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BODY SYSTEMS & PHYSICAL ACTIVITY.

1. Introduction: The organism is a very well "designed" system. It responds as a whole to any situation, involving all

the systems that compose it.

It is obvious that during physical activity the same happens. When we exercise physically, our body

needs a series of functions that allow us to start our muscles, which a series of chain reactions that can

be summarized as follows:

- The nervous system will be the one that initiates the whole process, preparing and sending the

necessary information to the different organs involved.

- The locomotor system will be responsible for keeping the body in its natural position, and serving as

hinges, like in a door, so that they can move. Without them, we could not stand up or maintain

positions.

- The nerve signal arrives to the muscles generating the contraction that will allow the movement of the

body segments from the joints.

- The muscular tissue needs more nutrients and oxygen than when the body is at rest.

- To provide these nutrients and oxygen the heart pumps more blood and the circulatory system specially

focuses on where it is necessary.

- To increase the amount of oxygen, the respiratory system also increases the supply through

breathing.

- The necessary energy for this muscular contraction is obtained from the nutrients extracted from

the previously consumed food, both solid and liquid.

- All this activity implies an increase in body temperature, which must be solved by means of sweat

(excretory system).

- All nutrients and oxygen used by the body become waste products that are toxic. These must be

treated and eliminated. This process is developed by the respiratory system and the excretory

system.

This is the way the body acts as a whole to meet all the demands created by physical activity in all

the specific systems, which work together thanks to the nervous system. The nervous system makes the

other systems function properly and in an organised way.

Throughout this topic, we will analyse more specifically each of these systems and their relationship with

physical activity.

1. Nervous System.

The nervous system is a network of highly specialized

tissues, which coordinates all control functions of the body,

both conscious and unconscious. Its cells are the neurons.

According to their function, neurons are classified as:

Sensory: Conduct information from the receptors to

the most important nerve centres. Motor neuron: They transmit the orders to the organs.

Interneuron: They are located between the sensory and

motor neurons and are located in the higher nervous centres.

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The nervous system is very complex, but for its study we can differentiate it into central nervous system

and peripheral nervous system.

The central nervous system (CNS) is made up of the brain and

the spinal cord. It is protected by the skull and the spine

The groups of neurons in the brain have specialized functions. For

example, some relate to thinking, learning and memory. Others are

responsible for receiving sensory information. Others communicate

with the muscles, stimulating them for action.

The central nervous system performs four essential functions in

physical activity, which are:

1. Receiving stimuli from the outside world. 2. Transmitting sensitive nerve impulses to processing centres. 3. The Creation of responses and effector impulses that will start

them up.

4. The Transmission of these effector impulses to the skeletal

muscles.

The peripheral nervous system is responsible for connecting

the organs of the senses with the nerve centres, and the nerve

centres with the effector organs (which perform the orders

created). It is formed by the branches that emerge from the central nervous system throughout the body,

known as nerves.

Nerves are thin cords that branch out through all the organs of the body.

Physical activity is very influenced by the nervous system. The nerves are the communication channels

where our senses capture the information of the environment that will be sent to the different nervous centres

to be treated, and in this way, send back an action, mainly motor, that determines the movement to be carried

out according to the circumstances.

The performance of physical activity also has an influence on the functioning of the nervous system,

as it happens with the rest of the body's systems.

The usual and systematic practice of physical activity has a number of benefits in the nervous system:

it improves muscle coordination and reflexes, it reduces the transmission time in neuronal junctions, it

improves reaction capacity, it decreases levels of anxiety and aggressiveness, it improves rest and sleep, it

can help prevent depressive or stressful situations. It is important to emphasize that, due to the greater

contribution of nutrients that the brain has during the practice of physical activity, exercise has proven to be

an excellent method of protection against neurodegenerative diseases such as Alzheimer or Parkinson.

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2. Circulatory System. The circulatory system allows blood to circulate and transport nutrients,

oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body

and help in fighting diseases, stabilize temperature and pH, and maintain

homeostasis (inside body balance)

The vascular system carry out several functions with an important role to live.

- Transport: moving important component around the body in the bloodstream,

like oxygen, nutrients and water to cells and organs, and waste product from this

up to excretory systems to eliminate them.

- Body temperature control: more blood near the skin cools the body quicker.

That´s why your skin looks redder after exercise.

- Protection: moving antibodies around the body to fight disease. Blood clotting seals cuts.

Heart, blood, blood vessels and lymphatic system compose

human circulatory system. The lymphatic systems will be developed

in biology.

