Pathogens & Diseases Part 3

Learning Objectives

• Main methods of disease transmission
• Methods of controlling pathogens

Types of transmission

-airborne

-contact

-food borne

-water borne

Airborne/ Droplet Transmission

• Pathogens suspended in the air & travel from source to host
• Source: humans, animal, soil, food, water
• Transmitted by coughing, sneezing, vocalization

Contact

• By coming together or touching of the source of the pathogen & the host

Food & Water Borne Transmission

• Contaminated food & water contaminated can cause inflammation of the stomach & intestinal lining ( acute gastroenteritis)
• Examples: cholera, botulism, salmonellosis, traveler's diarrhea

Prevention & Controls

Hygiene practices

• Sterilisation(special equipment such as auto clave) / Disinfection (Detol, alcohol)
• Washing (with soaps)
• Others

Physical protection

• Use of surgical masks (3-ply)
• Use of gloves (latex gloves)

Control of Vectors (mosquitoes, rat)

• Fumigation
• Trapping / killing of vectors

Control of microbes

• Use of antiseptics (useful against bacteria but not viruses)
• Use of antibiotics (against bacteria only)

Vaccination

• Immunization of the body using vaccines

           

Pathogen&Diseases Part 2

HIV: human immunodeficiency virus (a virus, NOT a disease)
AIDs: Acquired Immuno-deficiency Syndrome.

Examples of Contagious diseases
-SARS
-AIDs
-H1N1
-measles
-chicken pox
-small pox
-shingles
-measles
-chicken pox
-small pox
-Dengue(spread from person via mosquito)
-HFMD (hand, foot, mouth disease)
-H5N1
-mumps (swelling of salivary glands and rashes)
-typhus
-

Pathogens & Diseases Part 1

Learning Objectives

• Behaviour of a system in an equilibrium - what happens when there are disturbances?
• What are feedback mechanisms and how is it linked to homeostasis
• The human body as a system - its behaviour when it is healthy versus when it is diseased
• Any system is usually connected to other systems, both internally and externally
• Thinking about things as systems means looking for how every part relates to others
• The output of one part of a system can become the input to other parts.
• Such feedback can serve to control what goes on in the system as a whole & serves to keep changes within specific limits.

Homeostasis is the tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, to maintain *equilibrium or stability within its internal environment, regardless of the outside changing conditions.

(*equilibrium=stay healthy)

A system of equilibrium may return to the same state of equilibrium if the disturbances it experiences are small. 

(e.g. When our body temperature increases during an exercise, we perspire and subsequently the body temperature decreases)

How this works

As temperature increases, nerves detect the increase and sends signal to brain. When the brain realises, it sends signal to sweat glands to perspire.

But large disturbances may cause it to escape that equilibrium and eventually settle into some other state of equilibrium. 

(e.g. When our body temperature increases, even though we perspire, the body temperature continues to increase.) 

^This happens during a fever.

Nutrition

Digestive system

The alimentary canal ---consists of--- mouth, esophagus, stomach, small intestine, large intestine, rectum, anus

The accessory organs ---consist of--- salivary glands, liver, gall-bladder, and pancreas

(not part of the alimentary canals but produce/store substances required for digestion.)

2 Types of digestion

• Mechanical digestion

          ->physical digestion

          ->move in some way over and over/ repeatedly.

          (e.g. stomach, mouth aided by teeth)

• Chemical digestion

          ->break down of foor using enzymes

          (e.g. small intestine, stomach, mouth-salivary amylase)

Nutrient and Digestive System

What nutrients do we need?

Organic Nutrients (obtained from living organisms, are all compounds of carbon)

• Carbohydrates
• Lipids
• Proteins
• Vitamins
• Dietary Fibre

Inorganic Nutrients

• Water
• Mineral salts

Carbohydrates

-Organic compounds that are made up of C, H & O.

For example...

Lipids (fat)

*But there is a difference between lipids and fats.

Hydrolysis of a Fat Molecule

Proteins

-Made up of amino acids of which there are 20 naturally occurring types.

Functions of Proteins

-Essential for the synthesis of protoplasm, for growth and repair of worn out cells.

