Foundations Lecture - Introduction to Human Development: Difference between revisions
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:'''Links:''' [http:// | :'''Links:''' [http://embryology.med.unsw.edu.au/embryology/index.php?title=Foundations_Lecture_-_Introduction_to_Human_Development&printable=yes Printable Lecture Page] | [http://embryology.med.unsw.edu.au/embryology/index.php?title=Foundations_Lecture_-_Introduction_to_Human_Development&oldid=117829 2012] | [[Media:2012_Foundations_Lecture_-_Introduction_to_Human_Development_-_Embryology.pdf|PDF version (873 KB, 6 pages)]] | ||
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Revision as of 08:16, 23 April 2013
Introduction
Human development is one of the most exciting topics to study not only as a medical student, but also for our fundamental understanding of the human body. Of all health issues in Medicine, fertility and reproduction is a topic that will affect everyone. This lecture is going to take you briefly through key biological concepts in human development, these will later be explored in more detail through the BGD course. I will be using simplified terms in the lecture slides (with developmental term in brackets).
- Australian Statistics On 23 April 2013 at 08:02:20 AM (Canberra time), the resident population of Australia is projected to be: 22,999,392
The lecture will be followed by a practical class introducing online resources for independent study and working through similar embryology concepts.
Other Foundations links |
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The following lecture, practical and practical support pages for Foundations can be found on this current site.
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Aims
- Purpose of learning embryology
- Basic facts about early human development
- Appreciate differences between the conceptus, embryo and fetus
- General understanding of the term “critical periods” of development
Concepts: Fertilization, Early conceptus, Germ layers, Embryo, Tissue origins, Timetable/stages of development, Fetus, Placenta
Background Lectures: Cell Structure (structure and function), Cell Division (mitosis, meiosis, lifespan, cell death), 4 Basic Tissues (Epithelial, Connective, Muscular, Nervous)
Links: 2013 Practical | Embryology Textbooks
Human Development Timeline
Last Menstrual Period (LMP) today -> Birth Date - January 30, 2014 |
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Gestation Calculation
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UNSW Embryology Online
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<mediaplayer width='360' height='410' image="http://embryology.med.unsw.edu.au/embryology/images/6/61/Human_development_001_icon.jpg">File:Human development 001.mp4</mediaplayer> |
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Using these resources (online navigation, organization and printing) will be covered in the introduction to the associated Practical class.
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Textbooks
- There are many different excellent embryology textbooks
- I have included 2 that cover the clinical topics as well. More Textbooks?
- Links: More Embryology Textbooks
Four Basic Tissue Types
Tissues and organs of the body consist of combinations of 4 basic tissue organisations:
- Epithelial
- Connective
- Muscular
- Nervous
- Where do they come from?
- How do they develop?
Human Reproductive Cycle
- Meiosis in gonad produces haploid gametes
- testis the sperm (spermatozoa)
- ovary the egg (oocyte)
- there are several differences in when and how gametes are formed in the male and female gonad.
Female
- Menstrual Cycle a regular cycle of reproduction (28 days)
- begins at puberty
- release of 1 egg (oocyte) every cycle
- Endocrine controlled (HPG axis)
- Hypothalamus
- Pituitary
- Gonad
Male
- begins at puberty
- continuous production of sperm (spermatozoa, human male 2,000/second)
- release millions of spermatozoa (require activation, capacitation)
Ovary
- Paired organs
- lying in the peritoneal cavity
Ovulation
- ovulation is the release of the egg (oocyte) at about the middle of the menstrual cycle
Human ovulation
Fertilization
- the process of the 2 haploid gametes (egg and sperm) fusing and combining genetic material.
- conceptus - the entire product of fertilization
Early Development
- occurs during week 1 following fertilization
- last menstrual period (LMP) week 3
- mitosis to form solid ball of cells (morula), then hollow ball (blastocyst)
Week 1 Development
- occurs freely floating in uterus
Week 2 Development
- Implantation - initial attachment to uterine wall, and then invasion of the uterine wall.
