cardiff exam style questions Flashcards
define infection
invasion of an organism’s tissues by disease causing microorganisms, their multiplication and the reaction of host tissues to infectious agents
what is a pathogenic microorganism
microorganism that can enter the body and cause harm
define immunology
the branch of medicine and biology concerned with immunity.
what is immunity
protection against infectious diseases caused by microorganisms and cancer
what microorganisms cause infectious disease?
- protozoa
- fungi
- bacteria
- viruses
- parasites
what are the means of pathogen transmission
- airborne through respiratory tract
- oral-fecal route
- contaminated water
- blood transfusion and sharing of needles
categorize the immune system and its types
what is the immune function of the skin
- it acts as a barrier between the body and the external environment, preventing pathogen entry (stratum corneum)
- dendritic cells (Langerhans cells) present in the epidermis; they are responsible for the capture, processing, and presentation of antigens to T lymphocytes in local lymphoid organs. As a result, T lymphocytes express the cutaneous lymphocyte antigen (CLA) molecule, a modified form of P-selectin glycoprotein ligand-1.[1] Lymphocytes move to the epidermis where they reside as memory T cells, they will thus be activated and will trigger an inflammatory response.
what is the immune function of secretions e.g. tears/saliva
contain molecules that can neutralize bacteria
1- what is the thymus?
2- what is its function?
3- where is it located?
- encapsulated lymphoid organ where t cell maturation and differentiation occurs
- creates lymphocytes
- behind the sternum in the mediastinum
list the primary lymphoid tissues responsible for the proliferation of lymphocytes
- thymus
- bone marrow
- list the secondary lymphoid tissues
- what is the main function of the secondary lymphoid tissues
- lymph nodes/spleen/tonsils
- provide the environment for proliferation and maturation of adaptive immune cells (t/b) to filter and trap pathogens
what is a lymph node
encapsulated, trabeculated lymphoid organ that has many afferent and one or more efferent branches
what is the function of lymph nodes?
it functions as a filter, storage and active centre for t/b cells and antibody production
what are the 3 main components of the lymph nodes, and what are their roles
- follicle: b cell storage and proliferation
- medulla: has medullary cords and sinuses as filters
- paracortex: location of t cells
what are the anatomic structures of the spleen, and what are their roles
- sinusoids: elongated channels with fenestrated membranes and adjacent macrophages
- periarterial lymphatic sheath: red pulp that houses t cells
- follice: white pulp that houses b cells
what is the difference between adaptive and innate immunity?
adaptive: specific response to infectious agents that depend on antigen presentation, recognition and antibody response (memory/antibodies)
innate: physical and biochemical barriers inside and outside the body (no memory/no antibodies)
what organs are considered to be the first lines of defense?
- skin
- respiratory system
- gut
- genitourinary
- mucos/cilia/reflexes
true or false
elevation of body temperature is a first line of defense
true
what are the two main types of innate immune cells
- natural killer cells (cytolytic and cytotoxic granules)
- phagocytes (macrophages/neutrophils)
what is the difference between the two innate cells (natural killer and phagocytes)?
natural killer → recognize virally infected and malignant changes on the surfaces of cells and opsonized cells
phagocytes → engulf debris, destroy and remove them
what 3 main cells are capable of phagocytosis?
neutrophils
macrophages
dendritic cells
what is phagocytosis
recognition and ingestion of particles larger than 0.5 μm into a plasma membrane derived vesicle, known as phagosome
what is the function of mast cells and basophils
- secrete histamines (inflammatory mediators)
- responsible for allergic reactions (hypersensitivity type 1)
where do mast cells and basophils reside?
mast cells → tissues
basophils → blood
what is the function of phagocytes
- phagocytosis/neutralization
- respond to inflammation in tissues
how are phagocytes able to recognize microorganisms?
via pathogen associated molecular patterns on their surface and via pattern recognition receptors
briefly, what are the steps of phagocytosis
(i) recognition of the target particle,
(ii) signaling to activate the internalization machinery,
(iii) phagosome formation
(iv) phagolysosome maturation
what are the cell surface proteins of macrophages?
