Tuesday, August 23, 2016

Sensation and Perception

Sensation and Perception

What is Sensation

Sensation is the processes or experiences aroused when a stimulus has excited a receptor or when any of the sense organs are stimulated.

What are Receptors

Receptors are specialized cells in the sense organs, muscles, skin and joints that detect physical and chemical changes and translates these events into impulses and passes the electrical signals to connecting neurons.

What is Stimulus

Stimulus (or stimuli) is a form of physical energy inside or outside the body which initiates activity.

The signal that travels up to the spinal cord until it reaches its receiving area in the cortex, with different receiving areas for different sensory modalities (electric signals results in sensory experience). Thus, when we experience touch, the experience is occurring in our brain, into in our skin. The electrical impulses on our brain that directly mediate the experience of touch are themselves caused by electrical impulses in touch receptors located in the skin.

Classification of Receptors
  1. Exteroceptors are the sense organs whose stimuli arise outside of the body
  2. Interoceptors are the sense organs within the body proper that gives information about visceral processes (visceral organs enclosed in the abdominal and thoracic cavities).
  3. Proprioceptors are found in the linings of the tendons, muscles and joints, and are stimulated by energy changes resulting from the movements of these structures.

Wednesday, September 2, 2015

Peripheral Nervous System (PNS)

Peripheral Nervous System includes all nerve fibers and nerve cells not found in the CNS (spinal and cranial nerves). It conveys sensory information to and from the CNS to the muscles and glands.

Two main divisions of Peripheral Nervous System

1. Somatic Nervous System (SNS)
  • Somatic Nervous System is composed of 43 major pairs of nerves, which includes all the sensory systems and the motor nerves that activates the skeletal muscles responsible for movements. It receives sensory information from the sensory organs and controls the movements of the skeletal muscles. It comprises all voluntary and conscious movements.
    • Cranial nerves (12 pairs) serve the sensory and motor functions of the head and neck region.
    • Spinal nerves (31 pairs) serves the chest, trunk and extremities. Spinal nerves have sensory nevers that give rise to skin sensations and motor nerves involved in the movements of arms, legs, and portions of the trunk. (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygcal)
2. Autonomic Nervous System (ANS)
  • Autonomic Nervous System is concerned with the regulation of the smooth muscles, glands, and internal organs. It is especially important in emotional behavior.
    • Sympathetic Division is composed of a chain of ganglia (clusters of never cells) located along each sides of the Spinal Cord. It sends our motor fibers to various internal organs of the body. It causes activation and enrgy expenditure. It is dominant in emergency situations and profound body changes.
    • Parasympathetic Division is composed of nerves from the brainstem and the lower parts of the spinal cord. It is system dominant in digestion, elimination, sexual arousal and energy conservation. It slows the heart rate, constricts pupil of the eye and stimulates the flow of saliva.

Biology: Cortical Areas of the Brain

  1. Visual Area is located at the back of each occipital lobes. It analyzes, integrates, and translates into sight impulses projected from our visual receptors.
  2. Auditory Area is located at the surface of the temporal lobe. It is involved in the analysis of complex auditory signals and temporal patterning of sounds.
  3. Somesthic/Body Sense Area is located in the parietal lobe. It receives impulses from receptors in the skin, musclesm tendons and joints, thus causing us to experience heat, cold and pressure.
  4. Motor Area lies in front of the central fissure. It controls voluntary movements of the body and muscles movements
  5. Broca's Area is located below the motor area. It is also called the speech-motor area. Integrates and coordinates our speech.
  6. Association Area connects with the different parts of the brain. It may mediate complex functions associated with memory, perception, judgment and language. It has a special importance in integrating and coordinating thinking and problem solving.

What is Reticular Activating System (RAS)

Reticular Activating System is important in activating the cortex of the cerebral hemispheres. It has a significant role in consciousness, attention and sleep. It controls the state of arousal of awareness (as in changing from sleep to waking, or from diffuse awareness to alert attention).

