PNB Midterm Test Prep Lecture 1 PDF

Lecture Notes Neuroscience Rules- 1. Symmetry: What is on the left is also on the right of the brain When you look at a section of the brain, you cannot tell which is the left and which is the right 2. Localization Of Function: Each part of the brain is responsible for a certai...

Lecture Notes Neuroscience Rules- 1. Symmetry: What is on the left is also on the right of the brain When you look at a section of the brain, you cannot tell which is the left and which is the right 2. Localization Of Function: Each part of the brain is responsible for a certain function There are 4 lobes in the brain with each responsible for something 1. Frontal lobe- cognition, language, and movement Cognition is processed in the prefrontal cortex Language is proceeded in Broca’s area which is responsible for language production Movement is processed by the primary motor cortex 2. Parietal lobe- touch Touch is processed by the primary somatosensory cortex 3. Occipital lobe- vision Vision is processed by the primary visual cortex {V1} 4. Temporal lobe- language and hearing Language is processed in the Wernick’s area where language processing occurs Hearing is processed in the primary auditory cortex  Gyrus= the peaks Sulcus= the grooves ○ Central sulcus: separates the frontal and parietal lobe It is inbetween the primary motor cortex and the somatosensory cortex ○ Lateral sylvian fissure: a reall deep sulcus: separated the frontal lobe+parietal lobe form the temporal lobe 3. Contralarity: Moving a part of the body activates the opposite side of the brain If you were to move your left hand, the right side of your brain is activating If you were to move your right hand, the left side of your brain is activating 4. Topography: Each section of the brain has highly ordered neurons responsible for it in the brain ➔ Motor homunculus- ◆ In the frontal lobe ◆ Responsible for the movement of certain body parts depending on their location ◆ The hand including the wrist, the thumb and the fingers as well as the face are larger here ➔ Sensory homunculus- ◆ In the parietal lobe ◆ Responsible for processing the sensory information from certain parts of the body Navigating The Nervous System- Positional terms: Superior- above Inferior- below Posterior- behind Anterior- in front of Dorsal- to the back Ventral- to the stomach Rostral- to the forehead Casual- to the back of the head Midline- the line separating the left from the right side of the body Medial- close to the midline Lateral- far from the midline  Decussate- crossing from one side to the other, crossing the midline Ipsilateral- same side Contralateral- different sides Proximal- close to the point of reference Distal- far from the point of reference Efferent- leaving the point of reference Afferent- going towards the point of reference Planes Of Section coronal/ frontal - From left to right ear Sagittal - From the nose to the back of the head Horizontal - Through the eyes (flat cut) The Brain- The 3lb universe Approximately 100 billion neurons {same number as start} ○ 100 billion=100 x 10^9= 10^11 Each neuron has a cell body diameter of 10um ○ 10um=10^-6m We use 100% or our brain capacity The brain has 20watts in power ○ Watts are jouled/second ○ The entire body has power of about 100watts The Neuron- Is at -65mV at rest The most common neurotransmitter is glutamate The inside of the neuron is -ve whilst its outside is +ve Sodium(Na+) , Potassium (K+), Chloride (Cl-) and Calcium (Ca2+) are the ion involved in the neruror electric activity of the neuron Neurons and other cells  ○ Similarities: They are both enclosed very similarly; the lipid bilayer membrane They also have the same organelles; such as he nucleus and the mitochondria ○ Differences: They are different in morphology; they have dendrites and an axon Morphology means the shape and structure dendrites= receive neurotransmitters (the input structures of a neuron) axons= send off neurotransmitters (the output structures of a neuron) They can be electrically excited, this is through the process of action potential Morphological variations ○ They can differ in shape depending on their dendrites Glial Cells-  ❖ These are non-neural cells in the nervous system ❖ There are 3 types 1. Astrocyte ○ They maintain the ionic environment of the neuron ○ They also regulate the blood-brain barrier 2. Oligodendrocyte ○ They help the neurons by moving the action potential down to the axon ○ This is done by myelinating the neurons 3. Microglia ○ They respond to intercellular injury ○ They look for damaged cellular debris and degrade them The Nervous System- Central Nervous System {CNS} ➔ All the parts that are compacted between bones ➔ The brain and the spinal cord, the brainstem and the cerebral cortex ◆ Brainstem: midbrain, pons, medulla ◆ Spinal Cord: cervical, thoracic, lumbar, sacral Peripheral Nervous System {PNS} ➔ All the parts not within bone ➔ The nerves (peripheral nerves) Technique Of The Week- Nissle Stain: Process: ○ A coronal slice of the brain ○ Take a small section (2mm) ○ Stain it then put it under a microscope It stained the ER it stained RNA thus only staining cell bodies, nothing else It allowed us to explore the structural features of a neuron ○ These include the dendrites, the cell body, and the axons It also was through this technique that they found that the no homogeneous distribution of neurons  ○ This means that theri distribution depends greatly on their specific functions, for example, neurons responsible for the lips are greater in numbers in the motor homuncolus and are theus mush more dense in that location compared to the foot. Other important things ○ Discovered that there are 6 cell layers ○ And that between neurons, there is fluid. Dicroverd By: Franz Nissl (1860-1919) Broddman’s Areas- Using the Nissl Stain, Korbinian Brodmann (1868-1018), discovered 52 areas in the cerebral cortex The cerebral cortex, is the outer most layer of the brain Area to memorize: ➔ 3,1,2,= Primary somatosensory cortex ◆ Located in the parietal lobe ◆ Arranged in the way they appear, so 3, is the most superior and 2 is the most inferior ➔ 4= primary motor cortex ◆ Located in the frontal lobe ➔ 17= primary visual cortex ◆ V1 ◆ Located in the occipital lobe ➔ 41,42= primary auditory cortex ◆ Located right beside the lateral fissure ◆ In the temporal lobe Cerebrospinal Fluid {CSF}- The fluid that surrounds the neurons It is a salty water kind of fluid It contains sodium, potassium, chloride, and other ions Ion Movement Through The Lipid Bilayer- The membrane (the bilayer) itself is impermeable, meaning no ion can go through the actual membrane but there are different easy of transportation that allow ions to flow in and out of the cell, these are: ★ Ion Transportes: ○ Active transporters- Require energy  Move selected ions against their concentration gradient From areas of low concentration to areas of high concentration ★ Ion Channels: ○ These are pores within the membrane that are selectively permeable to specific ions Only certain ions can flow through them ○ The ions are able to flow either way ○ Sodium Potassium Pump It uses energy to move the ions 2 K+ in and 3Na+ out Potassium concentration gradient High conc in Low conc out Sodium concentration gradient High conc out Low conc in Resting Potential- Negative because… ○ The K+ concentration is greater inside than outside due to the sodiun/ potassium pump ○ When the cell is at rest, it is primarily permeable to K+ as the membrane has k+ leaky channels ○ K+ diffuses out the cell and thus makes the cell more negative due to the loss of a lot of the +vely charged potassium ions Electrochemical Equilirbirum- Potassium will eventually stop diffusing and will start to go back into the cell due to the great attraction of opposit charges The inside of the cell is negative due to the diffusion of K+ but because it is very negative it now attracts +ve charges, including potassium ions But at the moment where the potassium stops diffusing and begins entering back into the cell, there is a moment where the net flow of K+ is 0, this is the equilibrium potential of potassium !!!It is important to note that the resting potential is specific to a neuron, and the electrochemical equilibrium is specific to ions!!! There are two things that establish an equilibrium potential: 1. Diffusion:  K+ diffuses down its concentration gradient ○ From high conc to low conc (like stairs) 2. Electrostatic force: As K+ diffuses out, the inside becomes more negative, thus attracting K+ into the cell ○ Opposite charges attract The Nernst Equation- z= is the electrical charge of an ion (valence charge) Ionic concentrations table: Inside (mM) Outside (mM) Ex (mV) Notes Potassium (K+) 140 5 -84 As observed, the K+ equilibrium is much more negative and that is why Sodium (Na+) 10 145 +64 when the neuron is at rest, the action potential is negative, this is attributed to the fact that at rest the neuron is primarily permeable to K+ due to their leaky channels.