What Is Coordination And Control?




INTRODUCTION: 

Humans use a network of nerve cells to

collecti nformation. These information

include the body's internal and external

environment. Nerve sends messages to

the body's muscles and glands. Our body

collects data from inside and outside by

means of nerves and sends it to the control

centre for analysis and decision. Thus all the

organs of our body work together according

to the needs of the whole body. It means all

the activities of the organs are coordinated

and controlled. 

COORDINATION:

       The co-operative work of cells, tissue Stomach wall activation. Then the three muscle layers of the stomach wall become active; they compress and pummel the food, breaking it apart physically, all the while continuously mixing the food with the enzyme-containing gastric juice so that the semifluid chyme is formed.

 

Food Propulsion

Peristalsis is responsible for the movement of food towards the digestive site until the intestines.

• Peristalsis. Once the food has been well mixed, a rippling peristalsis begins in the upper half of the stomach, and the contractions increase in force as the food approaches the pyloric valve.

• Pyloric passage. The pylorus of the stomach, which holds about 30 ml of chyme, acts like a meter that allows only liquids and very small particles to pass through the pyloric sphincter; and because the pyloric sphincter barely opens, each contraction of the stomach muscle squirts 3 ml or less of chyme into the small intestine.

• Enterogastric reflex. When the duodenum is filled with chyme and its wall is stretched, a nervous reflex, the enterogastric reflex, occurs; this reflex “puts the brakes on” gastric activity and slows the emptying of the stomach by inhibiting the vagus nerves and tightening the pyloric sphincter, thus allowing time for intestinal processing to catch up.

 

Activities of the Large Intestine

The activities of the large intestine are food breakdown and absorption and defecation.

Food Breakdown and Absorption

What is finally delivered to the large intestine contains few nutrients, but that residue still has 12 to 24 hours more to spend there.

• Metabolism. The “resident” bacteria that live in its lumen metabolize some of the remaining nutrients, releasing gases (methane and hydrogen sulfide) that contribute to the odor of feces.

• Flatus. About 50 ml of gas (flatus) is produced each day, much more when certain carbohydrate-rich foods are eaten.

• Absorption. Absorption by the large intestine is limited to the absorption of vitamin K, some B vitamins, some ions, and most of the remaining water.

• Feces. Feces, the more or less solid product delivered to the rectum, contains undigested food residues, mucus, millions of bacteria, and just enough water to allow their smooth passage.

 

Propulsion of the Residue and Defecation

When presented with residue, the colon becomes mobile, but its contractions are sluggish or short-lived.

• Haustral contractions. The movements most seen in the colon are haustral contractions, slow segmenting movements lasting about one minute that occur every 30 minutes or so.

• Propulsion. As the haustrum fills with food residue, the distension stimulates its muscle to contract, which propels the luminal contents into the next haustrum.

• Mass movements. Mass movements are long, slow-moving, but powerful contractile waves that move over large areas of the colon three or four times daily and force the contents toward the rectum.

• Rectum. The rectum is generally empty, but when feces are forced into it by mass movements and its wall is stretched, the defecation reflex is initiated.

• Defecation reflex. The defecation reflex is a spinal (sacral region) reflex that causes the walls of the sigmoid colon and the rectum to contract and anal sphincters to relax.

• Impulses. As the feces is forced into the anal canal, messages reach the brain giving us time to make a decision as to whether the external voluntary sphincter should remain open or be constricted to stop passage of feces.

• Relaxation. Within a few seconds, the reflex

end and rectal walls relax; with the next mass

movement, the defecation reflex is initiated

again organs to function properly is called

coordination. Coordination helps to fulfil the

need of the whole body. Coordination provides

better changes for the successful performance

of a particular function.

 For Example:

       In catching a ball, different organs and

systems work collectively. Nervous system

sends information to the organs and muscle

to take action. Contraction of arm muscles

occurs in correct order, with power and

proper time. Thus many organs and systems

coordinate to catch the ball and make the

event successful. 

 TYPES OF COORDINATION:

       Coordination in organisms is of to types:

 1. Nervous coordination 

2. Chemical coordination 


 1). NERVOUS COORDINATION:

      

   The coordination in humans is controlled by

Nervous system. It consists of the central

nervous system (CNS) and peripheral nervous

system (PNS).

 i) Neuron is the basic unit of structure and

function of the nervous system. 

 ii) Neurons consist of long thread like structure

called nerve fibers.

