Case 1a Flashcards
Function of mitochondria?
Contain DNA, Site of ATP synthesis (energy production)
Where is mitochondrial DNA inherited from?
Mother
Function of lysosomes?
Destroy unwanted proteins and chemicals, Contain enzymes to perform this function, Break down small food molecules
Function of peroxisome organelle?
Breakdown of long chain fatty acids, which are then further broken down in mitochondria, Detoxifies harmful substances like hydrogen peroxide
Function of smooth endoplasmic reticulum?
Site of lipid and steroid synthesis
Why are there lots of smooth endoplasmic reticulum’s in the cells of the ovaries and testes?
Steroid hormone production
Functions of plasma membranes?
Retains cytoplasm, maintains cellular homeostasis, selective permeability, interacts with other cells with receptors
What is function of Golgi apparatus?
Modifies proteins by attaching carbohydrates to them, Packages proteins and some lipids received from the endoplasmic reticulum into vesicles
What is the function of the rough endoplasmic reticulum?
Coated in ribosomes, Site of protein synthesis, folding, modification and transport
What is the function of the nucleus?
Contains chromosomes, containing DNA, Site of DNA replication, transcription and RNA processing
What does DNA stand for?
Deoxyribonucleic acid
What does RNA stand for?
Ribonucleic acid
Function of ribosomes?
Site of protein synthesis, Interpret mRNA and assemble amino acid chains
Where are ribosomes found in the cell?
Free floating in the cytoplasm or attached to the rough endoplasmic reticulum
What is cytosol?
The liquid component of cytoplasm
Label a mammalian cell?
Insert photo
What are the 3 main areas of the sperm?
Head, Mid/connecting piece, Flagellum (tail)
What is contained in the head of the sperm?
Acrosome - tip of sperm’s head, Most of the sperm’s head is the nucleus
What is contained in the mid piece of the sperm?
Lots of mitochondria (to provide energy - ATP for sperm movement)
What is the flagellum of the sperm?
‘Tail’ like structure for movement
Label a sperm cell?
Insert image here
What is Zona pellucida?
A layer surrounding ovum. It contains lots of glycoproteins
What is the function of zona pellucida?
Protects egg from damage, Only allows one sperm through to fertilise the egg, Contains proteins the sperm can identify so they attach to the egg
What is corona radiata?
Layer of cells surrounding zona pellucida of ovum
Function of corona radiata?
Provides essential nutrients and hormones to developing egg to support it, Serves as additional protective layer, Guides and supports sperm as it approaches ovum, Regulates development and maturation of ovum
What are cortical granules?
Structures found in the cytoplasm of an ovum cell, Prevent multiple sperm entering the egg
What is perivitelline space?
Area between zona pellucida and plasma membrane of an ovum, Cortical granules release enzymes in here to prevent polyspermy (multiple sperm entering egg)
Draw an egg cell?
Insert an image here
What is spermatogenesis?
Sperm production in testes
Process of Spermatogenesis?
1) Mitotic proliferation: At puberty 2 types of spermatogonia proliferated Type A spermatogonia - Stem Cells (2n) Type B spermatogonia - These differentiate into primary spermatocytes (2n)
2) Meiotic differentiation
Type B spermatogonia -> primary spermatocytes (2n) via differentiation
Primary spermatocytes -> 2 x secondary spermatocytes (2n) via 1st meiotic division
2 x Secondary spermatocytes -> 4 x Spermatids (n) via 2nd meiotic division
3) Spermiogenesis (Round) Spermatids develop into spermatozoa (sing. Spermatozoon) They are remodelled and acrosome and flagellum develop. Nuclear condensation and cytoplasm shedding makes it more streamlined.
What is oogenesis?
Creation of ovum (inside follicle). The creation of the ovum (oogenesis) is a separate process to the development of the follicle around it (Folliculogenesis)
Describe process of oogenesis?
Inside embryo
1) Primordial germ cells from the yolk sac of the female embryo move to the developing ovaries.
2) These divide by mitosis to form millions of oogonia
3) Oogonia start first meiotic division, though stop at the diplotene stage of prophase 1, becoming primary oocytes. They stay this way throughout childhood until puberty.
After puberty
4) Between birth and puberty many primary oocytes die via apoptosis
5) Hormone cycles of LH and FSH cause a small number of primary oocytes to be recruited each month, though usually only one fully matures
6) The primary oocyte completes first meiotic division and divides into a larger secondary oocyte and a polar body
7) A singular secondary oocyte is released from ovaries every month and waits in the ovarian tube to be fertilised by a sperm.
