Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MTM > Week 4 > Flashcards

Week 4 Flashcards

(115 cards)

Start Studying
1
Q

What are the functions of skin

A

Physical protection -acts as a barrier
Thermoregulation
Sensation - lots of sensory receptors in skin
Metabolic functions- fat, adipose tissue, Vit D production
Indicator of general health
Shock absorption
Maintenance of fluid balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the three main layers of skin

A

Epidermis
Dermis
Hypodermis/ subcutis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the epidermis

A

Keratinised stratified squamous epithelium
Mostly filled with keratinocytes
Four/five discrete layers
Cuboidal cells at the basal layer (stratum basale)
Squamous layer at top

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the stratum basale/basal layer

A

Cuboidal cells
Most deep layer
Sat on the basement membrane
Mitosis occurs to replenish above layers
Melanocytes present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the stratum spinosum/ prickle layer

A

8-10 cell layers- biggest layer in epidermis
Connected by desmosomes
Gives prickly appearance on dehydration
Produces cytokeratin- intermediate filament of cytoskeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the stratum granulosum/ granular layer

A

3-5 cell layers
Become squamous cells
Granules contain keratohyalin- one of steps in keratin maturation
Stains deeply with H&E

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Keratin maturation

A

Keratin is produced as intermediate filaments- cytokeratin, which matures into packed extracellular keratin
The epidermis is constantly being replenished every 25-30 days in normal skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Process of keratin maturation in layers

A

Stratum corneum- keratin
Stratum granulosum- keratohyaline granules
Stratum spinosum- cytokeratin- tonofibrils
Stratum basale- mitosis, some cytokeratin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the stratum lucidum

A

Layer between the stratum granulosum and corneum
Only present in thick skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the stratum corneum/cornified layer

A

Mature keratin= cytokeratin & keratohyaline
Dead/dying keratinocytes cells ‘squames’
No cytoplasm/nucleus/organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what aremelanocytes

A

Produce melanin
Found in basal layer
Can’t see with H&E
UV protection
Pigment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are Merkel cells

A

In stratum basale
Associated with free nerve endings
Sensory- light touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are Langherhan’s cells

A

Found in all layers and dermis
Immune cell, like a macrophage
Specialised immune cell
Antigen presenting cell
Involved in immune and allergic reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the papillary layer

A

In dermis
Above the reticular dermis
The dermal papillae (elevations) increase surface area, diffusion nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the reticular layer

A

Dense irregular collagenous tissue- more collagen
Elastin present throughout dermis
This elastic reduces age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Neurovascular supply in the dermis

A

Complex of vessels present
Subpapillary and cutaneous plexus with shunting vessels between
Important in thermoregulation
Controlled by ANS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Types of skin mechanoreceptors

A

Meissner corpuscle - papillary layer
Pacinian corpuscle - dermis & hypodermis
Ruffini’s corpuscles
Merkels disks
Free nerve endings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are free nerve endings for

A

Pain, nociception (feeling pain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Merkel disks

A

Perception of shape , texture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Meissners corpuscle

A

Motion detection
Grip control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Ruffini ending

A

Skin stretch
Tangential force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Pacinian corpuscle

A

Perception of distant events through vibrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the unencapsulated mechanoreceptors

A

Merkel
Free nerve endings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are encapsulated mechanoreceptors