-Synthesis of enzymes and hormones

-Formation of antibodies to combat diseases

-Source of energy (17KJ/g)

Malnutrition: The consequences of deficiencies

Kwashiorkor - Lack of protein

Kwashiorkor is an African word meaning the disease the first child gets when the second is born or the 'disease of the first child gets when the second is born or the disease of the deposed child'

Symptoms:

-Greying hair

-Swelling of the abdomen

-Skin crack and become scaly

Deficiency in Vitamins

Vitamin A

Signs of deficiency: Poor night vision or night blindness, loss of appetite, increased susceptibility to infection, and changes in the skin and teeth

Vitamin E

Signs of deficiency: *Anemia in infants and nerve damage in adults.

*decrease in the red blood cells

Vitamin K

Signs of deficiency: Excessive bleeding and an inability for blood to clot

Vitamin C

Signs of deficiency: black-and-blue marks, bleeding gums, nose bleeds and wounds that heal slower than normal. Swollen, tender joints and aching bones, general weakness, loss of appetite and dry, scaly skin.

->> Scurvy (deficiency in Vitamin C)

       - painful, swollen joints

       -Swollen, bleeding gums; loss of teeth

Vitamin D

Signs of deficiency: A prolonged lack of this nutrient results in changes in the bones of children and adults.

Minerals

-Calcium

->> Rickets- deficiency in Vitamin D or Calcium

(bow-legged; bending of legs)

-Iron

Deficiency causes anaemia.

Other deficiencies

-Iodine deficiency is the main cause of potentially preventable mental retardation in childhood , as well as causing goitre and hypothyroidism in people of all ages.

-Iron deficiency may lead to anemia and eventually fatigue.

Mammalian Transport System - Part 3

Learning Objectives

• Learn about the structure and function of arteries, veins and capillaries. 
• Compare and contrast the structure of arteries and veins, and state how they are adapted for its function.
• Learn about the components of blood.
• Understanding blood pressure.

From very big vessels, blood flows at a very fast rate. When it goes to the smaller vessels, extremely slow.(capillary)

Capillary, Arteriole, venule -----> no muscles

Functional Comparison Between Arteries & Veins

Arteries

-Transport blood away from the heart

-Transports blood under higher pressure (than veins)

-Carry oxygenated blood (except in the case of the pulmonary artery)

Veins                                                             

-Transports blood towards the heart              

-Transports blood under lower pressure (than arteries)      

-Carry de-oxygenated blood (except in the case of the pulmonary vein) 

Structural Comparison Between Arteries & Veins

Arteries

-Have relatively more muscle/ elastic tissue; 

-Have relatively narrow lumens

-Do not have valves (except for the semi-luna valves of the pulmonary artery and theaorta)

Veins

-Have relatively less muscle/elastic tissue

-Have relatively wider lumens

-Have valve throughout the main veins of the body. These are to prevent blood flowing in the wrong direction, as this could (in theory) return waste materials to the tissues.

                                                            

Mammalian Transport System- Part 1

Human Circulatory System

Consist of 

1. Cardiovascular System                        2. Lymphatic System

• Made up of

         -Heart 

         -Blood vessels

         -Blood

Cardiovascular System

1. Blood - The main 'transportation service' that handles the distribution of nutrients, oxygen and hormones to the various regions of the body.
2. Arteries & Veins - A system of tubes that form the transport route where blood flows. 
3. Heart - The motor of this transport service.
4. Capillaries - are sites of exchange

Human Cardiovascular System 

• Divided into :

          1.Pulmonary System & Heart

              -Pulmonary = lungs

         

          2. Coronary System 

              -Coronary = heart

         

          3. Systemic Circulation

              -Systemic= rest of body

Transport in Mammals-Part 2

Learning Objectives

• Know that blood is pumped around the circulatory system by the action of the heart.
• Know that the heart is a muscular organ which requires its own supply of oxygen and nutrients (via coronary arteries).
• Label and identify the principle structures of a mammalian heart, including the valves within it and the inter-connecting blood vessels & associated valves.
• Trace the path of blood through the circulatory system, in particular the pathway of oxygenated and deoxygenated blood through the heart.

THE HEART

•  Involuntary muscle
•  Has 4 chambers
  

     -Right & Left single atrium/ auricle
     -Right & left ventricle



Why is the left ventricle wall so thick?
This is because the blood from the left ventricle goes to the rest of the body. To send the blood to such a far distance, the left ventricle must have a lot of muscles, hence it is thick.

