Lecture 13 Flashcards
What is the function of a nervous system?
- coordinate the activity of the muscles
- monitor (regulate) the organs
- construct and stop (control) input from the senses (sight, hearing, touch, smell, taste)
- initiate actions
What are cells that receive sensations called?
Receptors
What are cells that make the appropriate response called?
Effectors
What are the two sub-divisions of the Nervous System?
- Central Nervous System(CNS):
- Brain
- Spinal cord - Peripheral Nervous System(PNS):
- All other nerves and neurons that do not lie within the CNS
How does the CNS develop?
Under the control of the notocord, the ectodermal cells come together to form a plate, crest, then finally a tube. This tube is the CNS
What is the development of the CNS called?
Neurulation
What are malformations of the neural tube called?
Neural Tube Disorders (NTDs)
What are the most common tube defects?
- Anencephaly (head):
When the anterior part of the tube fails to close over. The brain doesn’t form properly. - Encephalocele (head)
When the tube doesn’t close properly and some of the fluid forms a bag-like structure coming off of the head. - Spina bifida (spine):
When the posterior part of the tube doesn’t close completely. Results in some of the musculature that would normally be around the base of the spine to be able to protrude out/grow uncontrolled
How to prevent Neural Tube Disorders (NTDs)?
Take folic acid supplements early on and before pregnancy (vitamin b)
Why take vitamin b to combat NTDs?
Bc the DNA synthesises thats happening at the very early stages of embryo development requires folic acid to occur successfully
What are the two parts of the PNS?
- Autonomic nervous system (ANS)
- Somatic nervous system
Somatic nervous system function?
- Controls all of the conscious movement in the body (through efferent nerves)
- Deals with sensory information being sent into the CNS (through afferent nerve)
Autonomic nervous system (ANS) catagories?
- Sympathetic
- Parasympathetic
- Enteric
Autonomic nervous system (ANS) function?
- Controls all of the unconscious movement in the body
- Supplies all the internal organs
Sympathetic?
- Excites muscle (fight or flight responses)
Parasympathetic?
Relaxes muscle (rest and digest responses)
Enteric system?
The autonomic nervous system portion of the digestive system
e.g. Peristaltic wave in GIT
What are the 4 parts of a neuron?
- Dendrites
- Soma (cell body)
- Axon
- Synaptic terminal
What is the structural and functional unit of the nervous system?
The neuron
Where is the nucleus in a neruon?
Centrally placed in the soma
Where does a signal coming into a nerve get received first by?
The dendrites
What is in the centre of the dendrites?
The nucleus/cell body/soma
What carries the signal away from the soma?
The axon
Where does the axon terminate?
At the synaptic terminal, which is the connection point between two neurons
What is the perikaryon?
The internal structure of a cell body
What are the 3 types of specialised organs in the perikaryon?
- Nissl body:
- A large aggregation of rough ER
- Produce neurotransmitters
- Site of protein synthesis - Neurofilaments:
- Internal microfilaments
- Help to direct the neurotransmitter down to the synapse at the end of the axon - Neurotubules:
- Internal microtubules
- Help to direct the neurotransmitter down to the synapse at the end of the axon
- Found in axons and dendrites
Dendrites length?
Are short in general
Axon length?
Can be VERY long (up to 1 m)
What is the longest nerve in the body?
Sciatic nerve
What is damage to the Sciatic nerve called?
Sciatica
What are the three types of neurons?
Pseudounipolar, bipolar and multipolar
What happens if the brachial plexus gets damaged?
- limp or paralysed arm, lack of muscle control in the arm, hand, or wrist, and lack of feeling or sensation in the arm or hand
- Many brachial plexus injuries happen during birth if the baby’s shoulders become impacted
