Thursday, October 25, 2012

Periodic Table of The Cupcakes

Today the Chemistry Club had these for sale to make money for the club.  Obviously there are some missing due to previous sales, so the table is not complete.

Sold for $2 each, here is the one I bought:


If you came here wanting to see an actual periodic table, here you go:

And check out this super cool website that has a video for every single element in the periodic table!  Some have explosions and other fun stuff, and of course the guy with the sweet hair-do. :)   - Periodic Table of Videos
Here's an example, with the video on Sodium (Na):



Also at UVU today right next to the periodic table of cupcakes, they did "Pie Your Professor" for a fundraiser.  I took these pictures with my iPod so sorry they're pretty blurry.
Here's a student taking a shot at (and missing) Dr. Halling:



Here are the Chemistry professors- the brave ones have their hoods down.. haha.


Quite the pile of debris left behind...  these guys are good sports.


Kudos, Chemistry Club, you've got some fun ways to raise funds. ;)





Wednesday, October 24, 2012

Muscle Contraction

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Thursday, October 18, 2012

Brain Anatomy and Functions

Let's talk about the most amazing organ in the most complex organism on the planet, shall we? :)

Here is a basic orientation:


Brain Stem
The most ancient ("primitive") part of the brain is the brain stem.  This part of your brain is responsible for basic functions to keep you alive.  Includes the Medulla oblongata, Pons, and Midbrain.  First a look at the parts:

Source

Here is a view of a frontal slice through the human brain stem:
1- Cerebrum, 2- thalamus, 3-midbrain, 4- pons, 5- medulla oblongata, 6- spinal cord (Source)






Now a look at each part and the centers each contains that help keep you alive in-the-moment.  Things that could kill you in a matter of seconds or minutes if they don't work properly are controlled here.  We'll start with the most inferior part and move up.

Medulla Oblongota

Control centers of Medulla:
  • Vasomotor- regulate blood pressure
  • Cardiac center - controls heart rate, strength of contraction
  • Respiratory center - controls respiratory muscles, is sensitive to pH (so it can respond by increasing or decreasing respiratory rate which will bring the body back into homeostasis as far as pH)
  • Respiratory reflexes - vomiting, swallowing, coughing, sneezing


Mnemonic from Physiology student - "programming your VCR makes you vomit"

Another cool thing that happens in the medulla:
Source

  • Decussation of fiber tracts - decussation is a fancy scientific word for swapping.  As you all know, the right side of the brain controls the left side of the body, and vice verse.  The medulla is where the nerve fibers cross over.  (Also referred to as "decussation of pyramids".)
     Source
     
Pons
  • Pathway between spinal cord and brain
  • Fine control of respiration
Inferior view (looking up at bottom of brain) showing the Pons (Wikipedia)

Mesencephalon (midbrain)
  • Conduction pathway between cerebral hemispheres
  • Reflexes based on visual stimuli (moves head and eyes to protect them from being hit or poked)

That is the brain stem.  Next we will continue superiorly.

Thalamus
Paired organ at top of brain stem, see picture below
Thalamus is the purple part.  Detailed anatomy of brain stem if you want that info. (Source)
  •  General sensations of pain, heat, cold, pressure (can't pinpoint location or intensity)
  • Sensory Gatekeeper - pathway between cerebral cortex and sensory/somatic systems.  Shuts out some sensory info to allow for greater focus on important things.  So it takes in all that general info and filters out what's not important (such as the sensation of your clothes touching your skin so stuff like that doesn't become distracting)

Reticular Activating System
Housed in the brainstem and thalamus is the Reticular Activating System, shown below in red.
 
reticularactivatingsystem.org
This system controls your waking state and alertness, sending signals to the cerebral cortex to keep you awake and alert.  This allows you to direct your attention to specific events.  It also holds back sensory info at other times to allow you to sleep, and controls your circadian rhythms (sleep-wake transition).  In fact, if I understand correctly, the RAS has an inhibatory affect on the part of the brain that contributes to sleepiness - the Preoptic Area (POA) of the Hypothalamus.  Likewise, the POA can inhibit the RAS when it's time to sleep.  Pretty cool.
An even more cool fact - this alertness center is very active when awake, and is suppressed during deep sleep, but during REM sleep when you are dreaming, the RAS is just as active as when you are awake! :)

Hypothalamus
The inferior part (floor) of the thalamus.  See picture above, the purple front section on left picture.  Also, the picture below gives a more general orientation.  Here are its functions.

