FINAL EXAM Y12 Flashcards
- How do you Write a hypothesis?
By using An if then statement. It should include both an independent variable (the factor you change in an experiment) and a dependent variable (the factor you observe or measure in an experiment) and it must be testable
What is an independent variable?
The factor you will change in an experiment
What is a dependent variable?
The factor you observe or measure in an experiment
What are controlled variables?
Controlled variables are quantities that a scientist wants to remain constant, and she must observe them as carefully as the dependent variables.
What is the difference between a control and experimental test?
The control is the thing you are comparing to and experimental is the things you are testing
What is the purpose of a control group?
It helps rule out alternate explanations of the experimental results.
Role of the placebo in an investigation
Something which tests is a the results from an investigation are psychological or not
What is quantitative data?
Quantitative research gathers data in numerical form which can be put into categories, or in rank order, or measured in units of measurement
What is qualitative data?
Qualitative research gathers information that is not in numerical form.
What ethical issues that might arise from investigation?
Things to consider to make sure that an investigation is ethics/ moral Ethical if: Voluntary participation Informed consent No risk of harm Confidentiality
Validity vs reliability
Validity: does the experiment test what it was actually supposed to test. how well experiment relates to the aim of the experiment.
Eg. Appropriate equipment for measurements, eliminates uncontrollable factors
Reliability: the extent to which an experiment gives the same result each time it’s performed (how close repeated measurements are to each other.)
Eg. Fixed control variables so all test carried out same, choice of equipment
Errors and limitations in data
Measurement errors
Surveys?
Surveys: a systematic collection, analysis and interpretation of information about a particular question or series of questions; usually designed so that data is collected from a large number of subjects.
Case study?
Case studies: an in-depth investigation of one particular person or situation
Longitudinal study?
Longitudinal study: a study concerned over a long period of time; may be carried out over years or decades
Secondary data?
Secondary data: data collected by someone other than people who are using the data
Define mean, median, range and probability
mean: average
median: middle number
range: the difference between highest and lowest measurements in a group
probability; the likelihood that a particular event will occur
Trends vs patterns?
trends: The general direction which something is developing or changing
patterns: Repeated pattern or sequence
What are confidence intervals used for?
confidence intervals can be used to predict the reliability of the data.
Where do independent and dependent variables go on a graph?
Dependent variable on vertical axis ( side) dependent variable on horizontal ( bottom)
Define immunity
Immunity: resistance to infection from invading microorganisms
Define immune system?
Immune system: different types of cells that occur in most organs of the body and that protect against foreign organisms, alien chemicals and abnormal cells
Define immune response
Immune response: a response triggered by foreign substances or microorganisms entering the body.
self antigen vs non self antigen
Self antigen: any large molecule produced in a persons own body ; does not cause an immune response in that person
Non self antigen: any compound foreign to the body that triggers an immune response.
Define infectious disease
Infectious diseases: Diseases caused by foreign organisms invading the body and multiplying there
Define pathogen?
Pathogen: A disease causing organism often referred to as a pathogenic organism
Define vector?
Vectors: An agent such as an insect capable of transferring a disease causing organism from one person to another
Infectious diseases can be caused by….
bacterial and viruses ( also fungi and animal parasites)
Physical characteristics of bacteria?
Physical characteristics of bacteria: single celled, seen only with a microscope, cell shape is used to classify into 4 catergories : cocci ( circular), bacilli ( rods), spirilla (loose coils) and vibrio ( curved rods)
Mode of action for bacteria?
Mode of action for bacteria: releasing toxins which inhibit/ alter cell activity or poisons which alter metabolism, they may also cause allergic reactions. Endotoxins- released when bacteria die, exotoxins- released by living bacteria.
Bacterial antigen- allergic/ immune response
Diseases caused by bacteria?
Diseases caused by bacteria: Chlamydia Cholera Gonnorrhoea Dental caries (tooth decay) Leprosy Pneumonia
Physical characteristics of viruses’
viruses
Physical characteristics: molecules of DNA or RNA, small, wrapped in proteins.
Mode of action for viruses?
Mode of action: DNA or DNA induce cell to manufacture more virus particles, attaching to the outside of a host cell allowing the nucleic acid to enter the cell, new viral genes are then produced by the host.
Diseases caused by viruses?
Diseases caused by viruses: HIV/AIDS, Bird flu Chickenpox Herpes Colds Ebola
Ways transmissionof pathogens can occur?
Direct:
Transmission by touch: direct and fomite(indirect)
Transmission by bodily fluids: through blood or other mucus membranes ( from nose, mouth, throat, genitals) eg. HIV, hepatitis b & c
Waterborne transmission: from drinking contaminated water or from droplets of moisture w/ pathogenic organisms are emitted when breathing, talking, sneezing or coughing eg. Influenza
Airborne transmission:moisture in exhaled droplets carry viruses and some bacteria
Ingestion: food or drink contaminated eg. Salmonella
Transmission of vectors: transfer of pathogens by other animals such as insects, ticks or mites. Some transfer directly others ( house flys) via food and water.
Forms of transmission by contact: direct( Touching an Infected person) or indirect (touching an object that has been touched by an infected individual, also known as fomite transmission )
Disease specific vectors- malaria> mosquitos
Define bacteriophage?
Bacteriophage:Viruses which multiply in bacterial cells causing death to the bacterium
Parasites.
Mode of action, physical characteristics and diseases
parasites
Diseases: Malaria, roundworms, lice
Physical characteristics:Multicellular, ecto and endo
Mode of action:Parasites cause infection by living and multiplying in another organism. This can cause fever, inflammation and other physical problems
Fungi.
Mode of action, physical characteristics and diseases
fungi
Diseases: ringworm
Physical characteristics: Multicellular, Eukaryotic
Mode of action: Reproduce by spreading microscopic spores, spores often found in air and soil where they can be inhaled or come in contact with body surfaces
Prions.
Mode of action, diseases and physical characteristics
Prions
Diseases: Mad cow disease
Physical characteristics: Folded protein structure
Mode of action: Prions are a type of protein that can trigger normal proteins in the brain to fold abnormally
Protozoa.
Physical characteristics, mode of action and diseases
Protozoa
Physical characteristics:Moves independently, single cellular
Modes of action: Produce toxin and multiply inside other cells
Disease: malaria
What are the 3 lines of defence?
First of defence: external barriers
physical + chemical barriers/ protective reflexes -> prevent entry into the body
Second line of defence: non specific internal defences
inflammation, fever, roaming macrophages-> destroy and remove pathogens if enter.
Third line of defence: specific internal defences
- antibody and cell mediated defences-> specialised lymphocytes target specific pathogens to destroy and remove from the body.
Outline external defence mechanisms of first line of defence?
skin: covers the outside of the body, stopping entry of microorganisms
Bacteria - huge number of bacteria live on the skin at a time????
Sebum- oily secretion secreted by the oil grands in the skin that kills some pathogenic bacteria.
Sweat- secreted onto skin and contains salts and fatty acids that prevent the growth of many microorganisms.
Mucus membranes- line body cavities that open to the exterior. They secrete mucus, which inhibits the entry of microorganisms to the organs of the body. The whole digestive, urinary and reproductive tracts are protected in this way. Also in ears.
Cilia- hair like projections that like tranche and brochi, that beat, moving mucus and trapping particles and microorganisms towards the throat where it may be coughed up or swallowed.
Acids- in stomach kill bacteria taken in with food or contained in mucus swallowed from the nose and windpipe, the vagina also has acid secretions that reduce growth of microorganisms. The sweat on the skin is also slightly acidic.
Lysozyme: enzyme that kill bacteria, found in tears, saliva, sweat, secretions of nose and tissue fluid,
Cerumen- earwax. Protects ear against bacteria as is slightly acidic and contains lysozyme enzymes.
Flushing of body fluids keeps areas relatively free of pathogens. Eg, Urine flow through urethra.
Hairs- found in nodal cavity and ears protect again invading microorganisms
+ protective reflexes
Define protective reflexes?
