Learning outcomes Flashcards
Define aetiology and pathogenesis
Aetiology = cause of disease Pathogenesis = how it develops
Define symptoms and signs
Symptom = what patient feels Sign = our (doctors) observations
Define diagnosis and prognosis
Diagnosis = Defined abnormalities Prognosis = Predicted outcome
Define natural history and classification of disease
Natural history = course of disease without treatment
Classification of disease:
1. Inflammation - Response of living tissue when injured
2. Circulatory disturbances - Abnormalities of blood components, vessels or flow.
3. Disorders of growth - Abnormal cell growth (types - maturation, differentiation, control, quantity)
4. Degenerative disease - Abnormalities of tissue and organs
5. Developmental - Abnormalities in the genetic information of gametes or embryos (gametogenesis and embryogenesis)
6. Unnatural - Traumatic (accident) and Iatrogenic (as a result of treatment)
Understand the general organisation of the body systems
The body is made up of cells. A group of cells that share the same characteristics or specialisation and perform the same function are called tissues. A collection of tissues usually of different types that synchronise to perform a more complex function is called an organ. When multiple organs work in synchrony this is known as a organ system. Multiple organ systems working together creates an organism.
Organ systems are designed to support the production of energy. The study of how the systems function and work together is called physiology. Each system has a role in maintaining life. Therefore their role can be shown in relation to the equation of life. Nutrients + O2 = Energy (ATP) + waste (incl. CO2)
Be able to outline the role of each major system in maintaining health and optimal
homeostasis
Cardiovascular System = Delivers O2 and nutrients to cells, removes waste from cells
Respiratory System = Acquires O2, disposes of CO2
Gastrointestinal System = Acquires nutrients, disposes of waste (faeces)
Renal System = Disposes of waste (urine)
Musculoskeletal System = Sources nutrients (allows you to find and eat food), removes us from danger, protects from threat (allowing us to continue living and eating).
Immune System = Protects us from infection (conserving energy? and allowing other systems to function)
Nervous System = Coordinates other systems
Endocrine System = Coordinates other systems, major role in allowing cellular access to nutrients that have been absorbed. (Takes nutrients from blood to cells)
Reproductive System = Ensures continuation of life
Define the term homeostasis
The prevention of the disturbance in the system is known as homeostasis.
Explain the importance of maintaining constancy of the internal environment
Our bodies are not very tolerant to change and therefore are constantly monitoring their internal state and responding to any threat to a change in there ‘similar internal conditions’.
Failure to adequately correct imbalances results in illness and disease, or pathology (Latin for suffering).
For example if you ate a sugary donut, glucose is absorbed across intestinal tract and the hormone insulin is released to remove glucose from the blood almost as fast as it enters to prevent blood glucose levels from rocketing.
Describe the principles behind negative feedback control systems
This mechanism is called “Negative” feedback because the condition that triggered the homeostatic response becomes switched off/removed by that response.
The size of the response is proportional to the size of the disturbance.
When a condition that is homeostatically regulated (e.g. body temperature), is sensed to have shifted from the normal range, a signal (usually nervous or endocrine), is generated that produces a response (e.g. shivering or sweating), that corrects the original disturbance and brings the regulated condition back within the normal range
Characteristics: . There is oscillation around the set point. Restores the regulated condition after its initial disturbance, but cannot prevent it happening
Explain what is meant by feed forward control
Feed forward systems are more sophisticated and can, to some extent, predict and prevent change. Feed forward systems contain additional receptors that permit system to anticipate change and therefore activate response earlier.
i.e. when you are thirsty the kidney detects the increased body fluid concentration and pre-empts a state of dehydration. It responds by producing smaller volumes of urine, and a more concentrated form of urine, thus conserving water.
Illustrate the concept of homeostasis by outlining daily water balance in man
When a person is working outside on a hot dry day there body looses water through evaporation. This results in the body fluid becoming more concentration, Internal receptors sense change in this internal condition and simulate the thirst pathway. The person seeks out water and drinks. This process demonstrates both negative feedback and feedforward pathways. The water balance of a person is homeostatically controlled and therefore when the concentration changes the body responses by releasing signals which lead to the return to normal concentration.
Identify the different body fluid compartments
Water is stored in 3 different compartments.
- Intracellular fluid
- Interstitial fluid (fluid between cells)
- Plasma (fluid component of blood)
The plasma and interstitial fluid make up what is known as the extracellular fluid.
Explain the importance of the nature of the barriers which separate the body
compartments
Natural barrier are important in maintaining concentration gradients within the body. The composition of plasma and interstitial fluid is very similar because the natural barrier that separates them is not very selective. However the composition of the extracellular fluid and the intercellular fluid is significantly different because the cell membrane is very selectively permeable. Life can only be maintained while the composition of these different fluid compartments is maintained therefore the natural barriers are extremely important.
