IMMS Flashcards
What does allosteric mean?
It is altering the activity of an enzyme by means of a conformational change induced by a different molecule
What forms the secondary yolk sac?
The hypoblast forms new cells that migrate along the exocoelomic membrane, proliferate it and gradually form a new cavity within the primitive yolk sac. This is the secondary yolk sac and it replaces the primitive yolk sac.
What does the embryoblast differentiate into?
The epiblast and the hypoblast. The two layers together form the bilaminar disc.
What does the epiblast cells do?
The epiblast cells give rise to amnioblasts that line the amniotic cavity superior to the epiblast layer
What do the hypoblast cells do?
The hypoblast gives rise to cells that line the blastocyte cavity and the inner surface of the trophoblast. They form the exocoelomic membrane. The cavity is now the primitive yolk sac/exocoelomic cavity
What does the trophoblast differentiate into?
The cytotrophoblast and the syncytiotrophoblast.
What is the syncytiotrophoblast?
The syncytiotrophoblast is the outer layer of the trophoblast. It erodes maternal tissue and is how the maternal blood enters the embryo
What is the extraembryonic mesoderm
A new population of cells appear between the inner surface of the cytotrophoblast and the outer surface of the exocoelomic membrane of the primitive yolk sac. These cells, derived from yolk sac cells, form a fine, loose, connective tissue, which is the extraembryonic membrane
What is epicenesis?
The development of an egg or seed through cell division and the formation of organs
What is preformation?
A pre-formed, miniature human is in the sperm and is planted in the female during intercourse
What is development biology?
Examining the correlations between genes and morphological changes that occur in the embryo
What is the embryonic period?
It is the time between fertilisation to the beginning of the ninth week
What does virtue ethics believe in?
It focuses on the character of the agent. It integrates reason and emotion.
What are the five focal virtues?
Compassion, discernment, trustworthiness, integrity and conscientiousness. These virtues are acquired, just like skills.
What is deontology?
It believes the features of the act themselves determine worthiness. There are hypothetical and categorical imperatives from which duties and obligations are derived.
What is utilitarianism?
An act is evaluated solely in terms of its consequences. It believes in maximising good. It considers the likely consequences and picks the best one
What is hedonistic utilitarianism?
Pleasure vs pain - simple sensory vs higher cognitive
What is preference utilitarianism?
Utility increases as preference/desire is satisfied
What is closed awareness?
The patient doesn’t know they are going to die but others do and haven’t told them
What is suspicion awareness?
The patient doesn’t know they are going to die but has their suspicions even though the health professionals haven’t confirmed anything
What is mutual pretence?
Everyone ones the patient is going to die but nobody talks about it
What is open awareness?
Everyone knows the patient is going to die and everybody talks about it openly
What is acute illness?
A disease of short duration that starts quickly and had sever symptoms
What is chronic illness?
A persistent or recurring condition. The distance, which may or may not be severe, often starts gradually and changes will be slow
What are the three health behaviours?
Health behaviour, illness behaviour and sick role behaviour
What is health behaviour?
A behaviour aimed to prevent disease
What is illness behaviour?
A behaviour aimed to seek remedy (like going to the doctors)
What is the sick role behaviour?
Any activity aimed at getting well (taking antibiotics)
What is unrealistic optimism?
Individuals continue to damage their health due to inaccurate perceptions or risk and susceptibility due to: lack of personal experience with the problem; belief it is preventable by personal action; belief that if its not happened by now, it’s not going to; belief that a problem is infrequent
What is a cohort study?
It is an observational, analytical study. Start with the population, look at if they were exposed to the variable then see if they develop the disease
What is a case-control study?
It is an observational, analytical study. Start with the cases and controls, look back at whether they were exposed to the variable
What are the five steps of evidence based practise?
- Asking focused questions. 2. Finding the evidence. 3. Critical appraisal. 4. Making a decision. 5. Evaluating performance
What is a cross-sectional study?
An observational, analytical study. It looks at association at one time point
What is demography?
The anatomy of the population
What is sociology?
The physiology of the population
What is epidemiology?
The pathology of the population
What is FAD?
It a coenzyme that carries hydrogen. It is derived from the vitamin riboflavin. It is bound to its enzyme which in turn in ‘stuck’ in the inner membrane of the mitochondrion. Each FAD is oxidised by the respiratory chain to produce 1.5 ATP molecules
What is NAD?
It is a coenzyme that carries hydrogen. It is derived from the vitamin niacin. It is involved in redox reactions. The reduced form is NADH. Each NADH is oxidised by the respiratory chain to produce 2.5 ATP molecules
How is ATP regenerated?
It requires a source of energy. A controlled series of chemical reactions including: glycolysis; the Krebs cycle; oxidative phosphorylation. This created ATP directly through substrate level phosphorylation and via electrons by oxidative phosphorylation.
What are the key functions of the sodium potassium pump?
(1) it established an intracellular environment high in K+ and low in Na+ (2) control of cell volume (3) provides an electrochemical gradient for sodium, driving other active transport systems (4) establishing a resting potential both directly and indirectly via the ion gradient
What does phosphocreatine do?
Phosphocreatine serves as a ready source of phosphoryl groups to synthesis ATP from ADP. The phosphocreatine concentration in skeletal muscle is considerably higher than in other tissues. The enzyme creatine kinase catalyses the reversible reaction.
What is Gibbs free energy?
It is the energy liberated and available for use. It depends on the difference in energy between the products and the substrates. For ATP hydrolysis it is -7.3kcal/mole
How is Gibbs free energy related to ATP?
A reaction is spontaneous if the Gibbs free energy is negative. Phosphoanhydride bonds tend to have a large negative Gibbs free energy of hydrolysis. The transfer of the phosphoryl group to a compound gives it free energy so it has more free energy to give up.
What is the structure of ATP?
It is made of adenine, three phosphate and a ribose sugar. Adenine and the sugar together is called adenosine. It has two phosphoanhydride bonds.
What are the three types of connective tissue?
Fibrous (both loose and dense). Hard (cartilage and bone) Fatty (white and brown)
What is biogenetics?
The study of energy relationships and energy transformations in living organisms.
How many types of fatty tissue are there?
2: brown and white
Describe a white fat cell
Large cells with a single fat globule in each one. They usually appear white in conventional slides.
Describe a brown fat cell
Cells with many globules of fat inside, they are found across shoulders and down the back of a newborn and is important in neonatal thermo-regulation because it gives off heat when broken down
How is collagen made?
Tropocollagen composed of a triple helix of peptides. Fibroblasts secrete tropocollagen subunits. The fibres are assembled extra-cellularly, they have variable thickness.
Name some different types of collagen
There are more than 12 types of collagen, they are often tissue specific. Type 1 is in the skin; type 2 is in the cartilage; type 3 is in the liver; type 4 is in the basement membrane; type 5 is in the placenta
Where is skeletal muscle found?
It is found in the larynx, the diaphragm and in the limbs
How are skeletal muscles formed?
Myoblasts fuse to form a multi-cells syncitium. Sarcomeres joined end to end to form myofibrils. Cytoplasm filled with myofibrils form a muscle fibre. Muscle fibres clump together to form fascicles, which are held together by connective tissue, epimycium and perimycium
What are the constituents of connective tissue?