Protective reflexes: Automatic, involuntary response to a stimulus that help to protect the body from injury or from infection
Outline protective reflexesa.
Sneezing-Dust particles and noxious fumes which are likely to carrying microorganisms cause irritation. Stimulus is irritation of the walls of the nasal cavity, response is a forceful expulsion of air from the lungs which carry mucus, foreign particles and irritating gases through the nose and mouth
Coughing- Stimulus for coughing is irritation of respiratory tract (bronchi and bronchioles) resulting in air being forced from lungs to remove irritant.
- air drives mucus and foreign matter up the trachea towards the throat and mouth.
Vomiting- Vomiting has a psychological stimuli. Excessive stretching of the stomach and bacterial toxins can induce vomiting, Which is the contraction of muscles of the abdomen and diaphragm in order to expel the stomach contents.
Diarrhoea-Irritation of small and large intestines by bacteria, viruses or Protozoans can cause diarrhoea. The irritation causes increased concentrations of the muscles of the walls of the intestines so that the irritant can be removed as quickly as possible.
-Diarrhoea happens when material does not stay in large intestines long enough for water to be absorbed to the faeces are very watery
Define phagocytes?
Phagocytes- cells that are able to engulf microorganisms and cell debris
Phagocytosis?
Phagocytosis: ‘ cellular eating’
Leukocytes?
Leucocytes- a white blood cell
Define macrophages?
Macrophages- a phagocytise cell derived from a monocyte (type of white blood cell)
Define inflammation?
Inflammation- the response to damage to a tissue; involves swelling, heat, pain and redness in the affected area.
Purpose of inflammation?
Purpose of inflammation:
> reduce spread of any pathogen, to destroy the, and to prevent the entry of additional pathogens
> remove damaged tissue and cell debris
> begin repair of the damaged tissue
Outline inflammatory response?
Inflammatory response
1. Damaged mast cells in connective tissue cause release of histamine and heparin
- Histamine increases blood flow to site of injury. Vessel becomes leaky, bringing necessary components to site.
- heparin prevents blood clot to immediate area. (Clot forms around actual damaged vessels to prevent spread of infection)
- Mast cells initiate release chemicals which attract phagocytes (chemotaxis) causing phagocytosis of debris and invading pathogens
- Abnormal conditions in the tissue stimulate pain receptors, and so the person feels pain in the inflamed area
- Phagocytes filled with bacteria and debris-> die and become pus
- Mitosis-> produces new cells and repair damaged tissue
Pyrexia?
Pyrexia- body temperature above the normal range (37°c) with no known cause ( exercise/ menstural cycle not regarded as fever)
What controls fever?
Hypothalamus ( above pituitary gland)- controls body temperature thermostat set at 37°.
If cold-> goosebumps, conscious changes, vasoconstriction, shivering
If hot-> sweat, vasodilation
Outline fever process?
dangerous if too hot around 41°-> body tissue/ enzymes start to denature - convulsions (fit) + organ failure
- Pathogens enter body or cancer cells, autoimmune disease, heatstroke develop or medications cause response
- Pathogens are destroyed by leukocytes which then send a chemical message to the hypothalamus
- Thermostat is reset higher, body activity heats up to reach new temp initially person feels cold ( shivering and vasoconstriction) when body reaches temp person feels hot ( sweating and vasodilation)
- If pathogen removed thermostat resets to normal 37° and body cools down
- Of pathogen not removed, thermostat resets higher and process repeats itself
How does increasing body temperature affect your body?
Increasing body temperature:
Denatures and inactivates pathogens
Increases leukocyte activity so faster destruction and phagocytosis of pathogens
Increases rates of repair of damaged tissues#
What are antibiotics and what type of pathogens do they target?
Antibiotics: a chemical able to inhibit the growth of, or kill, microorganisms, particularly bacteria
What type of pathogen: they fight infections of microorganisms, particularly bacteria (sometimes fungi)
2 types of antibiotics?
bactericidal antibiotics- kill bacteria by changing the structure of the cell wall or cell membrane ( cell wall synthesis) by disrupting the action of essential enzymes,
Bacteriostatic antibiotics - rather than killing they stop bacteria from reproducing and inhibit growth, usually ( altering shape of ribosomes/ tRNA) by disrupting protein synthesis, preventing metabolic processes ( ie. cell respiration, altering nucleic acid/ preventing respiration
What are antivirals and what pathogens do they target?
Antivirals: a drug user for the treatment of viral infections
What type of pathogens?: viral infections
Antivirals mode of action and examples?
Mode of action:
Inhibit the development of viruses (inactivates) viral proteins are disabled by specifically designed chemical. They prevent viruses from entering cell, synthesis of virus genome, prevent synthesis of viral proteins and prevent release of virus.
Examples:
Acyclovir- herpes infections
Interferons- hepatitis B
How are they made?
…
What are the functions of the lymphatic system and roaming macrophages?
- Collect fluid lost by capillaries and returns it to the bloodstream
- Absorb fatty acids and glycerol in the small intestines
- Contains leukocytes which destroy and remove pathogens
Characteristics of lymph nodes
- numerous in neck, armpit and groin
- bean shaped
- 1-25 mm diameters
- encapsulated in connective tissue
contain macrophages
Characteristics of macrophages?
- large phagocytes
- roam in lymph targeting foreign bodies (non cell antigens)
phagocytosis takes pathogen into the cell and digests
Role of third line of defence
Guard against SPECIFIC types of antigens by initiating a response by specific leukocytes. B and T lymphocytes are programmed to recognise antigens on pathogens and are activated to initiate an immune response
Where do b and t t lymphocytes originate
Bcells : originate and mature in bone marrow
Tcells: orgininate in bone marrow and mature in thymus gland
Mode of action for b and t lymphocytes
B: chemical -> produce antibodies
T: cellular-> types of T cells with various roles
What cells are involved In antibody mediated response
B plasma cell- produce antibodies
B memory cell
Target of antibody mediated response
Extra cellular bacteria/ virus
Try to remove before cell in affected
Target of cell mediated response
Intracellular phase of infections to destroy affected cell , cancer, foreign tissues ( eg. Transplants) and larger particles
Longevity of b and T cells
B: relatively short lived ( b plasma cells)
T: relatively long lived
In humoral response, how do SPECIFIC B cells know what antigens on pathogens to target?
There are receptors on the B cells
What happens in the humoral response when a B cell is activated?
Growth and proliferation (cloning)
What group of proteins are antibodies a part of?
Immunoglobulins
What happens when antibodies meet with antigens?
- they inactivate the pathogen
- immobilise
- dissolve pathogen
- agglutination ( cause antigens to clump together)
- coat pathogen-> attract phagocytes
neutralise bacterial toxins or viruses by coating them and preventing them entering cells
Define T cells?
T cells- Lymphocytes that mature in the thymus gland containing receptors for specific antigens. They work against intracellular phase of infection to destroy affected cells, cancer cells and foreign tissue transplants.
Types of antigen presenting cells involved in cell mediated response?
Macrophages, B cells, helper T cells etc. come in contact with a specific T cell which is activated and then divides
What types of cells do T cells divide into?
Cytotoxic T cells, helper T cells, suppressor T cells and memory T cells
Role of cytotoxic/ killer T Cells
Cytotoxic T cells- Killer T cells that secrete a chemical which dissolves the pathogen or cause it to burst (lose)
Difference between primary and secondary immune response?
The primary response is the response to the initial exposure to the antigen. It takes more time for antibodies to be developed because of this and there symptoms are worse.
The secondary response is the response to the second or any subsequent responses after the initial. It takes less time for antibodies to develop as the body already contains memory cells. Because of this the symptoms are often less severe or they are no symptoms
What are the four types of immunity + examples?
