Biology Sem 1 Year 12 Flashcards
- Define homeostasis.
The condition of a
relatively stable internal
environment, maintained
within narrow limits,
regardless of the external
environment
Describe the negative feedback loop
Stimulus
Pain, smell, heat. light, visuals, salt, sugar,
Anything in the environment that the body needs to react to
Receptor
The element that is detecting changes/the stimulus
Example:
Chemoreceptor detects chemical stimuli
Mechanoreceptor detects mechanical stimuli
Processing Centre
Takes message from the receptor
The message of the presence of the stimulus is carried around the body
Nervous System for short/sharp responses
Endocrine System for slower/longer responses
Effector
What carries the response
-Muscles and endocrine glands
Response
-What the body actually does
Stimulus-response mechanisms usually have a Negative Feedback stage, in which the response produced reduces the effect of the original stimulus
Example, after eating sugar, the body tries to reduce the sugar level
Identify the structures, processes and behaviours that allow homeostasis to be maintained.
Thermoregulation
-Thermoregulation is a stimulus response system that maintains the body’s core temp at a steady state
-The hypothalamus is the control centre for thermoregulation as it receives signals from external and internal cold and hot receptors. It initiates a response
-As a result, numerous mechanisms are activated to warm/cool body
-Initiates negative feedback to reduce the stimulus
Body can gain heat by:
-increase in metabolic processes
-shivering
-exercise/muscular activity
-radiation/conduction to body
Can lose heat by
-Evaporation of sweat
-Panting
-convection
-radiation and conduction away from body
Or increasing/ decreasing surface area
The pili muscle (hair on arms erecting or laying flat) (Piloerection)
Recall one example of how homeostasis is maintained in the human body.
Explain the importance of homeostasis.
to ensure the internal evironment is at a good point so that funciton and physiology of the body can continue
The variables of the body are maintained correctly
Temperature
Blood glucose
Water Daily intake
Ions
pH of arterial blood
Blood pressure – arterial
Describe the different types of receptors.
Chemoreceptor detects chemical stimuli
Mechanoreceptor detects mechanical stimuli
Photoreceptor-light
Thermoreceptor-hot/cold
Nociceptor-pain
Osmoreceptor-water
Explain that the responses to a stimulus involve; a stimulus, receptor, messenger, effectors and
response
(using the example of the body responding to a cold environment)
1.Stimulus: decrease in body temp below normal
2.Receptor: decrease detected by thermoreceptors in SKIN, ORGANS and HYPOTHALAMUS
3.Control Centre: hypothalamus sends signals via nerve and hormonal systems to effectors
- Effectors: Skeletal muscles, blood vessels near skin, body cells involved in metabolism, cerebral cortex (behavioural)
- Response:
shivering, vasoconstriction of skin vessels, behavioural changes, increased metabolic rate, change in behaviour
Recall the main components of the central and peripheral nervous system.
Central nervous system (CNS) and peripheral nervous system (PNS)
Central nervous system (CNS)
-brain and spinal cord
Peripheral nervous system (PNS)
-nerves
-messages to and from brain
Explain the role of the autonomic and somatic nervous systems in homeostasis.
Autonomic and Somatic are both in the Peripheral Nervous System and both use nerve cells
Peripheral nervous system activates specific glands/ muslces
The SNS and the ANS work together to regulate bodily function and provide reactions to external stimuli
Coordinate behaviour and respond to the external environment
The somatic nervous system: Contraction of Leg
Controls skeletal muscles (used for movement). (walking)
Instructions generally originate from the primary
motor cortex of the brain.
Controls voluntary movements
Maintenance of tissue homeostasis in multicellular organisms.
Sensory messages/reactions
Enables for humans to move to warmer place in times of coldness
There are receptors in the skin, sense organs (eyes, mouth, nose, and ears), and skeletal muscles which are able to detect changes in the environment, such as temperature, light, or texture
The autonomic nervous system: Contraction of the Heart, not controllable
Controls involuntary functions, such as heart rate,
respiration, stomach, endocrine glands, pupil
dilation
Can control skeletal muscles if rapid response is required (reflex arc).