Cells (fibroblasts and fat cells) Visible fibres (collagen, elastic and reticulin) Ground substance (hydrophilic jelly): proteoglycans, glycosaminoglycans, laminin, fibronectin
How is smooth muscle formed?
Visceral (smooth) muscle cells are fusiform cells with an oval nucleus. It is in arterial walls, the walls of the intestine and the airways of the lungs
How is cardiac muscle formed?
Cardiac muscle is branching chains of cells, straited with a central nucleus. It is found in the heart and at the base of the great vessels.
What are the three types of simple epithelium?
Squamous: single layer of flattened cells with parallel oval nucleus Cuboidal: roughly square in profile, with a round nucleus Columnar: taller than they are wide with an oval, perpendicular nucleus
What are the functions of stratified epithelial?
It has a protective function; it is continually worn down; the worn away cells get replaced from below
Where is stratified epithelium found?
It is found in areas where there is continuous abrasion, like skin, the oesophagus and vagina
What are the subtypes of stratified epithelia?
Squamous: can be keratinised, like in skin or non-keratinised, like in the mouth, oesophagus and vagina Cuboidal: found in some large ducts
What are the junctions between cells?
There are adherent (tight) junctions; desmosomes; and gap junctions.
What are adherent junctions?
Band-like fusions between cells that are impervious to most molecules
What are desmosomes?
Plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells
What are gap junctions?
Electrical junctions that permit the transfer of small molecules. They can be gated channels
What does Vitamin A do?
It helps you see at day and night. It protects you from infection by keeping skin healthy. Promotes normal growth and development.
What does vitamin C do?
It helps heal cuts and wounds. It keeps the immune system healthy.
What does vitamin D do?
It increases the amount of calcium and phosphate absorbed and deposits it in bones and teeth to strengthen them.
What does Vitamin E do?
It strengthens the immune system
What does Vitamin K do?
It makes the blood clotting proteins and proteins for your blood, bones and kidneys.
What are the functions of epithelia?
It forms barriers for: protection (skin); absorption (gut); secretion (pancreas). All epithelia have a basement membrane.
What are the different types of epithelia?
Simple epithelium: it is a single layer of cells (lungs) Stratified epithelium: it is many layers of cells (skin) Pseudo-stratified epithelium: epithelia that doesn’t fit into either category
What does vitamin B1 do?
It helps with energy production in your body. It is also known as thiamin.
What does Vitamin B2 do?
It helps with energy production in your body and helps your body use other B vitamins. It is also known as riboflavin.
What does Vitamin B3?
It helps enzymes work properly and helps use protein, fat and carbohydrate to make energy
What does vitamin B6 do?
It helps form haemoglobin and helps to make and use protein and glycogen
What does iron do?
It helps energy transfer by haemoglobin and cytochromes
What does zinc do?
It helps growth, health and immune function
What does copper do?
It helps in connective tissue formation and energy transfer
What does manganese do?
It is involved with arginine, pyruvate and superoxide metabolism
What does chromium do?
It is part of the insulin receptor
What does selenium so?
It prevents peroxidation of reduced compounds such as glutathione
What is malnutrition?
A state of nutrition in which a deficiency, excess or imbalance of energy, protein or other nutrients causes measurable adverse effects on tissue/body form, body function and clinical outcome. It is screened for using the MUST screening tool
What are micronutrients used in?
Trace element and vitamins. Cofactors in metabolism. Gene expression. Structural compounds. Antioxidants
What is basal metabolic rate?
A measure of the energy required to maintain non-exercise bodily functions such as respiration, contraction of heart muscle and biosynthetic process.
What affects BMR?
BMI, hyperthyroidism, low ambient temperature, fever, caffeine, exercise and pregnancy all increase BMR. Age, being female, starvation, hypothyroidism and drugs decrease BMR.
What is F.I.S.H.?
It is fluorescence in situ hybridisation. We use DNA probes labelled with fluorochromes. They are hybridised directly to the chromosome preparation or interphase nuclei. The can count chromosomes in interphase nuclei. We can look for submicroscopic deletions using locus specific probes.
Where are dietary fats stored?
Fat: adipose tissue Carbohydrate: glycogen in liver and muscle Protein: muscle
How is the total energy expenditure spread out?
60% resting 30% activity induced 10% dietary
What are the four pathways of metabolism?
- Oxidative (catabolic) 2. Storage (anabolic) 3. Biosynthetic (anabolic) 4. Waste Disposal (catabolic)
What is the difference between anabolic or catabolic?
Anabolic is creating large molecules. Catabolic is breaking down large molecules
What is the role of cytogenetics?
Confirmation of malignancy. Classification of a disease type Prognosis Monitoring
What are acquired mutations?
-changes occur during a lifetime -restricted to malignant tissue -they are not heritable
What are constitutional mutations?
They occur at gametogenesis, it affects all cells of the body and they are heritable
What is hereditability?
The proportion of the aetiology that can be ascribed to genetic factors as opposed to environmental factors. It is expressed as a percentage. One way to calculate it is the concordance rate in monozygotic twins
What are the characteristics of multifactorial inheritance?
The incidence of the condition is greatest amongst relatives. The risk is greatest for the first degree relatives and it decreases rapidly in more distant relatives. If there is more than one affected relative then the risk increases.
What are the characteristics of X-linked inheritance?
The genes are carried on the X chromosome. Usually only makes affected, but it is transmitted (usually) through unaffected females. There is no male-to-male transmission. An affected male cannot have affected sons, but all his daughters will be carried.
What is lyonisation?
It means generally one of two X chromosomes active in each female cell, but it can be skewed
What is penetrance?
The percentage of individuals of a specific genotype showing the expected phenotype
What is the expressivity?
It refers to a range of phenotypes expressed by a specific genotype
What is anticipation?
It is when a genetic disorder affects successive generations earlier or more severely than expected
What is somatic mosaicism?
It is a genetic fault only in some tissue in the body
What is gonadal mosaicism?
It is a genetic fault in gonadal tissue
What is autosomal dominant inheritance?
It is a disease that manifests in the heterozygous state. It affects men and women in equal proportions. It affects individuals in multiple generations. Transmission by individuals of both sexes to both sexes. Don’t forget penetrance and variability
What is consanguinity?
Reproductive union between two relatives
What is autozygosity?
Homozygosity by descent. I.e. Inheritance of the same mutual allele through two branches of the same family
What are the types of genetic testing?
Diagnostic: to confirm a diagnosis Carrier: to determine if the patient is a carrier Predictive: to see if the patient will get the disease in the future
What is an autosomal chromosome?
Any chromosome, other than sex chromosomes, in pairs in diploid cells
What does recessive mean?
The disease only manifests in homozygotes
What does homozygous mean?
The presence of identical alleles at a given locus
What does heterozygous mean?
The presence of two different alleles at a given locus
What is an allele?
One or more alternative forms of a gene at a given locus
What is a locus?
The position of a gene/DNA on the genetic map
What is autosomal recessive inheritance?
A disease that manifests in the homozygous state. Males and females are affected in equal proportions. It only affects individuals in a single generation. 1/4 risk in offspring and 1/2 risk of being a carrier. It is more common consanguineous unions.
What is heterogeneity
There’s one gene, one mutation and one disease
What is allelic hetergenity?
Lots of different mutations in one gene
What is locus heterogeneity?
Mutations in different genes give the same condition
What are the types of genetic disorders?