Natural passive: immediate, temporary immunity with no human intervention. When pathogens are passed from 1 person to another
( mother to foetus across placenta and amniotic fluid)
Natural active: takes time and is prolonged immunity with nohuman intervention. When Natural exposure to antigens occurs. ( chicken pox, flu virus)
Artificial passive:immediate, temporary immunity with human intervention. When antibodies are injected into the blood stream. ( serious illness where immediate action is required eg, tetanus, diphtheria or if someone has a poor immune system )
Artificial active:takes time and is prolonged immunity with human intervention. Occurs when antigen injected into the body initiates an immune response to produce antibodies. ( vaccines, eg. Measles, mumps) it is preventative
Immunisation? + reasons for and against
Programming the immune system so that the body can respond rapidly to infecting microorganisms
Reasons for immunisation:
all tested rigorously by by law in AUS
herd immunity
Objections to immunisation:
some contain chemicals that are poisons such as mercury ( as a preservative)
May contain allergens
Religious objections
Vaccination, vaccine?
Vaccination: The introducing of antigens to a person so that they Aquire immunity without suffering from the illness
Vaccine: An antigen preparation used in immunisation
What are the 4 types of vaccines + examples of each type?
- living attenuated microorganisms eg. Measles, mumps and rubella ( reduce ability to produce disease symptoms)
- dead microorganisms eg. Cholera, bubonic plague ( immunity not as prolonged as first type)
- toxoids eg. Diphtheria, tetanus. ( made from filaments of bacterial cultures containing toxins- toxins are inactivated)
subunit eg. Human papilloma virus, hepatitis b. ( fragment of organism is used to provoke immune response )
Herd immunity?
Herd immunity: Type of group immunity that occurs when a high proportion of people in a population are immunised that those who are not immunised are protected
Alzheimer’s + causes and effects + treatment
Alzheimer’s: form of dementia causing problems with memory thinking and behaviour
Cause:
People with Alzheimer’s disease have abnormal clumps (amyloid plaques) & tangled bundles of fibres (tau tangles) in the brain. Symptoms
Effect:
Alzheimer’s disease is characterised by progressive & irreversible mental deterioration. It gradually destroys memory & thinking skills, eventually leading to confusion, mood swings, aggression & general withdrawal.
Treatment: Treatment Drugs are available to manage the symptoms of the illness & slow its progress. Drugs aim at increasing acetylcholine levels, as acetylcholine is a neurotransmitter essential for processing memory & learning.
Parkinson + causes, effect and treatment?
Cause:
Destruction of dopamine-producing cells in the basal nuclei of the cerebrum.
Symptoms:
Slowed physical & mental responses, muscular tremors, stiffness of the limbs, impaired balance & coordination.
Treatment:
A variety of medications which either contain or act like dopamine, block acetylcholine or prevent the breakdown of dopamine.
2 types of glands
Exocrine and endocrine
Endocrine glands: Glands that secrete hormones isn’t extracellular fluid that surrounds the cells that make up the gland. The secretion usually passes into the capillaries to be transported by the blood. Endocrine glands are ductless.
Exocrine glands: Glands that secrete hormones into a duct that carries the secretion to the body surface of to one of the body cavities
Endocrine vs exocrine glands examples?
Exocrine gland examples Sweat glands Salivary glands Sebaceous glands Glands of the alimentary canal
9 major endocrine glands Pineal Hypothalamus Pituitary Thyroid Parathyroid Thymus Adrenal Pancreas Gonads
Endocrine hormones of pituitary gland
Endocrine hormones of pituitary gland Follicle stimulating hormone Luteinising hormone Growth hormone Thyroid stimulating hormone Adrenocorticotropic hormones? Prolactin Antidiuretic hormone Oxytocin
Hormones produced by posterior lobe of pituitary gland
Oxytocin and antidiuretic hormone
Hormones released by thyroid
Thyroxine which targets most body cells to increase metabolic rate and thence oxygen consumption and heat production
Hormones released by parathyroid
Parathyroid hormone which targets the bones and kidneys to increase rate of osteoclast activity, increasing levels of calcium in blood and control phosphate levels
Target of follicle stimulating hormone
The gonads where it stimulates growth of follicles and the production of spermatogonia
Lutenising hormone target
- Ovaries in females where it is involved in ovulation and maintainance of corpus luteum.
- leydig cells in the testes of males where it stimulates secretion of testosterone
Growth hormone target
Growth hormone target
All cells, stimulating growth and protein synthesis
TSH target
TSH target
Thyroid stimulating production of hormones of thyroid gland
Adrenocorticotropic hormone target
Adrenocorticotropic hormone
The adrenal cortex where it stimulates secretion of hormones from the adrenal cortex
Prolactin hormone target
Prolactin hormone target
The mammary glands where it stimulates production of milk
Anti diuretic hormone target
ADH target The kidneys ( specifically the distal proximal tubule and collecting duct of nephrons) where it causes reabsorption of water
Oxytocin target
Oxytocin target
The uterus where it allows contractions during childbirth and
The mammary glands which allow the release of milk
Where is thymosins released and what is its effect?
It is released by the thymus and targets t lymphocytes to stimulate development and maturation of T lymphocytes
Where is aldosterone released and what is its effect?
Released by the adrenal cortex to target the kidney/ nephron ( WHERE SPECIFICALLY) where it increases reabsorbtion of sodium ions and secretion of water and potassium ions
Hormones released by adrenal cortex
Hormones released by adrenal cortex
Aldosterone and cortisol
Where is cortisol released and what is its effect?
Where is cortisol released and what is its effect?
The adrenal cortex to target most cells where it promotes normal metabolism; helps the body deal with stress and promotes repair of damaged tissues
Hormones produced by adrenal medulla
Adrenaline and noradrenaline
Where is adrenaline and noradrenaline released and what are their effects?
Produced by the adrenal medulla and targets most tissues where it prepares the body for fight or flight response ; reinforcing the effects of the sympathetic nervous system
Where is insulin released and what is its effect?
The pancreas to target most cells where it stimulates uptake of glucose; lowers blood glucose level
Where is glucagon released and what does it target?
Released by the pancreas and targets the liver and fat storage tissues to stimulate breakdown of Glycogen and fat; increase blood glucose levels
Where is Androgens (testosterone) released and what does it target?
In the testes where it targets many tissues to stimulate sperm production, growth of skeleton and muscles; male sexual characteristics
Where is ostrogen released and what does it target?.
Released by the ovaries, targeting many tissues to stimulate development of female secondary sexual characteristics and regulate menstrual cycle and development of endometrium
Where is progesterone released and what does it target?
Released via the ovaries to target
..the uterus where it regulates menstrual cycle and pregnancy and maintains endometrium
..the mammary glands where it prepares the mammary glands for milk secretion
Where is the hormone calcitonin produced and target once released?
Produced by the thyroid to target bones kidneys and intestines where it is involved in calcium regulation
How do proteins and amine hormones send chemical messages?
Proteins and amines are water soluble so they can’t enter, instead Hormone attaches to protein specific receptor in the membrane of the target cell. The combo of hormone with the receptor causes a secondary messenger substance to diffuse through the cell and activate Particular enzyme.
How do steroid hormones send chemical messages?
Steroid hormones are lipid soluable so they enter the target cell and combine to a receptor protein inside the cell. The receptor may be mitochondria, on other organelles of in the nucleus. The hormone receptor complex activates the genes controlling formation of particular proteins
What type/s of hormones can and can’t enter the cell?
Steroids can because Cell membrane is made of a phospholipid bylayer. Steroid hormones are lipid soluable so they enter the target cell and combine to a receptor protein inside the cell.
Protiens and amines can’t.Proteins and amines are water soluble so they can’t enter, instead Hormone attaches to protein specific receptor in the membrane of the target cell
What are the 2 lobes of the pituitary gland, how are they different?
Anterior lobe - releases and produces hormones. hormone secretions are controlled by regulating factors. Hormones are secreted into EF surrounding the cells of hypothalamus and carried by blood to Anterior lobe.
Posterior lobe- doesn’t produce hormones but releases them. Joined to hypothalamus by the nerve fibres that come from nerve cell bodies in hypothalamus and pass through the infundibulum to the posterior lobe.