Define the dilution principle
The dilution principles states that v = m/c
Describe the use of the dilution principle in the measurement of body fluid
compartments
Plasma is the only fluid compartment that we can access. Therefore:
Measuring the plasma volume: Add a dye or label that cannot cross the capillary wall. Let dye of label distribute then measure the concentration and calculate the volume using the dilution principle.
Measuring the extracellular volume: Add a molecule that can cross the capillary wall but not the cell wall. Let it distribute then measure the concentration and calculate the volume using the dilution principle.
measuring the total body fluid volume: Add a substance that can cross the capillary wall and cell wall i.e. heavy water . Let dye of label distribute then measure the concentration and calculate the volume using the dilution principle.
Measuring the interstitial fluid volume: Extracellular Fluid - Plasma Volume
Measuring the intracellular fluid: Total Body Water -Extracellular Fluid
Define metabolism catabolism and anabolism, and describe, in outline, how they are
interdependent
Metabolism describes the chemical processes of a living organisms by which the energy stored in food is used for tissue growth and energy production.
Metabolism can be split into two pathways. Anabolic and catabolic.
In the catabolic pathways food molecules are broken down and oxidised to form more simple molecules. Some of energy released from this is lost in heat (2nd law of thermodynamics) however most of it is used to fed the anabolic pathways.
In the anabolic pathway small molecules are combined to form more complex molecules.
Describe, in general terms, the structures and contributions to metabolic flow of ATP,
ADP, NADP, NAD, FAD
These are Intermediary Metabolites. These are used to store energy and therefore allow thermodynamically unfavourable reactions to proceed (anabolic pathways).
Compare, in outline, the processes of substrate-level and oxidative phosphorylation
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Phosphorylation and dephosphorylation is the process by which energy can be stored or released. ATP to ADP + Pi.
Define the major elements used to construct human biomolecules
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State the importance of chemical functional groups and molecular configuration and
conformation in determining biomolecular function
Functional groups determine the function of a molecule. Molecules often contain functional groups which are groups of elements bonded to a carbon atoms. Example of function groups include, Hydroxyl group (-OH), aldehyde group (-CHO ) and the Keto group (R2C=O). Biochemical molecules can be defined by these functional groups.
The function of molecules is also determined by their conformation. Molecules can be cis or trans. The orientation of this can completely change there function.
The polarity of a molecule can also determine its function. Polarity is the distribution of electrons within a bond.
List and give examples of the five kinds of chemical reaction occurring in living
organisms
- Redox reactions. i.e. glucose to pyruvate
- Making and breaking C-C bonds. i.e. Cleavage of glucose in glycolysis
- Internal rearrangements. i.e. The rearrangement of the conformation of G6P occurs before the sugar is split in glycolysis
- Group transfers. i.e. In an enzyme catalysed reaction, a phosphoryl group (PO32-) is transferred from ATP to F6P as part of glycolysis.
- Condensation and hydrolysis reactions. i.e. construction of a carbohydrate, sucrose.
Describe the general structures of proteins, nucleic acids, polysaccharides and lipids
Proteins are long chains of amino acids. Nucleic acids form the core structure of DNA and RNA. Nucleic acids are polymers composed of nucleotide monomers. A polysaccharides (complex carbohydrates) such as starch or glycogen are composed of many individual monosaccharide molecules e.g. glucose. Lipids consist of fatty acids. There are three classes of lipids: 1. Triacylglycerides 2. Phospholipids 3. Sterols
Describe the structures present in all cell types
All cells have a cell membrane and cell organelles. Cell organelles are the “machinery” of the cell. All substances entering or leaving the cell must cross the cell membrane
Define the roles of eukaryotic animal cell organelles: nucleus, nucleolus, endoplasmic
reticulum, ribosome, Golgi apparatus, lysosome, peroxisome, mitochondrion,
flagellum, cilium
Nucleus:
Contains DNA, nucleoprotein and some RNA
Nucleoli are sites of ribosomal RNA synthesis and ribosomal assembly. The nucleus is enclosed in the nuclear membrane which, like all biological membranes, is a phospholipid bilayer. It is closely associated with the Rough Endoplasmic Reticulum
Endoplasmic reticulum
Membrane bound organelles. Endoplasmic reticulum comes in rough (RER) and smooth (SER) varieties
RER has ribosomes attached giving it the “rough” appearance. RER modifies proteins. SER has no ribosomes attached and is mainly associated with lipid and steroid hormone production and metabolism of toxins
Ribosomes
Ribosomes synthesise proteins.
Golgi Apparatus
Golgi Apparatus packages up protein in preparation for transport out of the cell.
Lysosome
Enzymes are one form of protein packaged by the golgi apparatus. Enzymes catalyse reactions in cells but need to be stored until needed. Lysosomes are membrane bound vesicles containing enzymes – they separate enzymes from the rest of the cell. Used in autophagy (digestion of cells own materials) or digestion of engulfed particles (e.g. bacteria). Peroxisome are similar.