- MHC II
- B7
- CD40
- CD14
what is the main function of MHC II
present processed antigens, which are derived primarily from exogenous sources, to CD4(+) T-lymphocytes
why is MHC class II critical for the initiation of the antigen-specific immune response.
because they present processed antigens, which are derived primarily from exogenous sources, to CD4(+) T-lymphocytes
describe the mechanism of humoral innate response
defense mechanism that attacks pathogens in a rapid non-specific manner
what are examples of humoral innate response?
- fever
- complement
- inflammation
explain how fever occurs during infection
Exogenous pyrogens initiate fever by inducing host cells (primarily macrophages) to produce and release endogenous pyrogens such as interleukin-1
or
release of pyrogens increase body temperature via cyclooxegenase-2 (cox-2).
briefly explain the role of the complement system of humoral innate response
- plasma proteins, destroy cell membranes (lytic pore).
- Attract phagocytes & stimulate activity of other immune cells.(anaphylatoxins C3a, C5a).
- Promote phagocytosis (Opsonins, C3b/iC3b, C4b).
what causes an inflammation?
Mast cells release pro-inflammatory cytokines & chemokines causing blood vessels to dilate, allowing influx of immune cells and fluid (plasma). Symptoms are pain, swelling, redness and heat
what are the three methods by which the complement system is activated
classical → requires antibodies (IgM/IgG) to be bound to antigens
alternative → requires endotoxin or a foreign surface (bacterial surface)
lectin → requires bacterial carbohydrates
cell mediated adaptive immunity is activated upon ___________
humoral adaptive immunity is activated upon _______
direct contact with pathogen
antibodies
the adaptive immune response is said to be specific, what does that mean?
because of its ability to generate an immune memory, to clarify, repeated exposure to the same pathogen will produce an enhanced response to that same pathogen the next time it is exposed to
what are the main cells of the adaptive immune system
lymphocytes: T cells/ B cells
what is the function of t cells and b cells of the adaptive immune system
t cells → cell mediated activation of b cells and other immune cells (t helper/CD4+)/ direct killing (cytotoxic/CD8+)
b cells → make antibodies (IgM/IgG/IgA/IgE/IgD)
which cell structures allow adaptive specificity
b cell receptors
what does MHC stand for
major histocompatibility complex
where are the different classes of MHC expressed
MHC I → nucleated cell bodies
MHC II → on antigen presenting cells
what is the function of MHC
to bind peptide fragments derived from pathogens and display them on t cell receptors for recognition by the appropriate T cells
differentiate between cellular and humoral adaptive immune responses, providing appropriate examples
cellular
- targets cancer and infected body cells
- effected by cytotoxic t cells (CD8+)
humoral
- targets pathogens and antigens in blood/mucos
- t cells secrete cytokines to control activation of other cell type
what are the cell surface proteins expressed on each of the following immune cells
t-helper
cytotoxic t cells
t helper → CD4/TCR/CD3/CD28/CD40L
cytotoxic t cells → CD8/TCR/CD3
what is the function of cell surface proteins of T cells, provide an example
- recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules
- T helper bind and interact with b cells via CD40L on its surface and CD40 on the b cell
MHC is encoded by ________
human leukocyte antigen (HLA) genes
what are the HLA genes of MHC I/MHC II
MHC I → HLA-A/ HLA-B/HLA-C (on nucleated cells)
MHC II → HLA-DR/HLA-DP/HLA-DQ (antigen-presenting cells)
in the thymus, t cells differentiate into _____ & _____
CD4+ & CD8+
what do CD4+ cells differentiate into and what are their roles
they differentiate into T helper cells, which further differentiate into:
Th 1 → cellular adaptive response (Cytotoxic T cells, intracellular pathogens)
Th 2 → humoral adaptive response (B cells, extracellular pathogens)
Th 17 → extracellular bacteria and fungi, IL-17
T reg → control the immune response to self and foreign particles (antigens)
humoral adaptive immunity is dependent on ________& _______
antigens & antibodies
what is the difference between antigen and antibody
antigen: a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
antibody: a blood protein produced in response to and counteracting a specific antigen
describe the structure (fragments) of antibodies
fab fragment → binds to antigens with variable components of H/L chains recognizing antigens
Fc fragment → determines class of IgG/IgM fixes complement
what are the 3 main functions of antibodies
- opsonization: the antibody promotes phagocytosis
- neutralization: the antibody inhibits the antigen
- complement activation: trigger the classical pathway of complement.
