01.02 Brain and Behavior

Hormones are secreted from the endocrine system and released in the bloodstream. Some hormones are produced in the brain while others are produced elsewhere, like in the thyroid or adrenal glands. The impacts from hormones is longer term. For example, cortisol is a stress hormone that is responsible for our fight-or-flight response. Once cortisol is released, it slows down our digestive and reproductive systems, increases our heart rate, and pumps blood to our limbs. Once this is released, it can take several minutes to several hours to de-escalate and regulate our body to homeostasis again.  Hormones also always impact involuntary actions- such as heart rate and breathing. Examples of hormones include insulin, estrogen, progesterone, testosterone, serotonin, cortisol, and adrenaline. Neurotransmitters are produced by the nervous system and take place locally in the brain between neurons. Neurons are electrical devices.  Here we have one neuron next to another neuron. The space between them is called a synapse and that’s where the magic happens; this is how they talk to each other. Electrical events will cause this neuron to release a neurotransmitter and bind to a receptor in other neuron. The neurotransmitter can either excite or hinder the other neuron from firing its own electrical event. Neurotransmitters stay local to the brain and their actions are fast so they have short term impacts. For example, when we kiss the person we love we get a short lived burst of serotonin and dopamine that gives us lovey feelings. We may crave that again but the actual impact was short term. Neurotransmitters can impact voluntary or involuntary actions. An example of voluntary actions is eating. Eating tasty things like chocolate can stimulate the brain to release dopamine, which is a neurotransmitter connected to the reward center of our brains. Examples of neurotransmitters are acetylcholine, dopamine, norepinephrine, serotonin, GABA, and glutamate. Now let’s look specifically at the brain itself. The brain has three main parts- the cerebrum, cerebellum, and the brainstem. A key thing to remember is that the brain develops from bottom to top, or back to front.  The most primitive part of the brain is the brainstem, also known as the reptilian brain. It is responsible for basic body functions to keep you alive- like breathing, blood movement, and digestion. The cerebellum is responsible for coordinated movement like walking, kicking a soccer ball, or running a race. Then we have the cerebrum, which is made up of four lobes. Each hemisphere has these four lobes. Although each lobe serves a function, the brain works together to accomplish tasks and lobes do not function alone. 

The occipital lobes functions to interpret vision- colors, lights, movement. The temporal lobe functions to understand language, assists in memory, organization, and hearing. The parietal lobe helps interpret language and words, signals from vision and hearing. It also functions to understand spatial and visual perception. This lobe also has a sensory strip where it interprets senses like touch, pain, and temperature. Finally, the last to develop is the frontal lobe. This lobe is complex and vast; it’s what makes us human. It is responsible for our personality, behavior, emotions, intelligence, concentration, and self-awareness. Executive functions like judgement, planning, and complex problem-solving take place here. There’s a motor strip in this lobe that also helps with body movements. This lobe also helps with speech in regards to speaking and writing, also known as Broca’s area. Science supports that our brain are not fully mature until mid-late 20’s. Remember, the frontal lobe is the last to develop. In other words, the part of the brain that helps us make reasonable decisions while weighing possible outcomes is not developed until we’re between 25-30 years old.  We’ve discussed the main functions of different parts of the brain when all is well. You may come across patients that have brain lesions. “Lesions” is a vague term that includes abnormal tissue in or on the brain. It can incorporate different types of injury or abnormality to the brain, including brain injuries, stroke, or brain tumors. There are over 10 different category types to classify lesions. Depending on the region, size, and severity, the function of that area that the lesion is at may be impaired. For example, an injury to the temporal lobe may cause impairment with memory retention. Injury to the frontal lobe can impair judgement or the person may see more impulsive. Injury to the occipital lobe may cause issues with seeing colors or light. Parietal lobe damage may result in loss or diminished sensations like touch or smell. Similarly, disorders may also impact particular areas of the brain. Ataxia, for example, can impact the cerebellum and cause impairments with walking and balance. Again, none of the brain works alone so damage to any part may impact other functions as well. We love you guys! Go out and be your best self today! And as always, Happy Nursing!