Welcome To The Blog of Limbic System!

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Introduction to Human Physiology

What is Physiology?

Physiology is the study to recognize and to apply basic concepts of one’s body function in the body’s organ systems. In other way, it is said to be the study of the functions of living things and how the human body works. Human physiology offers to the study of human physiology across the molecular or cellular, systems, organisms, and behavioral levels.

Our bodies are actually made up of 11 organ systems. Although they have their own roles in the body, but they work together to make sure our bodies are functioning well. Let’s take a look below to find out more about the organ systems.

1.      Cardiovascular System

Organs : heart and blood vessels

Functions : the heart pumps the blood into the blood vessels and it will be transported to and from all body tissues. The blood vessels usually transport oxygen, carbon dioxide, hormones and nutrients as well as other substances to and from the tissue cells, where the exchange of material happens.

2.      Digestive System

Organs : oral cavity; which is the mouth, esophagus, stomach, small and large intestines, and lastly rectum

Functions : help in breaking down of food into smaller molecules or particles as well as delivering them to the blood for distribution to body cells.

3.      Endocrine System

Organs : pituitary thyroid, parathyroid, adrenals, thymus, pancreas, pineal, ovaries (of female) and testes (of male)

Functions : to produce and secrete hormones that affect every cell in the body. This system also controls body activities although slower than the nervous system.

4.      Integumentary System

Organs : skin, which is the external covering of our body

Functions : give waterproof effect to our body and protection to the tissues from injury by acting like a cushion. Besides regulating the body temperature, the skin absorbs and produces vitamin D.

5.      Lymphatic System

Organs : lymphatic vessels, lymph nodes, spleen and tonsils

Functions : complements the cardiovascular system by returning the fluid leaked from the blood back into the blood vessels so that the blood can be continuously circulated throughout the body.

6.      Muscular System

Organs : muscles that are involved in contraction and relaxation

Functions : our muscles maintain our posture, produce heat and also a thermal covering for the internal organs of our body. This differs from the muscles of the heart and other hollow organs of our body.

7.      Nervous System

Organs : brain, spinal cord, nerves, and sensory receptors

Functions : detect changes in and around the body and send messages to the central nervous system, which is the brain and spinal cord. The CNS responds by activating the respective muscles and glands after assessed the information.

8.      Reproductive System

Organs : the female reproductive system consists of ovaries, uterine tubes, uterus and vagina while the male reproductive system includes the testes, scrotum, penis, accessory glands, and the duct system

Functions : produce offspring

9.      Respiratory System

Organs : nasal passages, pharynx, larynx, trachea, bronchi, and lungs

Functions : keep the body constantly supplied with oxygen and to remove carbon dioxide. Gases are transported to and from the blood through the thin wall of the air sacs.

10.  Skeletal System

Organs : bones, cartilages, ligaments and joints

Functions : gives support and protection for the body organs. Skeletal muscles are involved in movement, and our bones act as a storage for minerals. Usually the formation of blood cells takes place within the cavities of our skeleton.

11.  Urinary System

Organs : kidneys, ureters, bladder, and urethra

Functions : flush wastes from the body in urine. Nitrogen is an example of waste, and is produced when the body cells break down proteins and nucleic acids. Besides, this system maintains the body’s water and electrolyte balance and regulation the acid-base balance of the blood.

It is important to study human physiology so that students are able to recognize and explain the basic concepts that govern each organ and organ systems and their integration to maintain homeostasis, as well as some other clinical aspects when these systems are in failure.

The Limbic System

What is limbic system?

The limbic system is located on top of the brainstem and is buried under the cortex. It is a set of evolutionarily primitive brain structures that are involved in mainly our emotions and motivations, especially those related to survival. Some of the emotions involved such as fear, anger and emotions are related to sexual behavior. Besides that, this system includes the feelings of pleasure in which those who experienced from eating and sex.

The functions of the limbic systems are as follows :

Amygdala is actually the almond-like shaped mass of nuclei involved in emotional responses, hormonal secretions, and memory. Amygdala is responsible for determining what and where memories are stored in the brain.