Lipid and water soluble hormones examples
Lipid soluble hormones- cortisol, aldosterone
Water soluble hormones- FSH, insulin,
Relationship between hypothalamus and pituitary gland? (Posterior lobe)
Posterior lobe-
+ not a true gland as doesn’t produce hormones. hormones are produced by neurosecretory neurons
+produced in the soma, travel down axon and are stored in the axon terminals in the posterior lobe.
+ nerve impulse triggers the release of hormones from axon terminals in the posterior lobe where they are stored until a nerve impulse initiates release and hormones are releases into bloodstream.
(Antidiuretic hormone and oxytocin)
Relationship between hypothalamus and pituitary gland? (Anterior lobe)
+Hypothalamus produces releasing and inhibiting factors in neurosecretory neurons.
+factor is secreted into hypophyseal portal system and bloodstream carries factors directly into the anterior lobe
+ factors reach target endocrine cells (with corresponding receptors) and initiate a response:
Releasing factor would increase production/ release of hormone. Inhibiting factor would decrease production/ release of hormone.
(Eg, growth hormone inhibiting and releasing factor)
hormones released travel through extracellular fluid and into the bloodstream, travelling around it until it reaches its target cells.
Infundibulum?
Infundibulum is the sack like structure that joins the pituitary gland to the hypothalamus
BMR or basal metabolic rate?
is the sum total of all the body’s reactions when at rest. It is the measure of the amount of energy the body uses when at rest.
Why is regulation of calcium essential?
Essential for nerve impulse contraction and bone strength. It is controlled by calcitonin, vitamin D and parathormone
What happens if blood calcium levels are low?
Stimulus: low blood calcium levels
Receptor: chemoreceptors in parathyroid gland
Modulator: parathyroid gland which releases parathormone
Effector:bones, kidneys, intestines
Response:
bones- osteoclast break down bone for calcium
kidneys- reabsorption of calcium
Intestines- absorption of calcium increase
Feedback: increased calcium in bloodstream (negative)
What happens if blood calcium levels are too High?
Stimulus: high blood calcium levels
Receptor: chemoreceptors in parathyroid gland
Modulator: thyroid which releases calcitonin
Effector:bones, kidneys, intestines
Response:
bones- osteoblasts build up bone for calcium
kidneys- decreased reabsorption of calcium
Intestines- decreased absorption of calcium increase
Feedback: decreased calcium in bloodstream ( negative)
What happens if thyroxine levels in blood are too high
Stimulus: high levels of thyroxine in blood
Receptor: chemoreceptors in hypothalamus
Modulator: hypothalamus produces thyroid stimulating hormone inhibiting factor which stimulates the anterior lobe of PG to decrease TSH production and release.
Effector: thyroid gland
Response:thyroid produceses less thyroxine
Feedback, decreased levelsof thyroxine in bloodstream ( negative)
What happens if thyroxine levels are too low
Stimulus: low levels of thyroxine in blood
Receptor: chemoreceptors in hypothalamus
Modulator: hypothalamus produces thyroid stimulating hormone inhibiting factor which stimulates the anterior lobe of PG to decrease TSH production and release.
Effector: thyroid gland
Response:thyroid produceses less thyroxine
Feedback, decreased levelsof thyroxine in bloodstream
What happens if there is high metabolism/ increased body temperature
Stimulus: increased metabolism/ body temperature
Receptor: thermoreceptors in the skin and hypothalamus as well as chemoreceptors in hypothalamus detect thyroxine levels
Modulator: hypothalamus releases thyroid stimulating hormone inhibiting factor which decreases TSH production in Anterior lobe of pituitary gland affecting the thyroid gland to produce less thyroxine
Effector: somatic cells
Response: decreased metabolism causes decreased protein synthesis and cell respiration
Feedback: reduced metabolism and reduced body temperature (negative)
What happens if there is low metabolism/ decreased body temperature
Stimulus: decreased metabolism/ body temperature
Receptor: thermoreceptors in the skin and hypothalamus as well as chemoreceptors in hypothalamus detect thyroxine levels
Modulator: hypothalamus releases thyroid stimulating hormone releasing factor which increases TSH production in Anterior lobe of pituitary gland affecting the thyroid gland to produce more thyroxine
Effector: somatic cells
Response: increased metabolism causes increased protein synthesis and cell respiration
Feedback: increased metabolism and increased body temperature (negatiVe)
Causes, effect and treatment of Hyperthyroidism
Hyperthyroidism: Overproduction of thyroxine
Eg. Graves’ disease: most common type
Cause: caused by an immune system reaction and there seems to be genetic predisposition for the condition
Effect: increased rate of metabolism, nervousness, anxiety, weight loss, rapid heart rate, hand tremors, sleeping problems, excessive sweating, feeling hot.
Treatment:
- drugs that blocks thyroid glands use of iodine
- surgery to remove some of or all of gland
- drink containing radioactive iodine molecules which are taken up by thyroid cells wh
Causes, effect and treatment of hypothyroidism
Hypothyroidism: underproduction of thyroxine
Eg. Hashimotos: deficiency caused by attack on the thyroid gland by patients immune system
Cause: problems which thyroid gland or pituitary gland or hypothalamus, lack or iodine in diet, surgery removing gland
Effect: weakness, fatigue, weight gain or difficultly regulating weight, intolerance to cold, muscle cramps, depression slowing of mental capabilities, rough or dry skin, deepening voice, memory loss, swollen younger and face, goitre
Treatment:
inclusion of extra iodine in diet
thyroxine tablets
no cure and hormone tablets must be taken for rest of life
What happens if there is an autoimmune attack on the thyroid causing over production of thyroxine.
Stimulus: high levels of thyroxine in blood
Receptor: chemoreceptors in hypothalamus
Modulator: hypothalamus produces TSHIF cause my decreased production and release of TSH in pituitary gland
Effector: autoimmune response leads to increase in size of thyroid
Response: thyroid continues to produce thyroxine despite no TSH available
Feedback: thyroxine remains high in blood ( positive)
What happens if there is a lack of iodine in diet due to an autoimmune response destroys that thyroid cells or surgery?
Stimulus: low levels of thyroxine
Receptor: chemoreceptors in hypothalamus detect
Modulator: hypothalamus releases TSHRF to pituitary gland causing increase TSH
Effector: thyroid gland is for whatever reason not able to respond
Response: no thyroxine produced
Feedback: low levels of thyroxine (positive)
Thermoregulation ?
Thermoregulation: The regulation of body temperature, the balance of heat gain and heat loss in order to maintain a constant internal body temperature independent of environmental temperature
Body responses to hot and cold
If body temperature is too hot:
- Vasodilation: radiation and convection
- Sweating: evaporation allows increased heat loss
- long term they can be an decrease in metabolic rate= heat loss
- behavioural response
If body temperature is too cold
vasoconstriction decreases blood flow to skin
adrenal medulla stimulated to secret adrenaline and noradrenaline
shivering increases friction and cell respiration
increased thyroxine production/ metabolism
behavioural response
How is low body temperature regulated through behavioural response?
S: Low temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus
E: cerebral cortex
R: conscious changes
F: increased body temp
How is low body temperature regulated through shivering?
S: Low temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus sends nerve impulse to cerebral cortex
E: primary motor area in frontal lobe
R: rhythmic contracting and relaxing causing increased cell respiration and friction
F: increased body temp
How is low body temperature regulated through vasoconstriction?
S: Low temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus sends nerve impulse to medulla which sends message to…
E: skin blood vessels
R: prevents blood going to skin= less heat lost
F: increased body temp
How is low body temperature regulated through increasing metabolism?
S: Low temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus
E: somatic cells
R: more thyroxine production increased respiration
F: increased body temp
How is low body temperature regulated through secreting adrenaline and noradrenaline ?
S: Low temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus sends nerve impulse to medulla olongata via Autonomic nervous system sympathetic route.