Pregnancy
Detect Pregnancy
- Clinically can be detected following implantation (week 2)
- Last Menstrual Period (LMP) - today ? ....... Birth Date - January 30, 2014
Trimesters
- Divide the pregnancy into 3 "blocks" of about 3 months (trimesters)
- First Trimester - embryonic period (organogenesis)
- Second and Trimester - fetal period (growth)
Implantation Sites
Abnormal Implantation
- Ectopic Sites
- external surface of uterus, ovary, bowel, gastrointestinal tract, mesentery, peritoneal wall
- If not spontaneous then, embryo has to be removed surgically
- Uterine - tubal pregnancy (most common ectopic)
Normal Implantation
- Uterine body
- posterior, anterior, superior, lateral (most common posterior)
- inferior implantation - placenta overlies internal os of uterus Placenta Previa
Early Placenta
- interaction between implanting conceptus and uterine wall (endometrium)
- The uterine lining following implantation (Decidua)
- forms 3 distinct regions, at approx 3 weeks
- Decidua Basalis - implantation site
- Decidua Capsularis - enclosing the conceptus
- Decidua Parietalis - remainder of uterus
- uterine cavity is lost by 12 weeks
Placenta
- Materno/fetal organ
- No exchange of blood
- Many different roles
- can be "sampled" as part of a prenatal diagnostic test
Embryonic Development
- Embryonic Period - Week 1 to 8 (first trimester)
- Establish the basic structure of organs and tissues (Organogenesis)
- development and growth of the placenta (Placentation)
Week 3
- 3 Key processes commence
1. Gastrulation
- the formation of the 3 layer embryo (trilaminar embryo)
- All tissues of the body are formed from these 3 embryonic tissue layers (germ layers)
- Ectoderm (epithelium)
- Mesoderm (connective tissue)
- Endoderm (epithelium)
- simplified explanation of the 3 layer contributions
Ectoderm
- forms the central and peripheral nervous system and epithelium of the skin
Endoderm
- forms gastrointestinal tract organs and the epithelium of the gastrointestinal and respiratory tracts
Mesoderm
- forms the body connective tissues: blood, bone, muscle, connective tissue skin, gastrointestinal and respiratory tracts
2. Somitogenesis
- segmentation of the mesoderm into somites
- forms the axial body plan
3. Neuralation
- segmentation of the ectoderm
- separates the neural tissue from the skin (epidermis)
Week 4
- heart formation (cardiogenesis)
- first functioning organ
Week 4-8
- early development of the other organs, tissues and limbs
Week 9 - 38
- Fetal Period - Second and Third Trimester
- Continuing growth and differentiation of organs formed in embryonic period
- some organs have a later development - neural, genital, respiratory, bones
- some continue to develop after birth - neural, genital, respiratory, bones
- growth in size, length (Second Trimester)
- growth in weight (Third Trimester)
Birth
- birth (parturition) is a complex physiological process between the fetus and mother
- thought to be initiated by the fetus
Maternal Birth Stages
- Dilatation
- Expulsion
- Placental
- Recovery
Australian Birth Rate 1998-2007
Newborn
Newborn (perinatal) needs to activate many systems and establish independent regulation (homeostasis)
- Lung function - Fluid drainage, Gas exchange, muscular activity
- Circulatory changes - Closure of 3 vascular shunts
- Thermoregulation - metabolic rate, fat metabolism
- Nutrition - gastrointestinal tract function, peristalsis
- Waste - kidney function
- Endocrine function - loss of placenta, maternal hormones
Critical Periods of Development
Abnormal Development
Three main causes:
- Genetic
- Environmental
- Unknown
- First trimester most critical
- Different effect depending on time of insult (teratogen)
Diagnosis
- Prenatal diagnosis - number of different techniques (non-invasive, invasive) for determining normal development
- Neonatal diagnosis (APGAR test, Guthrie test)
- Maternal diagnosis - often pregnancy will expose maternal health problems
- Gutherie card icon.jpg
Gutherie card
Revision Notes
- You don't need to know everything today, this is an introduction.
- Use the glossary to help understand new terms.
- Don't confuse "germ cell layers" (ectoderm, mesoderm, endoderm) with "germ cells" (egg, spermatazoa).
- Remember the difference between "clinical weeks" (last menstral period) and "embryonic weeks" (from ovulation/fertilisation, 2 weeks later).
- With abnormalities
- think about the types of prenatal dianostic techniques that are now available
- the 2 major types (genetic and environmental)
- the effect of maternal age/health/lifestyle.
Textbooks
Hill, M.A. (2013) UNSW Embryology (13th ed.). Sydney:UNSW.
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Keith L. Moore, T.V.N. Persaud, Mark G. Torchia. (2011). The Developing Human: clinically oriented embryology (9th ed.). Philadelphia: Saunders. | |
Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. and Francis-West, P.H. (2009). Larsen’s Human Embryology (4th ed.). New York; Edinburgh: Churchill Livingstone.
The following chapter links only work with a UNSW connection and can also be accessed through this UNSW Library connection. |
Foundations Practical - Introduction to Human Development
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, June 14) Embryology Foundations Lecture - Introduction to Human Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Foundations_Lecture_-_Introduction_to_Human_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G