Cingulate gyrus is a fold in the brain involved with sensory input concerning emotions and the regulation of aggressive behavior.

Fornix is an arching, fibrous band of nerve fibers that connect the hippocampus to the hypothalamus.

Hippocampus is a tiny nub that acts as a memory indexer. Its function is to send memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieving them when necessary.

Hypothalamus is about the size of a pearl, and it directs a multitude of important functions. Besides helping you to wake up in the morning, it controls the molecules that make you feel exhilarated, angry, or sad by becoming an emotional center.

Olfactory Cortex will receive sensory information from the olfactory bulb and mainly function in the determining of odors.

Thalamus is a large, dual lobed mass of grey matter cells in which will relay sensory signals to and from the spinal cord and the cerebrum.

Function of Limbic system

The limbic system has something to do with emotion and motivation. The amygdala attaches the emotional significance to the sensory input. Olfactory stimuli will enter the limbic loops through the entorhinal cortex of the parahippocampalgyrus. Besides having a direct influence on neuroendocrine, autonomic, and also behavior mechanisms, it also carries out an important role in functions such as fight or flight, homeostasis, self-maintenance, appetite, and sexuality.

The structures of the limbic system are highly interconnected with the rest of the brain, and they will likely form a gateway for communication between the cerebral cortex and the hypothalamus. This gateway gives cognitive processes to modify the effect of the limbic system on hypothalamic functions.

The hippocampus, formix, and mamillary bodies have an important role in memory and learning process. Left anterior temporal lobectomies may result in impaired verbal memory, meanwhile visual or spatial memory disturbances are associated with the right temporal lobectomy. The degree of impairment is directly related to the age of the patient. Usually young children have considerable plasticity, which allows other areas of the brain to take over the function of the resected portion.

Also, the decline in memory function after temporal lobectomy is directly related to the amount of medial temporal lobe resected and the level of the memory function prior to surgery, and it is the opposite related to the degree of hippocampal sclerosis of the resected lobe. Meaning, the more you have, the more you stand to lose.

Reference

1. Gabriel EM, Haglund MM, 1997. Neuropsychiatric complications after temporal lobe limbic system surgery. Neuroimag Clin North Am; 7:155-164.

2. Lauralee S, 2012. Introduction to Physiology and Homeostasis. Fundamentals of Human Physiology;  4:1-12.

What is Sleep?

Most of us are spending one-third of our life for sleeping.

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Sleep is not as simple as ‘switch off’ our mind and let it rest, but the dynamic and complicated condition that the brain is still active.

There are two behavior patterns during sleep which can be differentiate into two major types of sleep from the sleep cycle:

i.                    Slow-wave sleep (deep sleep)

The sleeper still have the considerable muscle tone in this stage of sleep, which means that their muscle is not relaxed during sleeping. He/she will frequently shift body position, easily awake due to disturbance, minor reduction in respiratory rate, heart rate and blood pressure. The sleeper’s mental activity is less visual than dreaming, and nightmare might occur in the stage of sleep.

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ii.                  Paradoxical sleep: Rapid Eye Movement (REM) Sleep.

The muscles of sleeper will completely relaxed in this stage in sleep cycle, except eye muscle. The heart beating rate and respiratory rate will be irregular, whereas the blood pressure will be fluctuated. Dreaming will occur here.
P/s: The rapid movement of eyes are driven in a locked and oscillating patterns which uninfluenced by dream content and it is NOT watching the dream imagery!

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Above is the image talking about human sleep cycle. The details of sleep cycle will be discussed in the following post in details.

The Sleep Cycle.

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There are five distinct stages in the sleep cycle.So,let us discuss the different stages of sleep in the cycle here:

Stage 1

This stage of sleep is considered as drowsiness. It is the transition stage from wakefulness to sleep. Within this stage, the sleeper’s eyes are closed with slower rolling movements, his/her respiratory rate will becomes more uniform. A person who is reading, watching television or attending an uninteresting lecture may fall to this stage accidently, or when the person is resting quietly. The person may undergo ‘hypnogogic experience’ during this period, which is dream –like sensations of falling, hearing sounds or seeing flashes of pictures. This stage is able to last from 5 to 10 minutes at the beginning of sleep, which is only around 5% of sleeping time in healthy adults.