Source
  •  Manager of the Autonomic Nervous System
    • Rage & aggression
    • Hunger & satiety
    • Fluid osmolarity
      • Thirst center
      • Anti-diuretic hormone (ADH)
    • Body temp
  • Regulates the Anterior Pituitary Gland, which affects:
    • Growth
    • Sexual Function
    • Lactation (breast feeding), regulated by oxytocin
    • Thyroid function
    • Stress, regulated by cortisol
Here's a more detailed diagram of the hypothalamus:
Source


Cerebellum


Source
The motor integrating center - makes last-minute fine tuning adjustments to motor activities, controlling coordination.
Tells "how far, how fast, and when to put the brakes on"
Sobriety tests are really testing the functionality of the cerebellum.  Depends on sight and proprioception (info on what your body position actually is right now) input.  Prevents dysmetria and past-pointing.  (Dysmetria = missing the mark; past-pointing = moving beyond the mark.)



Source
The cerebellum processes input from other areas of the brain, spinal cord and sensory receptors to provide precise timing for coordinated, smooth movements of the skeletal muscular system. A stroke affecting the cerebellum may cause dizziness, nausea, balance and coordination problems.

Cerebrum

Source


Basal Ganglia/ Basal Nuclei
Trains the brain to do fine motor activities
Suppresses unwanted movement
Initiates trained complex movement patterns
Lesion in this area causes Parkinson's disease


Source


Limbic System
Includes parts surrounding the brain stem: cerebral cortex, basal nuclei, thalamus, and hypothalamus
Source
Responsible for "fight or flight" type of survival, and species survival instincts:
  • aggression
  • fear
  • feeding
  • sexual behavior
  • motivation




Cortices of the Brain

Primary Motor Cortex
Voluntary contraction of skeletal muscle

Premotor Cortex
Stereotyped movements - "computer programmer" for repeatedly used actions
*Broca's Area
Controls muscles responsible for speech - only on the left side of the brain

Somatosensory Cortex
Pinpoints location and intensity of temperature, touch, pressure, and pain (general sensations of these come from thalamus, then are passed on here to get more details)
Proprioception

Primary Visual Cortex
Vision
Primary Auditory Cortex
Hearing
Olfactory Cortex
Smell
Gustatory Cortex
Taste

Parietal-Temporal-Occipital Association Cortex
Interprets primary sensations from somatic, auditory, and visual areas
*Wernicke's area
Allows for interpretation/ understanding of language (both written and spoken)


Prefrontal Association Cortex
Planning for voluntary activities
Perceiving consequences of future actions
Responsible for personality traits 
Teen drinking impairs the development in this area



For additional information related to the brain, see these other posts:

Action Potentials

Action Potentials Up Close

Neurons

Neuroglia


 Brain Food: Nutrition for Learning & Memory


Nervous System

Monday, October 8, 2012

Neurons

Conduction of an impulse down one neuron to the next.
(Click to enlarge)
Encyclopedia Britannica


Channels, Channels, Channels!
There are 9 different kinds of gates/channels/ pumps in neurons.  I will group them here by their function which can help you remember them.
So, just to be clear this is how I categorized the channels by what they do.

Maintain membrane potential:
Na+ diffusion channel (Sodium leak channel)
K+ diffusion channel (Potassium leak channel)
Sodium-potassium pump

Involved in action potentials:
Voltage-gated sodium channels (allow sodium to rush in, resulting in depolarization)
Voltage-gated potassium channels (allow potassium to rush out, resulting in repolarization)
Voltage-gated calcium channels (are triggered at the end of the axon, and trigger release of neurotransmitters)

Involved in post-synaptic reception:
Chemically-gated Na+/K+ channel (Ligand-gated sodium-potassium channel)
Chemically-gated K+ channel (Ligand-gated potassium channel)
Chemically-gated Cl- channel  (Ligand-gated chloride channel)

Here is a diagram I made, grouping the channels by function (each function has the same shape).

Notice that the 3 responsible for membrane potential (triangles) are all over the whole cell membrane.  The 3 responsible for action potentials (stars) are only on the axon (from axon hillock to axon terminal) because that is where the action potentials happen.  The 3 responsible for post-synaptic reception are the circles and are on the cell body.  I put them only on the post-synaptic neuron for simplicity.  But obviously the cell body of the pre-synaptic neuron would also have them.

The influx of Calcium triggers the neurotransmitters to exocytose and that is the end of the message for the pre-synaptic neuron.


Example of chemically-gated channels with Chloride channel being activated (notice the red triangles represent neurotransmitter and they do not enter the cell)
Neurotransmitter is not allowed into the postsynaptic neuron.  Rather, the neurotransmitter binds to the channel receptor, changing its shape and allowing a particular ion or ions to diffuse through, down their concentration gradient.  Each gate lets through what the name says it does.  For instance, Chemically-gated Chloride Channels let chloride through.  Here's a good diagram:
Source

Here's a fantastic little animation which has a dynamic way of illustrating the action potential moving down the axon and how the ions are moving to make that happen!  (Thanks David and Scott!)

Neurons are fascinating.  Please comment to let me know what you found useful in this post, or if you have suggestions for improvement.  Also, see the below post for more info:
Click here to learn about action potential
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