MMED Nervous Block

Question 1

DESCRIBE Levels of organisation in organisms

Answer 1

Organism: Systems packed into whole body
Systems: organs related and collected
Organs: made up of several tissue types
Tissues: groups of cells of similar specialization
Cells:cells are the basic unit of life
Molecules: various atoms and molecules make up the body

Question 2

DESCRIBE Types of tissue:

Answer 2

Epithelial Protection, secretion and absorption
Connective, Structural support
Muscle, movement
Nervous, communication, coordination and control

Question 3

DESCRIBE Systems of the body:

Answer 3

Circulatory (heart, vessels), digestive (mouth, liver), respiratory (nose, lungs), urinary, skeletal, muscular, integumery, immune, nervous,
Than endocrine, reproductive.

Question 4

DESCRIBE Homeostasis:

Answer 4

body cells are in a dynamic steady state in the internal environment. However life requires behaviour, exploratory behaviour.
Factors regulated: Concentration of nutrients, oxygen, waste, salt and other electrolytes. The pH, volume and temperature.

Question 5

DESCRIBE protein roles in cell

Answer 5

Enzymes
Cell signalling and signal transduction
Antibodies
Channels
Receptors
Structural cytoskeleton
Contractile filaments

Question 6

DESCRIBE How is ATP formed in cells:

Answer 6

Glycolysis - Glucose -> 2 pyruvate, 2 ATP
CAC - Acetyl CoA -> 2 CO2, 3 NADH, 1 FADH2, 1 ATP (per pyruvate)
ETC - 28ATP
Total of 32 ATP

Question 7

DESCRIBE CNS and PNS

Answer 7

CNS = brain / spinal cord
PNS = all other nervous systems

Question 8

DESCRIBE Cauda equina / CSF

Answer 8

Area at waist where spinal cord ends, followed by nerves.

Cerebrospinal fluid, similar to blood plasma

Question 9

DESCRIBE Neuron structure (multipolar)

Answer 9

Going from input signal to integration to output.
Dendrites come off cell body with nucleus leading to axon hillock to Axon, surrounded by myelin sheath ending at presynaptic axon terminal.

Question 10

DESCRIBE Neuron classifications

Answer 10

Sensory (afferent) - psudounipolar, bipolar - 2 axons leading from central body
Interneuron of CNS - anaxonic, multipolar - no axon or highly branched
Efferent neuron - multipolar - several dendrites off of cell body into axon.

Question 11

DESCRIBE Myelin

Answer 11

Increases speed of AP conduction, surrounds axon and some dendrites.
Cells are called Schwann in PNS and oligodendrocytes in CNS.

Question 12

DESCRIBE Grey matter / white matter

Answer 12

Grey matter is in the center of spinal cord has no myelin and non-neural cells
White matter is on the edges and consists of many myelinated nerves.

Question 13

DESCRIBE Describe the cross section of the spinal cord

Answer 13

Receptors pass charge through afferent fibers, passing cell body of afferent neuron in dorsal root ganglion, continuing through dorsal root, through grey matter to interneuron, to cell body of efferent neuron passing through ventral root out efferent fiber to effectors.

Question 14

DESCRIBE Afferent / efferent nerves

Answer 14

Afferent or sensory nerves travel to CNS through dorsal root.
Efferent or motor nerves travel from CNS through ventral root.

Question 15

DESCRIBE Describe organisation of nervous systems from inputs to outputs.

Answer 15

Sensory or visceral (internal) stimuli travel afferently to CNS, output efferently to somatic NS (then as motor neurons to muscles) or autonomic NS, as sympathetic NS (homeostasis / fight / flight), or parasympathetic NS (function / rest / digest), or enteric NS (digestive).

