Cells and autonomic nervous system

Question 1

What are neurons/nerve cells

Answer 1

Are the structural and functional units of nervous system
* Excitable cells that transmit electrical signals (specialized
in processing information)
* Cannot reproduce but can regenerate cell processes if
the cell body remains intact

Question 2

What are Neuroglial cells

Answer 2

They offer structural & functional support, protection, and
anchor neurons in place
* Not excitable (do not generate action potentials)
* Retain ability to continue dividing/reproduce

Question 3

What is the Cell body/Soma/perikaryon

Answer 3

(main part of the cell)

Question 4

What are dendrites

Answer 4

(short, numerous, and highly branched)
– Receive impulses (graded potentials) from other
neurons.

Question 5

What is the axon hillock

Answer 5

(trigger zone)
– Site were graded potentials are integrated to generate
an action potential/impulse.

Question 6

What is the Axon

Answer 6

– Conducts nerve impulses away from cell body.
– Are cylindrical and can be myelinated (with node of
Ranvier) or nonmyelinated.

Question 7

What is the synaptic knobs

Answer 7

(contain vesicles with neurotransmitters)
– Synapse - site of communication between a neuron and
a neuron/effector cell

Question 8

What are unipolar neurons

Answer 8

A single axon originating from the cell body
* They are found in invertebrates

Question 9

What are bipolar neurons

Answer 9

• Two axons originating from the cell body
• They are rare and are exclusively found in special
  sensory organs (retina and olfactory epithelium)

Question 10

What are pseudounipolar neurons

Answer 10

• A single axon originating from the cell body which
  splits into two branches (mostly found in PNS)

Question 11

What are multipolar neurons

Answer 11

• They have one axon and several dendrites
  originating from the cell body
• Most abundant neuron type in the CNS

Question 12

What are sensory neurons and what type of neuron are they

Answer 12

• transmit impulses to CNS (afferent)
• Mostly pseudounipolar, some are bipolar

Question 13

What are interneurons/relay and what type of neuron are they

Answer 13

• Link spinal motor and sensory neurons
• Transfer impulses between sensory and motor
  neurons
• They are multipolar

Question 14

What are motor neurons and what type of neurons are they

Answer 14

• Carry impulses away from CNS (efferent)
• Two types: lower motor and upper motor
  neurons
• They are multipolar

Question 15

What does the hypothalamus do

Answer 15

• Hypothalamus forms part of the limbic system
• Hypothalamus – below the thalamus
• Heavily involved in pituitary endocrine function
  – The pituitary gland sits ventrally to the hypothalamus
• Large role in homeostasis

Question 16

Name some hormones involved with hypothalamus and homeostasis

Answer 16

• Gonadotropin Releasing Hormone (GnRH)
• Corticotropin Releasing Hormone (CRH)
• Thyroid Releasing Hormone (TRH)
• Prolactin Releasing Hormone (PRH)
• Growth Hormone Releasing Hormone (GHRH)
• Antidiuretic Hormone (ADH)
• Oxytocin

Question 17

Ways of glucose being processed after entry into nerve cells

Answer 17

– Glycolysis
– The pentose phosphate pathway (PPP)
– Glycogenesis (in astrocytes only not nerve
cells)

Question 18

What is the sympathetic nervous system

Answer 18

fight and flight

Question 19

What is the parasympathetic nervous system

Answer 19

rest and digest

Question 20

Describe basic structure of both Autonomic nervous system

Answer 20

• Both divisions require a two-neuron chain between
  the nucleus of origin in the central nervous system
  (CNS) and the peripheral target organ.
• In both divisions, preganglionic fibres are
  myelinated, and postganglionic fibres are
  nonmyelinated.

Question 21

In ANS are preganglionic fibers myelinated or nonmyelinated

Answer 21

myelinated

Question 22

In ANS are postganglionic fibres myelinated or nonmyelinated

Answer 22

Non myelinated

Question 23

Describe position of cellbody location of postganlionic neurons in sympathetic division

Answer 23

– Sympathetic division found relatively close to
the spinal cord (paravertebral
ganglia/sympathetic trunk),

Question 24

Describe position of cellbody location of postganlionic neurons in parasympathetic division

Answer 24

– Parasympathetic division are located within
small ganglia near or incorporated within the
walls of the target organ(s).

Question 25

Describe position of cellbody location of preganglionic neurons in parasympathetic division

Answer 25

– Parasympathetic division: are restricted to the brainstem (to the nuclei of cranial nerves: III - oculomotor, VII - facial, IX - glossopharyngeal, and X- vagus); and in the sacral region of the spinal cord (S2 – S3/4: pelvic nerves).