Chromosome abnormalities Singe gene disorders Multifactorial and polygenic disorders
What are the mechanisms of allele dominance?
Loss of function mutations. Gain of function mutations. Dominant negative mutations.
What are loss of function mutations?
Only one allele is functioning, most of these mutations are recessive, unless the pathway is very sensitive
What is gain of function mutation?
Increased gene dosage or increased protein activity
What are dominant negative mutations?
Where the protein from the mutant allele interferes with the protein from the normal allele
What are the types of DNA mutations?
Duplications; deletions; slice site mutations; non-sense mutations; mia-sense mutations
What is a non-sense mutation?
Where an immature premature stop-codon occurs because of a mutation
What is a mis-sense mutation?
Where the mutation means the amino acid is replaced by another amino acid so the protein is changed
What are the functions of splicing?
It means different proteins can be made from the same gene. It allows new proteins to be made (this is useful in the immune system)
What is an out of frame deletion?
It is a deletion of one base
What is an in frame deletion?
It is the deletion of a whole codon
What inactivates genes?
-activation of repressors (RNA polymerase inhibitors) - each step of the transcription finds no longer actively produced transcription proteins -complexes do not form because of lack of phosphorylation -enzymes are no longer activated
What’s the difference between euchromatin and heterochromatin?
Euchromatin is accessible to transcription proteins and is activatable, it is unmethylated DNA. Heterochromatin is inaccessible to transcription factors.
What are the three types of RNA?
rRNA, mRNA, tRNA
What is mRNA?
mRNA is printed as a long linear transcript. It is then processed to the mature form (near the nuclear membrane). It has a 5 prime CAP and a 3 prime Poly A tail.
What is rRNA?
Ribosomes are abundant in eukaryotic cytoplasm, and four main types of rRNA combine with proteins to form 80S ribosomes
What is tRNA?
tRNA are very small molecules that carry an amino acid to ribosomes and check they are in the right position to match the anticodon
What enzymes are involved in DNA replication?
Polymerases, helicase, topoisomerase, ligase, primase
What do polymerases do in DNA replication?
They read the RNA from 3’ to 5’ but prints 5’ to 3’. The substrates are triphosphates and deoxyribonucleotides. The enzyme stays on the strand, at the same time it extends and proof reads.
What does helicase do in DNA replication?
It opens the strands
What does ligase do in DNA replication?
It joins the DNA strands back together
What does topoisomerase do in DNA replication?
It unwinds the separated DNA strands
What does primase do in DNA replication?
The building on the RNA primer is synthesised by primase
What does the unit kDa mean?
It is a kilodalton. 1000 atomic mass units. One dalton is the mass of a hydrogen atom
What does the unit S stand for?
It is a Svedburg unit. It refers to the mass and shape of cellular organelles. A high S means a high mass
What are the four stages of the cell cycle?
G1, S, G2, M
What happens in G1 during the cell cycle?
There is growth and metabolism in the cell. It is diploid and takes 12 hours
What happens during the S phase during the cell cycle?
DNA replication. It goes from 2n to 4n. It takes 8 hours
What happens during G2 in the cell cycle?
There is preparation for cell division. It is 4n. It takes 4 hours.
How long does mitosis take?
1 hour
What are the useful properties of DNA?
- Heat denaturation - Alkali dissociation - Hybridisation
What are the uses of enzymes?
- it can speed up the reaction - disease markers - drugs target
What is an isoenzyme?
Two enzymes that have different structure and sequence but catalyse the same reaction
What are the functions of DNA?
- Acts as a template and regulator for transcription and protein synthesis - It is the genetic material, structural basis of heredity and genetic diseases
What is a porphyrin ring in haemoglobin?
At the core of a haemoglobin molecule is a porphyrin ring, which holds an iron atom. When an iron atom is present in the ring it is termed a heme. The iron atom is the site of oxygen binding. Haemoglobin is when heme and globin are together
What is a beta sheet ?
It is formed by hydrogen bonds between linear regions of polypeptide chains. Chains can be parallel or anti-parallel, pleated or not. If the chain is folding back, the structure is usually a 4 aa turn, called hairpin looper beta-turn
What are the forces in protein chains?
Van der Waals forces, hydrogen bonds, hydrophobic forces, ionic bonds, disulphide bonds
What is the alpha helix?
Hydrogen bonds between each carbonyl group and the H attached to the N which is 4 amino acids along the chain. The side chains look outwards. Proline breaks the helix
What are the sugar derivatives?
Aminosugars; alcohol-sugars; phosphorylated; sulfated
What are hydrophobic forces?
Uncharged and non-polar side chains are poorly soluble in water and are effectively ‘repelled’ by water. These hydrophobic side chains tend to form tightly packed cores in the interior of proteins, excluding water molecules. This attraction is the hydrophobic force.
What are disaccharides?
They contain 2 monosaccharides joined by an O-glycosidic bond
What are oligosaccharides?
They contain 3-12 monosaccharides. They are products of digestion of polysaccharides or part of complex protein/lipids
What are examples of protein structure-function relationships?
- Immunoglobulins - Fibrous proteins: collagen - Enzymes in general - Channel and carrier proteins, receptors and neurotransmitters
What are Van der Waals forces?
Weak attractive interactions between atoms due to fluctuating electrical charges. They are only important when two macromolecular surfaces fit closely in shape. They can also be repulsive at a short distance.
What is a monosaccharide?
A chain of carbons, hydroxyl groups and one carbonyl group. An aldose has an aldehyde (C1). A ketose has a ketone (C2)
What is the formula for a carbohydrate?
Cn(H2O)n
What is lipofuscin?
It is a membrane-bound Orange-brown pigment common in the heart and liver. It is involved in peroxidation of lipids in old cells
What is a lipid?
It is in non-membrane-bound vacuoles in adipocytes and the liver. It appears as empty space as it dissolves in processing
What is glycogen?
It is a CHO polymer in cytoplasm and is normally only seen on electron microscopy
What are intermediate filaments?
They are anchored to transmembrane proteins to spread tensile forces through tissues. Their specific functions are generally not known but they are useful in immunohistochemistry to tell one cell type from another
What are microtubules?
25nm in diameter and consists of tubulin proteins. They are present in all cells except erythrocytes. It is made of alpha and beta tubulin, which are arranged in groups of 13 to form hollow tubes. They arise from centromeres.
What is a microfilament?
It is 5cm in diameter and is made of actin. Globular G-actin polymerises into filamentous F-actin, which forms a bracing mesh (cell cortex) on the inner surface of the cell membrane. This drives many cellular processes including cell motility and muscle contraction.
What is a cytoskeleton?
Filamentous proteins, which brace the internal structure of the cell. It is made of microfilaments, intermediate filaments and microtubules
What are peroxisomes?
They are small membrane-bound organelles containing enzymes which oxidise long-chain fatty acids. They contain D-amino acid oxidase catalase and ureate oxidase
What are lysosomes?
They are derived from the Golgi apparatus. The H+ ATPase on the membrane creates a low pH (pH 5) and it contains acids hydrolases.
How do lysosomes work?
Initial hydrolase vesicles fuse with endosomes with the correct membrane proteins to produce endolysosomes
What are vesicles?
They are very small, spherical, membrane-bound organelles derived from several compartments. There are cell-surface derived pinocytotic and phagocytotic vesicles, golgi-derived transport vesicles, ER-derived transport vesicles, lysosomes and peroxisomes
What are the functions of vesicles?
