V. Summary/Synthesis/Feedback

• The nervous system is composed of cells, tissues, and organs that regulate the body's responses to internal and external stimuli. Each component of the nervous system has a specific role to do as an important part of a team.

• The nervous system has two main divisions, which are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

• The Central Nervous System (CNS) serves as the main "processing center" for the entire nervous system. It has two main parts, which are the brain, and the spinal cord.

• The Peripheral Nervous System (PNS) contains all nerves that extend outside the brain and spinal cord. It has two main divisions, which are the Somatic Nervous System and the Autonomic Nervous System.

• The basic unit of the nervous system is the nerve cell. Nerve cells are called neurons. Neurons have dendrites and axons that aid in transmitting message.

• Neurons have the special ability to carry signals or impulses. A nerve impulse is an electrochemical gradient moving along a neuron. The space between neurons is called synapse. A stimulus is any factor in the environment that may induce a nerve impulse that initiates physiological and behavioural changes. A response is a reaction to a condition or stimulus. To survive, an organism must be able to respond to a stimulus. Reaction time is the length of time between application of a stimulus and detection of a response.

• When a receptor such as an organ perceives a stimulus, the impulse is sent to the brain by the sensory neurons, transmitting information from one nerve ceil to another. As the message reaches the brain, it processes the information and commands an effector such as a muscle or an organ to respond. The message coming from the brain is sent through the motor neurons.

• The Endocrine System consists of glands that secrete chemicals called hormones which control various body processes. This control systein usually brings about slow changes in the body because chemical messangers move more slowly than nerve impulses. The major glands in the body are the pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, ovaries and testis.

• Hormones affect various processes in the body as they regulate and balance the functioning of organs, tissues, and cells, Hormones greatly influence growth, appearance, emotions, and reproductive functions. These chemicals play an essential role in the occurrence of disorders such as diabetes, byrom disease, growth and/cr sexual dysfunction. Hormones act in very d amounts. An increase or decrease in the said amount may result in a body disorder due to hormonal imbalance.

• The Reproductive System is a collection of organs in an organism that function together for sexual reproduction. The male reproductive organs are the penis, the testicles, the epididymis, the vas deferens, and the prostate gland. The female reproductive organs are the vagina, uterus (womb), Fallopian tuben and ovaries.

• Hormones play an important role in both male and female reproductive systems. The pituitary gland controls the functions of both the testes and the overies: These hormones keep the reproductive system properly functioning

• Hormones secreted by the ovaries and a small gland in the brain called the pituitary gland control the menstrual cycle.

• Feedback mechanism is the process through which the level of one substance influences the level of another substance. A negative feedback affects the production of hormones in the menstrual cycle. High levels of one hormone may inhibit the production of another hormone.

• Homeostasis is the state reached when each part of the body functions in equilibrium with other parts. This is attained through the regulation of the bodily functions by the endocrine and nervous systems.