Mitochondria
Mitochondria are also organelles bound by a phospholipid bilayer. Outer membrane contains pores. Inner membrane has cristae (folds). Matrix contains most of the enzymes required for metabolising food molecules (e.g. Krebs cycle)
Some cells have surface projections supported by the cytoskeleton i.e. Cilia and eukaryotic flagella are made of microtubules. Cilia—short, usually many present, move with stiff power stroke and flexible recovery stroke. Flagella—longer, usually one or two present, movement is snakelike
Correlate organelle structure with function
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Describe the structure and function of the eukaryotic plasma membrane.
The cell membrane (Sometimes called the plasma membrane or plasmalemma) comprises of a double layer of lipid with attached phosphate groups. This double layer of lipids is known as the phospholipid bilayer (See Forces Across Membranes for more detail). Embedded in the membrane are proteins which act as receptors to detect chemical messengers and signalling molecules in the fluid surrounding cells (extracellular fluid)
The phospholipid bilayer forms a selective barrier, being choosy about what it allows to cross in or out of the cell
Define the role of the cytoskeleton
Supports and maintains cell shape
Holds organelles in position
Helps move organelles around the cell
It is compromised of one of three forms of protein: microfilaments, intermediate filaments, microtubules.
Describe the interactions between water molecules and solutes that determine solubility.
When charged (polar) particles are dissolved in water the water forms a “screen” around them. i.e. When sodium chloride (common salt) is dissolved in water, the water forms ‘screens’ around each ion keeping the Na+ and Cl- ions in solution once dissolved. (Preventing them from reacting and forming sodium chloride)
Define the term ‘pH’ and derive an expression that relates the degree of proton
dissociation of a weak acid to its ionisation constant and the pH
Describe what is meant by the term ‘buffer’
Describe the basic structure of membranes
Membranes are composed of a phospholipid bilayer (with hydrophilic head and hydrophobic tails) and proteins and or carbohydrates. Proteins can be peripheral or integral. The cell membrane is selectively permeable. This permeability may vary over time. The membrane is dynamic, continually being formed and dismantled. Membranes are flexible and can expand though they will burst if they expand too much. Membranes are excellent insulators against electrical charge.
Describe the functions of the cell membrane
Form a natural barrier between the intracellular and extracellular environments. The proteins embedded in the cell membrane are used as receptors, for transport (transporter and channel proteins), as enzymes, for maintenance of cell structure (anchorage) and for communication.
Define what is meant by diffusion across membranes
Diffusion is the process by which a gas or substance in solution expands to fill all the available volume. Therefore molecules spread from regions of high concentration to regions of low concentration, until the concentration is uniform throughout the volume
List the factors which favour diffusion through the lipid bilayer
Small, Uncharged and Lipophilic (hydrophobic)
Describe the different general types of membrane proteins and their functions
Peripheral proteins – associated only with the phosphate head of the lipid bi-layer and do not penetrate the hydrophobic core
Integral proteins – span the hydrophobic core of the lipid bi-layer
Define electrochemical gradients
Electrochemical gradient is the net effect of the electrical and concentration gradient which ultimately drives the direction of passive movement.
Explain what is meant by carrier mediated transport systems
Molecules too big to move through channel proteins use carrier-mediated transport proteins or “transporters”.
These proteins have binding sites for the solutes they transport such as glucose. When they bind the solute, the transporter undergoes a change in shape which exposes the binding site on the other side of the membrane. The solute moves away from the transporter and the transporter returns to its original configuration.
Explain the difference between osmolarity and tonicity
Osmolarity describes total number of particles in solution
Tonicity describes the number of non-penetrating particles in solution.
Understand the physiological significance of osmolarity vs tonicity
Almost 20% hospital patients suffer complications due to inappropriate fluid administration. Some of these people die. Intravascular haemolysis (cells bursting) can kill. This is because Lysed (burst) cells introduce protein to ISF, increasing tonicity of ECF in an uncontrolled manner, making management very complicated.
Explain the difference between an isosmotic solution and an isotonic solution
An isosmotic solution has the same total number of solute particles as normal ECF (plasma).
An isotonic solution has the same number of non-penetrating solute particles as normal ECF (plasma).
Describe the processes of endocytosis and exocytosis
These are mechanisms for moving macromolecules across membranes without disrupting them.
In endocytosis, there is invagination of the cell membrane to form a vesicle which eventually disintegrates on the cytoplasmic (inside) surface of the membrane, releasing contents which then migrate within the cell to their destination.
Endocytosis of membrane receptors is a common mechanism of terminating signals from extracellular ligands
List the major cells involved in the innate and adaptive immune response systems.
Innate: Epithelial barriers, phagocytes, dendritic cells, complement, natural killer cells, Eosinophils, mast cells, Basophils, cytokines.
Adaptive : B and T lymphocytes, Effector T cells