E: adrenal medulla
R: release noradrenaline to increase cell respiration and heat production
F: increased body temp
How is high body temperature regulated through behavioural response?
S: high temperature
R: heat thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus
E: cerebral cortex
R: conscious changes
F: decreased body temp
How is high body temperature regulated through sweating
S: high temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory centre of hypothalamus sends nerve impulse via Autonomic nervous system
E: sweat glands
R: produce and release sweat which then evaporates
F: decreased body temp
How is high body temperature regulated through vasodilation ?
S: high temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory centre of hypothalamus sends nerve impulse to medulla which sends Autonomic impulse to vessels
E: smooth muscles in arterialise going to skin
R: blood vessels vasodilation increasing blood flow to skin allowing radiation and convection
F: decreased body temp
How is high body temperature regulated through decreasing metabolism ?
S: high temperature
R: thermoreceptor in skin and hypothalamus
M: heat production centre of thermoregulatory center of hypothalamus
E: somatic cells
R: decreased metabolism= less heat production
F: decreased body temp
Heat transfer?
Heat transfer: Balancing the loss and gain of heat through transferring it.
Heat transfer types
Types of heat transfer: Conduction Convection Radiation Evaporation
Outline heat transfer methods
Conduction: -When heat energy moves FROM A WARMER OBJECT TO A COOLER OBJECT when they are in DIRECT PHYSICAL CONTACT
- if you touch a cold object passes from your body to the object and reverse happens when you touch something hotter than ur body
Convention: - An object will HEAT OR COOL AIR as it passes over the object
the CURRENTS OV MOVING AIR REMOVE HEAT ENERGY from the object
Radiation: - heat energy moves FROM A WARMER OBJECT ACROSS A SPACE
- no contact necessary
- if your body has higher temp than the environment you will radiate heat into environment which cools the body and visevera
Evaporation:- LIQUID water is CONVERTED to WATER VAPOR
- REQUIRES ENERGY (in the form of heat) which is taken from body-> body cools
as we sweat the evaporation of sweat from the skin cools the body
How is heat produced
How is heat produced?
Carbohydrates, proteins and lipids we eat contain energy and in the process of cellular respiration food is oxidized in cells and energy released. Whilst some energy is used for cellular and body activity, most is released in form of heat
Define metabolic rate
Metabolic rate: Rate at which energy is released by the breakdown of food.
Exercise, stress and body temperature all affect this
Types of thermoreceptors
Types of thermoreceptors: Peripheral and centeral
Central- hypothalamus
Peripheral- skin and some mucous membrane
Types of peripheral thermoreceptors?
Cold and heat receptors
# temperature above Above 45° is lethal #
Define heatstroke
Heatstroke: When body temperature continues to rise and regulatory Mechanisms cease and body cannot lose heat by radiation or evaporation( often due to humidity and high body temp)
Cured by quickly cooling body in cold water
Define heat exhaustion
Heat exhaustion: Loss of water reduces volume of blood plasma lowering blood pressure and output causing person to maybe collapse.
Often occurs as a result of extreme sweating and vasodilation
What is the optimum temperature for cellular respiration
37° is optimum for cellular respiration #
heat gain must be equal to heat loss, true or false..
True
High blood glucose can be an indication of ….
High blood sugar= can lead to diabetes
What is diabetes caused by?
Caused by not enough insulin to manage glucose levels or; when insulin is not effective enough because your body is ‘insensitive’ to insulin
What does glucagon do?
Increase glucose levels
Where does insulin come from?
Secreted by beta cells in islets of langerhan in pancreas gland
Where does glucagon come from?
Alpha cells In islets of langerhan in the pancreas
Blood glucose regulation feedback loop for low blood glucose
S= low blood glucose levels
R= pancreas has islets of langerhan alpha cells have chemoreceptors on them
M= alpha cells in pancreas secrete glucagon
E= liver, adipose tissue, cells
R= gluconeogenesis, lypolysis, glycogenlysis
F= increased blood glucose
(Negative feedback loop)
Lypogenesis
Lypogenesis: Metabolic formation of fat
-Happens to adipose tissue
(Decreases BG levels)
Gluconeogenesis:?
Making glucose from protein
-Happens to all cells
(Decreases BG levels)
Lipolysis?
Breakdown of fats and other lipids by hydrolysis to release fatty acids which converts into glucose
- adipose tissue
(Increases BG levels)
Translocation?
Movement of glucose from blood stream into cells
Happens at all cells (Decreases BG levels)
Protein synthesis role in glucose regulation?
Stimulated by the release of insulin and acts to reduce blood glucose levels
-Happens at all cells
(Decreases BG levels)
Glycogenolysis?
Glycogenolysis: Process of converting glycogen back to glucose
(Increases BG levels)
Glycogenesis?
is the process of glycogen synthesis, in which glucose molecules are added to chains of glycogen for storage.
(Decreases BG levels)
What responses occur to reduce blood glucose?
-translocation
-lipogenesis
- protein synthesis
glycogenesis
What responses occur to increase blood glucose levels?
- lypolysis
- glycogenolysis
gluconeogenesis
Benefits and long term effects of stress
Benefits of stress
- Warning system
- improve productivity and concentration
fights tiredness and fatigue
Long term effects of stress? - anxiety - depression - sleep problems - digestive problems heart problems ( like hypotension)
Stress feedback loop?
Stimulus- Stressful situation (fight or flight response) so low glucose levels
Receptors- sensory receptors in AMYGDALA
Modulator- hypothalamus initiates release of adrenaline and cortisol
Effector- liver, skeletal muscle, cardiac muscle and all cells
Response- flight or flight responses Eg. Increased heart rate and cellular respiration. Metabolic Processes of glyogenolysis, lipolysis and gluconeogenesis also increase
Feedback- overcome stressor, high glucose levels in blood so increased energy production
What is the amygdala
AMYGDALA: It is a section of nervous tissue in the brain responsible for emotions, survival instincts and memory
What does modulator do during stress (flight or flight response) in terms of ADRENALINE ?
Nerve impulses via Autonomic division
- > adrenal medulla
- > adrenaline
What does modulator do during stress (flight or flight response) in terms of CORTISOL?
hypothalamus
- > Adrenocorticotropic hormone releasing factor
- > Anterior pituitary gland
- > ACTH released
- > reaches Adrenal cortex
- > which then releases cortisol
Diabetes mellitius?
Diabetes mellitus: Abnormally high blood glucose levels (hypoglycaemia). There are two types, a diabetic doesn’t produce enough insulin or their cells have an abnormal resistance to the effects of insulin
Type 1 diabetes cause, effect and treatment
Type one diabetes
Cause:
- Type one is insulin dependent diabetes
occurs because of a fault in the patients immune system causes the destruction of beta cells in the islets of langerhans of the pancreas. Beta cells are therefore not producing insulin, usually begins at childbirth
Effects:
- Beta cells cease producing insulin, glucose therefore cannot enter.
- can lead to kidney failure and heart attacks
- can cause blurred vision, increased thirst, increased blood pressure, frequent urination
Treatment
- Disease can be managed by giving a person insulin
-Can’t be digested into alimentary canal so treatment is regular injections of insulin or; use of programmable pump that provides continuous supply of insulin under skin
no actual cure
Type 1 diabetes feedback loop?
Stimulus: high glucose in blood
Receptor: chemoreceptors in beta cells are damages
Modulator: beta cells do not produce insulin
Effector: liver, all cells, muscles and adipose tissue
Response: little activity (glycogenesis, lipolysis, p.synthesis, translocation)
Feedback: glucose remains high
(Positive fb loop)
Where on the fb loop does type 1 diabetes treatment occur?
Receptor: becomes monitoring machine
Modulator: injection or pump
Type two diabetes cause effect and treatment
Cause: Iifestyle disease caused by obesity or being overweight, risk increases when person has a diet high in fat, sugar, salt and low fibre, high blood pressure and smoking.