     

     The longest fiber is called axon. An axon can

be more than a meter long. The shortest fiber

is called dendron or dendrites. The brain and

spinal cord make the nervous system (CNS).

These transmit information in the form of

electrical signals called nerve impulse. Hence

nervous coordination is a type of electrical

coordination.

 2). CHEMICAL COORDINATION: 

         Chemical coordination takes place through

certain chemicals secreted from the glands,

called hormones. Chemical coordination is a

slow but important method; these hormones

are made in a special gland called endocrine

glands. The blood capillaries supply blood to

these glands. These glands prepare specific

hormones and release them directly into the

blood. Endocrine gland secretes these hormones.

These glands are ductless.

 For Example:

          Hormone adrenaline prepares the body

for action. There are two adrenal glands located

above each kidney. When you are excited or

frightened, the brain sends a message through

the nerve to the adrenaline glands. These glands

secrete adrenaline into the blood. It makes the

heart beat faster. Oxygen is very quickly supplied

to the brain and muscles. This gives them more

energy for fighting and running away from this

spot. Some of the important glands are situated

gland, thyroid gland and adrenal gland. 

Difference between nervous coordination

and chemical coordination: 

Nervous coordination:

 Number 1. 

It is under the control of the nervous system. 

Chemical coordination:

 Number 1. 

It is under the control of hormones.

 Nervous coordination:

 Number 2.

 It is through the nerve cells are neurons.

 Chemical coordination:

 Number 2.

 It is through these chemicals and blood. 

Nervous coordination:

 Number 3. 

It is an electrochemical response.

 Chemical coordination:

 Number 3. 

It is purely a chemical response.

 Nervous coordination:

 Number 4.

 Responses to the nerve impulse are faster.

 Chemical coordination: 

Number 4.

 Responses of the body to the hormones

are much slower depending on the speed

of the circulatory system.

 Nervous coordination:

 Number 5.

 It affects short-termed processes e.g.

Reflex action and Heart beat.

 Chemical coordination:

 Number 5. 

It affects long termed processes e.g.

Growth rate and pregnancy. 

Nervous coordination:

 Number 6.

 It is specific and in a very limited area of

he body such as blinking of the eye.

 Chemical coordination: 

Number 6.

 It may be generalized affecting many organs

and systems. 

Nervous coordination:

 Number 7. 

It provides for rapid and precise adaptation to

environmental factors. 

Chemical coordination: 

Number 7.

 It provides for less rapid but longer testing

adaptation such as growth of the body. Sex

organs etc.

 MECHANISM OF COORDINATION: 

      Coordination system can be differentiated

into three phases.

 1) Receptors 

2) Coordinators 

3) Effectors 

4) Responses 

 1) RECEPTORS: 

          Any changes in our external or internal

environment are called stimuli. These are

received by special organs, called receptors.

This sense organs like nose, ears, skin, eyes,

and tongue are the example of receptors.

For example: Sound waves are detected by

ears and Chemicals in the air by nose. Each

receives a particular type of stimulus.

 2) COORDINATORS:

         These are the organs that receive information

from the receptors. Brain and spinal cord are

nerve coordinators while endocrine glands

are the chemical coordinators.

 3) EFFECTORS: 

  Neurons carry messages from the coordinators,

brain and spinal cord to muscles are glands.

After receiving the message/information decision

is made. This decision is sent to the organs

muscle and gland of the body. These muscles

are glands called effectors. 


 4) RESPONSES: 

          When effectors receive the decision

then actions are performed by the effectors.

This action is called response. 

EXAMPLE:

          When the door of our house is knocked,

our ears (receptors) receive the sound wave

and send a message to our brain (coordinator).

Brain makes a decision which is sent to the

muscle (effectors). This message is sent to

hand which moves (responses) and the door

is opened.


 (i)Sound of knocking ---------->(ii) Ear.

       (Stimulus)                         (Receptor) 

(iii)Brain  --------> (iv)   Muscles and glands. 

   (Coordinator)                          (Effectors)  

 ---------->(v)Opening of door

                  (Responses).