8) If a sperm penetrates the secondary oocyte, it will complete the 2nd meiotic division, producing a mature ovum and a small polar body.
9) The ovum can now fuse with sperm to form a zygote
What is folliculogenesis?
Development of the follicle which surrounds the oocyte
What is a follicle?
Contains an oocyte surrounded by granulosa and theca cells
What does a follicle look like?
Insert photo
Function of follicle?
Hormone production, Provides necessary environment for development and growth of oocyte, Releases secondary oocyte into ovarian tube (ovulation), After ovulation, the ruptured follicle forms the corpus luteum
Describe process of folliculogenesis
1) Primordial follicle: A primary oocyte surrounded by a single layer of squamous (flat) granulosa cells
2) Primary follicle: Hormonal changes at puberty (mostly FSH) stimulate primordial follicle to activate. Granulosa cells change from squamous to cuboidal. Zona pellucida forms around oocyte
3) Secondary follicle: Granulosa cells proliferate and theca layer forms (outside granulosa cells) . Small fluid filled gaps between granulosa cells form.
4) Tertiary (Antral) follicle: Follicle continues to mature and fluid filled gaps merge, forming antrum (a cavity)
5) Graafian follicle (mature): It is fully matured and ready to release secondary oocyte inside in response to LH surge
Describe process of sperm meeting ovum?
1) Sperm in seminal fluid enters vagina 2) Contractions of uterine muscles caused by prostaglandins encourage sperm into uterus 3) Peristaltic action of oviduct wall moves ovum along uterine tube into ampulla (middle) 4) Sperm and ovum meet 5) Acrosome of sperm uses enzymes to break down zona pellucida of ovum (outer layer) 6) Sperm goes through perivitelline space of ovum before fusing 7) Sperm nucleus merges with ovum nucleus, forming a 46 chromosome zygote 8) Ovum releases enzymes from cortical granules into zona pellucida in order to prevent additional sperm entering (polyspermy)
What is a zygote?
A single cell organism formed when a sperm fertilises an ovum
How many chromosomes in: Sperm, ovum, normal cell, zygote?
Sperm-23, Ovum-23, Normal cell-46, Zygote-46
Give a very simplified step by step process of the first 3 weeks of pregnancy?
Day 1 - Fertilisation and zygote formation, Day 2-3 - Cleavage divisions (mitosis), Day 3-4 - Morula formation (8 cells), Day 4-5 - Blastocyst formation (32-64 cells), Day 5 - Blastocyst hatching, Day 6-7 - Implantation of blastocyst in endometrial lining of uterus, Week 2 - Bilaminar germ disc formation, Week 3 - Trilaminar germ disc formation
What is gastrulation?
Formation of trilaminar germ disc
Outline process of formation of a morula from a zygote?
Day 3-4 post fertilisation Zygote divides via mitosis into smaller cells called blastomeres (these are called cleavage divisions) Once there are about 8 cells they begin to compact and form a morula A morula is still within the zona pellucida so is about the same size as the original zygote The morula moves down the uterine tube towards the uterus
What is morula?
Collection of cells (8-16) formed from zygote during cleavage divisions
Outline process of formation of a blastocyst from a morula?
The morula continues dividing until it becomes a blastocyst (32-64 cells) The cells form a fluid filled cavity known as a blastocoel which starts to appear in the centre of the morula At this stage, the outer layer of the blastocyst will start to differentiate into trophoblast (which eventually becomes the placenta) and the inner layer becomes the embryoblast (which becomes the embryo)
What is a blastocyst?
A ball of cells (32-64) made of two distinct cell layers (trophoblast and embryoblast) surrounding a fluid filled cavity
What is the trophoblast?
Outer layer of cells which will become placenta
What is inner cell mass of blastocyst?
Group of cells which will form embryo
Outline process of hatching and implantation of blastocyst?
Day 5 - Blastocyst hatches from zona pellucida; It attaches to endometrial lining of uterus; The trophoblast of blastocyst differentiates into cytotrophoblasts and syncytiotrophoblasts
What is cytotrophoblast?
Inner cell layer of trophoblast
What is syncytiotrophoblasts?
Outer cell layer which invades endometrium and establishes future connections for nutrient exchange (eg glands and capillaries)
Outline process of bilaminar disc formation from blastocyst?