Thursday, August 27, 2015

Biology: The Lobes of the Brain

The Lobes of the Brain
The lobes of the brain are the parts of the cerebrum.

1. Frontal lobe (front)

In the human brain, the precentral gyrus and the related costical tissue that folds into the central sulcus comprise the primary motor cortex whic controls voluntary movements of specific body parts associated with areas of the gyrus.

2. Occipital lobe (back)

The smalles of four lobes of the brain, the occipital lobe is located in the rearmost portion of the skull. The first functional area is the primary visual cortex. It contains a low-level description of the local orientation, spatial-frequency and color properties within small receptive fields. Primary visual cortex projects to the occipital areas of the ventral stream (visual area 2 and visual area 4) and the occipital areas of the dorsal stream - visual area V3, visual area MT (v5) an visual area DP.

3. Parietal lobe (top)

The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. Example: It comprises somatosensory cortex and the dorsal strem of the visual system. This enables regions of the parietal cortex to map objects perceived visually into body coordinate positions.

4. Temporal lobe (below)

Temporal lobe is the part of cerebrum that are involved in speech, memory and hearing. It lies at the sides of the brain beneath the lateral or Slyvian fissure. Seen in profile view, the human brain looks something like a boxing glove. The temporal lobe is where the thumbs would be. The temporal lobe is involved in auditory processing and is home to the prmary auditory cortex. It is also heavily involved in semantics both in speeach and vision. The temporal lobe contains the hippocampus and is therefore involved in memory formation as well.

Tuesday, May 19, 2015

Featured: List of Philippine National Holidays for 2015

Declared by virtue of Proclamation No. 831, s. 2014, unless otherwise specified:
  • January 1, 2015, Thursday – New Year’s Day (Regular holiday)
  • January 2, 2015, Friday – Additional special non-working day (Special non-working day)
  • February 19, 2015, Thursday – Chinese New Year (Special non-working day)
  • February 25, 2015, Wednesday – EDSA Revolution anniversary (Special holiday for all schools)
  • April 2, 2015, Thursday – Maundy Thursday (Regular holiday)
  • April 3, 2015, Friday – Good Friday (Regular holiday)
  • April 4, 2015, Saturday – Black Saturday (Special non-working day)
  • April 9, 2015, Thursday – Araw ng Kagitingan (Regular holiday)
  • May 1, 2015, Friday – Labor Day (Regular holiday)
  • June 12, 2015, Friday – Independence Day (Regular holiday)
  • August 21, 2015, Friday – Ninoy Aquino Day (Special non-working day)
  • August 31, 2015, last Monday of August – National Heroes Day (Regular holiday)
  • November 1, 2015, Sunday – All Saints Day (Special non-working day)
  • November 30, 2015, Monday – Bonifacio Day (Regular holiday)
  • December 24, 2015, Thursday – Additional special non-working day (Special non-working day)
  • December 25, 2015, Friday – Christmas Day (Regular holiday)
  • December 30, 2015, Wednesday – Rizal Day (Regular holiday)
  • December 31, 2015, Thursday – Last day of the year (Special non-working day)
Information Source: gov.ph | Facebook

List of Philippine National Holidays for 2015

Wednesday, May 13, 2015

May 13th Google Doodle celebrating Inge Lehmann’s 127th Birthday - a Seismologist

Inge Lehmann was a Danish seismologist from Copenhagen, Denmark who discovered the Earth's inner core. In 1936, she assumed the existence of an inner core of the Earth's core (not just a single molten sphere) and suggested that this inner core has physical properties that are different from the outer core.

To know more about Inge or the Earth inner core, click the Google Doodle or google it up.

Image from Google Doodle

Monday, March 30, 2015

Tip No. 4: Always keep the references of your research

Always make sure to copy the website link or URL of the articles you found on the web.
If its a book, then copy it's title, author, publisher and year of publication.

It is important, especially if you need to find it again.