The heart is an organ with an involuntary special muscular

tissue, which pumps blood through the blood vessels of the

circulatory system between 60 and 100 times by minutes (heart

rate). The heart is located in the middle compartment of the chest.

The heart sends blood to the organs throughout blood vessels.

When blood go out of heart, it put pressure on the vessels named

blood pressure.

The vessels that carry blood away from the heart are called

arteries and arterioles.

The capillaries, responsible for the exchange of substances

between the organs and the blood,

Veins and venules collect the blood from the organs and parts

and return the blood to the heart.

You can see the procedure in the next video: https://www.youtube.com/watch?v=UFvhdXHV5CM

Normally, 7-8% of human body weight is from blood. This essential fluid carries out the critical functions

of transporting oxygen and nutrients to our cells and getting rid of carbon dioxide, ammonia, and other waste

products. In addition, it plays a vital role in our immune system and in maintaining a relatively constant body

temperature. The most important blood components are red cells, white cells, platelets, and plasma.

Red cells transport oxygen helped by hemoglobin from the lungs to all of the living tissues of the

body and carry away carbon dioxide.

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White cells, or leukocytes , participate in

different ways in our immune responses, helping our

body to fight versus virus and diseases.

Platelets or thrombocytes help stop bleeding.

Plasma is a yellow tinted mainly compose by

water (92%). Normally, 55% of our blood's volume is

made up of plasma. As the heart pumps blood to cells

throughout the body, plasma brings nutrients to them

and removes the waste products of metabolism.

You can see a video about blood component following

the next link: https://www.youtube.com/watch?v=R-

sKZWqsUpw

Physical activity produce immediate effects over cardiovascular system, and if you practice physical

activity at least 3 times per week (regular training), your vascular system will adapt and improve their

performance, helping to you to get better health.

a. Immediate effects when first exercising: b. Effects of regular training:

Heart contracts more often – increased heart

rate.

Heart contracts more powerfully – increased stroke

volume

Blood diverted to muscles, eg it is diverted from

the digestive system to the muscles.

Blood temperature rises.

Blood vessels near skin open to allow heat to be

lost.

Heart muscle increases in size and strength.

Cardiac output increases. Cardiac means relating to

the heart so this is the amount of blood that the

heart pumps out to the body.

Lower resting heart rate, quicker recovery from

exercise.

Reduced risk of heart disease.

Increased number of capillaries in muscles.

Increased volume of blood and red blood cells.

3. Respiratory System The main function of the

respiratory system is that of

oxygen capture from atmospheric

air and the elimination of carbon

dioxide from the body. Besides, has

other functions that are also

important for humans. It allows

phonation (the air produces

vibrations in the vocal cords, which

produce the sounds we emit to be

able to communicate through

speech). The respiratory system

also filters, heats and humidifies

the air before being absorbed into

the alveoli.

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The respiratory system consists of two parts: the respiratory airways and the lungs.

The respiratory airways is the communication path through which air flows from the outside to the lungs

and counter wise. It is made up: Nasal Passage; Pharynx or throat; Larynx: (Inside of the larynx are the

vocal cords. When we swallow the food, the larynx is closed by a kind of tongue called epiglottis); Trachea (It

goes to the thorax and bifurcates forming the bronchi); Bronchi (trachea´s bifurcations. They penetrate into

the lungs where they branch repeatedly, forming the bronchioles)

The Lungs are two reddish foamy organs located in the thorax and protected by the rib cage. Through

them breathing is done.

Inside the lungs, each main bronchus divides again, like the branches of a tree, into increasingly thinner

passages: secondary bronchi, bronchioles and alveolar ducts, until arriving at small sacs called alveoli. These

alveoli and their channels form the gas exchange system.

The lungs are divided into zones called lobes. The right lung is formed by three lobes and is bigger than

the left (which has to leave space for the heart), the left for two.

The respiratory mechanics is the part of breathing that produces the air movement from outside to inside

of the lungs (inspiration) and vice versa (expiration). This is known as pulmonary ventilation.

Inspiration is produced by respiratory muscles contraction (active phase) that increase the volume of the

rib cage. Expiration occurs when the respiratory muscles relax, just like a full balloon to let out the air. Under

normal conditions, this second phase of breathing is passive, produced by muscle relaxation. Sometimes, the

second phase can be active, during a forced expiration.

