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Speech and Language Therapy Y1 > BIOMED 2 > Flashcards

BIOMED 2 Flashcards

Intro to embryology + the pharyngeal apparatus (73 cards)

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1
Q

What is pre-natal development?

A

Gradual modification + growth of anatomical structures during the period from fertilisation to birth

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2
Q

What does pre-natal development involve?

A

Division and differentiation of cells
Changes that produce + modify anatomical structures

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3
Q

How long is full-term pre-natal development?

A

37-40 weeks (approx 9 months)

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4
Q

What are the 3 defined periods of pre-natal development in humans from fertilisation to birth?

A

Pre-embryonic period
Embryonic period
Foetal period

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5
Q

When does the pre-embryonic period take place and what happens in this period?

A

0-2w
Early cell division and implantation
Formation of a bilaminar (2-layer) structure

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6
Q

When does the embryonic period take place and what happens in this period?

A

3-8w
Trilaminar structure forms
Rudiments (basic form) of most organs + tissues develop

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7
Q

When does the foetal period take place and what happens in this period?

A

9w-birth
Rudiments grow and mature

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8
Q

When do the lip and palate develop?

A

Between weeks 4-10 of embryogenesis

note: disruptions during this period can leas to cleft lip/palate

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9
Q

Which weeks of development are a critical period for development of the head and neck?

A

6-9

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10
Q

What are stem cells?

A

Cells that have the potential to differentiate into more specialised cells

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11
Q

What are the 3 types of stem cells?

A

Totipotent
Pluripotent
Multipotent

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12
Q

What are totipotent stem cells?

A

Earliest cells after fertilisation- most potential

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13
Q

What are pluripotent stem cells?

A

Embryonic stem cells that can develop into different lineages

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14
Q

What are multipotent stem cells?

A

Can only develop into specific cells within a lineage

eg: haematopoietic stem cells can only differentiate into cells found in blood, not others eg: muscle

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15
Q

What are the 3 germ layers/lineages that pluripotent stem cells in the blastocyst differentiate into?

A

Ectoderm
Mesoderm
Endoderm

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16
Q

What is the ectoderm germ layer?

A

Nervous system + skin

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17
Q

What is the mesoderm germ layer?

A

Heart + blood vessels + muscles + cartilage + bone

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18
Q

What is the endoderm germ layer?

A

GI tract + associated internal organs

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19
Q

What is the name for a fertilised ovum?

A

Zygote

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20
Q

What happens in the first week, in the pre-embryonic stage?

A

Zygote undergoes cell divisions (cleavage)
Produces a morula (ball of 16 identical totipotent cells)
Morula cells differentiate and it develops into a blastocyst, which implants into the wall of the uterus (now pluripotent)

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21
Q

What is the last stage where there are ONLY totipotent cells present?

A

Morula

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22
Q

Until how many days are scientists allowed to do experiments in pre-natal development?

A

Up to 14 days

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23
Q

What happens in the second week of the pre-embryonic stage?

A

Cells in the inner part of the blastocyst differentiate to form a new cell layer
- original layer = epiblast
- new layer = hypoblast

Forms two-layered structure: bilaminar disk

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24
Q

What 2 processes occur during week 3 of development (week 1 of embryonic stage)?