Maintains homeostasis while the body is at rest or in an emergency
Regulates heart rate, blood pressure, body temperature, sweating and digestion.
Controls cardiac and smooth muscle, as well as glandular tissue
- Compare the sympathetic and parasympathetic nervous system.
Both are apart of the autonomic nervous system
Sympathetic- fight or flight, high sharp bursts of energy required (dialate pupils, increase heartbeat, inhibit stomach activity)
Parasympathetic-rest and digest
-controls basic bodily functions in a low stress environment (reading a book)
(constrict pupils, slow heartbeat, stimulate activity of the stomach)
ontrols basic bodily functions while one is sitting quietly reading a book.
- Draw and describe different types of neurons.
Nerve cell=neuron
A group of nerve cells make a nerve
What are the three types of nerve cells
AND
What are the 2 parts of a nerve cell u should look at t classify it
Sensory neuron
Interneuron
Motor neuron
Presence of Myelin Sheath
Where is the cell body located?
- Describe the structures and functions of the human eye as an example of the reflex arc.
Human reflexes-rapid and automatic
The path taken by the nerve impulses in a reflex is called a reflex arc.
The stimulus (a pin in the paw) stimulates the pain receptors of the skin, which initiate an impulse in a sensory neuron. This travels to the spinal cord where it passes, by means of a synapse, to a connecting neuron called the relay neuron situated in the spinal cord. The relay neuron in turn makes a synapse with one or more motor neurons that transmit the impulse to the muscles of the limb causing them to contract and remove the paw from the sharp object.
The iris reflex or person blinking when fly comes toward eye
iris contracting to prevent damage of the retina
The optic nerve is the main nerve that carries information to the CNS from the eye
- Describe the process of action potential.
Draw Diagram
An action potential is a rapid sequence of changes in the voltage across a membrane.
- Nerves are initially active and polarised
- At this point, it is resting potential, positive on outside, negative on inside.
- Sodium potassium pump is working (a pump on the surface of axons) Pump moves 3 sodium ions (Na +) out of the cell and 2 x potassium ions (k+) into the nerve
- This is distrupted by action (but continues through the process
- When a stimulus reaches a resting neuron- action potential
- Depolarisation- Sodium channels open, causing Na+ to enter the nerve. Therefore, the inside of the nerve becomes more positive. Resulting in depolarised. (sodium follows gradient into axon).
- This rush of sodium sends message down the nervous system
- At peak voltage, sodium channels close and potassium channels open (K+) moves out of nerve cell (repolarised)
- This reached hyperpolarization (opposite to polarisation) (sodium and potassium are wrong way)
- Sodium channels close , the sodium potassium pump returns the ions to the resting potential. To get back to normal.
When potassium channels open, the second nerve cells
- Define the term “threshold” and explain the all or nothing principle.
-threshold must be reached to ensure that the body doesn’t react unneccesarily to stimulus such as wind
All or nothing: reaction has to be over -55 volts in order for depolorisation to occur
Describe synaptic transmission by neurotransmitters and signal transduction.
There is space between each nerve cell- Synapse
This occurs at any point where 2 nerve cells are connecting Sensory, interneuron and motor neuron.
- Electrical impulse reaches the axon terminals of nerve cell 1
- Causes calcium channels to open, resulting in calcium being brought into the axon terminal
- Calcium causes vesicles (containing neurotransmitters) to fuse with the membrane, releasing the neurotransmitters to the synaptic cleft.
- Receptors on the dendrite of nerve cell 2 bind to neurotransmitter
- Sodium channels open and sodium is released into nerve cell 2, triggering the impulse in nerve cell 2
- Then, the neurotransmitter is recycled or destroyed by body
- Outline and explain the importance of the endocrine system in animals.
What is the endocrine system?
Uses chemical signals called hormones
to send messages around the body
These chemicals are produced in special
structures called endocrine glands in
response to a signal
Hormones are released into the
bloodstream and can travel to all parts
of the body
They only act on their ‘target cells’ (cells with the correct receptors can take the hormones in
The endorcirne system is a fundamental element of homeostasis. (glans releasing hormones when change of internal state is detected)
- Compare the role and response of the endocrine and nervous system.