The gases exchange between the air and the blood takes place through the thin walls of the alveoli and

blood capillaries. Venous blood, which comes through the pulmonary artery, is released from the carbon dioxide

produced by the metabolism of all the cells in the body, and takes the oxygen from the alveoli. The oxygenated

blood returns through the pulmonary vein to the heart that pumps it to the whole body.

Physical activity produces immediate effects on the respiratory system, mainly caused by the oxygen

demands increase of organism.

• Increased respiratory rate: increases the number of pulmonary ventilations per minute.

• Increased depth of breathing, which produces a greater air intake in each inspiration.

• Increases the gas exchange in the alveoli.

In addition, if you practice physical activity at least 3 times a week (regular training), the respiratory

system will adapt and improve its performance, helping you to obtain a better state of health.

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• Decreasing resting respiratory rate, faster recovery of exercise.

• Increasing maximum respiratory rate (during exercise)

• Increasing respiratory efficiency during the practice of physical activity

• Increasing gas exchange.

4. Muscular System Is the active part in the locomotor system. The muscle tissue has a very specific characteristic, it is able

to contract and vary its length, shortening and generating strength. This contraction, together with bones

and joints action, is what produces the body movements that are so important in physical activity and sport.

In the human body, there are 3 different types of muscle tissue: Cardiac, Smooth and striated muscle

tissue (or skeletal). Cardiac and smooth muscle tissue contraction is involuntary. Striated is the only can be

contracted voluntarily. Now you are going to learn about striated muscle tissue.

• Striated muscle tissue is very similar to heart tissue, but this time, the contraction of this muscle

tissue depends on the person. They are responsible for creating the movement and we are going to focus on

this topic.

To physical exercise it is important to know which muscles participate in each movement, and what

better way to start knowing the main muscle groups of the organism. Keep in mind that our body has about

650 muscles, and here only a small part is included.

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The muscles work in pairs. This means that every muscle that performs or produces an action has

another that generates the movement or the opposite action.

The muscle that contracts and generates movement is called the agonist muscle. The muscle that

performs the opposite action is the antagonist, which is also relaxed during the contraction of the agonist.

For example, the quadriceps are the muscle responsible for hip flexion. Its antagonist muscle is the

hamstrings, responsible for the extension of the hip.

Muscles, in addition to movement (including heart, vessels and organs) also help our body to perform other

functions such as maintaining a proper posture, chewing food, generating heat, shaping the body, through

movement also helping to communicate (gestures and mimicry) and have a protective function (for example,

the abdominal muscles protect the entire digestive system).

The usual and systematic practice of physical exercise also has positive effects on the muscular system

and health. Improves the use of energy substrates by muscle tissue, increases capillary muscle, also increases

muscle tone (responsible for maintaining good body posture), increases muscle tissue, which also leads to an

increase in metabolism (tissue muscle consumes more energy than fatty tissue) and helps shape the body.

5. Skeletal System. The skeletal system is the passive/ innactive part of the locomotor system which is formed by cells

(living tissue) and minerals (calcium).

Bones provide stability to the body. To allow movement, the different bones are connected by joints.

Cartilage is a tissue whose function is to prevent friction of the parts of the bones that form the joints.

There are three main types of joints:

fibrous (without movement: skull bones),

cartilaginous (small movements: vertebrae),

synovial (free movements: knee, elbow hip ...).

Although not all are equal, the most

interesting to human movements are the

cartilaginous and synovial, especially the

latter in which there are also other elements

that we will discuss next.

In synovial joints there are fibrous

cords that are responsible for keeping

the bones in proper position. These cords

are called ligaments. As not all joints fit

perfectly, there are elements that are

responsible for making everything work perfectly. These elements are the meniscus and joint

impellers. Surrounding the entire joint is an articular cuff (protection cover) that forms the joint

capsule. The inner part of this capsule is covered by the synovial membrane. Inside of the synobial

membrane is the synovial fluid, responsible for lubricating the joint and nourishing the cartilage.

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The muscule and skeletal systems are conected by tendons. Tendons are inserted into the bones to

transmit muscle strength and maintain proper body posture or perform movements.

Bone system is the responsible for support and the locomotion of humans, and the shape of the human

body. The skeletal system is the base to fix muscles and ligaments, has a protective function of many vital

organs (the skull protects the brain, the rib cage protects the heart and lungs, the spine protects the spinal

cord ...), it is a large reserve of calcium and, it is the responsible to the sounds transmission in the bones of

the ear.

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As with the muscular system, there are many bones that make up the human body, and it is very

important to know the most important ones in the locomotor system for movements, physical exercise and

sport. Next, you have the main bones and joints involved in the activities we practice in PE class.

