Studied by 3 people
Microbiology
The study of microorganisms or microbes
Microorganism
A small living plant or animal seen only with a microscope; a microbe
Types of pathogens
Bacteria, viruses, protozoa, fungi, helminths
Pathogen
An organism that causes disease
Virus
A tiny, non-living particle that invades and then reproduces inside a living cell. Has no cellular structure
Bacteria
A single-celled organism that lacks a nucleus; prokaryotes, mostly unicellular
Protozoa
Microscopic, unicellular animals often found in decayed materials and contaminated water. Eukaryotic.
Fungi
An organism that absorbs nutrients from the environment. Eukaryotic, can be unicellular or multicellular
Helminths
Multicellular parasitic organisms commonly called worms or flukes. Don’t typically reproduce in the host
Bacteria growth requirements
Temperature, acidity, nutrients, H20, oxygen, metabolism
Thermophiles
Archaea that thrive in very hot environments, such as volcanic springs
Mesophiles
Organisms that grow best between 20 and 40 degrees Celsius; the human pathogens are in this group
Psychrophiles
Cold-loving bacteria
Optimum bacteria temperature
37 degrees Celsius
Obligate aerobic bacteria
Bacteria that require oxygen for cellular respiration
Obligate anaerobes
Organisms that cannot live where molecular oxygen is present
Normal flora
Microorganisms that reside in or on the body without causing disease
Infectious agent
The pathogen (germ) that causes diseases
Reservoir
The place in the environment where the pathogen lives
e.g. Humans, animals, equipment, soil and water
Portal of exit
The way the infectious agent leaves the reservoir
e.g. Through open wounds, aerosols and body fluids (coughing, sneezing and saliva)
Mode of transmission
A way that the causative agent can be transmitted and passed onto another reservoir or host where it can live
e.g. Direct or indirect contact, ingestion or inhalation
Portal of entry
Any body opening on an uninfected person that allows pathogens to enter
e.g. Broken skin, respiratory tract, mucous membranes, catheters and tubes
Susceptible host
Any person, most vulnerable are those receiving healthcare, immunocompromised or have invasive medical devices
Chain of infection
Infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host
Sterilisation
The process that completely destroys al microbial life, including spores
Methods of sterilisation
Gas, dry heat, chemical and steam
Disinfection
A process the eliminates many or all microorganisms, with the exception of bacteria spores, from inanimate objects
Methods of disinfection
Physical, biological and chemical
Sanitation
Maintaining a clean condition in order to promote hygiene and prevent disease
Components of skin
Epidermis, dermis and hypodermis
Epidermis
The outermost layer of skin, provides a waterproof barrier and creates out skin tone. Keratinised, stratified squamous epithelium. Avascular
Cells of the epidermis
Keratinocytes, melanocytes, langerhan’s cells, merkel cells
Keratinocytes
Produces fibrous protein keratin. Most cells of the epidermis. Tightly connected by desmosomes
Melanocytes
10-25% of the cells in the deepest epidermis. Produces pigment melanin, packaged into melanosomes. Protects apical surface of keratinocyte nucleus from UV damage
Langerhan’s cells
Located in the stratum spinosum. Is macrophages that help activate the immune system. Originates from the bone marrow
Merkel cells
Functions as touch receptors in associated with sensory nerve endings
Layers of epidermis
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum
Stratum basale
The deepest layer of the epidermis consisting of stem cells capable of undergoing cell division to form new cells
Stratum spinosum
A layer of the epidermis that provides strength and flexibility to the skin
Stratum granulosum
A layer of the epidermis that marks the transition between the deeper, metabolically active strata and the dead cells of more superficial strata
Stratum lucidum
A layer of the epidermis found only in the thick skin of the fingers, palms and soles
Dermis
The middle layer of the skin, which contains most of the skin’s structures
Dermis cell types
Fibroblasts, macrophages and occasionally mast cells and white blood cells
Fibroblasts
In connective tissue, cells that secrete the proteins of the fibres
Macrophages
Found within the lymph nodes, they are phagocytes that destroy bacteria, cancer cells and other foreign matter in the lymphatic stream
Mast cells
Found in the connective tissue of the dermis; respond to injury, infection or allergy by producing and releasing substances, including heparin and histamine
Layers of the dermis
Papillary layer and reticular layer
Papillary layer
Outermost layer of the dermis, directly underneath the epidermis. Helps supply the epidermis
Reticular layer
Deeper layer of the dermis that supplied the skin with oxygen and nutrients
Hypodermis (subcutaneous layer)
Third layer of the skin; consists of connective tissue which binds the skin to the underlying muscle
Functions of the skin
Protection, prevents penetration, perception, temperature regulation, identification, communication, would repair, absorption and excretion, production of vitamin D
Function of the skin: protection
Skin covers the body and acts as a physical barrier that protects underlying tissue from physical cuts, bacterial invasions, dehydration and sunburn
Function of the skin: temperature regulation
Skin allows heat dissipation through sweat glands and heat storage through subcutaneous insulation
Function of the skin: cutaneous sensation
Sensory receptors on the skin allow us to feel touch, pressure, vibration, tickling, pain and etc.
