Human Body SystemsHuman Body SystemsUnderstanding how our body’s

systems work and how they interact

1. The Digestive 1. The Digestive SystemSystem

The role of the digestive system is to process the food you eat so that the nutrients and minerals become available to your body.

We will take a closer look at the journey of food from the time it enters your mouth, its fate inside the body, until it is finally excreted as waste.

Types of DigestionTypes of DigestionWhen we are referring to digestion there are two types:

mechanical digestion - involves the physical breakdown of food onto very small pieces

chemical digestion - involves the breakdown of large particles into smaller particles by chemical substances called enzymes

These two types occur in several places along the path

The Major OrgansThe Major OrgansThe food you eat will follow the digestive pathway through the following major organs: 1. mouth (oral cavity) 2. esophagus 3. stomach 4. small intestine 5. large intestine 6. rectum

We will take a closer look at the role of each organ.

The Supporting CastThe Supporting Cast

Alongside the major organs, there are other organs that play a role in the digestion of your food. These include:

- pancreas - liver - gall bladder

Though food never enters these organs, they also have an important role in digestion.

The MouthThe Mouth

Digestion begins as soon as food enters the mouth.

- mechanical digestion happens when you chew food- your food mixes with your saliva which contains enzymes, thus chemical digestion also occurs in your mouth- the enzymes in your saliva help to digest large starch molecules into smaller sugar molecules

You are ready to swallow... your tongue helps!

The EsophagusThe Esophagus

The esophagus is the soft-tissue tube that connects your mouth to your stomach.

- as you swallow, food is funneled into the esophagus- food is moved down to your stomach by a wave-like movement known as peristalsis (contraction of muscles that lines the esophagus)

The StomachThe Stomach

Food enters the stomach and chemical digestion occurs with a bit of mechanical help.

- the muscular wall of the stomach churns up the food mixing it with secretions from the wall of the stomach, known as gastric juice- gastric juice is composed of mucus, hydrochloric acid, water and digestive enzymes- enzymes and acid chemically digest proteins into smaller particles

The Small IntestineThe Small IntestineThe stomach slowly releases food, which is now liquid, into the small intestine.

- chemical digestion continues here- together with enzymes produced by the wall of the intestine, the pancreas sends digestive enzymes into the small intestine which work to complete the breakdown of starches and particles into very tiny particles- bile is produced by the liver and stored in the gall bladder

Small Intestine... continued

- the gall bladder sends bile into the small intestine where it breaks up large fat globules into smaller ones- the small intestine absorbs nutrients and transfers them to the blood stream to be circulated in the body- the inner wall surface of the small intestine is lined with finger-like projections called villi- villi increase the surface area through which the nutrients are absorbed

The Large IntestineThe Large Intestine

Mechanical and chemical digestion are complete by the time food reaches the large intestine.

- the role of the large intestine is to reabsorb water, along with some vitamins and minerals that the body needs

The RectumThe Rectum

The undigested parts of food are formed into feces and collected in the rectum until the body is ready to excrete it as waste from the body.

2. The Respiratory 2. The Respiratory SystemSystem

The respiratory system is responsible for supplying your blood with oxygen and removing the carbon dioxide from your blood and returning it to the air outside your body.

Your body performs this gas exchange through a process called breathing.

Major StructuresMajor Structures

The respiratory system includes the following structures: 1. nasal/oral cavity 2. trachea 3. bronchi 4. bronchioles 5. alveoli

Your breathing also relies on the diaphragm.

The Nasal/Oral CavityThe Nasal/Oral CavityThe first part of the respiratory tract is made up of the nose and nasal cavity.

Air that enters through the nasal cavity is warmed, moistened, and cleaned before it travels any further.

Air can also enter the respiratory tract via the oral cavity, however this air will not be warmed, moistened, or filtered as is air that enters through the nasal cavity.

The TracheaThe Trachea

The trachea is a rigid tube made up of cartilage located at the front of the neck and acts as a passage for air traveling to and from the lungs.

The structure needs to be rigid so that the trachea will not collapse while breathing.

The BronchiThe Bronchi

The bronchi are a set of tube-like passageways that branch off the main trachea toward each of the lungs.

They are lined with tough connective tissue to prevent collapsing.

The BronchiolesThe Bronchioles

The main bronchi then branch off into several bronchioles which are much more narrow and will allow the air to pass through.