Identify some of the glands and hormones involved in the endocrine system (pancreas, thyroid,
ovaries and testes and their hormones)
Pancreas Gland-
Located below the stomach
Produces hormones insulin and glucagon
Insulin reduces blood glucose levels (needed after eating)
Glucagon increases blood glucose levels (needed when hungry)
Thyroid Gland:
Located in the neck below the larynx
Produces thyroxine
Thyroxine controls the bodies metabolism
Gonad Glands: testes and ovaries
Ovaries
Testes releases androgens including testosterone
Androgens result in male sex characteristics
Ovaries produce oestrogen and progesterone
Results in female sex characteristics and regulates the menstrual cycle
Identify some of the glands and hormones involved in the endocrine system (pancreas, thyroid,
ovaries and testes and their hormones)
pancreas-
Thyroid Gland:
Located in the neck below the larynx
Produces thyroxine
Thyroxine controls the bodies metabolism
ovaries
testes and their hormones
- Describe the key role of the pituitary gland in mammals.
The hypothalamus is located in the base of the brain (so it is well protected)
It regulates basic functions including body temperature, water balance and heart rate
Pituitary gland is connected to the hypothalamus and is located just underneath
Pituitary gland has two lobes (posterior and anterior)
The Pituitary gland is considered to be the ‘master gland because it controls the function of other glands
Distinguish between posterior and anterior gland
Anterior
connected to hypothalamus by blood vessels
produces hormones based on signals that
come from the hypothalamus
Posterior
connected to hypothalamus by nerve fibres
not a true endocrine gland, as it does not make
any hormones.
Some hormones produced
by the hypothalamus pass down the nerve
fibre to the posterior pituitary gland and are
then secreted.
Homeostasis feedback loop: blood sugar levels
Describe/ draw feedback loop when blood glucose levels are too high
Stimulus-response system that maintains the body’s blood sugar levels within narrow limits
Too High:
Stimulus: blood sugar levels high
Receptor: Receptors on pancreas, (chemoreceptor)
Processing Centre: Endocrine System
Effectors: Body cells and livers
Response: Body cells take glucose for increased cellular respiration
Liver converts excess glucose to glycogen to store it for later use (such as when glucose is too low)
Negative Feedback: Blood sugar decreases
Too low:
Stimulus: Blood glucose too low
Receptor: chemoreceptors on pancreas
Processing centre: Endocrine system
Effector: Liver
Response: liver converts glucagen back to glucose and releases into the blood stream
Negative Feedback Loop
Diabetes: When the pancreas endocrine gland system goes wrong
Type 1 diabetes:
* When the body does not produce the
right amount (or any) insulin
-Usually develops in childhood or
adolescence
Treatment: daily injections of insulin
Type 2
he pancreas produces insulin but
cells stop responding properly to
insulin
* Usually develops in older people
* May need oral drugs or insulin
injections to treat, but can also be
controlled by diet and exercise
Hyperglycaemia:
* Blood glucose is above normal
* Can lead to damage to cells, heart
attack or strokes
* Treat by administering insulin
Hypoglycaemia
* Blood glucose is below normal
* Can lead to confusion and loss of
consciousness
* Treat by giving glucose
- Define endotherm and ectotherm and recall an example of each type of animal.
An ectotherm (reptile/amphibian) relies primarily on its external environment to regulate the temperature of its body. Cold blooded. Have fluctuating body temperatures
Endotherms (birds, humans, mammals) are able to regulate their body temperatures by producing heat within the body. Have stable body core temp.
- Describe how endothermic organisms maintain homeostasis.
Endotherms use internally generated heat to maintain body temperature.
Use metabolic heat
Behavioural, structural and physiological adaptations
Numerous mechanisms and/or organs may be activated to warm up or cool
down the body
What is radiation, conduction and convention? (thermoregulation)
-Conduction
-heat moves to a cooler area via touch
-sitting on cold metal bench and bench gains heat
Convection:
-movement of heat away from source via airflow
-windy days are cooler than still days
Radiation:
-natural slow movement of heat away from a source
-body naturally cools down by releasing heat in a cooler room.
Describe the structure and lifecycle of bacteria, fungi, protozoa, fungi, prions and parasites.
Pathogen: Bacteria
Cellular
Features:
prokaryotic (no cell organelles and single celled)
-Fast reproduction through binary fission
-destroying cells and tissues and/or producing harmful toxins
Examples: Gastro, whooping cough
Treatment: Antibiotics
Pathogen: Fungi/ Yeast
Cellular
Features:
single celled but eukaryotic
spreads via spores
contains cell walls
Examples: Ringworm
Treatment: Fungicides to treat fungal infections
Pathogen: Protozoa
Cellular
Features:
-has multiple life stages in different hosts
-found in warm waterways
-single celled
-eukaryotic
Examples
fOWLERIA (brain eating ameoba)
Malaria
Treatment: hard to treat, extremely fatal,many different drugs have been tried
Pathogen: Parasites (Multicellular, endoparasites)
Cellular
Features
Internal infection
Produces toxins to destroy cell and tissues
Examples
Flatworms, tapeworms, nematodes (hookworms,
roundworms)
Treatment: Passing worms naturalls, antiworming tables
Pathogen: Parasites (Multicellular, ectoparasites)
Cellular
Features
Attach on outside of host (ecto)
Produce toxins
Examples
Fleas, ticks, mites
Treatment: Lice shampoo, removal of parasite
Pathogen: Virus
Non Cellular
Features
-can only replicate inside a living host
-infect all cellular organism
-small
Examples
-covid
-common flu
-cold sores
Treatment: Antivirals to stop virus from hijacking the cells genetic material
Pathogen: Prions
Non Cellular
Features
Misfolded proteins
Affects the nervous system
-Transmissible through eating another infected thing
Examples
Mad Cow Disease
Treatment: no cure, universally fatal
WHAT is the definition of a disease
any condition that adversely affects the normal
functioning of any part of a living thing
-this would include serious injury which inst a disease
Infectious vs non infectious diseases
Infectious: a disease caused by an organism or infective agent (pathogen)
Non-infectious: a disease that is not caused by a pathogen, and, with the exception of inherited diseases, cannot be passed from one person to another
What is a pathogen?
A disease causing agent or organism
Can be cellular (considered to be living and made of cells) or non cellular
Pathogens can be intracellular (inside of cell )or extracellular (outside of cell)
The Nature of Pathogens
What is the impact of having a cell nutrient environment?
How can pathogens damage a host by?
-they can reproduce rapidly in a nutrient rich environment
-280 billion bacteria in 8 hours
Pathogens may rapidly evolve and avoid the host immune response.
Destroying cells and tissues with enzymes.
* Producing toxins which are harmful to the host.
* Causing the initiation of a debilitating immune system response.
What are toxins?
A poisonous substance produced within living organisms
Toxins are often proteins which interact and interfere with cells.
Tetanus is caused by deadly toxins of bacteria
Anti-pathogenic substances
What are they and examples
Antibiotics: anti-pathogenic substances produced by other microorganisms
(e.g. fungi and bacteria).
commonly used to fight bacterial infections
- Antiseptics and disinfectants.
- Antivirals, fungicides.
Spread of Diseases
What does it depend on?
Disease transmission is not constant and will vary depending on
type of disease, the population and the time
What are epidemic and endemic diseases?
Endemic diseases – a disease that occurs at a relatively
constant rate in the population
Epidemic diseases – a disease that is uncommon, occurs when
there is a spike in cases in the population above what is
considered to be normal
Pathogen factors that affect disease
transmission
Infectivity
Virulence
Infectivity – How easily the pathogen can jump from host to host
Virulence – the capacity of the pathogen to cause severe disease in the host
How long the pathogen can persist in an asymptomatic host
Pathogens want to spread to as many hosts as possible
Environmental factors that affect
disease transmission
Available infrastructure
* Climate
* Density of the population
* Proportion of the population immune to infection
* Movement of individuals in the population
Amount of travel
Planes make disease easy to spread
Were there people wearing masks to reduce droplets?