Question 26

Describe position of cellbody location of preganglionic neurons in sympathetic division

Answer 26

– Sympathetic division: Spinal cord, between the first thoracic and middle lumbar segments (T1 to L3).

Question 27

What is the sympathetic and parasympathetic preganglionic neurotransmitter

Answer 27

Acetylcholine

Question 28

What is the Sympathetic postganglionic neurotransmitter

Answer 28

norepinephrine

Question 29

What is the parasympathetic postganglionic neurotransmitter

Answer 29

Acetylcholine

Question 30

What neurotransmission division/receptor is PNS reffered to as

Answer 30

cholinergic

Question 31

What neurotransmission division/receptor is SNS reffered to as

Answer 31

adrenergic

Question 32

What are the 2 exceptions for SNS neurotransmission

Answer 32

* merocrine/eccrine sweat glands innervated by cholinergic sympathetic postganglionic fibres. * epinephrine/adrenaline produced and released into bloodstream by the adrenal medulla (chromaffin cells)

Question 33

What are the 2 types of receptors

Answer 33

cholinergic and adrenergic

Question 34

What are the 2 types of cholinergic receptors

Answer 34

Nicotinic acetylcholine receptor and muscarinic acetylcholine receptor

Question 35

What are Nicotinic acetylcholine receptors (nAChR)

Answer 35

* present at neuromuscular synapses * present at all autonomic ganglia (i.e., at synapses connecting preganglionic to postganglionic neurons). * activation of nAChR results in excitatory postsynaptic potentials (EPSPs).

Question 36

What are * Muscarinic acetylcholine receptors (mAChR)

Answer 36

– present in effector tissues innervated by parasympathetic postganglionic fibres. – present in the merocrine sweat glands innervated by cholinergic sympathetic fibres. – have several subtypes (M1, M2, M3, etc.), all coupled to G proteins linked to second messenger systems. – activation of mAChR leads to either excitatory or inhibitory postsynaptic potentials (EPSPs or IPSPs).

Question 37

What are the 2 types of adrenergic receptors

Answer 37

Alpha and beta

Question 38

What are – α‐adrenergic receptors (α1, α2)

Answer 38

* are mostly excitatory

Question 39

What are – β‐Adrenergic receptors

Answer 39

* have several subtypes (e.g., β1, β2, β3)

Question 40

What are the main differences between the somatic and autonomic systems

Answer 40

– the target tissues/organs (effectors) (somatic - skeletal muscle vs ANS - viscera e.g., cardiac, smooth muscle, glandular tissue, etc). – ANS has two-neuron chain between nucleus of origin in CNS and target organ.

Question 41

Which has more discrete activities PNS or the SNS

Answer 41

PNS

Question 42

Where is location of PNS ganglia/ why is PNS activities more discrete

Answer 42

– The location of PNS ganglia close by or even within the target organ also contributes to the localisation of responses. – Acetylcholine used at the last synapse in the PNS is liberated and destroyed locally and has very specific effects.

Question 43

Where is location of SNS ganglia/ why is SNS activities less discrete

Answer 43

* In contract, SNS ganglia are located closer to the CNS (spinal cord), as such SNS postganglionic fibres radiate more widely before reaching their target organ, resulting in more general and less discrete sympathetic responses. – Also, epinephrine/adrenaline produced by the adrenal medulla is released directly into the bloodstream, evoking a mass sympathetic response.

Question 44

Describe upper motor neuron

Answer 44

* UMNs are efferent neurons originating within the brain that do not innervate somatic or visceral muscle directly, * Rather they synapse indirectly (via an interneuron) with LMNs to modify their activity. * UMN cell bodies/nuclei are located in the cerebral cortex, midbrain or brainstem. * UMNs are responsible for voluntary muscle control, regulation of muscle tone, and maintenance of posture against gravity.

Question 45

Describe Lower motor neuron

Answer 45

* LMNs are efferent neurons connecting the CNS to somatic or visceral muscle. * LMN cell bodies/nuclei are located within the grey matter in the ventral horn of the spinal cord (from C6-T2 & L4-S3) and within the cranial nerve nucleus of the brainstem. * LMN axons leave the CNS as ventral nerve roots, become spinal nerves that innervate effector organ(s) (muscle or gland). * LMNs are the last neurons in a chain of neurons that produce the muscular contraction necessary to maintain posture, support bodyweight and provide gait.