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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.