The Nervous System Flashcards
Identify the major components of the nervous system
Outline the functions of the brain stem
The brainstem sends messages between your brain and other parts of your body. It’s function is to regulate and control some body functions, including:
-Balance
-Blood pressure
-Breathing
-Facial sensations
-Hearing
-Heart rhythms
-Swallowing
Three parts of the brain stem:
1. Medulla – where the brain stem connects to the spinal cord
2. Pons – connects medulla and midbrain
3. Midbrain
Label the meninges of the brain and spinal cord
Meninges - (3 layers of membrane that protect brain and spinal cord)
- dura mater
- arachnoid mater
- pia mater
Identify the origins of CSF and its functions
CSF- cerebrospinal fluid
-circulates constantly from the ventricles through the subarachnoid space around the brain and the spinal cord.
-formed in cerebral ventricles
-originates in the choroid plexus
- provides suitable chemical environment for neuronal signaling – balance of ions helps to facilitate action potentials
- physical protection, shock absorbing medium- prevents brain and spinal cord from any trauma
- exchange of nutrients/wastes between the blood and nerve tissue
Describe and depict the structure of a nerve cell
With reference to neuronal structure, briefly outline the processes of action potential generation and axonal conduction
• Neurons send chemical signals across and this is ions moving in and out of neurons.
• Na+ sits outside the cell and K+ sits inside the cell
• When the cells are at rest there is a ‘resting membrane potential’, this means there is a charged difference between the outside of the cell and the inside of the cell
• Inside of the neuron is -, and outside is +, it sits at around -70
• But then there becomes a charge difference and a chemical difference this can then stimulate a neuron to send a signal.
• First we need something to excite the neuron for example neurotransmitters, and these neurotransmitters will go and bind to their specific receptors and they open up and allow Na to move through (through diffusion)
• Na+ goes inside the cell with its positive charge and so it makes the neuron side more positive, and more neurotransmitters bind to allow more Na so it becomes more positive, it becomes + all the way to -55.
• Once it goes to -55, the voltage-gated sodium channel gates open up and sodium rushes in (depolarization) with its + and so that part of the neuron becomes more + and hit -55 again and so it opens the next part of the voltage-gated sodium channel – domino-like fashion all the gates open
• It becomes so positive it spikes up to +30 in which these sodium channels close and the sodium is then trapped inside the neuron
• When it becomes +30, it triggers the opening of the voltage-gated potassium channel and potassium will then diffuse from inside the cell to the outside (repolarization), taking its + with it that the positivity decreases inside the cell all the way to -90 (hyperpolarization – so the neuron won’t send another signal as quickly)
• Embedded in the neuron there is a pump that resets it all and sends the Na out and brings the potassium in.
With reference to neuronal structure, briefly outline the processes of synaptic and neuromuscular transmission
• All the sodium gates are opened up and at the end of the neuron it becomes very positive and it stimulates a different type of voltage gated channel
• It stimulates the voltage gated calcium channel and they start to flip their lids and so the Ca2+ from the outside also rushes in
• When calcium enters it stimulates ‘vesicles’ plasma membrane with neurotransmitters inside, it stimulates them to start moving their way towards the plasma membrane and they fuse with the plasma membrane to release their contents
• If they are stimulatory neurotransmitters they cross the synaptic cleft and bind to receptors on the next neuron and then repeat the whole process
• However if they are inhibitory neurotransmitters, it may open up Cl channels for – chrolide to go in and makes the cell negative and stops the electrical signal from sending.
Identify how sensory information is conveyed to the central nervous system through activation of sensory receptors
A neuron works with a sensory receptor, a cell, or cell process that is specialized to engage with and detect a specific stimulus. Stimulation of the sensory receptor activates the associated afferent neuron, which carries information about the stimulus to the central nervous system
Compare the functions of the sympathetic and parasympathetic divisions of the autonomic nervous system
The autonomic nervous system is autonomous, acting independently of the body’s consciousness. They both happen to maintain homeostatis.
Both of them are made from two neurons, with the preganglionic neuron and the post ganglionic neuron (cell body outside the nervous system)
Sympathetic nervous system:
This is used in situations that require alertness and energy such as facing danger or doing physical exercise, this is activated to mobilize the body for action.
- instant response
- increases BP – vasoconstriction
- increases cardiac output
- accelerates respiratory rate
- releases stored glucose
- dilates pupils
- it inhibits body processes that are less important such as digestion and urination
- adrenal gland secrete noradrenaline and adrenaline into bloodstream in response to simulation
-these hormones act as neurotransmitters when they reach target organs
- ‘fight or flight’ - body prepares itself for exercise
- If body still under perceived threat: Hypathalamus releases CRH (corticotropin-releasing hormone) travels to pituitary glands which then triggers adrenocorticotropic hormone (ACTH). Cortisol then released by the adrenal glands.
Parasympathetic nervous system:
- usually slows down cardiac and respiratory activity but stimulates digestion and absorption of food
- removes waste and stores energy
- ‘rest and digest’
- The neurons release acetylcholine which inhibits cortisol response thus returning the body to normal
- SLUDD shows that’s the parasympathetic nervous system is working properly – saliva, lacrimation (tears), urination, digestion, defecation
Identify the following parts of the brain and outline their functions: medulla, pons, midbrain, cerebellum, hypothalamus, thalamus, cerebrum
• Cerebrum: higher-order functions: language memory, responsibility, thinking, learning, sensory perception of pain temp touch sight, initiation and control of skeletal muscle; contraction + voluntary movement
• Hypothalamus: effectors of the autonomic nervous system, body temp, appetite, emotional reactions, circadian rhythms eg sleeping + waking cycle
• Thalamus: sensory receptors send info on touch, pain + temp. Involved in arousal, Processing some emotions + complex reflexes
• Cerebellum: controls and coordinates movements of various groups of skeletal muscle, maintenance of posture, balance + equilibrium
• Medulla: controlling autonomic activities, such as heartbeat and respiration.
• Pons: generating the respiratory rhythm of breathing.
• Midbrain: serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing.