They can transport materials, store materials, exchange cell membrane between cell compartments
What is the Golgi apparatus?
It is a parallel stack of membrane that processes macromolecules synthesised in the ER. It does this by modifying macromolecules by adding sugars and proteolysis of peptides into active forms and sorts macromolecules
What are the parts of the Golgi apparatus?
The cis face is nuclear facing and receives transport vesicles from the smooth ER and phosphorylates some proteins. The medial golgi is the central part and forms complex oligosaccharides by adding sugars to lipids and peptides. The trans golgi performs proteolysis and sorts macromolecules into vesicles which bud from the surface membrane
What is the rough endoplasmic reticulum?
It is the site of protein synthesis and is made of highly folded flattened membrane sheets
What is the smooth endoplasmic reticulum?
It is the site of membrane lipid synthesis and it processes synthesised proteins. It is also made of highly folded flattened membrane sheets
What does the inner membrane of the mitochondria do?
It is used in the respiratory chain and in ATP production
What is the mitochondrial matrix used for?
It is used in the Krebs cycle and the intermembranous space is used in nucleotide phosphorylation
What are the forms of DNA in the nucleus?
There are two forms: euchromatin and heterochromatin. Euchromatin is dispersed and not readily stainable, it is prevalent in transcriptionally active cells. Heterochromatin is small and dark staining and is prevalent in less active cells.
What does the nucleus do?
It is the brain of the cell. It is enclosed by a double membrane and houses DNA in both euchromatin and heterochromatin forms. It contains the nucleolus, which is the site of ribosomal RNA formation
What is mitochondrial inheritance?
All mitochondrial DNA is from the mother so if free mother is affected all her children will have it but if the father is affected none of the children will have it
What is X-linked recessive inheritance?
It is caused by the mutations in genes on the X chromosomes. If it is from the mother the offspring has 50% chance of being a carrier. If it is from the father the male offspring aren’t affected and the female offspring will be carriers
What is autosomal recessive inheritance?
It is a disease which is manifest in the homozygous state. There is a 25% chance the offspring will get the disease and a 50% chance the offspring will be a carrier
What is autosomal dominant inheritance?
A disease that manifest in the heterozygous state. There is a 50% chance the offspring will get the disease
What is Q-banding?
It a fluorescent stain for chromosomes that produces specific banding patterns for each pair of homologous chromosomes. It uses the dye quinacrine. Banding patterns are similar to those obtained with G-banding stain
What is G-banding?
Staining chromosomes with Giemsa dye. AT rich DNA is relatively gene poor and stains more darkly in G banding. Less condensed chromatin, which tends to be GC rich and more transcriptionally active incorporates less Giemsa so the region appears as a light band
What is a primordial germ cell?
Any of the large spherical diploid cells that are formed in the early stages of embryonic development and are precursors of the oogenia and spermatogenia. They are formed outside the gonads and migrate to the embryonic ovaries and testes for maturation
What is a spermatogonia?
A cell produced at an early stage in the formation of spermatozoa, formed in the wall of a seminiferous tubule and giving rise by mitosis to spermatocytes
What is the glycolysis reaction?
Glucose + 2 NAD+ + 2 Pi + 2 ADP = 2 Pyruvate + 2 NADH + 2 H+ + 2ATP + 2 H2O
What is the extraembryonic mesoderm?
It eventually fills all of the space between the cytotrophoblast and the exocoelomic membrane. Large cavities form in the mesoderm, which become confluent and form a new space called the extraembryonic or chorionic cavity.
What does the extraembryonic mesoderm split into?
It forms two layers, the splanchopleuric (visceral) and somatopleuric (parietal) layers. The mesoderm looks and acts like an embryonic mesoderm but it is outside the embryo. It is responsible for the formation of blood vessels that connect the embryo to the placenta.
What is homeostasis?
The maintenance of a constant internal environment
What are the three major communication systems?
Endocrine, nervous and immune
What are the types of signals in the body?
Electrical, ions, hormones
What are free radicals?
They are atoms, molecules or ions with an unpaired electron in outer orbital. They may be generated by single electron reduction steps. The role of free radicals in signalling is very important
What are the key features of oxygen?
It favours reduction in single electron steps. It has two unpaired electrons in the outer orbitals so it has parallel spins. It permits combustion. It permits cellular respiration. It permits the formation of free radicle a
What is the reactive oxygen series?
O2 -> superoxide -> peroxide -> hydrogen peroxide -> hydroxyl radical -> H2O
What is the Fenton reaction?
H2O2 + Fe2+ = Fe3+ + OH• + OH-
What is the Haber-Weiss reaction?
O2- + H2O2 = O2 + H2O + OH•
What cellular damage is caused by radicals?
They damage proteins, lipids, carbohydrates and nucleic acids. It damages the membranes of the cells and their organelles. This increases the permeability which leads to an influx of calcium, water and sodium
What are the cellular defences against oxygen toxicity?
Cellular compartments; repair; antioxidant vitamins; and antioxidant enzymes (superoxide dismutase, catalase, gluthanione peroxidase)
What are the types of cell communication?
Autocrine (cells talking to themselves) Paracrine (cells talking to neighbouring cells) Endocrine (cells talking to other cells elsewhere in the body)
What are the features or paracrine communication?
The signal diffuses across the gap between cells. It is inactivated locally, so it doesn’t enter the blood stream
What are the compounds in the reactive oxygen series?
Superoxide; hydrogen peroxide; hydroxyl; organic radicals; organic peroxide; hyperchlorous acid. The hydroxyl radical is the most reactive radical
What are hormones?
They are molecules that act as chemical messengers. There are peptide, steroid and amino acid hormones
What are peptide hormones?
They are made of amino acids; they vary is size; some have carbohydrate side chains (glycoproteins); they are hydrophilic; the examples are insulin, TSH, growth hormone
What are steroid hormones?
They are synthesised from cholesterol; different enzymes modify the molecules to produce different hormones; they are lipid soluble; testosterone, oestrogen.
What are amino acid derivative hormones?
They are synthesised from tyrosine; adrenaline and thyroid hormones
What is hydrostatic pressure?
The pressure difference between capillary blood (plasma) and interstitial fluid. Water and dilutes move from plasma into interstitial fluid
What is oncotic pressure?
Osmotic pressure is caused by the difference in protein concentration between the plasma and interstitial fluid. Only water moves from interstitial fluid to plasma
What is oedema?
Excess water in intercellular tissue spaces
What is serous effusion?
Excess water in a body cavity
How is body water divided?
40% intracellular 20% extracellular: of which much more is interstitial fluid rather than plasma
What is the route of the endocrine system?
The hypothalamus -> anterior pituitary -> endocrine gland -> target tissue
What are the protein mechanisms in membranes?
Transporters, anchors, receptors and enzymes
What is the fetal period?
From the beginning of the 9th week to the birth, it is the second two trimesters
What is the crown-rump length?
The length between the top of the head to the area above where the legs begin
What is the crown-heel length?
The length from the vertex of the skull to the heel
What is fertilisation?
The union of a male and female gametes to produce a fertilised zygote
How is the blastocyst formed?
A fertilised zygote undergoes rapid, mitotic division to form a 16-cell morula, which enters the uterus on day 3/4. A cavity begins to form along with the blastocyst
When is the blastocyst implanted into the uterus?