Day 6-7 Blastocyst is implanted in endometrial lining of uterus; Day 7-8 Inner cell mass of blastocyst differentiates into: Epiblast - upper layer which will form trilaminar disc (then embryo); Hypoblast - lower layer which will form extra embryonic structures such as yolk sac; Day 8: Small fluid filled amniotic cavity forms above epiblast; Day 9-10: Yolk sac forms from hypoblast; Day 11-12: layer of extra embryonic mesoderm forms between trophoblast and newly formed aminon and yolk sac; Extraembryonic coelum (cavity) forms which surrounds amniotic cavity and yolk sac
Structure of bilaminar disc?
Top layer - epiblast (will form trilaminar disc and then embryo); Bottom layer - Hypoblast (will form extraembryonic structures such as yolk sac)
What is extraembryonic coelom/ chorionic cavity?
Fluid filled space which forms in early embryonic development and surrounds developing embryo; Plays significant role in separating different layers of extraembryonic tissues
What is extraembryonic mesoderm?
Plays crucial role in development of extraembryonic membranes that support placenta; Particularly placenta, yolk sac and Chorion
What is gastrulation?
Formation of trilaminar disc from bilaminar disc
Outline process of gastrulation?
Week 3; 1)Primitive streak formation: A line of thickened epiblast cells form on the top all the way along midline of the bilaminar disc; 2)cells in epiblast move towards streak and dive down into embryo and form 3 germ layers: endoderm, mesoderm, ectoderm; 3)Primative node forms at the head of of the primitive streak. It acts as a control centre for development of embryo
What are the 3 layers of the trilaminar embryonic disc?
Ectoderm (external), Mesoderm (middle), Endoderm (inside)
What is derived from Ectoderm (Outer)?
Mostly external and nervous structures; -Nervous system; -Epidermis, hair, nails; -Sweat and sebaceous glands; -Retina and lens of eye; -Inner ear; -Mucous membranes; -Tooth enamel
What is derived from mesoderm (Middle)?
-Muscle; -Bones and cartilage; -Heart, blood vessels and blood cells; -Kidneys; -Connective tissues (tendons and ligaments); -Lymphatic system
What is derived from endoderm (Inner)?
-Epithelial lining of GI tract; -Liver and pancreas; -Lining of resp tract; -Bladder and urethra; -Thyroid and parathyroid gland; -Thymus
What is an extra embryonic membrane?
Structures that form outside of the embryo during early stages of development in womb
Give examples of extraembryonic membranes ?
Yolk sac, Amnion, Chorion, Allantois
What is Yolk sac?
First site of blood cell formation; Provides nutrients to embryo before placenta is fully functional
What is amnion?
Surrounds embryo (makes cavity filled with amniotic fluid)
What is chorion?
Becomes part of the placenta
What is allantois?
Becomes vascular connection between embryo and placenta
What is homeostasis?
Maintainence of a relatively constant internal environment in response to environmental changes.; Maintains various ‘levels’ throughout body - eg blood glucose, water levels, temperature and pH; Uses both nervous and endocrine systems
How does nervous system work in homeostasis?
Acts quickly to restore balance; Involved in immediate responses - eg shivering/sweating to cold/hot
How does endocrine system work in homeostasis?
Works slowly; Releases hormones into blood which travel to target organs and cause long lasting effects; Eg blood glucose control
Ideal body temperature?
37c
What are the 2 part of the nervous system?
Central nervous system and peripheral nervous system
What is in Central nervous system?
Brain and spinal cord
What is In peripheral nervous system?
Connects brain and spinal cord to the rest of the body; Spinal and cranial nerves; Sensory, motor and autonomic nerves
What is negative feedback?
Response decreases the effect of the original stimulus (usually to maintain constant internal environment - homeostasis)
What is positive feedback?
Response increases effect of original stimulus
Outline the process of negative feedback?
1)Stimulus (initial change) occurs; 2)Receptors detect change; 3)Receptors send messages to the control centre (usually brain or endocrine gland); 4)Control centre responds by releasing chemicals or hormones which will reverse the change; 5)Effector (such as muscle, gland or organ) responds to counteract change, bringing the body back to normal; 6)Body returns to normal range and negative feedback loop ends
Outline the process of positive feedback?
1)Stimulus (initial change) occurs; 2)Receptors detect change; 3)Receptors send messages to the control centre (usually brain or endocrine gland); 4)Control centre responds by releasing chemicals or hormones which will amplify the change; 5)Effector (such as muscle, gland or organ) carries out response to amplify the original change; 6)The cycle repeats, further intensifying original stimulus
Function of hypothalamus?
