Term 3: Cognition Flashcards
What is “sensing”? Is it involuntary, voluntary or both?
It is being able to detect abnormalities within our internal/external environment with the use of sensory receptors. The message is then sent to the brain. This can be voluntary with the use of eyes/ears/skin etc or involuntary like changes to BP.
Describe the process of sensory input, integration and motor output.
Sensory input - sensory receptors pass message on to the brain via afferent/sensory neurons. Integration - information is received by brain or spinal cord and action is determined. (Memory often plays a part here, how did the body previously respond?) Motor output - the action determined by integration. The outgoing message/response sent via efferent/motor neurons.
What are the two subdivisions of the nervous system and what are the main parts they consist of and their function?
Central Nervous System (CNS) - brain and spinal cord. Most active are the cerebral regions. Function is to receive information and interpret it. Peripheral Nervous System (PNS) - consists of receptors which detect change, and nerves which carry information. It branches off in to somatic (sensors in eyes/ears/skin etc.) and autonomic (sensors in organs) Autonomic then branches off to sympathetic (fight or flight response) and parasympathetic (rest and digest).
What is the outermost layer of brain cells called? What happens here?
The cortex. This is where thinking and voluntary movements begin.
Where is the brain stem and what functions does it control?
The brain stem is between the spinal cord and the rest of the brain. Basic functions like breathing and sleep are controlled here.
There is a cluster of structures in the centre of the brain. They coordinate messages between multiple other brain areas. What are they called?
Basal ganglia.
Where is the cerebellum and what is it responsible for?
The cerebellum is at the base and the back of the brain. The cerebellum is responsible for coordination and balance.
What lobes is the brain divided in to and what is the function?
- frontal lobes: problem solving, judgement and motor function
- parietal lobes: sensation, handwriting, body position.
- temporal lobes: hearing and memory
- occipital lobes: visual processing system
Define meninges?
Connective tissue membrane protecting the skull and spinal cord.
What are the three layers of the meninges of the brain?
Dura mater - this is the outermost layer connecting to inside of cranial bones. It consists of two layers, and blood vessels are located between them.
Arachnoid - this is under the dura mater and below this is the subarachnoid space. In this space lies fibres that further stabilise the brain and vertebrae, cerebrospinal fluid and most of the blood vessels are located here.
Pia mater - this is the innermost layer. Pia mmater translates to “gentle mother” it is the delicate layer that clings tightly to the brain and spinal cord’s surface.
What is CSF and what is the function?
Cerebrospinal fluid.
- made up of mostly water, adults have approx. 150ml but produce 500ml per day to maintain pressure.
- cushions the brain and spinal cord, contributes with movement of substances within the blood.
Brain capillaries are extremely permeable, true or false? Why/why not?
FALSE. Brain capillaries are not very permeable and this plays a protective function stopping unwanted substances entering the brain tissue. This is called the blood-brain barrier.
Some that can enter include fat soluble sunbstances such as nicotene, alcohol, blood gases, caffiene and some bacteria eg. the bacteria that causes meningitis.
What are the three types of neurons?
- sensory neurons
- interneurons
- motor neurons
What are the three parts of a neuron and what does each part do?
Neurons carry electrical signals.
- cell body: integrates information
- dendrites: recieve information
- axon: transmits information
When looking at the pathways of messaging via neurons we describe their pathway as either afferent/efferent. What is the difference?
- Afferent – information that is coming from the periphery into the nervous system
- Efferent – information that is going away from the nervous system to the periphery
How do neurons communicate?
- Communication involves the generation and movement of an electrical impulse down the neuron
- The electrical impulse derives from the establishment of an action potential.
- The action potential results from the movement of Na, K & Ca ions across the cell
- Separating each neuron from each other is a synaptic gap
What is membrane potential?
- Ions have an electrical charge in different concentrations across a cell membrane. This means there will be a difference in electrical potential across the cell membrane.
- This is called Membrane Potential It is measured in millivolts
What is a resting neuron potential?
The voltage across the membrane when a neuron or muscle cell is not producing an action potential
-70 millivolts
Describe action potential.
- Stimulus to neuron(eg heat to thermo receptor)
- Stimulus causes Na+ channels in neuron cell membrane to open.
- Resting Membrane potential changes and depolarisation occurs
- Na+ channels close and K+ channels open and repolarisation occurs
What is the difference between the absolute refractory period and the relative refractory period?
- Absolute refractory period: during sodium entry (depolarisation ) the neuron is unable to respond to a stimulus.
- Relative refractory period: after sodium channels are shut (repolarisation) it is difficult but not impossible to respond to another stimulus.
What is a synapse?
- Neurons don’t meet. The small space between them is called the synapse
- Synapses are essential to nervous system communication
- Impulses are transmitted across a synapse by chemical messengers
What is the role of the neurotransmitters?
- They are chemicals that enable signals to be transmitted across the synapse
- In this process, calcium needs to enter the cell to allow neurotransmitters to be released
- Neurotransmitter binds to receptors but can only bind to a specific receptor
How many cranial nerves are there and what do they do?
- Extending from the brain are 12 pairs of nerves
- These are responsible for motor and sensory messages between the brain and the body.
They are numbered using a roman numerical system, named based on the area of the body they are responsible for.
What is the role of the spinal cord? (two points)
- Provides pathways to and from the brain both ascending (up the cord) and descending (down the cord)
- Produces reflexes without input from the brain that require no conscious effort (involuntary) in response to pain