At the end of week 1 the blastocyst begins to implant in the uterine wall, by the end of week 2 it is completely embedded
What does the blastocyst differentiate into?
The cells differentiate into the embryoblast and the trophoblast
How are peptide hormones transported?
They are transported freely in plasma
How are peptide hormones stored?
They were stored in secretory vesicles
Where is the receptor for peptide hormones?
On the plasma membrane
How does the peptide hormone work?
It signals a transduction cascade
How fast is the peptide hormone reaction time?
It is fast, within minutes
How are steroid hormones transported?
They are protein bound when they are transported in plasma
Where are the steroid hormone receptors?
The receptor is intracellular
How do steroid hormones work?
The directly alter gene transcription
How fast is the steroid hormone reaction time?
It is slow, within days/weeks
What electrolyte is predominant in intracellular fluid?
Potassium
What electrolytes are predominant in extracellular fluid?
Sodium, chloride and bicarbonate
What causes an increase in osmolality?
An increase in solutes in an increase in water
What detects an increase in osmolality?
It is detected by pamper rotors in the hypothalamus
What is the response to an increase in osmolality ?
ADH is released by the posterior pituitary, which increases water reabsorption in the kidneys to dilute the solute or return the water
What is the role of osmosis in water homeostasis?
All the body’s fluid compartments are in osmotic equilibrium. Osmotically active substances create an osmotic gradient across a membrane. Any change in solute concentration in a compartment causes a shift in water
What is haematopoiesis?
The making of cells
How is potassium homeostasis maintained?
It is maintained by excretion from the intestines and the kidneys (Na/K ATPase pump under control of aldosterone
What is the composition of blood?
56% fluid (plasma) 43% RBC 1% WBC
What causes a decrease in renal blood flow?
There is a decrease in water in the ECF so there is a decrease in effective circulating volume, so there is a decrease in renal blood flow.
What is the effect of decreased renal blood flow?
Renin is released from the kidneys, this stimulates angiotensin release, which stimulates aldosterone release. Angiotensin II and aldosterone increase sodium reabsorption in the kidneys, which brings water with it, it excretes potassium and hydrogen and stimulates ADH release
Where are RBCs produced and destroyed?
They are produced in bone marrow and destroyed in the liver and spleen. They have a lifespan of 120 days.
What is the function of RBCs?
They are enucleate, biconcave disc that carries haemoglobin, which transports oxygen and carbon dioxide around the body
What granules are present in neutrophils?
They contain primary (lysosomes), secondary (specific ones that secrete substances that mobilise inflammatory mediators), and tertiary (secrete gelatinases and promote cell adhesion)
What are the key features of neutrophils?
From the granulocyte series. Most abundant WBC. Multi-lobed nucleus and granular cytoplasm. They circulate in blood and invade tissue. They are phagocytic so play a role in immune system.
What are the key features of eosinophils?
From the granulocyte series. They have a lobed nucleus and distinctive large orange/red cytoplasmic granules. They are phagocytic with affinity for particular antibodies. They are receptors for IgE. They inhibit mast cell secretion. They neutralise histamine
What are the key features of basophils?
The least common WBCs. It has a bilobed nucleus and prominent blue-staining cytoplasmic granules. The granules contain histamine and act to prevent coagulation and aggulation. They are the circulating form of mast cells, receptors for IgE.
What are the key features of lymphocytes?
Most types have very few cytoplasmic inclusions and a clear blue/grey cytoplasm. There are B cells, T helper cells, T cytotoxic cells, T suppressor cells and natural killer cells
What are B cells?
They become plasma cells and activate macrophages
What are T helper cells?
They help B cells and activate macrophages
What do T cytotoxic cells do?
The kill previously marked cells
What do T suppressor cells do?
They suppress T helper cells and suppress the immune response
What do natural killer cells do?
The mainly kill virus infected cells
What do monocytes do?
They are immature cells that circulate briefly in the blood. They are larger than lymphocytes with a characteristically kidney-shaped nucleus. The differentiate mainly into macrophages. They had small cytoplasmic granules (mainly lysosomes)
What are platelets?
Fragments of cell derived from large multi-nucleated megakaryotes in the bone marrow. They are surrounded by a cell membrane and containing vesicles with coagulation factors
What do platelets do?
They are responsible for clotting of blood, notably when the endothelium lining of a blood vessel is breached
What are capillaries?
They are composed entirely of thin-walled endothelial cells with no surrounding muscle or tissue. They can be closed or fenestrated
What are the layers of muscular blood vessels?
- Intima - Media: composed of smooth muscle - Adventia: composed of connective tissue
What is the Henderson-Hasselbach equation?
pH = pK + log([HCO3-]/[CO2])
What is a small peripheral nerve fibre?
A bundle of axons interspersed with endoneurium and surrounded by perineurium and epineurium
What is the composition of cartilage?
-Cells: chondroblasts secrete the cell and surround themselves to become chondrocytes -Fibres: strands of collagen and elastic fibres -Matrix: hydrophilic consdroitin sulphate-rich amorphous jelly, compressible, contains fibres
What are the types of cartilage?
Hyaline: glassy amorphous matrix (joints) Elastic: visible elastic fibres within matrix (pinna of ear) Fibrous: visible collagen fibres within the matrix (intervertebral discs)
What is hyaline cartilage?
It is chondrocytes in lacunae surrounded by amorphous matrix with not much structure. This is surrounded by a capsule of collagen called the perichondrium
What is elastic cartilage?
The structure in the jelly matrix is produced by elastin. It is able to spring back to its original shape more easily than other types of cartilage
What is fibrous cartilage?
it is in the annulus fibrosus of an inter-vertebral disc. The outer shell is made of cartilage, jelly-like centre made of fibrous cartilage mixed with collagen fibres. It seems to look layered.
What are the types of bone?
Primary bone: first to be formed, it is a disorganised matrix. Secondary bone: remodelled bone, laminated, lighter and stronger
What is the composition of bone?
Cells (osteoblasts, osteocytes, osteoclasts) Matrix (organic and inorganic)
What do osteoblasts do?
They actively synthesise bone
What do osteocytes do?
They maintain bone and regulate calcium levels
What do osteoclasts do?
They breakdown bone and aid in remodelling bone
What is the organic matrix in bone?
It is mostly collagen
What is the inorganic matrix in bone?
It is calcium mostly in the form of crystalline hydroxyapatite
What is spongy bone?
It has holes, it is lightweight, it is in the centre of long bones
What is cancellous bone?
It has holes, like spongy bone
What is compact bone?
It is usually secondary and is the outer shafts of long bones
What is membrane formation bone?
It is formed directly in the mesenchyme, it is primary bone
What is endochondrial formation bone?
It is formed by replacement of cartilage
What is osteons deposition bone?
It is secondary bone, concentrically deposited around central vessels
What is appositional deposited bone?
It is deposited in layers of external surface of the bone
What is the chorion?
It is the membrane between the foetus and the mother. It is the extraembryonic mesoderm and the trophoblast. Chorionic villi invade the endometrium and allow transfer of nutrients from maternal blood to foetal blood
What does the ectoderm give rise to?
It gives rise to the CNS, the PNS, the sensory epithelium of the nose, eat and eye, skin, hair and nails, pituitary, mammary and sweat glands, enamel of the teeth
What are the three parts of the mesoderm?