how do antibodies perform opsonization?
via Fc receptors on phagocytes recognizing antibody-antigen complexes and binding antibody via its Fc fragment, thus promoting phagocytosis
how do antibodies neutralize foreign particles
for example, bacterial adherence by binding and blocking a surface protein on bacteria required for adhering to cell surfaces
how do antibodies trigger the classical complement pathway
antibody-antigen complexes bind C1q within the C1 complex and trigger the classical pathway of complement, once activated, it creates opsonins C4b and also C3b and amplification via the alternative pathway.
compare he primary antibody response vs secondary antibody response
primary
- b cells proliferate plasma cells
- secrete antibodies
- create memory
- IgM
Secondary
- antigen specific memory b cells create antibodies
- isotype switching
- IgG
- high affinity/ serum concentration
what is isotype switching?
a biological mechanism that changes a B cell’s production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG
what do cytokines do
- Stimulate or inhibit the differentiation, proliferation and activity of immune cells
what types of cytokines are there and what are their mode of actions
define cytokines
any of a number of substances, such as interferon, interleukin, and growth factors, which are secreted by certain cells of the immune system and have an effect on other cells
what is haematopoiesis
the formation of blood or of blood cells in the living body
___________ is the site of circulating blood cell production – haematopoiesis
Bone marrow
what does HSC stand for
hematopoietic stem cells
talk about the division of HSC in hematopoieses
- one daughter cell remains in the bone marrow to continue renewing the HSC pool
- other daughter cell will pass through several stages of development (see Figure) resulting in mature blood cells
blood and tissue production occur in the ____
bone marrow
what do HSC differentiate into?
- MPPs (multipotent progenitors)
- CLPs (common lymphoid progenitors)
- CMPs (common myeloid progenitors)
Myeloproliferative disorders are characterized by the overproduction of one type of blood cell such as _______
essential thrombocythaemia (platelets)
polycythaemia vera (red blood cells)
myelofibrosis (fibroblasts)
a spectrum of disorders (overproduction of one or more type of blood cell)
Myelodysplastic syndromes (MDS)
Multiple myeloma and Aplastic anemia are examples of _________
Myelodysplastic syndromes (MDS)
•Leukemias are malignant diseases of the _______
bone marrow
leukemias occur during haematopoietic development of ____________ & __________
- lymphoid lineages in acute or chronic lymphoblastic leukaemia (ALL/CLL)
- myeloid lineages in acute or chronic myeloid leukaemia (AML/CML)
what is the function of lymph nodes
filter and drainage system through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease
B and T cells leave the node via ______ lymphatic vessels in the central ______ region
‘efferent’
‘medullary’
what are the Gut-associated lymphoid tissues
- peyer’s patches
- mesenteric lymph nodes
which immune cells are activated and regulated in the Mucosal epithelium
•T cells, plasma cells, mast cells, dendritic cells, macrophages
what could cause irritable bowel disease?
defects in the barrier function of the intestine
how do the nasopharynx and tonsillar regions serve as immune barriers
clear by inertial force (coughing and sneezing)
describe immunity in mucociliary surface in the lungs
- Mucociliary surface•capture and expelling via upper airways
- Antimicrobial compounds•Collectins, surfactant proteins
- Get recognized by innate immune cells and the complement system
- Antimicrobial peptide secretions
which cells in the lungs are responsible for phagocytosis, and recruitment of other immune cells
alveolar macrophages
list all immune organs
- Bone marrow
- Thymus.
