Nerves, hormones and homeostasis

Topic 6.5

6.5.1 & 6.5.3: Introduction to the Nervous System

The nervous system consists of the central nervous system (CNS) and the peripheral nerves. It is composed of cells called neurons that can carry rapid electrical impulses. There are two types of neurons: sensory neurons which carry nerve impulses from sense organs to the central nervous system and motor neurons which carry nerve impulses from the central nervous system to effectors which produce the response. Within the CNS the impulses are carried by relay neurons. Figure 1 below illustrates a structure of the motor neuron.

Structure of the CNS

6.5.2: Stucture of a motor neuron

Structure of a motor neuron

6.5.4: How is resting potential created?

Resting potential

6.5.5: Nerve impulses in a non-myelinated neuron?

nerve impulse link nerve impulse animation
Resting potential

6.5.6: Principles of synaptic transmission

Key points to understanding synaptic transmission includes the release, diffusion and binding of the neurotransmitter, and initiation of an action potential in the post-synaptic membrane, and subsequent removal of the neurotransmitter. A detailed explanation of the principles of synaptic transmission are shown in the figure below.

synapses link nerve impulse across a synapse animation
Synaptic transmission

6.5.7 - 6.5.9: Homeostasis: monitoring the levels of internal variables

Homeostasis false maintaining the internal environment between limits,including blood pH, carbon dioxide concentration, blood glucose concentration, body temperature and water balance. The internal environment consists of the blood and tissue fluid. The endocrine system consists of glands that release hormones that are transported in the blood and are very important in homeostasis. Negative feedback mechanisms are also used during homeostasis to correct any changes in variable levels.

Homeostasis

6.5.10: The control of body temperature

Control of body temperature

6.5.11: The control of blood glucose

Using Figure 6.5.7 (above) on homeostatic control and the animation below to complete a diagram for the regulation of blood glucose.

blood glucose link blood glucose animation
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Control of blood glucose

6.5.12: Diabetes

Diabetes is having increased effect on human societies around the world, including personal suffering due to ill health and diabetes directly but also side effects such as kidney failure, eye problems, skin sores and infection. Table 1 distinguishes between type I and type II diabetes.

Type I diabetes Type II diabetes
A condition in which the body failures to produce insulin and results in insulin deficiency. Requires the person to inject insulin. A condition in which the body's cells do not properly and results in insulin resistance. Can be controlled by diet and/or medication.
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