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what are exosomes, what do they contain and how used in future

lipid vesicles that contain regulatory elements within that are transferred between cells
also have mRNA within and nucleic acids to change the target cell
possible communicators and therefore therapeutics


autocoids what are they

- Local mediators
- Diverse group of (patho)physiological mediators.
- Often considered as defense mediators - formation and release associated with infection and inflammation
Are important therapeutic targets.


functions of autocoids

- Smooth muscle tone/length
- Glandular secretion
- Permeability (vascular & airway)
- Sensory nerves (pain & itch)


histamine what is the precursor, list 3 cells stored and released from, how many receptors and what are they

decarboxylated histidine
mast cells
enterochromaffin like cells - regulate acid secretion
H1-4 all GPCRs


What are H1 and H2 recptors and what antagonists useful in treating

H1 - antagonist antihistamines
useful in treating: hayfever, bites and sting, anaphylaxis
H2 - antagonist revolutionary in treatment for peptic ulcers as H2 receptors present on parietal cell so block that block acid secretion in stomach


bradykinin what receptors what are they and clinical uses

B1 and B2 both GPCRs but limited clinical use at the moment


salicylate (aspirin) how does it exert anti-pyretic (fever) and anti-inflammatory effects

blocks the effects of prostaglandin


what is the rate limiting step in the production of eicosanoids

arachidonic acid being cleaved from phospholipid and released - enzyme involved is phospholipase A2


what is special about prostaglandins that is important when blocking its production

has additive effect with bradykinin (BK) in terms of pain
synergistic factors that work with other molecules like bradykinin to exert stronger effects
therefore if bock one then block a large proportion of pain


how do NSAIDS exert their effects

- Block cyclooxygenase COX enzyme and therefore block the production and effects of prostanoids
- Although doesn't block bradykinin blocks prostaglandin therefore synergistic actions doesn't take place so dramatically dampen the inflammatory and pain response


list 3 ways glucocorticoids exert their anti-inflammatory effects

1) Inhibition of the eicosanoid synthesis pathway (at several levels)
○ Inhibits COX/PLA2 induction at the gene level
○ Generate an inhibitor of PLA2 (phospholipase A2) activity - block whole pathway
2) Broad inhibition of the generation of cytokines
3) Inhibition of adhesion molecule expression etc - which immune cells bind to in order to enter the tissues


Define Growth, differentiation, induction, morphogenesis, embryogenesis

Growth (quantitative)
- Increase in size; cell number, cell size and accumulation of cell products
Differentiation and induction
- Differentiation is the process of cells becoming different from one another.
- Induction is when tissues interact and become permanently changed
- Ordered assembly of cells to form complex organs
- Formation of body structures and organs (organogenesis)
- Requires cell division and differentiation


define gamete, zygote, blastocyst, embryo and foetus

A specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring; a sperm or an egg.
- The first diploid cell formed by fusion of egg and sperm and the combination of their separate genomes
- early stage in development before implantation on the uterus, consists of outer trophoblast and inner cell mass
- An egg that has been fertilized by a sperm and undergone one or more divisions.
- In mammals, description of development following the embryonic period


what are the 3 broad periods of gestation

1) Ovum
2) Embryo
3) Foetus


Ovum time frame and main events

- Fertilisation to end of 1st week of gestation
- Transport of zygote from oviduct to uterus
○ Release of egg through ova duct where get fertilised into the uterus before implantation - Multiple mitotic cell divisions
- Transformation from zygote – Morula - blastocyst


embryo time frame and main events

- 2nd week to 4th week
Rapid growth
starts with blastocyst elongation and ends with extensive differentiation of tissue and establishment of organs and foetal membranes fully formed


foetus time frame and main events

- Extends from 4th week to term
- Further growth and differentiation of established organ systems


requirement for implantation

1) Development within zona pellucida
2) Hatching of the blastocyst out of the zona pellucida
3) Maternal recognition of pregnancy - needs to be receptive of implantation
4) Formation of the extra-embryonic membranes - attachment to the foetus, start to form after gastrulation


early embryogenesis what are the 5 main stages

1) cleavage
2) morula
3) blastocyst
4) eruption/hatching
5) gastrulation


cleavage where occurs, what occurs and morula what occurs

onset of cell division after fetilsation occurs within the zona pellucida and involves no increase in size due to the vesicle restraint
morula - cleavage results in cluster of cells (morula) blastocyst loses spherical shape and forms blastocyst


2 cellular features of the blastocyst

1. Embryonic disk
- Or Inner cell mass
- Or Blastodisk
- Or Embryo proper
- Gap junctions for cellular communication
2. Trophoblast cells
- Absorption of nutrients
- Extra embryonic membranes
- Tight junctions


how does the endoderm, mesoderm and ectoderm layers form in gastrulation and what does mesoderm split into

Migration of epiblast cells through primitive streak
- Forms the endoderm and mesoderm layers
○ First migrating cells form endoderm
○ Major enter coelom and become mesoderm
- Mesenchyme (mesoderm) cells migrate laterally and cranially and splits into 2 layers
1) Somatic mesoderm (attached to ectoderm)
2) Splanchic mesoderm (endoderm attached)
Remaining epiblast that doesn't migrate becomes the ectoderm


what are the 4 extra-embryonic membranes what derived from and function

1) Chorion
- Derived from trophectoderm and mesoderm
- Mediates attachment to the uterus
2) Amnion
- Derived from trophectoderm and mesoderm
- Fluid filled sac that protects the embryo
3) Yolk sac
- Derived from primitive endoderm
- Regresses with time in mammals
- Contributes primitive germ cells
4) Allantois
- Derived from primitive gut
- Fluid filled sac that collects waste from the embryo
- Eventually fuses with chorion


what is neurulation what is it driven by and the 4 steps

- Is the initial development of the gut, heart and formation of the nervous system
- Driven by the notochord formation
1) Ectoderm above the notochord thickens to form the neural plate
2) Neural plate is bound by elevations called neural folds
3) The plate becomes depressed in midline forming neural groove
4) Neural fold becomes more elevated and fold converge towards midline and fuse together forming neural tube
- Some cells migrate to lateral margins of the cell and are called neural crest cells


what is involved with gut tube formation

mirrors neural tube formation


what are somitomeres what do they contribute to, what do they lead to and what does that lead to

somitomeres are thickening of the paraxial mesoderm, first 7 contribute to the head region caudal 7 become organised into somites


what forms urinary and reproductive systems and the body cavities

intermediate mesoderm - urinary and reproductive systems
lateral mesoderm form somatic and splanchic mesoderm layers that fuse forming the body caivties (pleural, pericardial and peritoneal)


define congential and what does this indicate about the cause of the lesion

congenital = present at birth
implies nothing about the cause of abnormality
could be genetic abnormalities (inherited or spontaneous), could be exposure to teratogenic agents in utero


define agenesis

agenesis = complete failure of a tissue or organ to develop


define aplasia and which organs commonly undergo segmental aplasia during in utero development

aplasia = failure of a tissue or organ to grow
tissue is present but small and rudimentary
e.g. segmental aplasia of the small or large intestine