- Lymphoid organs
- Lymph nodes
- Spleen
- Tonsils
- Mucous membranes
how does the spleen serve as an immune organ
it serves as ‘ lymph node’ for the blood
true or false
If the spleen needs to be removed completely (splenectomy), other immune system organs can carry out its roles.
true
Infections, mostly by encapsulated organisms, are the most well-known complications following splenectomy.
provide one example of an infection
pneumococcal infections
Pneumococcal polysaccharide conjugate vaccine
Meningococcal groups A with C and B vaccine
Influenza vaccine
are required for
- asplenia
- splenic dysfunction
- complement disorder
what types of tonsils are there?
palatine tonsils
adenoids
lingual tonsil.
qTonsils also contain a lot of_______ blood cells.
white
More than half of all the body’s cells that lead to production of antibodies (B cell derived plasma cells) are found in the ________ especially in the last part of the small intestine and in the appendix
bowel wall
how does the intestine function as an immune organ
- microbiome, competes with other microorganisms for sites of nutrients thus making it difficult to survive or navigate through the body
- The immune system cells are directly beneath the mucous membranes, where they prevent bacteria and viruses from attaching
describe the type of immune functions of each of the following
- homeostatic function
- surveillance
- defense
- eliminate injured and senile cells and tolerance of self-components
- destruction of dysfunctional cells, preventing persistent infection (accumulation causes degenerative disease)
- clearance of infection (hypersensitivity/immunodeficiency)
describe the three lines of defence of the immune system
- The first line of defence are the physical and chemical barriers, which are considered functions of innate immunity.
- The second line of defence is nonspecific resistance, which also is considered a function of innate immunity.
- The third line of defence is specific resistance, which is considered a function of acquired immunity.
provide examples of pathogens and describe the infections they cause
what are the first line of innate defence
- Skin (tough, difficult for pathogens to penetrate)
- Mucous membranes (secrete mucus that traps pathogens, hair-like cilia that remove pathogens)
- Sneeze or cough (removes pathogens from nose or throat or upper airways)
- Tears (wash pathogens from the eyes)
what types of chemical barriers are there
- Sweat, mucus, tears, saliva contain enzymes that kill pathogens
- Urine is too acidic for many pathogens
- Stomach acid kills pathogens that enter the GI tract with food or drink
what are the molecular responses of the first lines of defense?
- Complement system in the blood
- PAMP-PAR
- Lysozymes in tears, nasal secretions, saliva, gastric secretions
- Interferons (IFN)
- C-reactive protein (CRP) in the blood
what are interferons
qsignalling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumour cells.
what do lysozymes do
they are lytic enzyme that attacks the protective cell walls of bacteria
what do PAMP-AR do
recognize conserved molecular patterns common to various microbes (PAMPs – pathogen-associated molecular patterns)
what are the first line of defence in biological barriers
Organisms that help protect the body
Harmless bacteria on skin or in GI tract
Microbiome
what happens after a pathogen gains entry to the body
- initiation of inflammatory response triggered by chemical mediators: cytokines, histamines
- Chemical mediators communicate with other cells and coordinate the inflammatory response
- Symptoms at the site of infection/wound: red, warm, swollen
The chemicals that trigger the inflammatory response attract ________ to the site of injury or infection.
leukocytes
true or false
Leukocytes may respond with either a nonspecific or a specific defence.
true
provide an example of a nonspecific defence
phagocytosis.
- What are the three main cell types of the lymphoid class of immune cells?
