Animal Tissue and Anatomy

• The outermost part of human ear is called pinna (external ear).
• Pinna is followed by auditory canal. It is a tube by which pinna is connected to middle ear.
• The auditory canal extends from pinna to tympanic membrane (ear drum).
• Tympanic membrane is followed by three ear ossicles, malleus, incus and stapes.
• Stapes is attached to oval window of cochlea and transfers the vibrations to the fluid of cochlea. Cochlea is a part of inner ear.
• Inner ear contains vestibular apparatus and auditory nerve along with cochlea.

The vestibular system, which is responsible for balance, consists of the semicircular canals and the otolith organs, which include the utriculus and sacculus.

The structures responsible for balance, specifically the vestibular system (semicircular canals and otolith organs), are located within the inner ear.

The functional components of the membranous labyrinth involved in the sensations of static and dynamic equilibrium are a system of thin walled, intercommunicating tubes and ducts situated within the petrous part of the temporal bone at the base of the skull. There are five vestibular structures, each containing a specialized mechanoreceptor, (maculae), within the utricle and saccule, and cristae within the ampulla of the superior, horizontal, and posterior semicircular canals.

Ear acts as the dual receptor in the following ways:

The semicircular canals are three canals used to provide information to the brain on directional balance. Each canal is lined with cilia and filled with fluid, called as endolymph. As the head and body move, the fluid moves and pushes the cilia back and forth to create a motion sensor. The three main parts of the semicircular canals are the horizontal, posterior and superior. The superior is responsible for head rotation, the posterior canal detects movement and rotation on the sagittal plane, and the horizontal senses on a vertical basis.

• Semicircular canals are three tiny fluid-filled tube in our inner ear that helps to keep our balance.
  
• Cochlea transforms the sound or vibration of cochlear liquid into neural signals.
  
• Utriculus and Sacculus are part of balancing apparatus of ear located within the vestibule of the bony labyrinth which respond to change in the position of the head with respect to gravity (linear acceleration).
  

A semicircular canal or a semicircular duct is one of three semicircular, interconnected tubes located inside each ear. The three canals are the horizontal semicircular canal (also known as the lateral semicircular canal),     superior semicircular canal (also known as the anterior semicircular canal)     and the posterior semicircular canal (also known as the inferior semicircular canal).
It helps in regulating body balance. Endolymph, which is present in the ear plays a major role in regulating body balance.

The Juxta medullary nephron is one in which the renal corpuscle (Malphigian corpuscle having the Malphigian body) is located in the cortex but near to the medulla and the other regions, such as the proximal convulated tubule, the loop of Henle, and the distal convulated tubule are located deeper in the medulla. The only region present in the cortex is malphigian body. So, the correct answer is A.

A malphagian body is constituted of two parts - Glomerulus and Bowman's capsule. The glomerulus is the tuft of capillaries and has the filtering apparatus. The Bowman's capsule has a cup-like sack present at the beginning of the tubular component of a nephron.

Ependymal cells are the cube-shaped epithelial cells that forms the epithelial lining of the cavities in brain and central canal of spinal cord. These cells are formed from a layer of embryonic tissue known as neuroectoderm and secrete cerebrospinal fluid for mechanical protection.

Three layers of protective tissue that surround the brain and spinal cord are called meninges. These three layers are dura mater, arachnoid mater, and pia mater.