It is important to emphasize that the spine is formed by 3 sections: the cervical spine (which also forms

the neck), the thoracic spine and the dorsal spine, and continued by the sacrum and coccyx. In addition, the

carpus bones are the wrist bones, the metacarpals are the palm bones and the phalanges are the fingers.

The foot has a structure similar to the hand, being formed by bones called tarsus (some of them form the

ankle next to the tibia and the fibula), metatarsus (sole of the foot) and toes (phalanges). All fingers (hands

and feet) have 3 phalanges, except the thumb that only has 2.

Regular and systematic practice of Physical Activity, at least 3 days a week for 60 minutes each day, also

develops a series of benefits for the bone system: increase in bone mineral density, which also increases

bone resistance to fractures, increase the resistance of ligaments and tendons. In addition, specifically in

children, it contributes to the proper development of bones, in women´s body, after menopause, decreases

the loss of bone mass. Physical exercise helps to elderly people to prevent osteoporosis.

6. Digestive System The digestive system transforms food into simple molecules in order to be used by the organism. It is a

process that occurs step by step in its different parts: mouth, pharynx, oesophagus, stomach, small

intestine, large intestine and anus. Different enzymes, secreted by the walls of the intestine or by

specialized glands, completely break down the food, leaving it ready to be distributed to the cells. The

digestive system is really a tube.

During this process the food undergoes a series of actions that transform it. Two types of actions: some

mechanical (the food is fragmented, kneaded, mixed, etc.) and others chemical (certain substances,

digestive enzymes, attack the food by breaking it down, other chemical substances aid the action of

enzymes). Just the selection of the food (diet), the way we cook it, and the first phase of digestion

(chewing ) are voluntary. That is why it is very important to chew food well before swallowing it, so that the

rest of the process can more easily extract the nutrients and make the most of the food.

During physical exercise the digestive system also moves. The intestine increases its motility

(characteristic movement that helps food not get stuck in it), which reduces constipation (is not a common

cold); In addition, it has been demonstrated that physical exercise practice decreases the incidence of

colon cancer and keeps the digestive system healthy.

It is also recommended a healthy and balanced diet, a fixed schedule and enough time for meals, and a

correct hydration (2 litres of water per day at least).

During digestion, large amounts of blood accumulate in all the organs involved, producing a sensation

of relaxation and sleepiness, which seems a situation of lethargy. During digestion the activity of the rest of

the body systems decreases.

The larger the amount of food ingested prior to physical activity, the less amount of blood supply the

organism will have available to carry out the activity. If we force the muscles that intervene in the activity

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to continue doing so, the result may be perjudicial for the organism. It can be dangerous because blood will

trespass to other places and leave the digestive system with a poor supply and the digestive process will be

frozen. This can lead to a series of disruptions and physical discomfort.

That is why it is recommended not to practice physical activity until 3 hours after you have taken a

significant amount of food (for example, at lunch or at dinner).

In addition, it should be noted that regular and systematic physical activity improves appetite control.

7. Excretory System Excretion is the process through the human body

removes waste (toxic and/or unnecessary products) that

cells discharge into the blood.

In humans, excretion is mainly done by the urinary

system, although some substances are also excreted through

the bile that reaches the intestine and sweat from the sweat

glands of the skin.

The excretory system is composed by: kidneys (they

eliminate a lot of substances by means of the urine, since the

blood is filtered in them), lungs (they eliminate CO2), skin

(removes water, some salts and organic substances) and liver

(removes some toxins and lipids).

Sweat is produced due to an increase of the body’s

temperature during physical exercise, but not only occurs during this activity. Its main function is to

control body temperature by cooling the skin. Sweat is generated in the sweat glands that produce it from

water of blood capillaries, Therefore, a good level of hydration is very important to be able to practice

physical activity in a healthy way, which involves drinking water before, during and after the practice of

physical activity, before thirst appears. You should drink 2 litres of water per day, increasing this amount

when you practice physical exercise.

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NOW YOU!!!!

1. Describe the main function of each body system.

2. In your opinion, which is the most important? Justify your answer.

3. Complete the next picture with main muscles: trapezius, deltoids, triceps brachii, biceps

brachii, latissimus dorsi, erector spinae, rectus abdominus, gluteus, sartorious, adductor,

quadriceps, hamstring, calves muscle.

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4. Fill the bones picture with the correct bones names. Draw a circle where the joints

are located and write their names. If you have any doubts, check the picture above.