Paraxial plate mesoderm, intermediate plate mesoderm and the lateral plate mesoderm
What does the paraxial plate mesoderm give rise to?
It gives rise to somites, which give rise to supporting tissue of the body (myotome, sclerotome, dermatome)
What does the intermediate plate mesoderm give rise to?
It generates the urogenital system
What does the lateral plate mesoderm give rise to?
It is found at the periphery of the embryo, it splits into the somatic (parietal) layer, that forms the future body wall and the splachnic (visceral) layer that forms the circulatory system, muscle, connective tissue and peritoneum of the gut and connective tissue for the glands
What does the endoderm give rise to?
It gives rise to the - The epithelial lining of the GI tract, respiratory tract and urinary bladder - The parenchyma of the thyroid gland, parathyroid gland, liver and pancreas - The epithelial lining of the tympanic cavity and auditory tube
What is the oropharyngeal membrane?
It is located at the cranial end of the embryonic disc, it consists of a small region of tightly adherent ectoderm and endoderm cells, it represents the future opening of the oral cavity
What is the cloacal membrane?
It is formed at the caudal end of the embryonic disc. It consists of tightly adherent ectoderm and endoderm cells. When this membrane appears, the posterior wall of the yolk sac forms a small diverticulum, the Allantois, which extends into the connecting stalk
What does the cranial flexing do?
The cranial flexion brings the oropharyngeal membrane, cardiogenic area, septum transversum ventrally, forming the ventral surface of the future face, neck and chest. It brings the heart into its thoracic position and septum transversum to the diaphragm
What does the caudal flexion do?
It brings the cloacal membrane onto the ventral surface of the embryo
What does the lateral folding do?
It results in the incorporation of a portion of the yolk sac into the embryo to form the primitive gut. It also forms the body cavities
Where is the DNA stored?
It is stored in the nucleus and he mitochondria
What is the structure of DNA?
It is a double helix with complementary base pairing (adenine and thymine, guanine and cytosine). It could around nucleosomes, then coils again into supercoils and again into chromosomes
How many chromosomes are in the human genome?
22 pairs and a pair of sex chromosomes
How many base pairs does each chromosome contain?
Approximately 10x7 base pairs
How many arms does each chromosome have?
Each chromosome has a long arm (q) and a short arm (p) separated by the centromere
How are chromosome stained?
They can be stained using Geimsa (G-banding) or Quinacrine (Q-banding)
What is mitosis used for?
Producing two genetically daughter cells; growth and replacing dead cells
What are the phases of the cell cycle?
G1 (growth phase) -> synthesis phase (DNA & centrosome replication take place here) -> G2 growth phase -> mitosis
What happens during prophase?
- Chromatin condenses into chromosomes - Centrosomes nucleate microtubules and move to opposite poles of the nucleus
What happens during prometaphase?
- Nuclear membrane breaks down - Microtubules invade nuclear space - Chromatids attach to microtubules
What happens during metaphase?
Chromosomes line up along the equatorial plane (metaphase plate)
What happens during anaphase?
The sister chromatids separate and are pushed to opposite poles of the cell
What happens during telophase?
- The nuclear membranes reform - Chromosomes unfold into chromatin - Cytokineses begins
How is meiosis different to mitosis?
It is only in the gametes; the recombination of genetic material generates diversity; there are two cell divisions; it creates four genetically different haploid daughter cells; there is crossing over and independent assortment in prophase 1.
What happens during sperm production?
Primordial germ cells-> lots of mitoses (at puberty) -> spermotogonia The cytoplasm divides evenly and after meiosis 2 four equal gametes have been produced.
What happens during egg production?
Primordial germ cells -> 30 mitoses -> oogenia. Oogenia enter prophase of meiosis I by 8th month of intrauterine life, the process is suspended. Cells enter ovulation 10-50 years later. Cytoplasm divides unequally into 1 egg and 3 polar bodies that apoptose.
What is non-disjunction?
It is the failure of chromosome pairs to separate in meiosis I or sister chromatids to separate properly in meiosis II
What is gonadal mosaicism?
Occurs when precursor germline cells to ova or spermatozoa are a mixture of two of more genetically different cell lines. One line is normal, the other mutated. The parent is healthy, but the fetus may have a disease. Incidence increases with advances paternal age
What are tissues made of?
Cells make up a lot of tissue volume. Interstitial fluid consists of water; salts in solution; plasma proteins and hormones. It is the main component of extracellular fluid Extracellular material; fibres(tendons); jelly and inorganic salts as solids (calcium in bone)
What cells last for your whole life?
Nerves and brain; cardiac muscle; germ cells
What cells last for nearly your whole life?
Skeletal muscle
What cells last a few years?
Bones and tendons
What cells last a month?
Lots of tissues; blood; skin and connective tissue
What cells last a few days?
The lining of the gut
What are the types of tissue?
Epithelia, supporting tissue, muscle, nerves, germ cells
What is PAS used to stain?
Sugars
What is Van Gieson used to dye?
Elastic
What is Alcian blue used to stain?
Mucus
What forms macromolecules?
Simple molecules like sugars, lipids, amino acids can form complex large molecules
What are the structures of macromolecules?
They can have osmotic, structural, optical, enzymatic and other complex functions. They are very heterogenous. Often specific conformations are associated to definite functions
What is the formula for carbohydrates?
Cn(H2O)n
What is a glycosidic bond?
The hydroxyl group of a monosaccharide can react with an OH or a NH group, to form glycosides
What is a fatty acid?
Straight carbon chains (mostly 16-20) with a methyl and a carbonyl group at the ends. Melting point decreases with degree of unsaturation. In unsaturated fatty acids double bonds are commonly cis and spaced at 3C intervals
What are the properties of a peptide bond?
- Very stable - Cleaved by proteolytic enzymes (proteases or peptidases) - Partial double bond - Flexibilty around C atoms not in double bond allows multiple conformations
What are coenzymes?
- They are complex organic structures which help to maximise the repertoire of enzymes functional groups. - They can just be metal ions or organic or both
What are the types of coenzymes?
Activation-transfer coenzymes form a covalent bond and are regenerated at the end of the reaction Oxidation-reduction coenzymes are involved in reactions where electrons are transferred from one compound to another
How does cell division work in prokaryotes?
A binding protein (DNAa) starts the process at a single point of origin (oriC). The parental strands separate & form a bubble. Both strands are copied simultaneously and in opposite directions. DNA is circularised by ligases, then cell division takes place
What is a pathogenic mutation?
A variation in a gene that causes the gene to behave abnormally or be inactivated
What is GWAS
It is genome wide association studies. It compares the frequency of markers in a sample of healthy and unhealthy patients. Look for markers and sequence that area to identify the gene and allele associated with the increased likelihood of developing the condition
At rest what is the main source of ATP?
The oxidative system is the primary source of ATP supplied. It uses mainly carbohydrates and fats as substrates. At rest approx 70% of the ATP produced is derived from fats and 30% from carbohydrates
During heavy exercise what is the main source of ATP?
Almost 100% of the energy is derived from carbohydrates if they are available. Protein is only used during long term starvation and in over 90 minutes worth of exercise
What substrates are used during the preparative phase of glycolysis?
Glucose, glucose-6-phosphate, fructose-6-phosphate, which goes to fructose-1,6-biphosphate
What are the substrates in the generative phase of glycolysis?