Question 16

DESCRIBE Neurotransmitters

Answer 16

Stored in vesicles in presynaptic terminal. Transfer to other cells from neurons after AP stimulation. Interaction with other cell may be excitoray (causing AP, contraction, secretion), or it may be inhibitory (preventing AP, relaxation, preventing secretion)

Question 17

DESCRIBE Release mechanism for neurotransmitter

Answer 17

AP travels to presynaptic terminal, depolarises membrane, opening voltage activated Ca channels, Ca enters terminal, Ca triggers fusion of neurotransmitter containing vesicles.
Neurotransmitter passes accross sunaptic cleft to receptors on postsynaptic membrane.

Question 18

DESCRIBE Postsynaptic mechanisms

Answer 18

2 neurotransmitter receptors
Ligand gated channels - causes membrane potential changes, opens on reception allowing for ion passage.
G protein couples receptors - may have many reactions, G protein made of a, b, y subunits with GDP in (a) unit. Reception causes GTP to bind and (a) to detach and bind to enzyme activating it. (a) then recombines with G protein.
This may or may not occur as protein and enzyme are free floating.

Question 19

DESCRIBE Autonomic cotransmitters

Answer 19

Autonomic fibers can release cotransmitters with neurotransmitters, presynaptic receptores may be activated by cotransmitters. These can modulate the release of neurotransmitter from the presynapse.

Question 20

DESCRIBE Nerve trunks

Answer 20

Formed by nerve roots after leaving spinal cord

Question 21

DESCRIBE Sensory modalities

Answer 21

Mediated by different types of receptor neurons in specific organs
Vision, smell, taste, touch, thermal, pain, hearing, balance, proprioception

Question 22

DESCRIBE Type of receptors

Answer 22

Chemoreceptors - taste / smell/ arterial O2 / H+
Photoreceptors - images / light intensity
Thermoreceptors - surface / core temperature
Nociceptors - pain / damage / strong stimulation of other receptors
Mechanoreceptors - pressure / vibration / tendon length / sound

Question 23

DESCRIBE Somatosensory signals

Answer 23

Sensory information travels to thalamus via spinal cord / dorsal root, through to primary somatosensory region of cerebral cortex on opposite side to the stimulus

Question 24

DESCRIBE Sensory pathway

Answer 24

2 pathways to the brain
Dorsal column pathway (touch) -  fibers run up spinal cord in dorsal columns, pathway has synapse in lower medulla where it decussates to the other side, ending in sensory cortex.
Spinothalamic pathway (pain) - fibers enter spinal cord synapse with interneurons, crossing to other side, then to sensory cortex.

Question 25

DESCRIBE Somatosensory cortex

Answer 25

Exists in cerebral cortex, different areas correspond to different body parts.

Question 26

DESCRIBE The autonomic nervous system ganglionic details

Answer 26

Sympathetic - axons (sympathetic postganglionic fibers) to organs coming from ganglia receiving message from spinal cord from preganglionic fibers. At ganglion is nicotinc receptor for ACh and at target is noradrenaline receptor Parasympathetic - long preganglionic fibers from CNS in brain or low segment of spinal cord to parasympathetic ganglion close to target with short postganglionic fiber. At ganglion is nicotinic receptor for ACh, at target is muscarinic receptor Enteric - NS of GI tract, largest, input from parasympathetic preganglionic axons / sympathetic postganglionic axons. Independant from brain. Ganglion close to target with nicotinic receptor for ACh. complex ganglion to ganglion activity.

Question 27

DESCRIBE Adrenal medulla

Answer 27

The central part of the adrenal gland, part of sympathetic NS, secrets adrenaline into blood upon reception of ACh on nicotinic receptors from nerve fibers.

Question 28

DESCRIBE Neural reflexes

Answer 28

Stimulus activates sensory receptor, AP sent to CNS via afferent pathway, CNS initiates AP in efferent neurons via ventral roots to muscle and gland targets. This is an involuntary response.

Question 29

DESCRIBE Feedback mechanism for limb position

Answer 29

(muscle spindle) receptor detects change, sends AP afferently via dorasl root, integration in CNS results in Efferent message via ventral roots to effector (muscle groups).