Function of the skin: metabolic function
Produces vitamin D (when exposed to UV)
Function of the skin: excretion
Skin can secrete limited amounts of nitrogenous wastes, such as ammonia, urea and uric acid. Sweating can cause salt and water loss. Absorbs vitamins and oxygen
Skin colour
Three pigments contribute: melanin, carotene and hemoglobin
Melatin
A pigment that gives skin its colour, the darker the skin the more (---). Found in stratum corneum
Carotene
Yellow to orange pigment. Most obvious in the palms and soles of the feel. Accumulates in stratum corneum
globinHaem
Red pigment of the skin that carries oxygen
Jaudice
A yellow discolouration of the skin, mucous membranes and the eyes
Features of the Integumentary system
Nails, hair and glands
Nails
Horny plates made from flattened epithelial cells; found on the dorsal surface of the ends of the fingers and toes. Densely packed epithelial cells containing fibres of hard keratin. Provides protection to underlying nerves
Glands
Organs or tissues in the body that create chemicals that control many of out bodily functions. Clusters of specialised epithelia cells that secrete a substance
Sweat glands
The glands that secreate sweat, located in the dermal layer of the skin. Regulates body temperature
Hair
Compresses, keratinised cells that arise from hair follicles, the sacs that enclose the hair fibres. Provides protection and warmth
Roles of the Lymphatic system
Maintain blood pressure and fluid levels, circulation of important molecules/cells for maintaining overall body function and for defence against disease, absorption of fats from the intestine
Lymphatic system parts
Lymph nodes, lymphatic vessels, thymus, spleen, tonsils
Lymphocytes
The two types of white blood cells that are part of the body’s immune system: B lymphocytes form in the bone marrow and release antibodies that fight bacterial infections; T lymphocytes form in the thymus and other lymphatic tissue and attack cancer cells, viruses and foreign substances
Lymph
The watery fluid in the lymph vessels collected from the tissue spaces
Lymph flow through nodes
From subcapsular space (contains macrophages and dendritic cells), through outer cortex (contains B cells within germinal centers), through paracortex (dominated by T cells), through the core (medulla), organised into medullary cords, contains B cells and macrophages, then into efferent lymphatics at hilum
Red bone marrow
Contains haemopoietic stem cells (makes all red, white and platelet blood cells). Produces and matures B lymphocytes and makes T cells
Thymus gland
Located in the mediastinal cavity anterior to and above the heart; secretes thymosin for the maturation of T cells
Lymph nodes
Bean-shaped filters that cluster along the lymphatic vessels of the body. They function as a cleanser of lymph as well as a site of T an b cell activation
Spleen
An organ that is part of the lymphatic system; it produces lymphocytes, filters the blood, stores blood cells and destroys old blood cells
Diffuse lymphatic tissue
Scattered lymphocytes, macrophages and other cells found deep to mucous membranes
Oedema
Fluid-filled swelling (of an organ or structure)
Antigen
A toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies
Antibody
A substance produced by the body that destroys or inactivates an antigen that has entered the body
Non-specific immunity
Defenses that stop the invasion of pathogens; requires no previous encounter with a pathogen
Acquired immunity
Immunity that the body develops after overcoming a disease, through inoculation (such as flu vaccinations), or through exposure to natural allergens, such as pollen, cat dander and ragweed
First line of defense
Intact skin, mucous membranes and their secretions, normal microbiota
Second line of defense (innate immunity)
Phagocytes (such as neutrophils, eosinophils, dendric cells and macrophages), inflammation, fever, antimicrobial substances
Phagocytosis
A process in which extensions of cytoplasm surround and engulf large particles and take them into the cell
Antimicrobial chemicals
Solids, liquids, gaseous. For convenience, solid or gaseous antimicrobial chemicals are dissolved in water, alcohol or a mixture of the two
Inflammation
A localised physical condition in which part of the body becomes reddened, swollen, hot and often painful, especially as a reaction to injury or infection
Signs of inflammation
Redness, heat, swelling, pain and loss of function
Fever
A rise in the temperature of the body in an attempt to kill the enzymatic properties
Third line of defence
Immune response in which antibodies take action against foreign cells
B cells
Cells manufactured in the bone marrow that create antibodies for isolating and destroying invading bacterial and viruses
T cells (T lymphocytes)
Lymphocytes that develop in the thymus and are responsible for cell-mediated immunity. Their cell-surface antigen receptor is called the T-cell receptor
Types of T cells
Cytotoxic T cells, helper T cells, suppressor T cells, memory T cells
B cells defense against bacteria
Bacteria live between epithelial cells, attacked mostly by antibodies from B cells
Cytotoxic T cells
T cells, often called killer cells because of their inability to kill invading organisms
Helper T cells
T cells that help the immune system by increasing the activity of killer cells and stimulating the suppressor T cells
Suppressor T cells
Decrease B-cell response after infection is gone and antibodies aren’t needed
Memory T cells
Circulate the body, proliferate and respond to eliminate subsequent invasion by same antigen. Secondary response, takes less time, ~5 days