Effects:
- body is able to produce insulin but cells do not respond.
- undiagnosed can lead to heart disease, stroke, kidney disease etc.
- excessive hunger, thirst, fatigue
Treatment:
No cure but is managed by:
careful diet, regular physical activity, maintaining healthy weight and only sometimes medications that stimulate secretion of more insulin from pancreas or stimulate receptors to be more sensitive
Type 2 diabetes feedback loop
Type 2 diabetes feedback loop
Stimulus: high blood glucose
Receptor: chemoreceptors on beta cells
Modulator: beta cells produces insulin
Effector:insulin receptors on liver, muscle, adipose tissue (effectors) damaged
Response: slow response (glycogenesis, lipolysis, p.synthesis, translocation)
Feedback: glucose level in blood still high
Where on the fb loop does type2 diabetes treatment occur?
Stimulus: keeping a healthy diet, lifestyle
Effector: medication-> increases insulin sensitivity ( thence increase rate of response)
Gas concentration feedback loop stimulus for HIGH CARBON DIOXIDE
stimulus- high co2 level (byproduct of aerobic respiration) in bloodstream
So increased hydrogen ion levels
So decreased PH levels ( more acidic)
Receptor: Chemoreceptors in medulla oblongata and aortic and carotid bodies in arteries
Modulator: Medulla oblongata respiratory centre sends nerve impulses
( via intercostal nerve and phrenic nerve)
Effector: Intercostal muscles ( from intercostal nerve)
Diaphragm (from phrenic nerve)
Response: Increased breathing rate and depth
Feedback: Decreased co2 levels in blood
So decreased H+ ion levels
So increased ph ( neutral)
Order of menstural hormone release?
FOLP
FSH-> Oestrogen-> lutenising hormone-> progesterone
What does follicle stimulating hormone do?
At the beginning of menstural cycle Low levels of estrogen and progesterone signal the anterior lobe of the pituitary gland to produce Follicle Stimulating Hormone (FSH) which Causing growth of ova. FSH begins the process of maturing a follicle.
When does oestrogen develop and what does it do?
FSH levels after a point begin to decrease and The follicle produces more estrogen.
What happens as oestrogen increases during the menstural cycle?
The ruptured follicle (corpus luteum) then secretes progesterone and estrogen to continue to prepare the uterus for pregnancy
What happens if an egg is not fertilsed?
If the egg is not fertilized, estrogen and progesterone levels drop and, on Day 28, the menses begin.
Gas concentration feedback loop for very low oxygen levels?
Stimulus: Decreased o2 ( must be VERY low to stimulate a response)
Receptor: Chemoreceptors in MO and aortic and carotid bodies
Modulator: Medulla oblongata ‘respiratory center’
Via intercostal nerve and phrenic nerve
Effector:
Intercostal muscles
Diaphragm
Response:Increased breathing rate and depth
Feedback: Increases o2 levels
Hyperventilation feedback loop
Stimulus- no stimulus. Low co2 ( too low to stimulate breathing) Normal o2 levels (not low enough to stimulate breathing)
Receptor- chemoreceptors and aortic and carotid bodies don’t detect changes
Modulator- mo not instructed to initiate a response
Effector- diaphragm and intercostal muscles are relaxed
Response- no breathing
Feedback- increased co2, H+, and decreased PH. O2 is used up. Lower gas concentration after enough time to stimulate a response
Asthma Cause
Caused when an airway swells and becomes inflamed and narrow Symptoms : Shortness of breath Wheezing coughing
Asthma feedback loop
Stim: high co2, H+, low ph
Receptor: chemoreceptors in AC bodies and mo
Modulator:mo
Effector: diaphragm and intercostal muscles
Response: bronchioles are narrowed ( inflammation and constriction due to a trigger so breathing rate and depth don’t increase much
Feedback- co2 levels remain high, o2 decreases
Emphysema cause
Cause: Walls of airsacks in lungs (alveoli) weaken and rupture overtime reducing SA of lungs and amount of oxygen you get
Emphysema symptoms
Symptoms:
Shortness of breath
Wheezing
Chronic cough
Emphysema feedback loop
Stim: high co2, H+, low ph
Receptor: chemoreceptors in AC bodies and mo
Modulator:mo
Effector: diaphragm and intercostal muscles
Response: alveoli number has decreased so decreased SA and insufficient gas exchange
Feedback- co2 levels remain high, o2 decreases
Treatment would be at stimulus
What happens when dehydrated
Low water in bloodstream
- > low blood volume
- > low blood pressure
- > higher salt conc
- > higher osmotic pressure
Thirst reflex feedback loop
Stimulus- low h20 concentration and high osmotic pressure
Receptor- osmoreceptors in hypothalamus thirst center
Modulator- hypothalamus thirst center
Effector- cerebral cortex- frontal lobe =feel thirsty
Response- behavioural (drink water) and water is absorbed in digestive system
Feedback- increased h20 concentration and decreased osmosis pressure
Anti diuretic hormone feedback loop
Low water
Stimulus- low h20 concentration and high osmotic pressure
Receptor- osmoreceptors in hypothalamus
Modulator- hypothalamus-> nerve impulse-> post.pit.gland-> ADH released
Effector- kidney ( distal convoluted tubule, collecting duct)
Response- DCT+CD become more permeable -> ADH opens water channels and water is reabsorbed
Feedback- increased h20 concentration and decreased osmosis pressure
High water concentration feedback loop
ADH
Stimulus- high h20 concentration and low osmotic pressure
Receptor- osmoreceptors in hypothalamus don’t detect
Modulator- hypothalamus-> nerve impulse-> post.pit.gland-> no ADH released
Effector- kidney ( distal convoluted tubule, collecting duct)
Response- DCT+CD become less permeable -> ADH closes water channels and less water is reabsorbed
Feedback- decreased h20 concentration and increased osmosis pressure
What do alcohol and coffee do to ADH
Alcohol- prevents ADH release from pit
Caffeine- blocks ADH receptors
Aldosterone feedback loop for high salt concentration?
Stimulus-low h20 conc=increased osmotic pressure,high salt conc and low blood pressure
Receptors- chemoreceptors+ osmoreceptors in hypothalamus and baroreceptors in AC bodies; kidneys
Modulator- hypothalamus, ACTHRF, ant.pit.gland, ACTH, adrenal cortex, aldosterone
Effectors- kidneys- loop of henele DCT
Response- NA K pumps become active. NA is reabsorbed, K is secreted. This increases osmotic pressure as water moves from filtrate to blood stream to balance salt concentration
Feedback- high H20= decreased Osmotic pressure, decreased salt concentration, increased blood pressure
Aldosterone feedback loop for low salt concentration?
Stimulus-high h20 conc=decreased osmotic pressure,low salt conc and high blood pressure
Receptors- chemoreceptors+ osmoreceptors in hypothalamus and baroreceptors in AC bodies; kidneys
Modulator- hypothalamus, ACTHIF, ant.pit.gland, ACTH not produced, adrenal cortex not targeted, reduced aldosterone
Effectors- kidneys- loop of henele DCT
Response- NA K pumps become deactivated. NA stays in filtrate, K stays in blood. = maintained osmotic pressure, water doesn’t move from filtrate.
Feedback- low H20= increased Osmotic pressure, increased salt concentration, decreased blood pressure
High calcium feedback loop?
S- high blood calcium R- chemoreceptors on thyroid M- thyroid releases calcitonin E- kidneys, intestines, bones R-osteoblasts build up bone, less reabsorption of calcium in kidney,decreased absorption of calcium in intestines F- decreased blood calcium
What is calcium needed for?
Nerve impulses, muscle contraction and bone strength
Homeostasis?
Homeostasis: The maintenance of a constant internal environment. - 37° temperature - body fluid ( water) - ion concentration - glucose blood pressure
Feedback system steps:
- stimulus
- receptor
- Modulator
- effector
- Response
- Feedback
stimulus stage
A change in the environment, initiates a response.
receptor stage
Sensory cells detect the stimulus
modulator stage
The modulator is a control centre which processes the message from the receptors
effector stage
Effectors are Muscles, glands or cells which receive messages from the modular
response stage
The appropriate response is made by the effector
feedback stage
The response changes the original stimulus.