Fructose-1,6-biphosphate -> dihydroxyacetone phosphate -> glyceraldehyde-3-phosphate -> 1,3-biphosphoglycerate -> 3-phosphoglycerate -> 2-phosphoglycerate -> Phosphoenolpyruvate -> Pyruvate
How does AMP regulate glycolysis?
AMP is an allosteric activator of phosphofructokinase-1 in step 3. It binds to a non-catalytic site & causes a conformational change that increases its affinity for fructose-6-phosphate, which increases the rate of glycolysis
How does ATP regulate glycolysis?
When there is a low concentration of ATP then the increase in ATP increases the rate of reaction because it acts as a substrate. When there is a high concentration of ATP then an increase lowers the rate of reaction because the catalytic sites are substrates & ATO causes allosteric inhibition
How does insulin affect the rate of glycolysis?
High insulin increases the production of fructose-2,6-biphosphate, which allosterically activates phosphofructokinase-1 increasing the rate of glycolysis & production of fructose-1,6-biphosphate, which actives pyruvate kinase in the liver
How does glucagon affect the rate of glycolysis?
High glucagon reduces production of fructose-2,6-biphosphate so PFK-1 activity is not enhanced so the rate of glycolysis & production of fructose-1,6-bi phosphate is reduced and the pyruvate kinase activity is not enhanced
Where are fatty acids activated?
Fatty acids must be activated in the cytoplasm before being oxidised in the mitochondria
How are fatty acids activated?
Activation is catalyses by fatty Acyl-CoA ligase. The net result of the activation process is the consumption of 2 molar equivalents of ATP Fatty Acid + ATP + CoA -> Acyl-CoA +PPi + AMP
How are fatty acids transported after being activated?
The transport of fatty acyl-CoA into the mitochondria is via an acyl-carnitine intermediate, which is generated by carnitine acyltransferase-1. The molecule is then transported into the mitochondria where carnitine acyltransferase 2 catalyses the regeneration of the fatty Acyl-CoA
What is beta-oxidation of fatty acids?
Each round of beta-oxidation produces 1 NADH, 1 FADH2, 1 Acetyl-CoA. They Acetyl CoA then enters the Kreb’s cycle. Where it is further oxidised to produce CO2, 3 NADH, 1 FADH2, and 1 ATP, which enter the respiratory pathway for the production of ATP
How are lipids are absorbed?
Bile salts emulsify fats in the small intestine->intestinal lipases degrade triacylglycerols->fatty acids are taken up by the intestinal mucosa & converted into the triacylglycerols-> they are incorporated with cholesterol into chylomicrons
What happens in ketogenesis?
2 Acetyl-CoA -> acetoacetyl-CoA -> HMG-CoA -> acetoacetate -> acetone + D-beta-hydroxybutrate
Where are ketone bodies formed?
They are formed in the liver during high rates of fatty acid oxidation because large amounts of Acetyl-CoA exceed the capacity of the Kreb’s cycle. It is also used when there is low carbohydrate utilisation.
Where are ketone bodies not used?
They are used in extra hepatic tissues because the enzyme used to break down the ketone bodies isn’t present in the liver so ketone bodies can be used as a fuel source for other tissues during prolonged starvation
What is regulating ketogenesis?
The control of release of free fatty acids, this is substrate level regulation. The demand of ATP through the Kreb’s cycles affects the amount of Acetyl-CoA used for ketogenesis
What 3 phases can the Kreb’s cycle be split into?
(1) Acetyl-CoA production (2) Acetyl-CoA oxidation (3) Electron transfer and oxidative phosphorylation
What happens in Acetyl-CoA production?
Takes place in the cytosol with the Acetyl donors coming from either glycolysis (glucose) beta oxidation of fatty acids or amino acid production
What is the final protein in the electron transport chain?
Cytochrome A
What is a respiratory burst?
It is the immune system defence against bacteria. It is the rapid release of reactive oxygen species from phagocytes. It damages the bacterial cell membrane and lasts 30-60 minutes. They use NADPH oxidase to reduce 02 to H2O2.
What is anoikis?
When epithelial cells are detached from the basal lamina, it undergoes anoikis, which is just like apoptosis, resulting in the death of the cell.
What is the internal architecture of an epithelial cell?
The attachment of actin fibres to the internal cell structure defines the shape of the cell
What proteins facilitate endocytosis?
SNARE & SNAP. They dock with the vesicles, change orientation and expel the contents of the vesicles.
What are cell membranes composed of?
Lipid, protein and carbohydrate that exist in a fluid state. They define and control the composition of the cell. All membranes exist as phospholipid bilayers with dynamic structures throughout
Are the fatty acid tails of phospholipid bilayers saturated or unsaturated?
They can be either, except in lipid rafts where saturated acids predominate
How do substances move across cell membranes?
Simple diffusion, facilitated diffusion and active transport
How are hydrogen ions produced ?
Most H+ ions are produced when CO2 is released from aerobic metabolism when it reacts with H2O to form H2CO3, which dissociates into H+ and HCO3-. This can be sped up by carbonic anhydrase
What three systems are involved in the control of H+ concentration?
Blood and tissue buffering, excretion of CO2, renal excretion of H+ and regeneration of HCO3-
What buffers are in the body?
Bicarbonate, proteins (contain charged side groups) and haemoglobin (deoxygenated haemoglobin has the strongest affinity for both CO2 and H+
What is the function of the electron transport chain?
It is a process in which the NADH and FADH2 produced during glycolysis, beta oxidative beta oxidation and other catabolic processes are oxidised
What is chemiosmotic phosphorylation?
The mechanism by which ATP is formed in the electron transport chain
Is the inner mitochondrial membrane impermeable to protons?
Yes, which is why the pumping of the electron transport chain leads to a high concentration and provides energy for ATPsynthase
What is substrate level phosphorylation?
When a phosphate group is added from from a substrate
What is oxidative phosphorylation?
The metabolic pathway in which the mitochondria in cells use their structure, enzymes and energy released by the oxidative on of nutrients to reform ATP
Name 3 fatty acids
Palmitoleic acid, linoleic acid and palmitic acid
How do fatty acids gets taken through the inner mitochondrial membrane?
Using the carnitine shuttle, with the proteins carnitine acyltransferase 1 and 2
What is the function of a cell membrane?
To regulate what enters and leaves the cell
Physical boundary for the cell
Selectively permeable to ions and organic molecules
Receptors for cell-to-cell signalling
Attach cell to extracellular matrix
What is the nucleus?
Controls all cell activity; determines what proteins will be made, location of DNA
What is the function of the cytoplasm?
Contains the organelles; site of most cell activity
What is the function of the endoplasmic reticulum?
Where ribosomes do all their work
What is the function of the ribosomes?
Production of proteins
What is the function of the Golgi apparatus?
Prepares and packages proteins for use or export
What is the lysosomes?
Breaks down and absorbs unwanted material in the cytoplasm
What is the function of the cytoskeleton?
Maintains cell shape
What is the function of the mitochondria?
Produces energy for the cell to use
What is the cell membrane made of?
Phospholipid bilayer with embedded proteins
What are the type of cell receptor?
