Archive for category Anatomy
Brain Anatomy and Parts of the Brain
Posted by in Anatomy on June 30, 2011
Brain is a part of the central nervous system, which functions as the primary receiver, organizer and distributor of information of the body. It regulates all the major activities of the body such as perception, cognition, attention, emotion, memory, and action. It is estimated that brain is made up of 50-100 billions of nerve cells. Brain is suspended in the cerebrospinal fluid, continuous with the spinal cord (structure made up of neurons and nerve fibers) and enclosed within the skull. It is separated from the bloodstream by a cellular structure known as the blood-brain barrier. This barrier also acts as a filter and restricts the passage of chemical substances and microscopic particles inside the brain. However, it allows access to only those substances responsible for metabolism, for example, oxygen. It is due to this fact that infection of the brain is rare, as compared to other organs of the body.
Many of the psychiatric and genetically inherited diseases, for example, schizophrenia and multiple sclerosis respectively, are caused due to dysfunctions of the brain.
Brain Anatomy and Parts of the Brain
The brain is made up of three major segments – forebrain, midbrain and hindbrain. Each segment consists of different interdependent parts. Let’s see in detail about the parts of the brain.
Forebrain: The forebrain is the largest segment of the brain located in the uppermost part of the brain. It consists of the cerebrum, the thalamus and the hypothalamus.
Cerebrum - The cerebrum or the cortex is the largest part of the brain. Its functions include thinking, reasoning and remembering. The cerebrum is separated into two hemispheres (right and left) by a deep groove called as the longitudinal cerebral fissure. The right hemisphere controls the right side of the body and vice versa. Each hemisphere is again divided into four sections or lobes, namely, frontal, parietal, occipital, and temporal lobe. Each of the four lobes is responsible for specific activities. Frontal lobe is responsible for personality characteristics, parietal lobe controls interpretation of pain, occipital lobe is involved with vision and temporal lobe is responsible for memory, smell and speech.
The outer layer of the cerebrum is composed mostly of nerve cells, which is called as gray matter and controls the activity of the brain; the inner portion is made up of axons (nerve fibers) called as white matter. The axons, which are covered by myelin sheath, are responsible for transferring information in between the nerve cells. Read the rest of this entry »
Large Intestine Anatomy
Posted by in Anatomy on June 30, 2011
Intestine is that portion of the digestive tract, that runs between the stomach to the anus. It is divided into the small intestine and large intestine. The small intestine forms a major part of the human intestine with a length of around six meters. It can be found in the center of the abdominal cavity. Large intestine starts at the point, where the small intestine ends. As compared to the small intestine, large intestine has more width, but is only 1.5 meters in length, which is around one fifth of the length of the intestinal canal. The large intestine consists of the cecum, ascending colon, transverse colon, descending colon and sigmoid colon. Scroll down for more details about large intestine anatomy.
Large Intestine Anatomy and Physiology
As mentioned earlier, large intestine starts from the point, where the small intestine ends. To be more precise, it starts from the right iliac region of the pelvis, which is located at the right waist or just below it. The large intestine starts with the cecum (where the end point of the small intestine opens into the large intestine) and travels upwards, and then runs across the abdominal cavity, again turns down to end with the sigmoid canal, which is followed by the rectum, anal canal and the anus. The portion of the large intestine that comes after the cecum and runs upwards is called ascending colon and that travels across the abdomen is called transverse colon. The descending colon follows the transverse colon and turns downward to end in sigmoid colon, which is followed by the rectum.
The large intestine is almost like an arch, which surrounds the coiled small intestine in the abdominal cavity. As a major part of the digestive process is done in the small intestine, the large intestine is left with the function of absorbing water and some vitamins. It is mainly responsible for storing the fecal matter, solidifying it by absorbing water and expelling it with the help of rhythmic contractions (peristaltic movements) of the intestinal muscles. Read more on small intestine function.
Cecum: The large intestine starts with the cecum, which is like a pouch in structure and connects the ileum (the last part of the small intestine) to the ascending colon. It is separated from the ileum by the ileocecal valve or Bauhin’s valve and from the ascending colon by the cecocolic junction. It is about six centimeters in length and the vermiform appendix hangs from the cecum. Read more on appendix location – where is your appendix. Read the rest of this entry »