Neural Control and Coordination Test - 36

Nose is a most important sense organ of smell. The human nose can detect approximately 10,000 different odours. Nose also helps in the process of respiration.

A motor neuron is a nerve cell whose body is located in the spinal cord and the fiber projects outside the spinal cord. This directly or indirectly controls the effector organs such as the muscles and glands. The motor neurons are differentiated as alpha , beta and gamma motor neurons.  A single motor neuron may innervate many muscle fibers. The somatic nervous system also known as the voluntary nervous system consists of afferent and efferent nerves that innervate the skeletal muscles. 

Potassium channels are the non-gated always open passive ion channels that permit the diffusion of potassium ions out of the neuron down the concentration gradient and make the extracellular fluid outside the cell more positive as compared to cell's interior. This generates resting potential and allows normal functioning of the neuron. Thus, the correct answer is option A.

The medulla, located nearest the spinal cord, directs the spinal cord to maintain breathing, and the pons, a part of the brain very near the medulla, provides further smoothing of the respiration pattern. This control is automatic, involuntary and continuous. Hence, Medulla oblongata contains involuntary centres to control the breathing rate.

The myelin sheath of neurons provides them with an insulating covering. It allows rapid transmission of signals from the nervous system to the body and vice-versa. Any damage to the myelin sheath will cause hindrance and slowing down of the transmission of signals to the axons.

So, the correct answer is 'Action potentials would be conducted too slowly along the neurons'.

• The medulla oblongata (or medulla) is a long stem-like structure located in the brainstem
• . It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions ranging from vomiting to sneezing. 
• The medulla contains the cardiac, respiratory, vomiting and vasomotor centres and therefore deals with the autonomic functions of breathing, heart rate and blood pressure. Hence, a pair of brain structure and function is incorrect is Medulla: basic emotional drives.
So, the correct answer is 'Medulla: basic emotional drives'.

The arachnoid mater is the middle of three layers that make up the meninges, or membranes, that surround the spinal cord and brain. The dura mater is the outermost layer of the meninges. The innermost layer that contours closely to the many folds and crevices of the brain is called the pia mater. The space between the membrane is filled with cerebrospinal fluid.

• The nervous system is divided into two types CNS and peripheral nervous system.
• The peripheral nervous system is in turn divided into the somatic nervous system and autonomic nervous system.
• The autonomic nervous system regulates the internal and involuntary movement.For example,respiration,cardiovascular,digestive etc.
• The autonomic(visceral) nervous system is again divided into the sympathetic and parasympathetic nervous system.
• The enteric nervous system receives inputs from the parasympathetic and sympathetic parts of the nervous system,
  
• Sympathetic decreases the rate of digestion whereas parasympathetic increases the rate of digestion via the enteric nervous system.
• A nerve leading to the small intestine causes the rate of digestion to increase, this nerve belongs to Peripheral, Peripheral and Enteric.
  

So, the correct answer is 'I, III, and IV'.

• Neuron or nerve cells are the functional units of the nervous system. Each neuron has a cell body that encloses the nucleus and cytoplasm. 
• A number of processes arise from the cell body. These processes are called dendrites. In the given diagram P represents the dendrites. Dendrites play an important role in receiving nerve impulses from other neurons. 
• The cell body is the spherical part of the neuron that contains the nucleus and connects to the dendrites, which bring information into the neuron, and the axon, which sends information to other neurons.
  
• Myelin sheaths are sleeves of fatty tissue that protect the nerve cells. 
  
• The myelin sheath is regularly interrupted along the length of the axon by specialized regions called the nodes of Ranvier, which are necessary for the propagation of an action potential along the axon. The nodes of Ranvier are essential in the speed and timing of the delivery of impulses from one neuron to another.
  

Jacobson’s organ is also called as the vomeronasal organ. Jacobson's organ is found in an olfactory system of amphibians, reptiles, and mammals but it does not occur in all tetrapod groups. It is a patch of sensory cells within the main nasal chamber that detects heavy moisture-borne odour particles whereas airborne odours are detected by the olfactory sensory cells of the main nasal chambers.