Receptors with intrinsic enzyme activity
Receptors without intrinsic enzyme activity
Ion channels
G-protein coupled receptors
Define endocytosis:
The taking in of matter by a living cell by invagination of its membrane to form a vacuole
Define diffusion:
Passive movement of any substance from an area of high concentration to an area of low concentration
Define osmosis:
Passive diffusion of water through a semi-permeable membrane
Define facilitated diffusion:
Accomplished by proteins in the membrane that allow otherwise restricted molecules through
Define active transport:
The process of using energy (ATP) to ‘pump’ molecules across the membrane against the concentration gradient
Define phagocytosis:
Cell membrane engulfs a foreign body or substance
Define pinocytosis:
The membrane engulfs small droplets of water
What are the types of membrane transporters?
Uniporters (one molecule, one way)
Symporters (more than one molecule, one way)
Antiporters (more than one molecule, opposite directions)
Define homeostasis:
The tendency to a relatively stable equilibrium between interdependant elements, especially as maintained by physiological processes
Define negative feedback:
With negative feedback, the output reduced the original effect of the stimulus
Define positive feedback:
In a positive feedback system, the output enhances the original stimulus
How does water enter the body?
Food, Drink, IV fluids
How does water leave the body?
Kidneys - excretion
GI tract - faeces, vomit, blood loss
Sweating
Burns
What hormones influence water balance?
ADH/Vasopressin, Aldosterone, ANP
What is a glycosidic bond?
A type of covalent bond that joins a carbohydrate molcule to another molecule that may or may not be another carbohydrate
What are the main biological functions of lipids?
Storage of energy
Signalling
Structural components of cell membranes
Define metabolism:
The chemical processes that occur within a living organism to maintain life
How much energy do carbohydrates, protein, alcohol and lipids provide?
Carbohydrates: 4kcal/g
Protein: 4kcal/g
Alcohol: 7kcal/g
Lipids: 9kcal/g
What is the first step of glycolysis?
Glucose -> glucose-6-phosphate
It uses ATP.
What enzyme is used to turn glucose into
glucose-6-phosphate?
Hexose Kinase
What does glucose-6-phosphate go to in glycolysis?
Fructose-6-phosphate
What changes glucose-6-phosphate to
fructose-6-phosphate?
Phosphoglucose isomerase
Which steps in glycolysis use ATP? Which steps create it?
1, 3 use it
7 and 10 create it
What does fructose-6-phosphate go to in glycolysis?
Fructose-1,6-biphosphate.
It uses ATP
What does fructose-1,6-biphosphate go to in glycolysis?
DHAP and GLAP (both 3 carbon)
What enzyme catalyses the reaction of
fructose-1,6-biphosphate to DHAP and GLAP
Aldolase
What enzyme catalyses the reaction from DHAP to GLAP?
Triose Phosphate Isomerase
What does GLAP go to in glycolysis?
1,3-BiphosphoGlycerate.
It creates 2 NADH from 2 NAD+ and 2 Pi
What enzyme catalyses GLAP to
1,3-Biphosphoglycerate
GLAP Hydrogenase
What does 1,3-Biphosphoglycerate go to in glycolysis?
3-Phosphoglycerate.
It creates ATP
What enzyme catalyses 1,3-biphosphoglycerate into
3-phosphoglycerate?
Phosphoglycerokinase
What does 3-phosphoglycerate go to in glycolysis?
2-phosphoglycerate
What enzyme catalyses 3-phosphoglycerate into
2-phosphoglycerate?
Phosphoglyceromutase
What does 2-phosphoglycerate go to in glycolysis?
Phosphoenolpyruvate
What enzyme catalyses the reaction of
2-phosphoglycerate to phosphoenol pyruvate?
Enolase
What does phosphoenol pyruvate go to in glycolysis?
Pyruvate. It creates ATP
What enzyme catalyses the reaction of phosphoenol pyruvate to pyruvate?
Pyruvate kinase
What is the primary regulator of glycolysis?
Phosphofructokinase (affects 1st and 3rd step); it responds to both cellular energy and hormonal regulation
What regulates PFK-1 production?
It is pH dependant so it is inhibited in acidosis
What inhibits the Kreb’s cycle?
ATP, NADH
What activates the Kreb’s cycle?
ADP
Where does substrate-level phosphorylation take place?
In the cytoplasm of a cell
Where does oxidative phosphorylation take place?
In the mitochondria
What does a fatty acid immediately turn into in the process of beta oxidation?
Acyl adenylate.
This uses the adenosine of ATP.
What is acyl adenylate turned into in beta oxidation?
Acyl CoA.
It uses a CoA and produces an AMP.
What enzyme transfers acyl adenylate into Acyl CoA?
Acyl CoA synthase
What enzymes are used in the carnitine shuffle?
Carnatine Acyl transferase 1 and 2
What happens to the Acyl CoA during the carnitine shuffle?
Acyl CoA -> Acyl Carnitine -> Acyl CoA
How is Acyl CoA turned into Acetyl CoA
It looses 2 carbons
What does each round of beta oxidation produce?
1 NADH
1 FADH2
1 Acetyl-CoA
What is ketogenesis?
The process by which ketone bodies are produced as a result of fatty acid breakdown
What are ketones used for?
Energy at low fat states
Is an OH and H2O2 radical lipid soluble?
Yes
What produces ROS endogenously?
Natural by-product of O2 metabolism
Produced mainly inside cell organelles (mitochondria)
How are ROS produced exogenously?
UV radiation, smoking and inflammation
Where is simple squamous epithelium found?
Alveoli, serosa
Where is simple cuboidal epithelium found?
Kidney tubules, ducts of glands like the sweat, salivary and pancreatic glands
Where is simple columnar epithelium found?
Small intestine, gall bladder and bronchi
Where is stratified squamous non-keratinising epithelium found?
Mouth
Oropharynx
Oesophagus
Vagina
Where is psuedo-stratified squamous epithelium found?
Urinary tract
Trachea and large airways (respiratory epithelium)
What is an acid?
A proton donor
What is a base?
A proton acceptor
What is a weak acid?
An acid that partially dissociates into protons and a conjugate base in aqueous solution
What does a low ion difference lead to?
Increased dissociation of weak ions, including water
What is metabolic rate?
Total-body energy expenditure per unit time
What is the total energy expenditure?
Internal heat produced + external work performed + energy stored
What is glycogenesis?
Conversion of excess glucose into glycogen
How long does each energy source last?
Triglycerides: 3 months (15kg)
Protein: 7-10 days (6kg)
Glycogen: 12 hours (350g)
What is the mneumonic for kreb’s cycle substrates?
Can - citrate
I - isocitrate
Keep - alpha ketoglutarate
Selling - succinyl-CoA
Sex - succinate
For - fumarate
Money - malate
Officer - oxaloacetate
How are lipids transported?
As triglycerides or fatty acids bound to albumin on within lipoproteins
How do lipids enter cells?
TGs cannot diffuse across the cell membrane. Fatty acids are released through lipases to facilitate transport into cells, where they re-esterify into TGs.
Where does ketogenesis take place?
Mitochondria
What is a coenzyme?
An organic structure that helps maximise organic enzyme active site
Define insensible water loss:
Insensible water loss is defined as water loss via evaporation from the skin and respiration.
What are the two sources of body water gain?
- water produced from the oxidation of organic nutrients. 2. water ingested in liquids and food (a rare steak is approx 70% water)
What are the four sites of water loss in the body?
Skin, respiratory airways, GI tract and urinary tract. (menstrual flow in women)