Can either be positive feedback or negative.
If POSITIVE= process enhances stimulus
If NEGATIVE= process opposes stimulus
5 types of sensory receptors?
Thermoreceptors Chemoreceptors Pressoreceptors Nocireceptors Baroreceptors
What do the 5 sensory receptors detect?
thermoreceptors receptors detect
Heat and cold. temperature change
osmoreceptors?
Detect changes in osmotic pressure ( pressure applied to solvents is osmosis?)
chemoreceptors?
Detect changes in blood oxygen and carbon dioxide
pressoreceptors?
Detect changes in blood pressure
baroreceptors?
Detect changes in blood pressure.
nocireceptors?
Respond to damaging or potentially damaging stimuli ( pain receptors)
What is the nature of messages in the nervous system vs endocrine system?
N: Electrical impulses and neurotransmitters
E:Hormone
How are messages transported in the nervous system vs endocrine system.
N: Nerve impulses are Transported Along the membrane of neurons
E: By bloodstream
What cells are affected by nerve impulses and hormones in the nervous system vs endocrine system?
N: muscles, gland cells (Effectors) and other neurons
E: All body cells
What type of response occurs in the nervous system vs endocrine system?
N: Usually local and specific responses
E: May be very general and widespread
How long does it normally take to respond to a nerve impulse vs hormone ?
N: Rapid response- within milliseconds
E: Slower response- from seconds to days
What is the duration of a nerve impulse response vs hormone
N: Brief- stops quickly when the stimulus starts
E: Longer lasting and may continue long after the stimulus has stopped
Nervous system
Nervous system:Communication network and control center of body. It is involved in maintenance of homeostasis inside the body, a task it shares with the endocrine system
Central nervous system
Central nervous system
Control centre consisting of brain and spinal cord
Peripheral nervous system
Nerves that connect central nervous system with the receptors, muscles and glan
Neurons?
Neurons
Nerve cells which are the basic structural and functional units of whole nervous system
Myelin sheath
Myeline sheath: Layer of fatty material that covers axons acting as an insulator, protecting axon from damage and increasing the speed of the nerve impulse.
Neurilemma
Neurilemma- membrane that wraps around the myelin sheath and helps repair damaged fibres
Axon?
Axon: Long extension of nerve fibres from cell body. It carries nerve impulse away from nerve cell body to another nerve cell or effector.
Dendrite
Dendrites:Short extension of cytoplasm of cell body. They Often have many branches, receive messages from other neurons and carry them towards the cell body.
Cell body?
Cell body:Soma: contains nucleus and many other organelles
Node of ranvier?
Node of ranvier: Interval of gaps along the axon
Schwann cells?
Schwann cells: The cell that wraps around a nerve fibre forming the myelin sheath.
Motor end plate?
Motor end plate- point where branches of axon meet the muscle fibres
What kind of neurons are receptors found on?
Receptors found on Sensory neurons only
What are the types functional neurons?
Functional
- sensory
- motor
- interneuron
What are sensory (receptor) neurons?
receptor neurons
carry messages from receptors in the sense organs or in the skin to the CNS ( brain and spinal cord)
What are motor (effector) neurons?
effector neurons
- carry messages from the CNS to the muscles and glands ( the effectors)
What are interneurons
association neurons, connector neurons or relay neurons
located in the CNS and are links between sensory and motor neurons
Types of structural neurons?
Multipolar- 1 axon, multiple dendrites
Bipolar- 1 axon and 1 dendrite
Unipolar- 1 axon extension and cell body to one side of it.
What do functional neurons do?
Transmit information from the receptor to the effector to respond rapidly to stimuli with the purpose of maintaining homeostasis
Where do nerve impulses begin
nerve impulse starts in dendrite
Nerve fibres?
Nerve fibre: Any long extension of cytoplasm for a nerve cell body
Nerve?
Nerve: Bundle of nerve fibre held together by connective tissue
Nerve impulse generation ?
- Resting neuron contains POTENTIAL ENERGY. This comes from the difference between the electrical charge on the inside and outside of a neuron.
- Nerve impulse = ACTION POTENTIAL
A change in the EXtracellular fluid and intracellular fluid generates an impulse that propagates ( moves) along neuron.
~The nerve impulse undergoes polarisation, depolarisation, repolarisation, and hyperpolarisation~
Polarisation
there is a + EF (due to sodium) & - IF (due to large - proteins).
RESTING MEMBRANE POTENTIAL= -70mv
potassium readily diffuses through cell membrane into EF. The Na/ K pump actively pumps potassium back into cell.
Depolarisation
there is a - EF & + IF ( charges have swapped)
- a stimulus opens some Na+ voltage gated channels and Na+ moves into cell causing cell to become positive .
- when membrane potential reaches -55mv an all or none response occurs
- all Na+ voltage channels open in that area causing an influx of Na+ = positive IF
Repolarisation
Charges return to + EF & - IF
- Na+ ions diffuse through IF causing in adjacent parts of the neuron to depolarise. Na+ also stimulates k+ voltage gate channels to open.
- k+ moves out of the cell into the EF making it more positive. Thence IF is - charged ( large - proteins) and Charges are restored
- This process of repolarisation generates ACTION POTENTIAL which stimulates the Na+ V.G channel in adjacent areas to open.
- the Na+/ K+ pump restores ionic distribution Na+ out and K+ in. While the cell segment is restoring back to polarised state. It is in REFARACTORY PERIOD. This prevents the neuron from being stimulated again and prevents the nerve impulse from travelling backwards
Hyper polarisation
- the charges is more negative than resting ( in the cell?) causing K+ V.G to close
- K+/Na+ pump is restoring the ionic distribution
- cell is in refractory period and cannot be restimulated and the nerve impulse is prevented from moving backwards
2 ways nerve impulse moves across a neuron
Saltatory conduction- mylinated conduction
Continuous conduction- unmylinated conduction
Saltatory conduction process
- nerve impulses Jump from one node to the next, allowing nerve impulses to travel much faster
- it jumps from nodes because nerve fibres are insulated from the extracellular fluids at the nodes of ranvier and ions cannot flow between the inside and outside of the cell membrane and action potential cannot form.
Continuous production process
- Each action potential generates another action potential just in front of it, this repeats along the length of the whole membrane
depolarisation in one area of the membrane causes a local current flow between neighbouring areas on the membrane.
Nerve impulse
Nerve impulse: Electrochemical charge that travels along nerve fibre.
Neuromuscular junction vs synapse
Neuromuscular junction: Junction between branches of a motor neuron and a muscle fibre; also called the motor end plate
Synapse: Junction between branches of adjacent neurons. Messages are passed across the synapse. Messages are passed across the synapse
Transmission across a synapse process?
Action potential causes depolarisation of axon terminal membrane, causing calcium V.G channels to open causing calcium to enter the cell.
Calcium ions bind to the synaptic vesicles which contain neurotransmitters. These vesicles move and then bind to the presynaptic membrane allowing neurotransmitters to be released via exocytosis into synaptic cleft.
Neurotransmitters diffuse across the cleft and bind to receptors. i.e sodium ligand channels.
Protein channels open causing sodium to enter the cell causing depolarisation of post synaptic membrane
Action potential probates through post synaptic membrane. Neurotransmitters are broken down and removed from receptor mediated proteins.
i.e Aceylcholinenesterase breaks down Acetylcholine into Acetyl CoA and chlorine. Acetyl coa and chlorine are then recycled, taken up into the cell via endocytosis and converted back into acetylcholine at the axon terminal
Neurotransmitter
Neurotransmitters: Molecules that carries a nerve impulse across a small gap between branches of adjacent nerve cells,
Where are neurotransmitters released from in the somatic and autonomic divisions?
