Biology - Organ Systems, Medical Imaging Technology

Exploring the Organ Systems 

Digestive System 

• Four stages of the digestive process 

  • Ingestion—the intake of nutrient material

  • Digestion—the breakdown of molecules

  • Absorption—the intake of nutrients into cells

  • Excretion—the removal of waste

• Mouth 

  • Contains teeth used for mechanical digestion 

  • Salivary glands used for chemical digestion

  • Saliva serves two purposes 

    • Amylase  helps digest starch (a key component of plant material)

    • Helps lubricate the esophagus sp food can be delivered to the stomach more easily as a small ball (bolus)

• Pharynx 

  • An empty cavity at the back of the throat 

  • Blow it is 2 separate tubes

    • Esophagus 

      • Brings food to the stomach 

    • Trachea 

      • Brings air to the lungs 

  • To prevent food from going down the wrong tube, a small flap of tissue known as the epiglottis closes the trachea when food is being swallowed in order to direct the bolus down the correct pathway

• Esophagus 

  • is a tube of smooth muscle that connects the pharynx with the stomach

  • Food is pushed through this organ by smooth muscle contractions called peristalsis

  • As food moves down the esophagus, the muscle relaxes ahead of the food and contracts behind it, forcing it down towards the stomach

• Stomach 

  • entrance to the stomach is controlled by the cardiac sphincter

  • This ring of muscle is opened when sensory receptors detect the sensation/pressure of food

  • The cardiac sphincter is also responsible for preventing acid from splashing back upwards

  • After passing through the cardiac sphincter, food enters the J-shaped organ known as the stomach

  • Food that enters the stomach undergoes further mechanical digestion (through smooth muscle contractions) and chemical digestion (the stomach lining contains two different types of cells that secrete gastric juice, acid, and digestive enzymes)

  • Food is thoroughly digested in the stomach, it exits through the pyloric sphincter that leads to the small intestine

• Small Intestine 

  • Is a highly folded tube structure, approximately 7 m in length and 2.5 cm in diameter

  • It is divided into three sections along its length—the duodenum, the jejunum, and the ileum

  • The main function of the small intestine is to finish the digestive process and absorb essential nutrients

  • It does this using digestive enzymes and finger-like projections called villi, which line the inside wall of the small intestine and increase absorptive surface area

• Large Intestine 

  • Small intestine is connected to the large intestine, which is also divided into three sections—the cecum, the colon, and the rectum

  • The large intestine is 1.5 m in length and 5 cm in diameter

  • The main function of the large intestine is to absorb water

• Liver 

  • One of the largest organs in the body, the liver produces a substance called bile

  • Bile is responsible for the breakdown of lipids (fat) into glycerol and fatty acids

  • A yellowish-green fluid produced in the liver, bile is stored in the gall bladder until needed

  • The gall bladder is a small sac located under the liver

  • When needed in the digestive process, bile is secreted from the gall bladder through the bile duct and into the small intestine

• Pancreas 

  • Is best known for the secretion of insulin, a hormone that regulates blood sugar

  • The pancreas helps digestion by secreting digestive enzymes to break down carbohydrates, lipids, protein, and nucleic acids

  • It secretes sodium bicarbonate into the small intestine to help neutralize the acidic pH of the digested food coming out of the stomach

Circulatory System

• Critical systems in the entire human body

• Connected to every other system

• Four main functions

  • Transportation of oxygen and carbon dioxide: Oxygen is obtained from the lungs and carbon dioxide is delivered to the lungs

  • Transportation of nutrients and waste: Nutrients are delivered to all cells and waste is delivered to the kidneys

  • Maintenance of body temperature: Blood vessels in the skin dilate (expand) to dissipate heat when the organism is overheated, and constrict to reduce heat loss when the organism is cold

  • Circulation of hormones: Hormones are delivered from glands to organs through the bloodstream

• Three main components 

• Blood - A fluid in which material is transported 

  • Composed of plasma and cells

  • Transportation of oxygen and carbon dioxide is carried out by red blood cells

  • These cells are packed with oxygen binding proteins (hemoglobin)