-Produces releasing hormones (eg gonadotropin releasing hormone) and inhibiting hormones (eg growth hormone - inhibiting hormone) …which act on anterior pituitary; -Regulates homeostasis; -Controls autonomic functions (eg heart rate); -Plays a role in emotional regulation and behavioural stress response
Function of anterior pituitary?
-Produces and releases a wide range of hormones including growth hormone, thyroid-stimulating hormone, follicule-stimulating hormone and luteinizing hormone; -It is regulated by releasing-hormones and inhibiting-hormones which are released from hypothalamus
Function of posterior pituitary?
-It stores and releases hormones produced by hypothalamus (doesn’t produce hormones); -Hormones synthesised in hypothalamus are transported down the axons of hypothalmic neurons to posterior pituitary. They are released into blood stream as needed.; -Releases eg: Anti-diuretic hormone (ADH) and oxytocin
What type of feedback is regulation of body temperature?
Negative feedback
What type of feedback is childbirth?
Positive feedback
Describe the negative feedback response when body temperature is too high?
1)Increase in body temperature (stimulus); 2)Thermoreceptors in skin and hypothalamus detect change; 3)Thermoreceptors send nerve impulses to hypothalamus; 4)Hypothalamus releases substances to initiate negative feedback response; 5)Effects eg: Vasodilation, Sweating, Increased resp rate; 6)As body cools towards normal, signals from thermoreceptors to hypothalamus reduce in intensity
Describe the negative feedback response when body temp is too low?
1)Decrease in body temperature (stimulus); 2)Thermoreceptors in skin and hypothalamus detect change; 3)Thermoreceptors send nerve impulses to hypothalamus; 4)Hypothalamus releases substances to initiate negative feedback response; 5)Effects eg: Vasoconstriction, shivering, increased metabolism; 6)As body warms towards normal, signals from thermoreceptors to hypothalamus reduce in intensity
The five standard steps of cell signalling process?
1)Biosynthesis and release of signal; 2)Signal shared to target cell (disseminate); 3)Signal is detected by receptor and transduction occurs; 4)Cell phenotype is altered (cell responds to signal); 5)Signal is terminated (it has been responded to)
Dissemination meaning?
To spread widely throughout body’s tissues and organs
Transduction meaning?
Process of converting something (eg energy/message) into another form
Ligand meaning?
Chemical messenger/molecule that binds to another molecule (on receptor) to produce changes in the cell
Examples of signalling molecules?
Hormones (endocrine), neurotransmitters (synaptic), cytokines (immune), growth factors
What is paracrine signalling?
When a cell produces signalling molecules which affect nearby cells by binding to their receptors
What is autocrine signalling?
When a cell produces signalling molecules that bind to its OWN receptors
What is a paracrine gradient?
Concentration change of signalling molecule as you move away from the cell releasing them
Question
Answer
How does the paracrine gradient effect cells?
How close the cell is to the signalling cell effects the response it will have. Eg if it is closer it may have a stronger response, or in some cases eg development it may have a different response. Eg in development, the paracrine gradient controls what type of cell it will become.
What is sonic hedgehog (SHH) signalling?
Sonic hedgehog signalling pathway is used to control how cells grow, where they move, and what they become during development. It works through a gradient system where cells respond differently depending on how much SHH signal they receive. This ensures tissues and organs develop in the right place with the right structure.
What is endocrine signalling?
The release of hormones into the blood stream by endocrine glands which target cells throughout the body, causing a variety of effects eg. Sex hormones, growth hormones.
Steps of synaptic transmission?
1) Action potential arrives down pre-synaptic neurone causing depolarisation. 2) This triggers voltage gated calcium channels to open, allowing calcium ions into pre-synaptic terminal. 3) This prompts synaptic vesicles containing neurotransmitter to move towards presynaptic membrane and fuse with it. This causes neurotransmitters to be released into synaptic cleft. 4) Neurotransmitters diffuse across synaptic cleft and bind to receptors on post synaptic cell. 5) This binding triggers a response in post synaptic cell.
What is synaptic plasticity?
Synaptic plasticity is the ability of connections between neurones to change depending on how much they are being used. This is important for learning things and remembering information.
What is long term potentiation in terms of synaptic plasticity?
Long term potentiation is when you use a synapse a lot - eg studying or practicing a sport. The 2 neurones are activated together frequently, so synaptic strength increases. More receptors are created on the post synaptic membrane, enhancing the response created.