The branching produces progressively smaller diameter tubules.

The AlveoliThe AlveoliAlveoli are tiny air filled sacs found at the ends of the bronchioles.

The alveoli are made up of specialized epithelial tissue which is only a single cell layer thick.

Alveoli are surrounded by capillaries (tiny blood vessels)

Gas exchange occurs at the alveoli by way of diffusion

Gas ExchangeGas ExchangeOxygen-rich air is transferred from the lungs to the bloodstream at the alveoli. Oxygen is then carried throughout the body to cell that are in need.

Blood rich in carbon dioxide is transferred from the bloodstream to the lungs, again, through the alveoli.

Gases are exchanged by means of diffusion through the membranes of cells. (diffusion - the tendency of material to move from an area of high concentration to an area of low concentration)

The Role of the The Role of the DiaphragmDiaphragm

As stated previously, your breathing relies on the contraction and relaxation of muscles in the diaphragm.

Inhalation - when you inhale, your diaphragm muscles contract causing it to be pulled down and your ribs to be pulled up. This creates and increase in the size of your chest and lungs, thus pulling air into your lungs.

Exhalation - when you exhale, the opposite is true. The muscles in the diaphragm relax; ribs go down; diaphragm goes up; decrease size; thus forcing air out.

3. T3. The Circulatory he Circulatory SystemSystem

The circulatory system is your body’s transportation network.

The role of the circulatory system is to transport and deliver nutrients absorbed by your digestive system, transport oxygen to your cells, and to remove waste products.

Major PlayersMajor Players

Your blood constantly travels throughout your body through a complex network that includes: 1. heart 2. arteries 3. capillaries 4. veins 5. blood

Let’s take a closer look at each of these...

The HeartThe Heart

The heart is the body’s main pumping station. It is made up of muscular tissue that contracts and relaxes to allow blood to flow both into and out of the heart.

Your heart pumps carbon dioxide-rich blood to the lungs so that the carbon dioxide waste can be exhaled; while the blood that is high in oxygen is pumped to all other parts of your body.

Your heart muscles are strong enough to force blood to travel up to your brain and all the way dow to your toes!

Blood VesselsBlood Vessels

Blood vessels are made up of three types of tissue:- connective tissue on the outside- muscle tissue in the middle- epithelial tissue on the inside

Each type of blood vessel carries out a specialized function and therefore each a bit different in structure.

The ArteriesThe Arteries

These are the blood vessels that carry the oxygen-rich blood away from your heart to be delivered to all parts of the body.

Arteries have a thick, muscular layer that expands and contracts to help push blood along

You can feel this expansion of your arteries as a pulse.

The VeinsThe Veins

These blood vessels return blood that is rich in carbon dioxide back to your heart so it can then be pumped into your lungs where it will undergo an exchange of gases.

Veins are thinner and have valves that stop the blood from flowing backward.

The CapillariesThe CapillariesThese are highly specialized blood vessels that are located between arteries and veins.

Capillaries have two adaptations that make them suitable for exchanging gases and nutrients:1. they are made up of specialized epithelial tissue that is only one cell layer thick2. they are very narrow so that blood cells must pass through in single file

These adaptations increase the rate of diffusion.

The BloodThe BloodBelieve it or not... Blood is the second largest example of connective tissue in your body!

Blood is made up of red blood cells, white blood cells, platelets, and plasma (the liquid portion of your blood).

Plasma makes up 55% of your blood while the other parts combine to make up the other 45%.

Plasmas transports nutrients to your cells and carries wastes such as CO2 away.

Blood... continuedBlood... continuedRBCs are the oxygen carriers. To maximize the amount of oxygen they carry, RBCs have no nucleus.

WBCs are specialized to fight infection. Some are capable of ‘eating’ bacteria at infectious sites like cuts.

Platelets are cells that help stop bleeding at cuts. They are responsible for clotting of the blood.

The Circulatory system and the Respiratory system work together very closely to ensure the proper function of the body.

4. The Excretory 4. The Excretory SystemSystem

Your body produces a number different wastes. These wastes are poisonous an can cause serious harm if they are not removed from the body.

The role of the excretory system is to get rid of waste!

What Kind of Waste?What Kind of Waste?As we have discussed previously, the body produces carbon dioxide as a waste product and it is removed from the blood by the lungs.