• Arteries, Veins, Capillaries - A system of vessels to carry the fluid 

  • Arteries carry oxygenated blood from the heart to the rest of the body

  • Veins are responsible for delivering deoxygenated blood back to the heart so they can be reoxygenated and recirculated 

  • Capillaries are found within organs and connect arteries with veins

• Heart - A pump that pushes the fluid through the vessels

  • About the size of your fist and has a mass of 300 grams

  • It is slightly left of center in your chest 

  • This organ is made up of muscle tissue arranged into four chambers that are connected by valves

  • Two different forms of blood enter the lungs

  • Blood that returns to the heart from the rest of the body through veins lacks oxygen and is called deoxygenated blood

  • This blood enters the right side of the heart and goes through a process known as pulmonary circulation to the lungs to pick up oxygen

  • The oxygen-rich blood that enters the heart from the lungs is called oxygenated blood

  • It is ready to be sent to all the organs and tissues of the body through a process known as systemic circulation

Respiratory System 

• Located in the chest cavity 

• The purpose is to transport oxygen dom the air into the blood and excrete carbon dioxide out of the blood

• Nasal Cavity and Pharynx

  • The nasal cavity is found within the nose

  • Air entering the body is first brought here

  • The nasal cavity cleans, humidifies, and warms the air that enters the body

  • It is lined with mucus and hair to trap unwanted bacteria or other irritants

  • The nasal cavity draws in air and passes it into the pharynx (the same area where the tongue pushes the bolus)

  • Air is directed into the trachea (windpipe) via a small flap of tissue called the epiglottis

  • The epiglottis closes over the trachea when food is being swallowed so that it does not enter the lungs

• Trachea 

  • Is Below the pharynx is the trachea

  • Extends down through the neck beside the esophagus

  • The trachea is larger in diameter than the esophagus, being approximately 2–2.5 cm in diameter and 10–16 cm in length

  • A delicate organ, the trachea is held open by cartilaginous rings that prevent the collapse of the windpipe

• Lungs and Bronchi

  • Trachea branches into the left and right bronchi (singular: bronchus), which direct air into the left and right lung

  • The two lungs are not the same size

  • The right lung is divided into three lobes, the smaller left lung is divided into two

  • Makes room for the heart, also located on the left side of the chest cavity

  • The lungs are covered by a pleural membrane to protect them and prevent infection

• Bronchioles and Alveoli 

  • Within each lung, the bronchi divide into numerous small tubes called bronchioles

  • Approximately there are 30 000 bronchioles in each lung, each one about the diameter of a hair

  • At the end of each bronchiole is an alveolar sac (air sac)

  • The alveolar sac contains a cluster of alveoli tightly wrapped in capillaries

  • Alveoli are like clusters of tiny hollow grapes at the end of the bronchioles

  • The alveoli are lined with capillaries

  • The capillaries are the sites of gas exchange

  • Oxygen diffuses from the alveoli into the capillaries containing the red blood cells, and carbon dioxide diffuses from the red blood cells in the capillaries into the alveoli

  • The circulatory system can then transport the oxygen to all cells in your body

• Diaphragm 

  • Lungs operate by air-pressure changes within the bronchi and bronchioles

  • The pressure changes are caused by the expansion and contraction of a muscle called the diaphragm

  • The diaphragm is a dome-shaped muscle that extends across the bottom of the rib cage

  • It separates the thoracic (chest) cavity from the abdominal cavity

  • the diaphragm moves downward, allowing the tubes to dilate and bring in fresh outside air containing oxygen

  • When the diaphragm contracts, it moves up, causing the tubes to constrict and forcing out the waste air containing carbon dioxide

  • The entire thoracic cavity—including the lungs and heart—is covered by the rib cage, which provides support and protection

Medical Imaging Technology 

• Ultrasound 

  • is a procedure that involves exposing part of the body to high-frequency sound waves to produce pictures of the inside of the body

  • The transducer sends out high-frequency sound waves into the body and then listens for the returning echoes from the tissues in the body

  • These returning waves are measured and analyzed by a computer to create a picture of the object on the display screen

  • The patient must lie down on an examination table

  • Clear gel is applied to the area being studied to help the transducer make secure contact with the body

  • The ultrasound technician then presses the transducer firmly against the skin and sweeps it over the area

