Question

1. Trace the events occurring in a reflex action such as sneezing?

2. Write characteristics of hormones

Answer 1

1) The entire process of response to a peripheral nervous stimulation, that occurs involuntarily is called a reflex action.
*It is defined as an inborn, involuntary mechanical response to stimuli.
*The reflex pathway comprises atleast one afferent neuron and one efferent neuron appropriately arranged in a series.
*The afferent neuron receives signal from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS.
*The efferent neuron then carries signals from CNS to the effector.

2)

• Hormones are the chemical substances which coordinate the activities of living organisms and also their growth.
• Four characteristics of hormones in humans are:

1) Hormones are secreated in small amountsby endocrine glands

2) The hormones are poured directly into bloodand carried throughout the body

3) The hormones have their effect at the sight different from the sight at which they are made.

4) The hormones act only on target organs