E.4b Neurotransmitters & Personality

27/01/2014 § 1 Comment

So this part of the syllabus brings me back to CSI (the original one, none of that New York/Miami stuff) and the character Nathan “Nate” Haskell, who was a serial killer for a large part of the show. This guy was a serious nut job, a classic lunatic – he was legitimately psychotic. Just FYI (sort of spoilers, if you care?), it’s revealed later in an episode that he has a gene called the MAO-A gene which causes a predisposition towards violence. But yes, neurotransmitters and personality. A person’s personality is laced in his or her brain and depression and schizophrenia can have serious effects on personalities, but thankfully there are psychoactive drugs that have ways to help with such illnesses.

Depression happens when there’s a deficiency of norepinephrine or serotonin (excitatory neurotransmitters) in the brain. Psychoactive drugs can increase the levels of these neurotransmitters at synapses and at pre-synpatic neurons. Additionally, the enzymes that deactivate norepinephrine and serotonin at post-synaptic neurons are suppressed and the uptake of both neurotransmitters is inhibited at pre-synaptic neurons. This is meant to elevate the mood in normal people and to help with depression with people who are clinically depressed.

Schizophrenia happens when there is an excess of dopamine, but psychoactive drugs can decrease dopamine levels at synapses. Dopamine production is suppressed at pre-synaptic neurons and enzymatic deactivation of dopamine is increased at post-synaptic neurons and dopamine uptake increases at pre-synaptic neurons. These are the most effective agents to treat schizophrenia. But also also also, an increase in dopamine levels is caused by the usage of drugs, like too many amphetamines, and also cocaine is also known to cause paranoid or schizoid behaviour in normal people.

Scary stuff.

E.4a Neurotransmitters & Synapses

26/01/2014 § Leave a comment

Hey, Mr. Ferguson, what did one cell say to his sister cell when she stepped on his toe?

 

…MITOSIS.

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Okay, let’s do this. Assessment statement number 2 tells us to explain how decision-making in the CNS can result from the interaction between the activities of excitatory and inhibitory neurons at synapses. The CNS is the central nervous system that holds the sites where decision-making occurs. Action potentials in a neuron’s post-synaptic membrane (as a result of input from the pre-synpatic neurons) are the cause of excitatory and inhibitory activities. I think.

EPSPs are excitatory post-synaptic potentials, which obviously start through excitatory neurotransmitters. From what I understand, there are specific receptor proteins for these excitatory neurotransmitters, such as epinephrine, dopamine, and serotanin. When the neurotransmitter binds to the receptor protein, the result is a post-synaptic membrane that is permeable to sodium, which can then move across the membrane, depolarising it for enzyme to catabolise the neurotransmitters (an example of which is monoamine oxidase catabolising norepinephrine).

IPSPs are just the opposite; inhibitory post-synpatic potentials that root from inhibitory transmitters, like glycine, gamma-aminubutyric acid (GABA) and acetylcholine. When the neurotransmitter binds to the receptor proteins (which are specific for those inhibitory neurotransmitters), the result is a post-synaptic membrane that is less permeable to sodium. This allows potassium to diffuse across the post-synaptic membrane and hyperpolarise it.

E.5b Brain Function

20/01/2014 § Leave a comment

I’ve been listening to a lot of ’80s music these days. It helps deal with the senioritis.

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So one of the questions on the syllabus is “Explain sympathetic and parasympathetic control of the heart, movements of the iris, and flow of blood to the gut.” Well, okay, the sympathetic and parasympathetic controls are important in the autonomic nervous system, the heart, the blood flow of the gut, and the iris. GO FIGURE.

The sympathetic control of the ANS is for fight-or-flight while the parasympathetic control is for restorative, resting, and digestive purposes.In the heart, sympathetic control accelerates the heart, thus pumps more blood to the muscles while parasympathetic control does the opposite, slowing down the heart and pumping less blood to the muscles, letting the body relax. In the blood flow to the gut, the sympathetic control is to constrict the blood vessels, thus decrease the blood flow, and by contrast, the parasympathetic control is to dilate the blood vessels and increase the blood flow. Finally in the iris of the eye, the sympathetic control is for the radial muscles to contract, which in turns dilates the pupils (and lets it take in more light), and by contrast the parasympathetic control contracts the circular muscle fibers to contract to constrict the pupil and close it off from light.