A

Pacinian
Ruffinis
Meissners

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What type of skin are hairs found
Thin skin
26
What is hair made of
Keratin, densely packed
27
What are sabaceous glands
Secrete oily sebum on upper part of hair follicle
28
Sweat glands
Found in the superficial hypodermis Watery fluid Secrete sweat through exocytosis- termed merocrine secretion
29
Sebaceous glands
Attached to hair follicles Secrete sebum Cells fill with secretory vesicles then dissociates- termed Holocrine secretion
30
What are the two types of sweat glands
Eccrine Apocrine Both are merocrine secretion
31
Eccrine sweat glands
Directly on skin Function in heat loss (ANS) Less viscous Found everywhere
32
Apocrine sweat glands
Open into hair follicle Regulated by hormones More viscous Limited to axilla/ genitals and areola Secrete through merocrine secretion
33
burns classification
Superficial epidermal Partial thickness- superficial dermal Partial thickness- deep dermal Full thickness- burn extends through all layers of skin to subcutaneous tissue
34
What is an autograft
Layer of own skin used
35
What is a allograft
Donor skin cadaver
36
What does central dogma mean
A theory stating that genetic info flows only in one direction from DNA to RNA to protein
37
Structure DNA
Double stranded High molecular weight
38
Structure RNA
Single stranded Heterogeneous in size, smaller, vary in size
39
What does a nucleotide consist of
Phosphate group Pentose sugar Base
40
Sugar used in RNA
B-D-ribose
41
Sugar used in DNA
B-D-2-deoxyribose
42
What bonds join nucleotides
Phosphodiester bonds between phosphate group and sugar
43
Comparison of RNA and DNA
RNA has a OH group at ribose C2 DNA doesn’t RNA uses uracil where DNA used thymine
44
Why is RNA unstable
Because the lone pair of electrons on OH group on C2 can react with phosphate
45
What are purines
Adenine and guanine
46
Pyrimidines
Cytosine and thymine
47
How is DNA wound up
Double helix with antiparallel strands Helices interact via hydrogen bonding between complimentary bases G&C and A&T DNA strands have 5’ and 3’ ends The base sequence of one strand determines the sequence of the others
48
What does 5’ and 3’ mean
The number of carbon atoms in a deoxyribose sugar molecule to which phosphate group bonds
49
Is C&G or A&T stronger
Guanine-cytosine base pair
50
What is a chromosome
A single molecule of DNA
51
What is a gene
Sequence of nucleotides that codes for a protein
52
What are mitotic chromosomes formed from
Tightly packed chromatin
53
Where is DNA found
In the nucleus and in mitochondria
54
How is DNA packaged into chromatin
By histones and other chromosomal proteins
55
How can DNA sequence differences be used
To paint chromosomes Specific probes of different colours reveal each chromosome pair
56
What are exons
Coding DNA
57
What are introns
Non coding DNA Removed from primary RNA by splicing machinery
58
Human genome contains repeated sequences
Often occur in blocks of tandem repeats Called ‘satellite DNA’ - highly repetitive DNA consisting of short sequence so repeated a large number of times
59
Types of satellite DNA
Mini satellite - highly polymorphic up to 1000 copies in one block also found at telomeres Micro satellite- small arrays of simple sequence repeats Usually in intergenic/ intronic (non coding) DNA
60
Telomeres
Allow replication to tip of chromosomes Long tracts of repeats can be unstable= deletions immediately below telomeres
61
Centromeres
Essential for segregation during cell division Proteins involved in cell division bind to centromeric sequences
62
Mini satellite
No known purpose Can cause mispairing during cell division to give Large scale duplication/deletion between homologous chromosomes Translocation of DNA between non-homologous chromosomes
63
What is the fundamental unit of chromatin
The nucleosome- this is DNA wound a histone core
64
How are decondensed chromosomes structurally organised in non-dividing cells
Attachment to nuclear skeleton Has a functional role e.g. clustering of ribosomal genes in the nucleolus
65
What is nucleolus
Large structure within the nucleus where ribosomal RNA is transcribed and ribosomal subunits are assembled
66
What is euchromatin
Transcriptionally active form of chromatin Prevalent in gene rich areas less compact allowing access for proteins involved in transcription
67
What is heterochromatin
Highly condensed region of an interphase chromosome generally gene poor and transcriptionally inactive Can exist in active (decondensed) or inactive (condensed) forms Or can always be inactive and condensed Found at telomeres and centromeres
68
When does chromatin structure change
During the cell cycle Also modified during gene regulation (allowing access to regulatory proteins and RNA polymerase)
69
DNA replication is
Semi conservative
70
What end are nucleotides added
at the 3’ end dNTPs (deoxyribonucleotide triphosphate) required
71
Where is DNA replication initiated
At replication origins The double helix opened with aid of initiator proteins, single stranded DNA templates ready for DNA synthesis
72
DNA polymerase
Mediates DNA replication Proceeds in a 5’ to 3’ direction Adds 1000 bases/ second to the chain Requires dNTPs Must have template and RNA primer Has ‘proof reading’ activity
73
What is a mutation
Is a permanent change in the sequence of DNA
74
Why does DNA polymerase have a high fidelity
Stability of base pairing Proof reading by DNA polymerase
75
How do DNA repair mechanisms work