What is long term depression in terms of synaptic plasticity?
Long term depression is when you don’t use a synapse a lot. The number of receptors on the post synaptic membrane decreases, so the synapse is weakened.
What can happen if you have abnormal synaptic plasticity?
Neurological disorders such as autism, Alzheimer’s, Schizophrenia, depression, epilepsy.
Why must a neurotransmitter be removed from a synapse?
To prevent continuous stimulation of post synaptic neurone.
What are the 2 main methods of removing neurotransmitter from synapse?
Enzymic degradation - breaking down neurotransmitter with enzymes. Reuptake into presynaptic neurone.
What are ligand gated ion channels?
Proteins in cell membrane which are like gates which open/close to allow ions in and out of the cell.
How do ligand gated ion channels work?
Ligand (eg neurotransmitter) binds to the channel, causing it to change shape and let ions into the cell. This changes the charge inside the cell, causing effects such as nervous conduction or muscle contraction.
Is the effect of a ligand the same on different types of receptor?
No, ligands can have multiple functions depending on the receptor they interact with.
Give 2 examples of common ligand gated ion channels?
- Nicotinic acetylcholine receptors. - GABA receptors.
What are nicotinic acetylcholine receptors?
Ligand gated ion channels which respond to acetylcholine. When acetylcholine binds to nAChR (nicotinic acetylcholine receptor) it allows ions to flow into the cell causing depolarisation of a membrane.
What does depolarisation of cell membrane caused by acetylcholine binding cause in neurone cells?
Initiation of action potential.
What does depolarisation of cell membrane caused by acetylcholine binding cause in muscle cells?
Muscle contraction.
What is the meaning of depolarisation of a cell membrane?
Process of reducing the difference in charge across a cell membrane - making it closer to equilibrium.
Explain the process and effect of acetylcholine binding to nicotinic acetylcholine receptors (nAChR) of neurone cells?
1) Binding of acetylcholine to nAChR. 2) Receptor changes shape, sodium channels open and sodium ions diffuse into cell. 3) The cell becomes less negative, depolarising the cell membrane (due to the influx of sodium ions). 4) If the depolarisation is strong enough, the threshold is reached, triggering an action potential. This causes nervous transmission.
What is the function of GABA receptors?
GABA binds to GABA receptors, this causes an influx of chloride ions into the neurone. This makes the neurone more negatively charged, reducing the likelihood of the threshold for action potential to be reached. Overall, GABA slows down the activity of neurones.
What are cell-cell connections?
Connections which allow direct communication between adjacent cells (substance exchange).
What are gap junctions?
A channel made by proteins called connexins that joins 2 adjacent cells. It allows direct passage of ions and small molecules between cells. This allows for fast coordinated responses.
Give 2 common examples of where gap junctions are used?
Cardiac muscle. Smooth muscle.
What are G Protein Coupled receptors?
A large family of cell surface receptors attached to G proteins which detect various ligands and cause an intracellular response (wide range of uses).
What is the function of GDP and GTP (simple)?
Act as energy carriers and signalling molecules in cells (similar to ATP and ADP).
What is the structure of a G protein?
- Alpha subunit which binds to GDP or GTP. - Beta subunit. - Gamma subunit.
What is the difference between when the alpha subunit of a G protein is bound to GDP or GTP?
When bound to GDP it is inactivated. When bound to GTP it is activated.
Where is the G protein compared to the G protein coupled receptor?
The receptor is in the cell membrane and the G protein is inside the cell, attached to the receptor.
How do G-Protein coupled receptors work?
1) Ligand (eg hormone/neurotransmitter) binds to receptor. 2) G protein becomes activated - the alpha subunit exchanges ADP molecule for ATP, which activates it. 3) Alpha sub unit dissociates from Beta and Gamma subunits and moves further into cell. 4) This causes a cascade of intracellular responses which vary widely. 5) The GTP attached to the alpha subunit is then hydrolysed back into GDP. This disactivates G protein, stopping the intracellular response.
Why are G-Protein coupled receptors important?
- They are used to detect sight, smell and taste. - Many functions in body including in control of heartbeat, mood and stress and involved in immune response. - Many medicines target GPCRs.
What is a receptor tyrosine kinase?
A receptor which detect ligands mainly for processes like growth, healing and development. They have a receptor on the outside of the cell and a tyrosine kinase domain on the inside of the cell.
What is the extra cellular domain of a receptor?
The part of a receptor which sticks outside of the cell.
What is the transmembrane domain of a receptor?
The part of the receptor which passes through the cell membrane.
What is the intracellular domain of the receptor?
The part of the receptor which is inside the cell.
Describe the process of activation of receptor tyrosine kinases?
1) Ligand binds to a receptor tyrosine kinase. 2) Two receptors come together to form a pair - this is called dimerisation. 3) They phosphorylate (add phosphates to) each others tyrosine molecules (the part inside the cell). 4) This activates the receptors, triggering a cascade of intracellular pathways. 5) This can influence many processes like cell growth, differentiation and metabolism.
Why are receptor tyrosine kinases important?
- They control cell growth and division. - They have a role in development. - Used in tissue repair and healing. - Regulate metabolism. - Overactive RTKs can cause cancer.
How do hydrophobic ligands work?
Can pass through cell membrane. Bind to receptors located inside cell.
Examples of hydrophobic ligands?
Steroid hormones - eg testosterone and oestrogen.
How do hydrophilic ligands work?
Can’t pass through cell membrane. Bind to receptors on cell surface. They send signals inside the cell through a signalling pathway.
Examples of hydrophilic ligands?
Peptide hormones - eg insulin and growth factors.
Why must non-peptide ligands bind to carrier proteins so they can travel through the blood?
They are hydrophobic and blood has a lot of water in (Hydrophobic ligands - eg steroid hormones (oestrogen etc)).
What is phosphorylation?
Addition of a phosphate group PO₄³⁻ to a protein or molecule.
Function of kinases?
Catalyse phosphorylation (addition of phosphate group to a protein or molecule).
Function of phosphatases?
Reverse phosphorylation - remove phosphate group from a protein or molecule.
Function of phosphorylation examples?
- Activate and deactivate proteins (eg enzymes). - Used in signal transduction in signal cascades (eg one phosphorylated protein activates others).
What is a second messenger?
They help relay and amplify signals from first messenger (typically a ligand binding to receptor on cell surface) and cause intracellular response.
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Answer
Examples of common second messengers?
Cyclic AMP; Calcium ions
How does calcium work as a second messenger?
1) Ligand binds to ligand-gated calcium ion channel; 2) Calcium moves into the cell; 3) Calcium binds to proteins with binding sites
Function of phosphodiesterase?
Converts cAMP to AMP
Examples of uses of calcium as a second messenger?
Muscle contraction in muscle cells; Insulin release in beta cells
How does cAMP work as a second messenger?
1) Ligand binds; 2) This causes G protein on G protein-coupled receptor to become activated; 3) This activates adenylyl cyclase; 4) This leads to conversion of ATP to cAMP; 5) This activates protein kinase A
Examples of uses of cAMP as a second messenger?
Metabolism regulation; Hormone responses; Gene expression regulation
Explain process of phospholipid signalling?
1) Phospholipid signalling typically activated by ligand binding to a receptor; 2) Phosphatidylinositol biphosphate (PIP2) - a type of phospholipid in the membrane- is hydrolysed by enzymes (eg phospholipase C) into: inositol triphosphate (IP3) and diacylglycerol (DAG); 3) -IP3 acts as a second messenger that triggers calcium ion release
Examples of uses of phospholipid signalling?
Muscle contraction; Glucose metabolism; Cell growth and differentiation; Immune response
What type of cells in a multicellular vs a single cellular organism?
Eukaryotic - multi cellular; Prokaryotic - single cellular
How is genetic material stored in eukaryotic cells?
DNA in nucleus
How is genetic material stored in prokaryotic cells?
Cytoplasm
Function of the plasma membrane?
Defines the boundary; Retains the cytoplasm; Selectively permeable; Allows cells to interact with other cells via receptors
Composition of the plasma membrane?
Fluid mosaic; Made up of phospholipid bilayer; Proteins (eg receptors)
What is a cytoskeleton?
In eukaryotic cells. It provides structure
What is an epithelia?
Covers internal and external surfaces of organs
Where is the basal lamina found?
Under the epithelia
What is a simple epithelium?
Single layer of cells
What is a stratified epithelium?
Multiple layers of cells
What is a pseudostratified epithelium?
Appears to be in layers but is actually a single layer
What is a squamous epithelium?
Made of thin flat cells
What is a ciliated epithelium?
Contains cilia - tiny hair-like projections
What is a columnar epithelium?
Contains tall
What is a keratinised epithelium?
Contains keratin (for strength and waterproofing)
What is a cuboidal epithelium?
Cells are cube-shaped
Structure of simple squamous epithelium?
Flat surface cells
Function of simple squamous epithelium?
Exchange of nutrients and gases
Example locations of simple squamous epithelium?
Blood vessels; Chambers of the heart; Alveoli
Structure of stratified squamous epithelium?
Flat surface cells
Function of stratified squamous epithelium?
Protection and barrier
Example locations of stratified squamous epithelium?
Oral cavity; Anus; Vagina; Oesophagus; Skin; Corneal epithelium
Structure of keratinised stratified squamous epithelium?
Flat surface cells
Function of keratinised stratified squamous epithelium?
Waterproof barrier
Example locations of keratinised stratified squamous epithelium?
Epidermis of palm of hand; Sole of foot
Function of cuboidal epithelium?
Absorption and secretion
Example location of cuboidal epithelium?
Salivary glands; Lacrimal glands (tears); Pancreas; Kidney tubules
Function of columnar epithelium?
Absorption and secretion
Example locations of columnar epithelium?
Many sites in GI tract eg small intestine and gall bladder
Function of goblet cells?
Produce mucus
Where are goblet cells found?
Respiratory tract; GI tract
What are cilia?
Small hair-like structures
What are microvilli?
Tiny finger-like projections
What are stereocilia?
Specialised
What is a transitional epithelium?
Cells change shape eg. They flatten to accommodate bladder filling
4 types of connective tissue?
Connective tissue proper; Cartilage; Bone; Blood
What is the function of tendons?
Connect muscle to bone
What is the function of ligaments?
Connect bones to bones
What are the 2 types of connective tissue proper?
Loose connective tissue; Dense connective tissue
What are the 3 types of loose connective tissue?
Areolar; Adipose; Reticular
What are the 3 types of dense connective tissue?
Regular; Irregular; Elastic
What is areolar connective tissue?
Loose connective tissue; Provides flexibility and cushioning around organs and blood vessels
What is adipose connective tissue?
Loose connective tissue; Specialised for fat storage
What is reticular tissue?
Loose connective tissue; Supportive framework for organs like liver
What is dense regular connective tissue?
Contains tightly packed parallel collagen fibres; High tensile strength
What type of connective tissue forms tendons and ligaments?
Dense regular connective tissue
What is dense irregular connective tissue?
Irregularly arranged collagen fibres; Allows strength in multiple directions; Found In dermis
What type of connective tissue forms dermis of skin and a protective covering around organs?
Dense irregular connective tissue
What is dense elastic connective tissue?
Lots of elastic fibres and collagen fibres
What type of connective tissue found in arteries and bronchial tubes?
Dense elastic connective tissue
What are the 3 types of Cartilage?
Hyaline; Elastic; Fibrocartilage
What is hyaline cartilage?
Has a glassy smooth appearance; Made of a fine network of fine collagen fibres
What type of tissue is found on the articular surface of joints
costal cartilage
What type of cartilage is used during bone formation?
Hyaline cartilage
What is elastic cartilage?
Contains elastin and collagen fibres; Used for strength and elasticity
What type of cartilage in external ear and epiglottis?
Elastic cartilage
What is fibrocartilage?
Made of a dense network of thick collagen fibres; Strong support and a shock absorber
What type of cartilage in intervertebral discs and pubic symphysis?
Fibrocartilage
2 types of bone tissue?
Compact bone; Spongy bone
Characteristics of compact bone?
Dense and hard
Where is compact bone found?
The outer layer of all bones
Characteristics/structure of spongy bone?
Lattice-like structure with red bone marrow filling the gaps; Shock absorption
Where is spongy bone found?
Ends of long bones; Interior of short and flat bones
How to identify the epithelium on a microscope slide?
Dark when stained due to tightly packed cells
What is a mucosa?
Lines body’s canals and organs in digestive
What are the 3 layers of a mucosa?
Epithelial lining; Lamina propria; Muscularis mucosae
What is lamina propria?
Thin layer of connective tissue below epithelium in mucus membranes
What is muscularis mucosae?
Outer layer of the mucosa; Made of a very thin layer of smooth muscle cells
What is the submucosa?
Layer of connective tissue found just below the mucosa
What type of epithelium is in the oesophagus and why?
Non keratinised stratified squamous epithelium; It must be resistant to abrasion and friction as food and liquid are swallowed; No keratin to help the surface maintain moisture and flexibility
What are the lamina propria and submucosa layer made of in oesophagus?
Loose connective tissue
What type of epithelium is skin and why?