Pandemic and Epidemic
- Pandemic, global outbreak of a disease
Epidemic- widespread occurrence of
an infectious disease in a community or
in a restricted geographic area at a
particular time
An epidemic can develop into a
pandemic, but not vice versa
Controlling diseases and containment
How can diseases be prevented
Prevention:
Hand Washing
PPE
Hygiene
Disinfection
Isolation
Quarantine
Control Carriers
-kill infected herds
-eliminate vectors (eg mosquitos)
Vaccinate
Antibiotics vs Antivirals
Antibiotics work against bacteria – they kill bacteria or prevent their growth
Antiviral drugs are
specifically used to treat
viral infections
Often only effective only
when the virus is located
within a cell and is
undergoing replication
Antibiotics vs. Antivirals
Evaluate the use of vaccinations to control and prevent disease.
What are vaccines?
Injection of deactivated pathogen
(attenuated or killed), or toxoid
(deactivated form of toxin)
Injection still contains the antigen
which provokes immune response,
but does not cause the infection
Promotes primary immune response,
production of memory cells leads to
acquired immunity and future
protection
Multiple injections (boosters) may be
required over short term or long term
to increase memory cell number.
What is herd immunity
If a large enough proportion of the
population is immune to a disease,
there are too few susceptible
individuals to sustain disease
spread
Herd immunity is essential for the
protection of those who cannot be
vaccinated, or those with a
suppressed immune system
Transmissions of Disease/ Pathogens
Transmission by direct contact:
Transmitted from one host to another when the skin
of the two hosts come into contact
Reproduction of the pathogen causes lesions containing
millions of copies of the pathogen. These lesions are
itchy, and scratching allows the spread of the
pathogen
Example:
;Chickenpox
* Impetigo
* Cold sores
Bodily fluids:
liquids that come from inside the
body, including sweat, tears, vomit, nasal secretions,
blood, saliva and urine
Pathogens that are transmitted in this way need to
be able to survive outside of the body for substantial
periods of time.
* Glandular fever
* HIV
* HPV
Sexual contact, pregnancy, needle use, blood transfusions
Food Borne transmission
Pathogen enters the body via the gastrointestinal
tract via food.
Pathogen may spread to the food via faeces from an
infected person, or meats may be infected by
bacteria from the animal’s intestinal tract.
Food poisoning – Salmonella, E. coli etc.
Waterborne Transmissions
Pathogen is spread via bodies of water.
In many developing countries, sewage is can enter
the waterways, which can lead to faecal-oral
transmission of diseases
Hepatitis A
Airborne transmission
Pathogen is spread via the air.
Coughing or sneezing can release millions of
microbes into the air in droplets of mucus or saliva.
Some diseases promote this by causing excess nasal
secretions.
-common cold
Transmission by vectors
a living organism that transmits
pathogens from one host to another, for example,
mosquitoes
enable a pathogen to penetrate the
outer defences of the host in a way they cannot
unassisted
Malaria
Identify the three lines of defence used by the body.
What are there defining features and differences.
The innate response (non specific) 1st and 2nd line of defence
- Barriers to keep pathogens out; cells and molecules to indiscriminately destroy
pathogens that get in. - A rapid response. Has no memory of the infection and therefore has no faster
clearance on re-infection.
The adapted/acquired response (specific) 3rd line of defence
faster clearance rate on re-infection. Offers superior protection.
can take up to 2 weeks to work
Identify structures used as the first line of defence.
How do we keep pathogens out in the first line of defence?
Name the 3 types of barriers (p,c,m)
Give examples and describe for both plants and animals
What barrier don’t plants have?