Minimise introduction of mutations DNA mismatch repair proteins bind Removal of newly synthesised DNA strand Repair of gap by DNA polymerase and ligase
76
What is depurination
Lose a base
77
What is deamination
Cytosine becomes uracil
78
During which phase of cell cycle does DNA replication occur
S
79
Phases of mitosis
Prophase Prometaphase Metaphase Anaphase Telophase
80
What is the purpose of mitosis
Cell division Organismal growth Genetically identical products
81
Prophase
Chromosomes condense Centrosomes move apart
82
Prometaphase
Nuclear membrane breaks down Spindle microtubules attach to the kinetochores and move actively
83
Metaphase
Chromosomes align at the equator of the spindle Kinetochores from paired sister chromatids attach to opposite poles of spindle
84
Anaphase
Sister chromatids synchronously separate. Fast Kinetochore microtubules shorten Spindle poles move apart
85
Telophase
Chromosomes arrive at poles Nuclear envelope reassembles giving 2 new nuclei Nucleoli reappear- RNA synthesis begins Initiation of plasma membrane cleavage
86
Cytokinesis
Contractile ring is formed and mediates division of the cell in two
87
Function of meiosis
Reduction division (23 chromosomes per gamete) Re assortment of genes: independent segregation of chromosomes, crossing over
88
Mechanism of meiosis
Each homologue replicates to give two chromatids Homologous pair Exchange of material between non-sister chromatids Chiasmata (visible cytologically) are the physical manifestations of crossing over
89
What generates genetic variation
Independent assortment of maternal and paternal homologues at meiosis I Re-assortment of genes by crossing over
90
What are chiasmata
Hold chromosomes together first phase of meiosis Typical bivalent has at least one chiasma Larger chromosomes show more
91
Meiosis metaphase I
Kinetochore microtubules of sister chromatids point in same direction Kinetochores of sister chromatids function as a unit
92
Meiotic anaphase 1
Arms of sister chromatids become unglued
93
Meiotic metaphase II
Kinetochores point in opposite directions (as in mitosis)
94
Meiotic anaphase II
Cohesions in centromere degraded; sister chromatids separate
95
Difference between mitosis and meiosis
Mitosis designed to generate identical daughter cells Meiosis designed to make haploid gametes and generate genetic diversity
96
Genome
Complete set of DNA DNA sequence
97
Transcriptome
Complete set of RNA transcripts
98
Proteome
Complete set of proteins produced
99
Transcription
RNA synthesis needs a DNA template (RNA polymerase as enzyme) Nucleoside Triphosphates RNA is synthesised in a 5’ to 3’ direction Only one strand is copied RNA polymerase adds 50 bases per second
100
The ‘primary’ RNA transcript binds proteins involved in RNA processing ‘spliceosome’
Splicing requires RNA-protein complexes called snRNP Some genes have alternative splicing leading the production of different mRNA and proteins from same gene
101
What is tRNA
An adaptor molecule 3 ‘hairpin’ stem-loop structures Stabilised by base pairing Distinct functional regions Specific aminoacyl-tRNA synthetases Contains an anti codon
102
Polyribosome/polysome
More than one ribosome attaches to a single mRNA
103
How many possible reading frames does DNA sequence have
3 Defining start of coding region is important
104
The genetic code
Code is read in groups of 3 bases Read in a 5’ to 3’ direction 3 possible reading frames Each amino acid is coded for by a codon Some amino acids have more than one codon some only have one 3 codons do not encode amino acids (UAA, UGA and UAG are stop codons) Code is universal
105
Mutations can affect protein sequence
Deletion or insertion of one or more nucleotides Substitution or point mutations- alteration of a single base position Consequences depend on nature and position of mutation- biggest impact if in coding or regulatory region of gene
106
What is the name of the fascia that connects skin to body
Superficial fascia is found directly under the skin and superficial adipose layers
107
Epidermis definition
Keratinised stratified squamous epithelial cells. Located superficially to the dermis Avascular
108
Dermis definition
Deep to the epidermis and made of connective tissue Contains blood vessels and nerves Split into papillary and reticular dermis
109
Hypodermis definition
Loose connective tissue which connects skin to underlying tissues
110
Burns definition
Damage from heat, chemicals, electricity or radiation A scald is normally caused by water or steam
111
Skin appendages definition
Specialised structures associated with the skin such as hair, nails, glands
112
What is dermatitis
A medical condition in which skin becomes red, swollen and sore sometimes with small blisters Resulting from direct irritation of skin by an external agent or an allergic reaction
113
Eccrine sweat gland definition
A type of simple sweat gland that’s found in almost all regions of skin, these glands produce watery substance, sweat directly on skin surface Help to maintain homeostasis, primarily by stabilising body temperature, cools skin
114
Apocrine sweat gland definition
Open into the hair follicle leading to surface of skin Develop in areas with many hair follicles such as scalp, armpits and groin Tubular secretory glands Secrete a more viscous, odorous product
115
Sebaceous glands definition
Secrete sebum, which is an oily substance that helps skin/hair to be water-proof. Mostly associated with hair follicles Not found in palms and soles and are found in higher concentrations in face and scalp

MTM (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions