BMSC 207 Nervous System 4

Question 1

Difference between somatic and special senses?

Answer 1

Somatic Senses: Receptors associated with the Skin, Muscles, Joints, and Viscera.
Special Senses: These Include the senses of smell, Taste, Hearing, Static and dynamic equilibrium, and sight.

Question 2

Explain how receptors convert physical stimuli into electrical signals?

Answer 2

Physical Stimuli are transduced into Receptor Potentials (Graded Potential), Receptor potentials reaching threshold induce action potentials

Question 3

Receptive Fields

Answer 3

Sensory neurons are activated by stimuli that fall within a specific physical area.

Question 4

CNS distinguishes 4 properties of a Stimulus:

Answer 4

1. Modality - The physical stimuli being sensed, determined y the sensory receptors being activated, temperature vs touch receptor and where the pathways terminate in the brain.
2. Location - Coded according to which receptive fields are being activated.
3. Intensity - determined by the # of receptors being activated (Population coding) and the frequency of action potentials coming from those receptors (Frequency coding)
4. Duration - Stimulus is determined by how long AP’s are being activated.

Question 5

Tonic and Phasic Receptors

Answer 5

Tonic Receptors: Are Slowly adapting receptors that respond for the duration of a stimulus. (spends most the time in activated stage)
Phasic Receptors: Rapidly adapt to a constant stimulus and turn off. (Takes rests)

Question 6

Autonomic Nervous system

Answer 6

Involuntary control of smooth muscle, Cardiac muscle, Many glands and some adipose tissue.

Question 7

Autonomic Nervous System (subdivsions)

Answer 7

Sympathetic: Fight or flight
Parasympathetic: Rest and Digest

Question 8

What are Autonomic Reflexes important for?

Answer 8

Homeostasis

Question 9

Autonomic Pathways have two efferent pathways

Answer 9

Preganglionic Neuron: Originates in brainstem or spinal cord.
Postganglionic Neuron: Travels from ganglion to the muscle.

Question 10

Sympathetic Pathway

Answer 10

Ganglia are found in 2 ganglion chains running along side vertebral column.
Preganglionic neurons originate in thoracic and lumbar regions
Short Preganglionic, Long postganglionic.

Question 11

Parasympathetic Pathway

Answer 11

Preganglionic neurons originate in the brainstem and exit via cranial nerves or sacral region of spinal cord.
Ganglia are mainly located on or near their target organs
Long preganglionic, Short Postganglionic

Question 12

Sympathetic and Parasympathetic Pathways use _____?

Answer 12

Sympathetic: Acetylcholine and Norepinephrine
Parasympathetic: Acetylcholine

Question 13

Adrenal Medulla

Answer 13

Secretes Catecholamines
Neuroendocrine structure associated with the Sympathetic Nervous System (Fight or Flight)

Question 14

Autonomic Pathways

Answer 14

Target Smooth and Cardiac muscle, many exocrine glands, a few endocrine glands, lymphoid tissue, Liver and some adipose tissue.

Question 15

Neuroeffector Junction

Answer 15

Receptors are not clustered under varicosities, neurotransmitter diffuses to receptors.

Question 16

8 Stages of Autonomic Pathways

Answer 16

1. AP arrives at Varicosity
2. Depolarization opens voltage-gated Ca2+ channels
3. Ca2+ entry triggers exocytosis of synaptic vesicles
4. NE (Norepinephrine) binds to adrenergic receptor on target
5. Receptor activation ceases when NE diffuse away from the synapses
6. NE is removed from synapses
7. NE can be taken back into synaptic vesicles for re-release
8. NE is metabolized by monoamine oxidase (MAO)

Question 17

Sympathetic Adrenergic (NE and E) Receptors

Answer 17

all g-protein coupled receptors (metabotropic)
Two main categories:
Alpha, Beta

Question 18

Parasympathetic Cholinergic (ACh) Receptors

Answer 18

g-protein coupled receptors: Muscarinic Receptors
5 Subtypes: M1-M5