonipolar

Pseudonipolar

neuron type known for its role in transmitting sensory information to the central nervous system.

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Sensory

Detect mechanical, chemical, and thermal changes via specialized receotors

Sensory facts

• Bipolar for specialized sensory

  • Vision, hearing, smell, vestibular, taste

• Receptor cells

Vestibular

system responsible for balance and spatial orientation, using input from the inner ear.

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Efferent/motor

A neuron or pathway that carries info away from CNS

• Multipolar neuron

• Includes Somatic and Autonomic Nervous System

Multipolar neuron

A type of neuron characterized by multiple processes extending from its cell body, including one axon and several dendrites, allowing it to integrate and transmit information effectively.

Autonomic Nervous System

The part of the peripheral nervous system that controls involuntary bodily functions, such as heart rate, digestion, and respiratory rate. It is divided into the sympathetic and parasympathetic nervous systems.

Nociceptors

Sensory receptors that detect pain or harmful stimuli, signaling potential injury.

Propiceptors

Sensory receptors that sense body position and movement, providing information about the position of muscles and joints.

Mechanoreceptors

Sensory receptors that respond to mechanical pressure or distortion, facilitating the sensation of touch, sound, and vibration.

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Somatic Nervous System

Somatic motor component of PNS that includes network network of neurons innervating musculoskeletal structures (e. skeletal muscle)

Which nerves are in sensory?

Optic and Oflactory

SNS

• Somatic Motor Neurons (Lower Motor Neurons)

• Synapse at Neuromuscular junction

  • Presynaptic terminal

  • Synaptic cleft

  • Postsynaptic membrane

Somatic Motor Neurons synonym

Lower Motor Neurons

Presynaptic terminal

• Axon terminal

• Synaptic vesicles

Postsynaptic membrane

Receptors

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Basic Reflex Arc happens where?

Spinal cord

Basic Reflex Arc that that could go from brain to spinal cord back to brain

Response

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Automatic Nervous System (ANS)

Visceral motor component of PNS (smooth muscle, cadiac muscle, and glands)

Afferent vs. efferent

Afferent refers to sensory pathways carrying signals towards the central nervous system, while efferent refers to motor pathways carrying signals away from it.

Sympathetic Division of ANS

Fight or flight

Sympathetic Division of ANS responses

• Pupil dilation

• Increased heart rate

• Brondilation

• Glucose mobilization

Autonomous systems

• Sympathetic

• Paraysmpathetic

Dilate pupils when predator comes why?

To see everything

Increased heart rate needed in sympathetic whay?

To run and get nutrition

Bronchodilation

Airway in lung dilates to get more air -—> need more air supply so mitochondria to make ATP needs oxygen, also transported through blood that needs oxygen

Glucose mobilization

is the process of breaking down glycogen to release glucose into the bloodstream, providing immediate energy for muscle and brain function during stress or physical exertion.

Parasympathetic Division of ANS

Rest and digest

Parasympathetic Division of ANS responses

• Pupil constriction

• Decreased heart rate

• Bronchoconstriction

• Peristalsis and GI secretion

Bronchoconstriction

is the narrowing of the air passages in the lungs, usually as a response to the parasympathetic division of the autonomic nervous system, which helps reduce airflow.

Peristalsis and GI secretion

Refers to the rhythmic contractions of smooth muscles in the gastrointestinal tract that move food along the digestive tract and the production of digestive fluids; makes gastric enzymes to break down food

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Myasthenia Gravis: “Maison” signalment

Six-year-old MN Toy Poodle

Myasthenia Gravis: “Maison” chief complaint

Weakness and inability to jump or climb for the past week

• Intermittent paresis

Myasthenia Gravis: “Maison” chief other clinical signs

Regurgitation, voice change

Intermittent paresis

A fluctuating muscle weakness that occurs sporadically, affecting the ability to move.

Regurgitation vs. vomitting

Regurgitation is the passive expulsion of contents from the esophagus or stomach, often without nausea, while vomiting is an active process involving forceful expulsion of stomach contents.

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Def of Myasthenia Gravis: “Maison”

• Immune-mediated, neuromuscular disorder

• Characterized by muscle weakness and excessive fatigue

  • Oten associate with megaesophagus

Megaesophagus

A condition where the esophagus is enlarged and loses its ability to contract effectively, leading to difficulty in swallowing and regurgitation.

Etiology of Myasthenia Gravis: “Maison”

• Antibody destroying acetylcholine (AcCh) receptors located on the postsynaptic membrane

• Inefficient signaling to stimulate muscle contraction

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Acetylcholine (AcCh) receptors

Proteins on muscle cells that bind acetylcholine, facilitating nerve signal transmission for muscle contraction.

Postsynaptic membrane

The membrane of a neuron or muscle cell that receives neurotransmitters, allowing for signal transmission and response.

Specific Inefficient signaling to stimulate muscle contraction in Myasthenia Gravis

occurs when antibodies block or destroy acetylcholine receptors, diminishing communication between nerves and muscles.

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Diagnosis of Myasthenia Gravis: “Maison”

• PE: neurological focused

• Tensilon Testing (Edrophonium)

• Blood antibody test (ACh receptor antibodies)

Tensilon testing synonym

Edrophonium

Tensilon testing

is a diagnostic procedure that involves administering edrophonium chloride to temporarily improve muscle strength in patients suspected of having Myasthenia Gravis.

Blood antibody test (ACh receptor antibodies)

is a laboratory test used to detect the presence of antibodies against acetylcholine receptors, which are often found in patients with Myasthenia Gravis. This test helps confirm the diagnosis by identifying an immune response that interferes with neuromuscular transmission.

Treatment of Myasthenia Gravis

• Pharmaceutical: Acetylcholinesterase inhibitor

  • Pyridostigmine

• Bailey chairs

Acetylcholinesterase inhibitor

is a class of drugs that inhibit the enzyme acetylcholinesterase, leading to increased levels of acetylcholine at the neuromuscular junction and improving muscle strength in conditions like Myasthenia Gravis.

Pyridostigmine

is a medication classified as an acetylcholinesterase inhibitor used in the treatment of Myasthenia Gravis. It works by increasing the levels of acetylcholine at the neuromuscular junction, thereby improving muscle strength.

Bailey chairs

are specialized seating devices designed to assist individuals with muscle weakness in maintaining posture and mobility during daily activities.

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Idiopathic Trigeminal Neuritis: “Iris” signalment

9.5-year-old FS Golden Retriever

Idiopathic Trigeminal Neuritis: “Iris” chief complaint

Jaw paralysis with ptyalism (excessive drooling) and difficulty eating for a week

Idiopathic Trigeminal Neuritis: “Iris” other clinical signs

Inability to close the mouth-dropped-jaw

Idiopathic Trigeminal Neuritis defenition

• Disease process that affects all motor branches of the trigeminal nerve

• Bilateral

• Non-supportive

Idiopathic Trigeminal Neuritis Etiology

• Primary: Idiopathic

• Secondary: Cancer, inflammation, infection, traum to CN5 (Trigeminal Nerve)

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Diagnosis of Idiopathic Trigeminal Neuritis

• Diagnosis of exclusion

• PE: Neurological focused

  • Maybe oral exam (extra cancer/disease)

• Advanced imaging of the head: CT and MRI

Treatment of Idiopathic Trigeminal Neuritis

• Management/intensive nursing:

  • Tape muzzles

  • Placing balls of food at the back of dog’s mouth

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What medical issue did “Maison” have?

Myasthenia Gravis

What medical issue did “Iris” have?

Idiopathic Trigeminal Neuritis