THE VENTRICLES

• The ventricle pumps blood at high pressure out to the arteries (to the lungs or other parts of the body)
• The pressure generated by the left ventricle is greater than that generated by the right ventricle as the systemic circuit is more extensive than the pulmonary circuit.

Why is the muscle around the atria thinner than the muscle around the ventricles?

The blood from the atria goes to the ventricles while the blood from the ventricles goes to the circulatory system./The pressure generated by the atria is less than that generated by the ventricles since the distance from the atria to ventricles is less than that from ventricle to circulatory system.

THE ATRIUM

• The atrium receives blood at low pressure from the veins (coming from the lungs or other parts of the body)
• The pressure generated by the atria is less than that generated by the ventricles since the distance from the atria to ventricles is less than that from ventricle to circulatory system.

THE VALVES

• Ensure that the blood flows in the right direction
• Very important;  without them, the flow of blood would be chaotic
• Found in the heart and veins

TRICUSPID VALVE

• Separates the right atrium from the right ventricle
• It opens to allow the de-oxygenated blood collected in the right atrium to flow into the right ventricle.
• It closes as the right ventricle contracts, preventing blood from returning to the right atrium; thereby forcing it to exit through the pulmonary valve into the pulmonary artery.

BICUSPID VALVE(MITRAL VALVE)

• Separates the left atrium from the left ventricle.
• It opens to allow the oxygenated blood collected in the left atrium to flow into the left ventricle.
• It closed as the left ventricle contracts, thereby forcing it to exit through the aortic valve into the aorta.

PULMONARY VALVE

• Separates the right ventricle from the pulmonary artery.
• As the ventricles contract, it opens to allow the de-oxygenated blod collected in the right ventricle to flow to the lungs. 
• It closes as the ventricles relax, preventing blood from returning to the heart.

SUPERIOR & INFERIOR VENA CAVA

• Superior vena cava is one of the two main veins bringing de-oxygenated blood from the body to the heart.
• Veins from the head& upper body feed into the superior vena cava, which empties into the right atrium.
• Inferior vena cava is the other main vein bringing de-oxygenated blood from the body to the heart.
• Veins from the legs & lower torso feed into the inferior vena cava, which empties into the right atrium.

AORTA

• Carries oxygenated blood from the left ventricle to the systemic circulation.
• The aorta is a elastic artery and as such is quite distensible (ability to swell from pressure built within).
• When the left ventricle contracts to force blood into the aorta, the aorta expands. This stretching gives the potential energy that will help maintain blood pressure during diastole, as during diastole, as during this time the aorta contracts passively.

PULMONARY ARTERY

• The pulmonary arteries carry blood from the heart to the lungs. 
• They are the only arteries (other than umbilical arteries in the fetus) that carry deoxygenated blood.
• In the human heart, the pulmonary trunk (pulmonary artery or main pulmonary artery) begins at the base of the right ventricle)
• It is short and wide - about 5 cm in length and 3 cm in diameter.
• It then branches into two pulmonary arteries (left and right), which deliver deoxygenated blood to the corresponding lung.

PULMONARY VEIN

• The four pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.
• They are the only veins in the post-fetal human body that carry oxygenated blood.

CHORDAE TENDINEAE

• The chordae tendineae, or heart strings, are cord-like tendons to connect the papillary muscle to the tricuspid valve and the mitral valve in the heart.
• When the right ventricle of the heart contracts, the blood pressure pushed the tricuspid valve which closes and prevents a backflow of blood into the right atrium.
• The chordae tendineae prevents the flaps from being averted into the right atrium. Similarly, these cord-like tendons hold in position other flaps like the bicuspid or mitral valve.

PAPILLARY MUSCLE

• In anatomy, the papillary muscles of the heart serve to limit the movements of the mitral and tricuspid valves.
• These muscles contract to tighten the chordae tendineae, which in turn prevent inversion.
• This occurs in response to pressure gradients. Instead they brace the valves against the high pressure, preventing regurgitation of ventricular blood back into the atrial cavities.

CORONARY ARTERIES

• The heart is composed primarily of cardiac muscle that continuously contracts & relaxes, it must have a constant supply of oxygen & nutrients.
• Coronary arteries are a network of blood vessels that carry oxygen & nutrient rich blood to the cardiac muscle tissue.
• The larger vessels travel along the surface of the heart.
• The smaller branches, the capillaries, penetrate the heart muscle.
• They are so small that the RBC must travel in single file.