A

Gastrulation
Neurulation

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25
What is the definition of gastrulation?
The process by which 3 germ layers are established (trilaminar structure)
26
What is the process of gastrulation?
Epiblast cells (blue) form a primitive streak, and move down into the hypoblast layer, displacing it to form endoderm layer (yellow) More epiblast cells move between the epiblast and new endoderm layer to form mesoderm (pink) Epiblast layer becomes known as ectoderm (blue)
27
What type of stem cells are the 3 germ layers?
Multipotent stem cells Now called an embryo
28
What happens to the 3 embryonic (germ) layers?
Organs form by organogenesis
29
What is the fate of the ectoderm cell layer?
Outer layers of skin Nervous system Cornea, lens, pupillary muscle of eye
30
What is the fate of the mesoderm layer?
Skeleton, skeletal muscle Smooth muscle Circulatory system
31
What is the fate of the endoderm layer?
Epithelial lining of: digestive/respiratory tract + urethra + bladder + reproductive system Liver + pancreas
32
What is the definition of neurulation?
Forming the neural tube (brain + spinal cord)
33
What is the process of neurulation at day 18?
Central tube of mesoderm cells forms notochord (later becomes vertebral discs) Notochord stimulates ectoderm to thicken, forming a neural plate made of neuroectoderm cells
34
What is the process of neurulation at day 20?
Neural plate forms 2 ridges which fuse to form neural tube (future brain + spinal cord)
35
What are the cells on the neural crest called?
Neural crest cells: ectomesenchyme
36
What is the process of neurulation at day 22-24?
Ectoderm layer forms over neural tube: outer skin of developing embryo - thus gives rise to neural tube (nervous system) + skin
37
By when does the neural tube close?
By day 25 (3.5 weeks approx) Closes at cranial end (brain) & caudal end (spinal cord)
38
What occurs if the caudal neuropore doesn’t close?
Spina bifida: can be closed or open (open = more serious but rarer)
39
What occurs if the cranial neuropore doesn’t close?
Anencephaly: incomplete closure of skull, scalp + brain doesn’t develop properly, portions of brain + skull missing, brain tissue usually exposed as not enough skin + bone to cover
40
What happens at the end of neurulation?
Neural crest cells in anterior region become known as cranial neural crest cells (CNCC) CNCC migrate to pharyngeal region from neural crest, will start to form outgrowths
41
What happens in week 4 of development?
New outgrowths + structures start to form - lens placode (eye) - optic pit (inner ear) - heart - pharyngeal arches (will form mouth, face, head, neck)
42
Why is the development of the pharyngeal area critical for SLT?
Explains how mouth + lips _ face + jaw + ears + other tissues/nerves involved in speech and swallowing are formed - can give understanding of how defects in stages can cause changes to normal development of speech
43
What is the pharyngeal apparatus (3 structures)?
Arches Clefts Pouches
44
How many pharyngeal arches are there?
5 (I II III IV VI, V breaks down/disappears) Raised part on outside- ectoderm layer
45
How many pharyngeal clefts are there?
4 On outside- ectoderm layer
46
How many pharyngeal pouches are there?
4 On inside- endoderm layer
47
What does each pharyngeal arch have its own source of cells for?
Blood A specific nerve Skeletal components Musculature (mesoderm)
48
What do the pharyngeal arches form (with some contribution from the pouches + clefts)?
Craniofacial region
49
What cranial nerve does pharyngeal arch 1 give rise to?
Trigeminal (CN V)
50
What cranial nerve does pharyngeal arch 2 give rise to?
Facial nerve (CN VII)
51
What cranial nerve does pharyngeal arch 3 give rise to?
Glossopharyngeal nerve (CN IX)
52
What cranial nerve does pharyngeal arch 4+6 give rise to?
vagus nerve (CN X)
53
What are the muscle derivatives from pharyngeal arch 1?
Muscles of mastication (temporalis, masseter) Myelohyoid: for swallowing/speaking Anterior belly of digastric: stabilises hyoid bone whilst swallowing Tensor veil palatini: tenses the soft palate Tensor tympani: inner ear
54
What are the muscle derivatives from pharyngeal arch 2?
Muscles of facial expression Buccinator: blow, chew, suck Stylohyoid: elevates hyoid bone during swallowing Posterior belly of digastric: stabilises hyoid bone Stapedius: smallest muscle in body, moves stapes bone Platysma: superficial neck muscle
55
What is the muscle derivative from pharyngeal arch 3?
Sylopharyngeus: elevates pharynx during swallowing
56
What are the muscle derivatives from pharyngeal arch 4?
Cricothyroid muscle (larynx) Pharyngeal constrictors: used in swallowing Soft palate muscles
57
What are the muscle derivatives from pharyngeal arch 6?
Intrinsic muscles (except cricothyroid) of larynx: moves vocal cords to produce speech
58
What are the skeletal derivatives from pharyngeal arch 1?
Maxillary prominence: becomes maxilla + zygomatic bone + part of temporal bone + palatine bone + vomer (part of septum) Mandibular prominence (made of Meckel’s cartilage): becomes mandible + malleus + incus
59
What are the skeletal derivatives from pharyngeal arch 2?
Stapes Styloid process Part of hyoid bone
60
What is the skeletal derivative from pharyngeal arch 3?
Hyoid bone
61
What are the skeletal derivatives from pharyngeal arch 4?
Laryngeal cartilages Epiglottis
62
What is the skeletal derivative from pharyngeal arch 6?
Laryngeal cartilages
63
What is another name for the pharyngeal arches?
Branchial arches
64
What do the 1st pharyngeal cleft and corresponding pouch develop to form?
Cleft: external ear Pouch: middle ear cavity + auditory tube
65
Do the other pharyngeal clefts develop into anything?
No- they grow over and fuse together
66
What does the 2nd pharyngeal pouch form?
Palatine tonsil
67
What does the 3rd pharyngeal pouch form?
Inferior parathyroid gland Thymus
68
What does the 4th pharyngeal pouch form?
Superior parathyroid gland
69
Which structure does majority of developmental defects to the pharyngeal apparatus affect?
1st pharyngeal arch, mainly skeletal derivatives
70
What are 3 skeletal derivatives that may be affected by defects to the 1st pharyngeal arch?
Underdeveloped mandible (severe Class II malocclusion) Absent/reduced malleus + incus bones (conductive hearing loss) Malformed external ears
71
What are 3 rare conditions linked to pharyngeal apparatus defect?
Pierre Robin Sequence- 1:5000 Treacher Collins Syndrome- 1:50,000 Cleft lip and/or palate- 1:700
72
What is Pierre Robin Sequence?
Underdevelopment of lower jaw - tongue takes up most of space - articulation difficulties - swallowing/feeding difficulties - resonance disorders
73
What is Treacher Collins Syndrome?
Underdevelopment of jaw/palate Hearing loss

Speech and Language Therapy Y1 (14 decks)

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