SOMATIC REFLEXES and anatomy histology Flashcards
How are muscle spindles controlled to contract when carrying weight
- sensory nerve endings wrap around muscle fibres
- increase weight length– increase muscle stretch – increase sensory activity as threshold reached – release of excitatory NT– muscle contraction: PREVENTS DAMAGE
What happens with the patellar tendon organ in the knee jerk reflex
- PTO below stimulus – detected by muscle spindles which are stretch receptors in quad muscle–stretches spindle–stimulate SN– spinal cord– release NT to motor neurone – quad muscles – quad contracts
- PTO detected by stimulus – sensory neuron to SC – inhibitory neurotransmitter– stops motor neurons from firing – hamstring relaxes
: simultaneous of this will enable the leg to kick out
What happens when golgi tendon organ
sensory neuron in tendon - detects tension – sensory neuron– inhibitory NT– motor neuron and releaxes the mucle: : reverse (inverse) myotatic reflex
- muscle detects stretch receptors in muscle–sensory neuron– excitatory NT–spinal cord– motor neuron – contraction of skeletal muscle: myotatic reflex reverse
why is the reverse inverse myotatic reflex needed
- prevent damage due to overwork
- fine control of muscle tension
What happens in the cross extensor reflex
- noxious stimuli picked up by foot - dorsal part of spinal cord– 1 neuron to brain and some to motor neuron
1: extensor inhibited by exciatory that excites inhibitory NT– inhibits Motor neuron– extensor relaxes
2: sensory release excitatiry NT– excite exciatory – release of excitatory NT– contracts the flexor
POLYSYNAPTIC
What happens to adjust posture in the extensor reflex
- we need to influence muscles on left side to adjust posture and support body weight: LEFT LEG
–3rd: neuron travels in other side of SC– excite excitatory neuron- excitatory NT release- contracts extensor
4th: neuron travels to other side of SC – excitatory neuron to excite inhibitory– inhibitory– relaxes flexor
Why do lumbar vertebrae have larger vertebral bodies than cervical or thoracic
- have carry most of the bodies weight
What travels through the transverse foramen/foramen transversarium of the cervical vertebrae?
The vertebral artery passing supplying the brain
What is the function of intervertebral discs between each vertebrae and what is it made up of
- Solid enough to permit weight of the body and flexible enough to permit movement
- They absorb stress and shock from body
- Preventing the individual vertebrae from binding with each other
- They are made of fibrous cartilage
- The disk consist of outer ring of tough fibrous cartilage called the anulus fibrosus and a soft centre called the nucleus pulposus
- Limits the rotation of the vertebrae
- The nucleus pulposus will be the one that absorbs the shock – acts like a rubber ball
- The inner rings is cartilage and external that are made from ligaments
What are the differences in body shape, spinous process and vertebral foramen of cervical, thotacid and lumbar
BODY SHAPE:
C=curved
T=more triangular
L=large and more curved
SPINOUS PROCESS:
C= short
T= long
L= short
VERTEBRAL FORMAMEN SHAPE:
C= triangular
T= more curved
L= triangular
What is the white matter in the spinal cord CNS and the grey matter of the CNS
CNS - spinal cord – white matter= tracks
- white matter is with myelinated axons: contains fibrous astrocytes
Grey matter- consists of nerve cell bodies and interneurons: contains protoplasmic astrocytes
What is the layers of peripheral nerve
- peripheral nerves contain layers of connective tissue
- first layer is a connective tissue layer = EPINEURIUM
- each bundle of connective tissue= PERINEURIUM
- layer of connective tissue surrounding axon=ENDONEURIUM
- not all peripheral nerves myelinates- some schwann cells assosiate with non myelinated fibres
What are neuroglia cells
non neuronal cells in CNS: They maintain homeostasis, form myelin, and provide support and protection for neurons.
What are different neuroglia cells and what are their functions
- Oligodendrocytes (CNS equivalent of the Schwann cells)
Formation of myelin sheaths in the CNS.
▪ Astrocytes branched cells between the neurones that provide
mechanical support and mediate the exchange of metabolites
between neurones and the vascular system (blood-brain
barrier). Astrocytes play an important role in repair of CNS
tissue after damage
▪ Microglia monocyte-macrophage system (defence).
▪ Ependymal cells make up a specialised epithelium which lines
the ventricles and spinal canal
What are the functions of microglia
- monitor for pathogenic material
- macrophage cells and so remove microbial pathoegens of damaged synapses
- releases cytokines after they find damage