Animals: physical barriers
Epithelial cells
- Skin
- Lining of the respiratory,
gastrointestinal and urogenital tracts
* Adaptations
- Mucus-secreting membranes (mucus traps pathogens)
- Membranes lines with cilia (attempt to sweep pathogen out)
Plants: physical barriers
Cell wall in plant cells
* Bark in trees
* Ability to close stomata
* Positioning of leaves (so water does
not collect on the surface and attract pathogens)
Animal Chemical Barriers
* Lysozyme enzymes and fatty acids –
tears, sweat, saliva
* Low pH – stomach, vagina ( areas that are prone to pathogens have low ph in an attempt to kill the pathogens)
* Surfactants - lungs
Plants Chemical Barriers
Chemicals that inhibit the growth
and development of pathogens
- May be released into the
environment
- May remain in the plant
* Defensins – small stable peptides
that can inhibit development of
fungi, bacteria, viruses and insects
-caffeine, produced by plants is toxic to bugs and insects
Animals- Microbial barriers
Normal flora
- Skin
- In mouth, nose, throat, lower
gastrointestinal tract, urogenital tract
* Prevents growth and colonisation of other
bacteria
Bacteria lives a harmonious relationship with human , they can help to break down cellulose
List and describe the cells involved in the innate immune response (second line of defense).
What happens when organisms get in
Molecules
Complement proteins:
-system of over 20 proteins produced by liver and circulating in blood
-Bind cellular pathogens and target them for
destruction
- Release chemical signals to attract phagocytes
- Puncture bacterial cell walls and cause lysis
- Help stimulate inflammation
Cytokines:
Small signalling molecules that coordinate much of the immune response
Peptides, proteins or
glycoproteins
Released in response to cell damage or
the presence of pathogens
Can kill body cells
2 kinds of cytokines: interferons and chemokines
Inteferons:
-signals neighbouring uninfected cells to destroy RNA and reduce protein synthesis because they are factories for creating more virus if cell was to be infected in the future
-signals neighbouring infected cells to undergo apoptosis (programmed cell death, cell implodes without affecting other cell/ tissue )
-activates immune cells
Chemokines
-attract leukocytes (white blood cell and immune cells) to site of infection and inflammation
List the cells involved in the 2nd line of defence innate immune response.
- Complement Proteins
2.Cytokines
3.Interferon
4.Chemokines - Nonspecific phagocytes
Phagocytosis
-cleans up dead bacteria and viruses
-include macrophages, neutrophils, b cells and dendritic cells
-in charge of eliminating micro organisms and showing them to the rest of the immune system.
Describe The inflammation Response
redness, swelling, heat, pain and pus
(largely composed of dead white blood cells –
neutrophils).
Response to cut through skin or presence of pathogen
(infection).
A mechanism of ensuring our ‘troops’ get to the
location of the fight.
Inflammation occurs because there are lots of immune cells at the sight, which also means the area can feel warmer
The Clotting Response
Blood platelets adhere to surface of any
cut blood vessels to reduce blood loss
and prevent bacteria spreading
Fever Response
An increase in the bodies set point temperature in
response to infection (feel cold/chills even though body
temp. is raised) In an attempt to kill pathogens that cannot withstand that temperature This can be dangerous because it effects bodies thermoregulation and enzymes must be at a set temp.
May be triggered by molecules from the pathogens or
cytokines released by macrophages.
Thought to reduce the growth of bacteria and increase
the effectiveness of the immune system
Cells of the immune system
What are Neutrophils
Macrophages
Dendretic Cells
Natural Killer Cells
Eosinophils
Basophils
Neutrophils:
Phagocytes
Circulate in bloodstream
First to arrive at infection
sites
Release compounds that
disrupt bacterial and fungal
membranes
Release cytokines
Macrophages:
Phagocytes
Found in tissues
Eliminate microbes and cell debris
Dendritic Cells:
Phagocytes
Found in tissues
Engulf pathogens and present them to other
cells
Have many grooves, increasing surface area
Constantly patrolling the bloodstream
Natural Killer Cells:
Recognise virus-infected and cancerous
cells
Circulate in the blood
Trigger apoptosis in affected cells
Release cytokines to attract and activate
cells of the adaptive immune system
Eosinophils:
Secrete powerful enzymes capable of making holes in
multicellular pathogens (such as flukes and parasitic worms)
Basophils:
circulate in the blood and secrete histamines when damaged
Antigens
What are they
What are the two types?
unique molecules found in
all cells that can be recognised by our
immune system
Self Antigens:
-found in bodies own cells and recognised as being a part of our own immune system
Non Self antigens (mostly from pathogens)
-recognised as not belonging (not a self antigen) so many induce an immune response
In autoimmune diseases, the body attacks own antigens and organs
Major Histocompatibility Complex (MHC)
What is the role
WHAT ARE the two types of markers?