Also, have a brief definition of the pupil reflex, which is when a bright light shines into one eye, both eyes’ pupils will constrict. And okay okay okay, the brain is also the organ that perceives pain, responding by releasing endorphins to inhibit pain. Brains. Very cool.

E.5a Brain Structure

20/01/2014 § Leave a comment

Fun fact! Did you know that Sara Bellum, the mayor’s sexy, faceless secretary from The Powerpuff Girls was probably named after the “cerebellum” in the brain because she sort of ran the show in the city, provided the logic and did all the thinking for the mayor? I bet you didn’t.

So as always, there is diagramming to be done. The different parts of the brain that we need to know how to diagram are: the medulla oblongata, the cerebellum, the hypothalamus, the pituitary gland (sound familiar?) and the cerebral hemispheres.

As for how they work and what each part does:

  • the medulla oblongata is responsible for controlling homeostatic and automatic activities, like swelling and breathing
  • the cerebellum (not the secretary) controls something similar; it takes care of coordinating unconscious functions, like body movements, so motor skills
  • the hypothalamus is responsible for maintaing homeostasis in the different levels of the body, controlling the nervous and endocrine system, taking care of body temperature, sleep, appetite, secreting hormones to regulate these levels
  • the pituitary gland secretes hormones, many hormones, always hormones
  • the cerebral hemispheres are super important, if you think about it (hahahaha “think” because it’s a brain, get it) because they control vital aspects that make us human, like memory, the abilities to learn, feel emotions, use languages, as well as our sense of logic

E.2c Ears

20/01/2014 § Leave a comment

This is the perfect time for me to mention that my ears are really good so do not even try to whisper bad things about me when I’m nearby.

That is an ear, and we have to label the different parts in a diagram as part of the syllabus. The things that are absolutely necessary to include are:

  • pinna
  • eardrum
  • bones of middle ear
  • oval window
  • round window
  • semicircular canals
  • auditory nerve
  • cochlea

The ear perceives sound using little tiny hair  cells in the cochlea – I literally know this because of my math exploration, isn’t that just fantastic. Sound waves vibrate the hair cells, drawing reactions from the eardrum, the bones of the middle ear, and the oval and round windows. The vibrations of the hair bundles transmit action potentials to the auditory nerve, sending a signal to the auditory cortex in the brain. And this happens very fast, as I’m sure you all know.

E.2a Perception of Stimuli

14/01/2014 § Leave a comment

IS SEMESTER ONE ALMOST OVER?

 

DATA BASED QUESTIONS

Page 322

1.

a) Lassen County: 83.3% ; Santa Cruz: 15.4%

b) In Santa Cruz, the snakes began to eat more slugs while the snakes in Lassen County started to eat less slugs. However, as population grows, the competition also grows in environments, which is what happens in Lassen County. There are fewer slugs, so the competition is very intense as the snakes have to fight over their food supply.

2. Lassen County snakes will outcompete te Santa Cruz snakes because of natural selection!

3.

a) Over the course of time, natural selection will make it so that the slug eating response isn’t inherited, so less snakes ate slugs.

b) Because natural selection selected against the slug eating allele, as time passes, the allele will become recessive. The snakes wouldn’t be able to survive if the allele were dominant because they’d naturally try to hunt for slugs, and because the environment doesn’t have that supply, they would suffer.

4. MECHANORECEPTORS

 

11.2b Muscles & Movement

10/01/2014 § Leave a comment

Ah yes, this “new year, new me” crap. Note: I’ve just posted this because I realise that I missed the class and this blog post due to my English IOC. My bad.

 

DATA BASED QUESTIONS

Page 267, transverse sections of striated muscle

1. Explain the difference between a transverse and a longitudinal section of muscle. –> The transverse section is perpendicular to the longitudinal section and the longitudinal section runs along the longer axis.

2. Deduce what part of the myofibril is represented by the drawings as small dots. –> The small dots in the myofibril represent the actin.

3. Compare the pattern of dots in the three diagrams. –> The first and second diagrams have similarities in that they both have large dots. The first and third diagram by contrast both have smaller dots. The first diagram therefore seems to be a combination of the second and third diagram.

4. Explain the differences between the diagrams in the pattern of dots. –> While the second diagram only represents myosin and the third diagram only represents actin, the first diagram represents both.