Question 30

DESCRIBE Neural reflex categorisation

Answer 30

By division of efferent nervous system controling response CNS location where reflex integrates Whether reflex is inate or learned Number of neurons in pathway (monosynaptic / polysynaptic)

Question 31

DESCRIBE Skeletal muscle reflexes

Answer 31

Proprioceptors (spindle / golgi tendon) in joints, muscle and ligaments send signals afferently to CNS through sensory neurons. Following integration with excitatory / inhibitory neurones output efferently carried by somatic motor neurons to effectors of contractile skeletal muscle.

Question 32

DESCRIBE Golgi tendon

Answer 32

Golgi is in tendons near joints detecting joint position and rate of motion by small stretch. Allows proprioception in carrying force by inhibition of motor neuron involved in contraction.

Question 33

DESCRIBE Golgi tendon reflex

Answer 33

Increased muscle tension during contraction - golgi tendon organ afferent fiber firing increases with tension - excited inhibitory spinal interneuron - inhibits muscle contraction

Question 34

DESCRIBE Muscle spindle

Answer 34

Muscle spindle is modified muscle with sensory axons in muscle fibers and detects length and contraction through separate sensory supply, also has motor supply to maintain sensitivity. involved in mono-synaptic stretch reflex mediated muscle contraction.

Question 35

DESCRIBE | Muscle spindle reflex

Answer 35

Stretch - spindle afferent fibres - AP along sensory fibers - monosynaptic excitatory synapse on Alpha motor neuron to muscle - contraction of muscle Neurons also connect to antagonist muscle with inhibitory response to reduce antagonist movement through polysynaptic pathway

Question 36

DESCRIBE Flexor withdrawal reflex

Answer 36

Moves limb away from nociception or strong reception, AP enters spinal cord afferently, branches through interneurons to stimulate flexor muscles / inhibit extensor muscles. No control occurs thus is not negative feedback

Question 37

DESCRIBE Crossed extensor reflex

Answer 37

Polysynaptic pathway of flexor withdrawl where interneurons pass stimulus through to the opposite side of body to opposing limbs for balance. Where extensors/flexors are inhibited or contracted.

Question 38

DESCRIBE motor cortex

Answer 38

Posterior part of brain is parietal lobe, front section of parietal lobe is primary sensory cortex. Anterior part of brain is frontal lobe, back end is primary motor cortex, front end has supplementary motor area above pre-motor area.

Question 39

DESCRIBE Corticospinal tract

Answer 39

Initiating in frontal lobe of motor cortex, fibers run to spinal cord in corticospinal tract. Ventral tract controls proximal musculature, lateral tract is main tract, controls distal musculature / fine hand movement, is where nerves cross over.

Question 40

DESCRIBE Damage to corticospinal tract

Answer 40

Loss of motor control Increase in monosynaptic stretch reflex. Damage to the cerebral cortex will affect the opposite side of the body

Question 41

DESCRIBE Vasculature of brain

Answer 41

Anterior system - carotid arteries forming middle / anterior ceberal arteries Posterior system - vertebral arteries forming basilar artery then posterior cerebral arteries / cerebellar arteries Both systems join to form circle of willis (arterial circle). Any artery / branch can be blocked, ending flow to sections of the brain forming a stroke.

Question 42

DESCRIBE Cerebellum

Answer 42

Accounts for fast regulation of limb position / balance / coordination. Recieves information from spinal cord / cerebral cortex, sends message via brainstem nuclei. Is pricipal source of sensoimotor integration

Question 43

DESCRIBE Damage to cerebellum

Answer 43

``` Poor coordination (clumbsy), no distinct area targeted unlike cerebral cortex Lesion to right side will affect right side of body, central damage affects both sides ```

Question 44

DESCRIBE Basal ganglia

Answer 44

Group of nuclei at base of cerebral cortex with connections between eachother and with cerebral cortex / cerebellum. Important in voluntary movement.