Ammonia is a very toxic waste product that is produced when cells break down proteins.

Water and Salts are produced as waste when certain chemical processes take place in the cells.

Major OrgansMajor OrgansSome of the organs required for waste removal are also a part of other systems in the body. They include: 1. liver 2. kidneys 3. bladder 4. ureters and urethra 5. skin

We will discuss the processes for the removal of different of waste products.

The LiverThe LiverAlthough the liver is involved in digestion, it plays a major role in the excretory system as well.

It is responsible for taking the highly toxic ammonia, that is produced by cells, out of the bloodstream and converting it into a less harmful substance called urea.

Urea is less harmful but must still be disposed of.

Urea is released into the bloodstream on its way to the kidneys

The KidneysThe KidneysThe kidneys act as filters for the blood as they strain out any unwanted urea, water, and other salts, and they produce urine.

Every drop of your blood is filtered 300 times a day!

Even though about 180 L of blood pass through the kidneys, you produce only about 1.5 L of urine.

The amount of urine depends on how much water you drink.

The Formation of The Formation of UrineUrine

The blood enters the kidney by the renal artery. This artery branches into smaller and smaller vessels.

These capillaries enter filtering units called nephrons.

Nephrons are microscopic units that remove waste from the blood and produce urine.

The “clean” blood returns to the body through the renal vein, while the urine flow out a separate vessel and into the ureter.

Ureters, Bladder, & Ureters, Bladder, & UrethraUrethra

Ureters are long tubes that connect the kidneys to the bladder.

The bladder is a sac covered in muscle tissue. The bladder expands as the urine enters. Your bladder can store about one litre of urine!

When the bladder is full, the muscles contract and push the urine out though the urethra.

The SkinThe Skin

Your skin has thousands of tiny sweat glands just below the surface.

In addition to producing sweat to keep you cool, these glands remove excess salt from your blood.

When you sweat, you are excreting waste!

Did You Know...Did You Know...Urine can reveal disease.

Certain diseases can affect how the kidneys function, and these changes will show up in urine samples.

Proteins in the urine will denote kidney failure.

Glucose in the urine is often a sign of diabetes.

Doctors analyze urine samples to gain insight to how well your body systems are functioning.

The role of the nervous system is to monitor and respond to internal and external stimuli.

A stimulus is anything that causes a response in an organism. For example, you shiver when it’s cold; a goalie makes a save; your stomach produces gastric juice in response to food arriving in the stomach; etc.

5. The Nervous 5. The Nervous SystemSystem

Major Role PlayersMajor Role Players

The nervous system is mostly made up of one type of tissue called nervous tissue.

Nervous tissue is made entirely of specialized cells called neurons.

The nervous system is made up of: 1. brain 2. spinal cord 3. nerves

How the Nervous How the Nervous System is OrganizedSystem is OrganizedThe nervous system can be thought of as two major systems: - the central nervous system (composed of the brain and spinal cord)

- the peripheral nervous system (made up of the cranial and spinal nerves)

Peripheral Nervous Peripheral Nervous SystemSystem

Each nerve in the peripheral nervous system is made of of sensory neurons (which carry information from the body to the CNS) and motor neurons (which carry information from the CNS to the muscles or organs.

The peripheral nervous system can be sub-divided into two categories:1. somatic nervous system - control voluntary responses2. autonomic nervous system - control automatic responses

Central Nervous Central Nervous SystemSystem

The brain receives stimuli from the outside world, gathered by the sense organs: eyes, ears, mouth, nose, and skin.

The brain also receives stimuli from the body itself.

The brain reacts to stimuli and sends messages to the appropriate body parts.

The spinal cord connects the brain to the PNS, and acts as a highway for messages b/w brain and body.

Reflex ResponseReflex Response

A reflex is when sensory and motor neurons work together and respond without involving the brain. It is an automatic response by the nervous system to an external stimulus.

Reflexes protect you from injury by reducing the time it takes to react to harmful stimuli.

Sense of TouchSense of Touch

Unlike your other senses, the sense of touch is found in all areas of your skin (making it the largest sense organ).

When blind people read braille, there is a reason why they use their fingers... they are loaded with touch receptors.

Neuro

n

Question?Question?

How might the structure of a neuron help to carry out its function?