  • Doppler ultrasound images can help doctors see and evaluate the following

    • Blockages to blood flow (such as clots)

    • Narrowing of vessels (which may be caused by plaque)

    • Tumours and congenital malformation

• X-Ray

  • Form of electromagnetic radiation 

  • Is used for examining broken bones and teeth below the gumline, identifying tumours, and locating foreign objects (such as bullets) within tissue

  • Can damage tissue and even cause cancer in high doses

• CT Scan 

  • Is a large box-like machine with a tunnel through the centre

  • The patient lies on an examination table that can move in and out of the tunnel

  • An X-ray tube rotates around the patient and delivers information to a computer for processing

  • helps doctors diagnose and treat medical conditions

  • Scans can be done of internal organs, bone, soft tissue, and blood vessels

  • Provide more detail than an X-Ray

• MRI (Magnetic Resonance Imaging) 

  • Is an imaging technique used to visualize the internal structure of the body

  • Provides contrast between the different soft tissues of the body, making it very useful for studying the brain

  • The procedure uses a powerful magnetic field, radiofrequency pulses, and a computer to produce detailed pictures of body structures

  • can be used to evaluate organs of the chest, abdomen, pelvis, and brain

Understanding How Organ Systems Work Together

Organs systems 

Homeostasis 

• Maintain the internal environment by the chemical processes in the body

• Three main goals of this

  • Body temperature 

  • Breathing rate 

  • Heart rate

Body Temperature - Nervous, Circulatory, Respiratory, and Locomotive Systems

• Human body temperature is between 36.2oC and 37.2oC 

Resting Heart Rate - Nervous, Circulatory, and Respiratory Systems 

• Average is between 50-100 beats per minute

• This all depends on gender, age, weight, diet, and smoking 

• 70 beats per minute for adult male and 73 for adult female

  • With a range of about +/- 5 beats per minute

Resting Breathing Rate - Nervous, Circulatory, and Respiratory Systems 

• Average is 16 to 20 breaths per minute

• Below 16 could lead to hypoventilation and about 20 could lead to hyperventilation

Systems Working Together 

Respiratory System

• A key component is the alveolar sac

• They are covered with capillaries that provide a large contact area between the alveoli and blood

Circulatory System

• They regulate temperature

  • Transport oxygen, carbon dioxide, nutrients, wastes, and hormones

Example of Systems Work Together 

Example: Respiratory and Circulatory Systems

Steps:

1. Air is inhaled through the nose and travels down into the lungs. The blood in the alveoli is now oxygenated.

2. This oxygenated blood returns to the heart via the pulmonary vein, enters the left atrium, and passes into the left ventricle.

3. The contraction of the heart muscle forces the oxygenated blood up through the aortic valve and into the aorta.

4. The aorta sends oxygenated blood throughout the body through various arteries.

5. Once the tissues, glands and organs have had their oxygen delivered, this deoxygenated blood returns to the heart via the veins.

6.  The deoxygenated blood enters the heart, passes through the right atrium and ends up in the right ventricle.

7. A contraction of the heart muscle forces this blood up through the pulmonary valve of the heart and into the pulmonary artery.

8. This artery splits into two, each directed toward one lung.

9. The blood within the pulmonary arteries enters the lungs and branches down into small capillaries in the alveoli.

10. The alveoli facilitate gas exchange, allowing the oxygen to diffuse from the alveoli into the capillaries as the carbon dioxide diffuses from the capillaries into the alveoli to be exhaled.

Medical Conditions and Treatments 

Asthma (Respiratory Disorder)

• A common ailment that causes difficulty in breathing

• It can be faint to very severe

• Occurs when cells of the respiratory system are irritated causing inflammation or swelling of bronchi and bronchioles 

• The inflammation results in excess mucus production that narrows the airways

• An asthma attack is usually caused by some sort of allergic reaction 

• The treatment for this is usually an inhaler that contains corticosteroids 

Bronchitis (Respiratory Disorders)

• Is a severe prolonged form of asthma

• Involves inflammation and swelling of the bronchi and bronchioles resulting in narrow passageways

• Caused by some sort of viral bacterial infection

• Inhalers and antibiotics can treat this