Control and Communication of Cells - National 5 Bio

​Interdependency of cells

The cells in multicellular organisms do not work independently of each other. In animals, for example, muscle cells in the legs depend on red blood cells in the blood to supply them with oxygen and neurons in the brain to make them contract.

To ensure that all the cells in a multicellular organism function correctly for the survival of an organism, the cells need systems for communication with each other.

The nervous system

The building blocks of the nervous system are neurons (nerve cells). Neurons are specialised to allow rapid communication between cells in different parts of the body by transmitting electrical impulses.

There are three types of neurons:

• Sensory neurons

• Inter neurons

• Motor neurons

​Some neurons are specialised to allow them to detect changes in environmental factors such as light, sound and temperature.

These neurons are found in sense organs. The central nervous system (CNS) is composed of all the neurons that make up the brain and spinal cord.

​The function of the central nervous system (CNS) is:

• To process sensory information. The CNS receives electrical impulses from sensory neurons connected to the sense organs

• To coordinate the bodys response. The CNS transmits electrical impulses, along motor neurons, to gland and muscles.

• Muscles produce rapid responses by contracting.

• Glands produce responses more slowly by releasing chemicals.

The Brain

Do you know any of the parts of the brain and their functions?

​A large folded area of the brain which is responsible for conscious thoughts, reasoning, memory and emotions

​Located at the rear of the brain below the cerebrum, responsible for the control of balance and coordinated movement

​Located at the top of the spinal cord and contains groups of neurons that transmit electrical impulses to the heart and lungs to control involuntary responses such as heart rate, breathing rate and peristalsis.

Reflexes

A reflex action is a rapid automatic response to a stimulus. Reflex actions are involuntary and do not necessarily involve the brain.

Reflex actions protect the body from further damage by allowing it to react quickly to stimuli, such as high temperatures, that may be harmful.

The circuit of the neurons that act to produce the reflect action is called the reflex arc.

​Hormonal Control

Hormones are chemical messengers. Hormones are released into the bloodstream by groups of cell called endocrine glands. Hormones are transported In the blood plasma to target body tissues where they bind to cells to produce a response.

Blood Glucose regulation

The concentration of glucose in the blood must be kept at a set point. The concentration of glucose in the blood is regulated by the action of the hormones insulin and glucagon. The target cells of these hormones are found in the liver.

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