Stage 2

The fast-frequent burst of activity (sleep spindles) is occurring in this stage. From stage 2 until stage 4, the muscle tension, heart beating rate and respiratory rate, including body temperature of the person who is sleeping will gradually decline and becomes even more regular. The person is even less aware of their surrounding although is still easily arousable here.

Stage 3&4

Stages 3 and 4 are considered as the slow-wave sleep, which are the deep sleep stage. Muscles of the person will relax further here, and the breathing is very regular. The deep sleep stage normally occurs 30 minutes after the person falling asleep, he/she is extremely difficult to be aroused now. Brain activity now is showing a slower and more regular pattern under EEG. The sleep cycle will go back to stage 2 after this stage and then enter the REM sleep finally. The electroencephalogram (EEG) is a device that frequently used to sense the electrical activity in the brain.It is used in the detection of the sleep stages by defining specific electrical patterns in the brain.

Stage 5

The EEG tracing of the stage is similar to the beta waves that observed during the person is awake. Brain-imaging study also shows that the neurons in cerebral cortex are more active at this stage. It is different from the other stages of sleep as the brain is very active although the sleeping person is not aware of their surroundings at all. The REM sleep has make up 20% of sleeping time as we will go through this sleep cycle 5-6 times within 8 hours of sleep. We will experience vivid dream during this stage. Although brief dream images can occur during other stage, most of the complicated, bizarre and plot-driven experiences most people think of as dream occur during this stage.

Reference:
Gokalp, G. (1999). Sleep and Dreams. Available: http://www.csun.edu/~vcpsy00h/students/dreams.htm. Last accessed 10th March 2013.

 

Limbic System and The Dream

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What is dreaming?

Dreaming is defined as perceived experiences of sensory images and sounds when sleep. Dream occurs when rapid eye movement (REM) stage in sleeping. It may take about 2 hour in total but 5-20 minutes for dreaming.

REM sleep occurs when pons in brain “switch off” the signal to the spinal cord, dream will begin. The thalamus directs the pons sends signal to cerebral cortex. When REM happens, cerebral cortex will “switch on” for memory and learning.

Activation theory

There are two types of theory, which are Freud’s theory and activation theory. However here only discuss about activation theory. This theory states that the hindbrain transmits chaotic patterns of signals to the cerebal cortex, and then higher-level cognitive processes in the cerebral cortex try to integrate these signals into a dream plot (Hobson and Stickgold, 1995).

According to physiological process, Dreaming may be our most creative conscious state, one in which the chaotic, spontaneous recombination of cognitive elements produces novel configurations of information: new ideas. While many or even most of these ideas may be nonsensical, if even a few of its fanciful products are truly useful, our dream time will not have been wasted (Hobson and Stickgold, 1995).

This theory also explains how brain activity leads to dreaming. Further explanation are circuit in brain stem are “switch on” during REM. Then, amygdala and hippocampus in limbic system also “sitch on”. Limbic system takes part of emotion, sensations and also memory. This is why some people will feel fear when nightmare occurs in dreaming. Lastly, brain synthesizes and interprets this internal activity and try to know the meaning, tis result in dreaming.

Facts about dreams

1)      Everyone can dream.

-     Men, women and also babies can do it. People spend average six years for dreaming among whole life.

2)      But you forget most of your dream

-     About 95% of all dreams are quickly forgotten shortly after waking. Why this can happen? This

      is because brain does not support information processing and storage for formation of memory

     during sleeping.

3)      Not all dreams are in colour

-     About 80% of dream are in colour and minor is black and white. Mostly in soft pastel colors.

4)      Men and women dream differently

-     Men dream about aggressive than women. While, women have longer dream and more

      characters. Men often dream about women but women is both sexes.

5)      Animals may have dream

-     Animals also go through REM and NREM cycle of sleep. Animals such as elephants sleep

      standing up during non-REM sleep but lie down for REM sleep.

6)      You can control dream

-     In lucid dream, you can control the content of the dream. Lucid dream is the dream

      which you aware you are dreaming although when sleeping.