-how cells tell friends from foes
-determined by the genotype of an individual, inque for each person
MHC 1 markers
-on all cells
-shows the immune system what is inside each cell
MHC 2 markers
-on antigen presenting cells (not all cells)
-antigen presenting cells include macrophages, dendretic cells and B lymphocytes to
-shows that they have englufed pathogen
-Presenting engulfed pathogens is the hallmark of the third line of defence
The adaptive IMMUNE response
Describe humoral and cell mediated immunity (third line of defense).
Humoral Immunity-Body fluid (blood etc, not in cells yet)
-B lymphocytes and antibodies
-(T helper cells (Th) and cytokines also involved)
Fight occurs in the bodies ‘humours’ (body fluids
Cell-Mediated Immunity:
T lymphocytes
T helper cells (Th), antigen presenting cells and cytokines also involved)
Fights against intracellular pathogens
THIRD line of defence: Humoral Immunity
The Lymphatic System- What is it?
What is it made up of?
Body Fluid Draining
Collects interstitial fluid (Fluid found in the spaces around cells. It comes from substances that leak out of blood capillaries )and filters it back into
the blood system.
Includes blind ending capillaries which collect
into vessels and on to lymph nodes.
Transports a range of white blood cells and is
the site of much immune response
Checks body fluid for anything foreign
-Drainage Systems, constantly checking for pathogens
-Anything leaking out of bloodstream is checked because lymphatic system is intertwined with vessels and arteries
It includes:
-lymph
-lymph vessels
-lymph nodes
-spleen
-thymus
-Bone Marrow - produces red blood cell
THIRD line of defence: Humoral Immunity - The Lymphatic System
Types of Lymphocytes
Lymphocytes= immune cells made in the bone marrow
- Cytotoxic T cells (CD8)
-kill virus infected and damaged cells - hELPER t CELLS (CD4)
-help cytotoxic t cells and b cells in their immune function (double checking) - B cells
-produce antibodies
Each lymphocyte has a different receptor for a particular antigen
There is a diverse range of lymphocyte receptors
One of these is the right shape to bind to the right antigen
It is important that the antigen finds the right lymphocyte to bind with so that it can be replicated
Clonal Population of lymphocytes- some of these will become effector cells and others memory cells
All lymphocytes do this
humoral immunity and antibodies
What are antibodies
Where do b lymphocytes grow and mature?
Involves B lymphocytes which produce specific antibodies (glycoprotein molecules)
against foreign antigens
These antibodies are bound to the plasma membrane surface:
* Act as receptors for binding an antigen
* Stimulate further antibody production
Also known as immunoglobulins (Ig)
Bind to specific antigen molecules
Y-shaped molecule that consists of:
* Two identical long heavy chains
* Two identical short light chains
Antibodies have two distinct regions:
* Constant region (can have one of 5 forms)
* Variable region (can have infinite forms)
The variable region allows different antigens
to bind
The constant region recruits other members
of the immune system
Antibody function
Antibodies bind to antigens, forming an antigen-
antibody complex.
Leads to:
* Neutralisation of bacterial toxins
* Prevents pathogens binding to body cells
* Agglutination – clumps the antigens together
* Makes antigen more susceptible to the action of
phagocytes
* Activates complement proteins and cytotoxic T
cells
B lymphocytes are produced, and mature in, bone
marrow
.
You have billions of different types of B cells in your body, each with surface
antibodies for different antigens.
The type of antibody created depends on a semi-random genetic lottery. You
have B cells with antibodies for antigens your body hasn’t met yet, or that
doesn’t even exist yet.
Any B cell with an antibody that recognises a self antigen is normally destroyed.
This creates “tolerance of self”.
You have billions of different types of B cells in your body, each with surface
antibodies for different antigens.
The type of antibody created depends on a semi-random genetic lottery. You
have B cells with antibodies for antigens your body hasn’t met yet, or that
doesn’t even exist yet.
Any B cell with an antibody that recognises a self antigen is normally destroyed.