Keratinised stratified squamous epithelium; Needs to be water resistant and very protective
What type of epithelium are alveoli and why?
Simple squamous epithelium; Must be extremely thin for rapid gaseous exchange
What type of epithelium is the thyroid and why?
Simple cuboidal epithelium; Both diffusion (needs thin layer) and secretion occur; Cuboidal cells are used in secretion
What type of epithelium in small intestine and why?
Simple columnar epithelium with villi
What are plicae circulares in small intestine?
Large
What type of tissue are lamina propria and submucosa of small intestine made of?
Loose connective tissue
Question
Answer
What type of epithelium in trachea and why?
Pseudostratified, ciliated, columnar epithelium with goblet cells and cilia. Goblet cells for secretion, Cilia for mucus clearance. Pseudostratified to balance having a protective function with being thin and flexible
What are lamina propria and submucosa of trachea made of?
Loose connective tissue
Genotype?
Genes of a person
Phenotype?
Observable characteristics of a person
Allele?
Different versions of the same gene
Autosome?
All chromosomes except sex chromosomes
Sex chromosomes?
X and Y chromosomes
Homozygous?
2 identical alleles of a gene
Heterozygous?
2 different alleles of a gene
Hemizygous?
A person only has one copy of a gene rather than the usual two
Congenital?
Disease present since birth
Dominant?
Expressed when one copy
Recessive?
Only expressed when both alleles are the same
Meaning of X linked inheritance?
Gene is on the X chromosome
Meaning of Y linked inheritance?
Gene is on the Y chromosome
Meaning of autosomal inheritance?
Gene is on an autosome
Social impacts of a long term health condition?
Social isolation, changes in relationships, loss of independence, change in social activities, stigma
Personal impacts of a long term health condition?
Emotional wellbeing, coping mechanisms, finance, quality of life, self-esteem
3 primary layers of skin?
Epidermis
Describe the epidermis?
Outermost layer of skin made of stratified squamous epithelium
5 layers of epidermis?
Stratum corneum
Describe stratum corneum?
Outermost layer composed of dead, flattened keratinised cells to form a protective barrier
Describe stratum lucidum?
Found only in thick skin (eg palms and soles), additional layer of protection
Describe stratum granulosum?
Contains keratinocytes that begin to flatten and lose their nuclei, becoming more keratinised
Describe stratum spinosum?
Several layers of keratinocytes connected by desmosomes, providing strength and flexibility
Describe stratum basale?
Deepest layer where new keratinocytes are created. This layer also contains melanocytes (produce melanin) and merkel cells (touch receptors)
What are keratinocytes?
A type of cell which make up a lot of the epidermis
What are merkel cells?
Specialised skin cells found in epidermis which detect light touch and texture
Describe the dermis?
It is below epidermis and is thicker, made of connective tissue. Provides strength and elasticity due to collagen and elastin fibres
What are the 2 layers of the dermis?
Papillary dermis and reticular dermis
Describe papillary dermis?
Upper layer of dermis. Contains loose connective tissue, contains capillaries, touch receptors, and nerve endings
Describe reticular dermis?
Thickest lower layer of dermis containing dense irregular connective tissue. Contains larger blood vessels, glands, hair follicles, and deeper pressure receptors (Pacinian corpuscles)
Describe hypodermis?
Deepest layer of skin, below dermis. Composed mostly of connective tissue and adipose tissue (fat). Helps insulate the body, absorb shock, and anchors skin to muscles and bones below
What is an epithelial appendage?
Structures which derive from the epithelia
Examples of epidermal appendages?
Hair follicles, sebaceous glands, sweat glands, nails, sensory receptors
Where are hair follicles in the skin?
Extend from epidermis into dermis
What are sebaceous glands?
Secrete sebum into hair follicles. Help lubricate skin and hair and have antibacterial properties
2 types of sweat glands and where are they found?
Eccrine glands - all over body - secrete watery sweat. Apocrine glands - in armpits and groin - secrete thicker sweat
What are Meissners corpuscles?
Touch receptors located in papillary dermis, sensitive to light touch
What are Pacinian corpuscles?
Pressure receptors located deep in dermis and hypodermis, sensitive to deep pressure and vibration
What are the major functions of the skin?
Physical protective barrier, UV protection, Regulates body temperature by vasodilation/constriction and sweating, Sensation due to receptors so body can respond to external environment, Excretion of waste products through sweat, First line of defense for immune system, Site of vitamin D synthesis