7)      Mostly is negative emotion

-     Negative emotion such as anxiety and angry more than positive emotion such as joy and

      happiness.

8)      Blind people dream

-     They usually do not have visual dream. The blind people dreams normally are information from other senses such as sound and taste.

9)      No dream in snoring people


More information may refer to this video:  Why Do We Dream?

References

Hobson, J.A. and Stickgold, R. (1995). The conscious state paradigm: A neurocognitive approach to waking, sleeping, and dreaming. In M.S. Gazzaniga (ed.), The Cognitive Neurosciences. Cambridge, MA: MIT Press.  

Is “ghost press bed” real?

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Many people experience “ghost press bed” during sleeping. People who do not have the experience do not believe the fact. However, is “ghost press bed” really happen? This question is confusing the community. Therefore, we will reveal and discuss the fact in the following section.

Sleep Paralysis

So-called “ghost press bed” is actually sleep paralysis which is a sleep disorder disease. This phenomenon is nothing related to the ghost. Sleep paralysis is a normal physiological phenomenon in which people, either when falling asleep or wakening, temporarily experience an inability to move. It can occur at sleep onset or upon awakening, and it is often accompanying with terrifying visions (e.g. an intruder in the room), to which one is unable to react due to paralysis. As we discussed before, paralysis is caused by the releasing of glycine from the brain stem onto the motor neurons during the REM sleep. With the presence of glycine in the motor neurons, when there is disruption during REM sleep, which is normally characterized by complete muscle weakness, individuals are preventing from acting out their dreams.

During the sleep paralysis condition, the person is switching on and off around the sleep-wake border, brain wave amplitude is clear, some people still and the image will have illusion, but to minimize the muscle tension, the body could not move, as if cast a protective shield-like, which is generally known as “ghost pressure body” phenomenon. Sleep paralysis is usually relatively related to large pressure, excessive fatigue, lack of rest, insomnia, anxiety, more likely to occur under the circumstances.

Sleep paralysis occurs mainly at the early relationship between REM, resulting in the REM stage of coordination inconsistent. The basic cause of the sleep paralysis is REM atonia, a natural process which happens to everyone, every night. “Atonia” means lack of muscle tension. REM atonia is an essential sleep mechanism. As we asleep, it cuts off the electrical signals between the muscles and the brain so that we can sleep peacefully each night. In short, REM stops us from acting out our dreams. The experience of sleep paralysis occurs when our mind (in part) wakes up, but our body remains asleep. Physically asleep, we remain paralyzed, but mentally conscious, we may start to panic and the half-dreaming mind conjures up nightmarish images to “explain” what is happening.

Why the effects are so real? This state is a very clever merge of walking consciousness with the dream world. It is a bizarre mind trick. For instance, footsteps thumping towards the bed are often a distortion of the sound of your heartbeat, pounding in your chest due to all the adrenaline. Hearing your assailant breathing unnaturally is common too- thought to be the sound of your own gasps for breath in this panicked state. The perceived difficulty to breathe properly is what causes many people to imagine an entity to harm them (by stopping them breathing or crushing their chest). It is important to remember that the effect is psychosomatic.

Sleep Paralysis

How to Stop Sleep Paralysis

·         Relax your body into the paralysis. Do not try to fight it forcefully as this will create panic and increase the chance of negative hallucinations.

·         Try to gently wiggle your fingers and toes. These tiny movements will eventually tell your brain that your body is awake and it will stop the atonia.

·         Try to move your eyes by blinking and looking around the room.

·         Try to move your lips and facial muscles.

·         Breath as deeply as you can and not letting panic overtaken your thoughts.

·         Keep your mental state positive and calm.

Maintain these goals for the duration of the sleep paralysis. As soon as your brain receives adequate signals that you are awake, it will shut down the REM atonia, and you will be able to move your whole body again, and the hallucination will disappear.

References

Rebecca, T. (2009). How to Stop Sleep Paralysis and Turn It Into Lucid Dream. Retrieved from http://www.world-of-lucid-dreaming.com/sleep-paralysis.html