This creates “tolerance of self”.
Cell Mediated IMMUNITY
what molecules/cells does it include
- Pathogens and antigens
- T lymphocytes (T cells)
– Cytotoxic T cells
– Helper T cells - Antigen presenting cells
Helper T cells and cytotoxic T cells.
Produced in the bone marrow, migrate
and mature in the thymus
Have specific T cell receptors (TCR) on
their membrane.
T cells can’t recognise antigens on their
own, it must be presented to them by
Antigen Presenting Cells (APC) in order
to become activated
T helper cell will recognise specific
complementary antigens on the MHC II
markers of an APC.
Once activated, Th cell will undergo clonal
expansion (multiply) and produce
effector and memory Th cells.
Effector Th cells release cytokines to
excite:
Cytotoxic T cells.
Activated B cells.
How do memory cells work?
Memory T Cells (both helper and cytotoxic) generally remain for life and respond when they recognise the specific foreign antigen presented on MHC markers. Therefore the response to secondary infection is faster and larger.
Describe passive and active immunity
Immunity
May be innate, acquired or herd.
Can be acquired naturally, meaning no ‘technological’ intervention, or
artificially, through assisted measures.
Can be acquired passively, through input of antibodies from another
organism, or actively, through the bodies own immune response.
Active Natural Immunity: Through the bodies own
immune response to foreign
antigens, B cells and T cells.
Creates memory cells and long-
term immunity.
Passive Natural : Receiving already made
antibodies. Does not lead to memory cell
creation or long-term immunity.
Protects foetus/child whilst their
own immune system builds:
– Foetus receives antibodies from
mother across the placenta in
the womb.
– Child receives antibodies in
breast milk.
Describe passive and active immunity
Immunity
May be innate, acquired or herd.
Can be acquired naturally, meaning no ‘technological’ intervention, or
artificially, through assisted measures.
Can be acquired passively, through input of antibodies from another
organism, or actively, through the bodies own immune response.
Active Natural Immunity: Through the bodies own
immune response to foreign
antigens, B cells and T cells.
Creates memory cells and long-
term immunity.
Passive Natural : Receiving already made
antibodies. Does not lead to memory cell
creation or long-term immunity.
Protects foetus/child whilst their
own immune system builds:
– Foetus receives antibodies from
mother across the placenta in
the womb.
– Child receives antibodies in
breast milk.
Describe passive and active immunity
Immunity
May be innate, acquired or herd.
Can be acquired naturally, meaning no ‘technological’ intervention, or
artificially, through assisted measures.
Can be acquired passively, through input of antibodies from another
organism, or actively, through the bodies own immune response.
Active Natural Immunity: Through the bodies own
immune response to foreign
antigens, B cells and T cells.
Creates memory cells and long-
term immunity.
Passive Natural : Receiving already made
antibodies. Does not lead to memory cell
creation or long-term immunity.
Protects foetus/child whilst their
own immune system builds:
– Foetus receives antibodies from
mother across the placenta in
the womb.
– Child receives antibodies in
breast milk.
Active Artificial
-immunisation from vaccination
Passive Artificial
-antivenom, bodies response takes too long
What is vaccination:
Vaccination (immunisation)
Injection of deactivated pathogen
(attenuated or killed), or toxoid
(deactivated form of toxin).
Injection still contains the antigen
which provokes immune response,
but does not cause the infection.
Promotes primary immune response,
production of memory cells leads to
acquired immunity and future
protection.
Multiple injections (boosters) may be
required over short term or long term
to increase memory cell number.
What is vaccination:
Vaccination (immunisation)
Injection of deactivated pathogen
(attenuated or killed), or toxoid
(deactivated form of toxin).
Injection still contains the antigen
which provokes immune response,
but does not cause the infection.
Promotes primary immune response,
production of memory cells leads to
acquired immunity and future
protection.
Multiple injections (boosters) may be
required over short term or long term
to increase memory cell number.
- Describe the structures and functions of the human eye as an example of the reflex arc.
light reflex
photo receptros
when cornea is touched
reacting to bright light
reflex arc are built in or innate behaviours
by passes the brain, but still sends message.
