Locomtion in Earthworm

Animation of locomotion in earthworm

Locomotion in Earthworm

Histology Animations

Growth of cartilage is either interstitial growth, resulting from the mitotic division and reactivation of preexisting chondrocytes, or more commonly appositional growth, resulting from the differentiation of perichondrial cells.In a growing bone, metaphysis includes a cartilaginous epiphyseal plate that allows diaphysis to grow in length. The epiphyseal plate disappears in adults leaving a bony epiphyseal line. Hence bone does not grow in length occur in adults. Bone can grow in thickness only by appositional growth resulting from the differentiation of periosteal cells. Continue reading the full post to view the animation.

Click here to view animation

Evolution Animations

Animations in Evolutions....

Origin of Eukaryotes
Miller and Urey Experiment
Mechanism of Evolution
Genetic Drift
Phylogenetic Trees

Genetics Animations

Incomplete Linkage
Lyonization
Hershey and Chase Experiment
DNA Replication
Gene Expression
Transcription
Translation
Lac Operon:Control
Lac Operon
Control of Gene Expression in Eukaryotes
RNA Splicing
Spliceosomes
Evolution of Gene Families
Transposition
FISH
Steps in Cloning a Gene
PCR
DNA Fingerprinting

Flash cards on Zoology - The Basics Branches of Biology

Gastrulation Video

Key for Earthworm upto Digestive System

To see the key click HERE. Key mistakes, if any, may be posted as comments.

Animal Associations (Question Papers)

Question Papers  on Animal Associations for Jr.Inter (2008-09) and Keys
Click on the following links to open the question papers. Any key mistakes/doubts may be posted as comments
Taenia and Wuchereria Question Paper
Key for Taenia and Wuchereria
Animal Associations upto Mature Proglottid of Taenia solium
Key For Animal Associations upto Mature Proglottid of Taenia solium
Preweekend Test (30 Questions in Animal Associations upto Mature Proglottid of Taenia solium)
Key for Preweekend Test (30 Questions in Animal Associations upto Mature Proglottid of Taenia solium)

Osmotic Gradient in Renal Medulla

The osmolarity of the interstitial fluid in the medulla of the kidney is much higher, increasing progressively to about 1200 to 1400 mOsm/L in the pelvic tip of the medulla. What are the factors that contribute to the hyperosmolarity of renal medulla?The osmolarity of interstitial fluid in almost all parts of the body is about 300 mOsm/L, which is similar to the plasma osmolarity. The osmolarity of the interstitial fluid in the medulla of the kidney is much higher, increasing progressively to about 1200 to 1400 mOsm/L in the pelvic tip of the medulla. This means that the renal medullary interstitium has accumulated solutes in great excess of water. Once the high solute concentration in the medulla is achieved, it is maintained by a balanced inflow and outflow of solutes and water in the medulla.
What are the factors that contribute to the hyperosmolarity of renal medulla?

The major factors that contribute to the buildup of solute concentration in the renal medulla are:
1. Active transport of sodium ions and co-transport of potassium, chloride, and other ions out of the thick portion of the ascending limb of the loop of Henle into the medullary interstitium
2. Active transport of ions from the collecting ducts into the medullary interstitium
3. Facilitated diffusion of large amounts of urea from the inner medullary collecting ducts into the medullary interstitium
4. Diffusion of only small amounts of water from the medullary tubules into the medullary interstitium,
far less than the reabsorption of solutes into the medullary interstitium.
Special Characteristics of Loop of Henle That Cause Solutes to Be Trapped in the Renal Medulla.
The most important cause of the high medullary osmolarity is active transport of sodium and cotransport of potassium, chloride, and other ions from the thick ascending loop of Henle into the interstitium. Because the thick ascending limb is virtually impermeable to water, the solutes pumped out are not followed by osmotic flow of water into the interstitium.
The descending limb of Henle's loop is very permeable to water. Therefore, water diffuses out of the descending limb of Henle's loop into the interstitium, and the tubular fluid osmolarity gradually rises as it flows toward the tip of the loop of Henle.

Taenia Solium T.S

There are many labeling mistakes in the figure of T.S.of Taenia solium in the text book. Correcting labeling for the Figure 5.4.3 (page no.186) is given hereunder.

Joints - Images

Colourful images of various types of joints are given under this post. Observe the arrows given in diarthroses that explain whether the joint is monaxial, biaxial or nonaxial depending on the number of axes around which movement is possible at the joint.

* Coronal Suture is between frontal and parietal bones.
* Observe the chord-like ligament and sheet-like interosseous membrane
* Periodontal Membrane joins root of tooth to the alveolar socket in thecodont teeth * When the elongation of the bone caeses, epiphyseal plate (hyaline cartilage without perichondrium) is replaced by bone, thus, he joint becomes a synostosis (bony joint) * Functionally, symphysis is an amphiarthrose (slightly movable joint) and facilitates parturition (labour)
* Observe that ball bearing bone can rotate around several axes (multiaxial)
* Hinge joint allows motion around only one axis (monaxial) * Classic example of pivot joint is the atlanto-axial joint, that permits the head to turn from side to side as when you shake your head while saying "no". Radioulnar joint shown here enables palms to turn anteriorly and posteriorly * Notice the arrow marks that explain the biaxial nature of saddle joint.