T-lymphocytes, B-lymphocytes, and natural killer cells
how is body temperature regulated
Interactions occur between ________&________ lead to homeostasis
nerve fibers and hormones
what are the main endocrine glands and where are they located
what are the main hormones of the hypothalamus?
- Gonadotrophin Releasing Hormone
- Thyrotrophin Releasing Hormone
- Growth Hormone Releasing Hormone
- Corticotrophin Releasing Hormone
- Somatostatin
- Dopamine
what are the main hormones of the anterior pituitary gland?
- Follicle stimulating hormone
- Luteinizing hormone
- Thyroid Stimulating Hormone
- Growth Hormone
- Prolactin
- Adrenocorticotrophic Hormone
what are the main hormones of the posterior pituitary gland
- oxytocin
- vasopressin
what hormones does the thyroid gland produce
- thyroxine T4
- triiodothyronine T3
- clacitonin
what do the adrenal glands produce?
depending on the region:
Cortex: Cortisol/Aldosterone
Medulla: Adrenaline/Noradrenaline
what are the hormones of the pancreas?
glucagon
insulin
the liver and the kidney produce what hormone?
calcitriol
what are the hormones of the ovaries
estrogen
progesterone
what is the function of hormones?
- Control reproduction
- general growth and development
- Regulation of electrolyte composition of body fluids
- control energy metabolism
________________ is essential for growth to normal stature and average life expectancy.
growth hormone
how do hormones regulate energy metabolism
Thyroid hormones are crucial to our ability to regulate our body temperature and thus survive on earth.
____________ hormone is essential for the control of body fluid volume
vasopressin
_____________ are essential for reproduction and the perpetuation of mankind.
Oestrogen and testosterone
explain the difference between direct and indirect negative feedback mechanisms
direct:
An increase in the level of a circulating hormone directly decreases the secretory activity of the cells which make it.
indirect
An increase in the level of a circulating hormone A decreases the secretory activity of cells responsible for secreting hormone B which stimulates the production of hormone A.
provide an example of direct negative feedback mechanism
during the production of glucocorticoids by the adrenal glands, they are released into the body and eventually arrive at the pituitary, thus switching off the production of ACTH that acts on the adrenal cortex influencing it to stop producing glucocorticoids from the adrenal glands
provide an example of the indirect negative feedback mechanism
during the production of glucocorticoids by the adrenal glands, they are released into the body and eventually arrive at the hypothalamus, thus switching off the production of CRH that acts on the pituitary, thus inhibiting the release of ACTH which will stop the production of glucocorticoids
define positive feedback
An increase in the level of a circulating hormone increases its own production either directly or indirectly.
provide an example of positive feedback
The first contractions of labor (the stimulus) push the baby toward the cervix (the lowest part of the uterus). The cervix contains stretch-sensitive nerve cells that monitor the degree of stretching (the sensors). These nerve cells send messages to the brain, which in turn causes the pituitary gland at the base of the brain to release the hormone oxytocin into the bloodstream. Oxytocin causes stronger contractions of the smooth muscles in of the uterus (the effectors), pushing the baby further down the birth canal. This causes even greater stretching of the cervix.
oxytocin release will only stop when the baby is born
what is the fate/pathway of hypothalamic hormones
- released into the blood and affect the release of trophic hormones from the pituitary
- are transported down axons to the posterior pituitary for release.
what is the function of the hypothalamus
- controlling the intake of food and drink
- sexual behaviour
- sleep-wake cycle
- regulating blood pressure and heart rate
- maintaining body temperature
- modulating emotions.
________ pituitary develops from the roof of the embryonic mouth and the ________ pituitary from the brain.
Anterior
posterior
The hypothalamus and pituitary are connected via the pituitary or __________
infundibular stalk
what are the properties of hypothalamic hormones
- Pulsatile release
- Made by neurones, delivered by the vasculature
- Act on specific receptors on target cells in the anterior pituitary
- Stimulate trophin synthesis
- Can also inhibit trophin release
- Release regulated by negative feedback