Somatic- synapse
ANS- ganglion
Describe the parietal, frontal, occipital and temporal cerebral lobe?
Parietal
- It is in between the frontal and occipital lobe
- primary sensory strip and association area
processes tactile information, pain etc.
frontal lobe
- front of the brain
- voluntary control of muscles
- judgement, emotions, motivation and memory
categorising, thinking and expressive language
occipital lobe
- Helps with vision
behind the parietal lobe
temporal lobe
- olfactory (smelling) and auditory areas
- speech auditory processing
processing of emotional responses
Physical features and function of the cerebrum?
- largest part of brain
- divided into four lobes
- cerebral cortex is its outer layer
- below cerebral cortex is white matter
convoluted surface
Function of cerebrum?
Frontal- primary motor cortex, responsible for voluntary movement of muscles, judgement and emotions
Temporal- olfactory, auditory processing and emotional responses
Occipital- vision
Parietal- processing tactile information, pain ect. Sensory association area
Physical features and function of cerebral cortex?
- 2-4cm thick
- outer surface of cerebrum
- grey matter
Function of cerebral cortex!
Higher order functions such as thinking, reasoning, memory, learning and conscious awareness of surroundings
Frontal lobe physical features and function ?
Front of brain…
Frontal lobe function?
-Primary motor cortex
- responsible for voluntary control of muscles
forming strong memories, thinking, reasoning and expressive language
Corpus callosum physical features and function
- wide band of nerve fibres that lie underneath cerebrum at the base of the longitudinal fissure
nerve fibres cross from one cerebral hemisphere to another allowing communication between sides
Corpus callosum function?
Communication between two hemispheres
Physical features and function of thalamus?
- Large
- dual lobed
- mass of grey matter
- beneath cerebral cortex
Function of thalamus?
- directs nerve impulses to correct parts of brain
- relate sensory motor signals to cerebral cortex
receives auditory and visual signals
Physical features and function of hypothalamus?
- middle of the brain, can’t be seen from outside
small
Function of hypothalamus?
- involved in homeostasis
- eg, regulation of autonomic nervous system ( regulation of heart rate, blood pressure etc.)
regulation of body temperature , food and water intake, patterns of waking and sleeping and control of urinary bladder
Physical features and function of pituitary gland
- ductless
- middle of the base of skull
- pea sized
- below hypothalamus
Function of pituitary gland
secretes hormones directly into bloodstream and produces hormones for various bodily functions
Physical features and function of pons
- part of brain stem
- a bulge
Function of pons
- message station that directs Impulses
- relays signals from forebrain to cerebellum
- has sensory soles in hearing, taste and facial sensations
Physical features and function of spinal cord?
- roughly cylindrical in structure
- extends from the large opening at the base of the skull to the second lumbar vertebrae
- about 44cm
- enclosed in vertebrae canal and bone
cross section shows grey matter at center surrounded by white matter (g matter is H shape )
Function of spinal cord
-Carry sensory impulses up to brain and motor impulses down from brain
integrate certain reflexes (fast automatic responses)
Physical features and function of cerebellum?
- under rear part of cerebrum
- second largest part of brain
- surface folded into series of parallel ridges
- outer folded part is grey matter
inside is white matter that branches to all parts of cerebellum
Function of cerebellum?
- Control over fine body movement, posture, balance and coordination of voluntary muscle movement
does this by receiving sensory information from inner ear ( for posture and balance) and from stretch receptors in skeletal muscles
Physical features and function of medulla oblongata
- continuation of spinal cord
- 3cm long
- extends from where spinal cord enters skull
nerve fibres pass through going to and from parts of brain
Function of medulla oblongata
Cardiac centre- regulates the rate and force of heart rate
Respiratory centre- controls rate and depth of breathing
Vasomotor centre- regulates diameter of blood vessels
+ others they regulate reflexes of swallowing, sneezing and vomiting.
- centres are controlled by higher centres in the brain.
What type/part of neuron would Salutatory conduction occur in?
Myelinated
What type/part of neuron continuous conduction occur in?
Unmyelinated
Speed of salutary vs continuous conduction?
Saltatory = 140 m/s
Continuous= 2 m/s
structural features of a sensory, interneurons and motor neurons?
Sensory
- unipolar
- myelinated
- sense receptors on the end of the axons. Dendrites are attached to receptors
axon terminals of on the opposite side of the axon
Structural features of interneurons
- multipolar
- multipolar
dendrites surround cellbody
Structural features of motor neurons
- multipolar
- mylinated
effectors on one end and dendrites on other surrounding cell body
From to and from the Central nervous system where does an impules go?
Either via the after afferent division (sensory) of the Efferent division (motor)
Afferent pathway?
Going towards the brain
2 afferent pathways
—SENSORY ( towards CNS)—-
Somatic sensory: info from skin and muscles
Visceral: information from internal organs
Efferent pathway?
(Exiting) going away from the brain to the internal organs and glands
2 efferent pathways
—motor division (away from CNS)——
Somatic division: sends impulses to skin and muscles
Autonomic division: sends impulses to involuntary muscles
Where do impulses of the afferent route come from?
They come from either somatic sensory neurons or visceral sensory neurons
What are the two route motor impulses may take?
Somatic- sends impulses to skin and muscles
autonomic- sends impulses to involuntary muscles, organs
Where do impulses that travel via the Autonomic nervous system division go?/ What are the divisions of the Autonomic division?
Via the sympathetic route or the parasympathetic route.
Sympathetic- controls body when active, fight of flight. It’s a longer neuron pathway so it’s the slower system
Eg. Heart> increased rate, lungs> dilates bronchioles, blood vessels of skin> constricts
Parasympathetic- controls body when resting, quiet. Very short neurons, faster
Eg. Heart> decreased rate, lungs> constricts bronchioles, blood vessels of skin> little effect
where does an impulse go ( when it has come from either afferent or efferent pathway)
To the CNS and back
Features of the spinal cord looking at diagram
- dorsal root with ganglion ( lump)
- dorsal root (back of spine, vertebrae)
- sensory neuron
- ganglion ( cell bodies on sensory neurons)
- interneuron
- central canal ( inside H shaped grey matter)
- white matter ( surrounding H)
- motor neuron through ventral root
What is the hole in the middle of the spinal column grey matter called?
Central Canal
Dorsal route ganglion?
A group of cell bodies ( somas)
Protective reflexes vs aquired reflexes
Protective reflexes
- born with them Eg. Sneezing, coughing, blinking
- protect the body from injury
- up spinal cord only
Acquired reflexes
reflexes learnt through constant repetition.
Eg, maintenance of balance while riding a bike, jamming brakes on car to avoid dangerous situations or flinching when ball is coming
What does the spinal column contain
- vertebrae ( bones forming the backbone)
-vertebral Canal ( fat, blood vessels, connective tissue which provide extra cushioning)
meninges and cerebrospinal fluid
When a sensory impulse reaches grey matter in spine, how does it get up to the brain? And back
Sensory neuron sends the impulse to an interneuron which sends the impulse to another a sensory neuron which leads it up the ascending tract to the brain. A motor neuron then brings it back down the descending tract sending the impulse to an interneuron which transmits the message to another motor neuron which takes it to the effector.
What is a mixed nerve?
a nerve containing both sensory and motor fibers
What are the protective features of the CNS?
-Skin: It is the outermost layer it acts as a barrier
-periosteum: Acts as a layer of connective tissue which surrounds bone
- bone: Brain is protected by the skull and the cranium which house it.
Vertebrae also protect spinal cord by covering it
meninges consisting of the Dura Mater, arachnoid and Pia Mater
Layers of meninges
Dura Mater
Arachnoids mater
Pia Mater
How do the meninges layers protect the cns
Dura Mater Pain sensitive, has own blood supply, sticks closely to bones of skull but on inside of vertebral Canal is not so close fitting, tough and fibrous, Toughest outermost layer of meninges
arachnoids mater - - middle layers - filled with web of collagen - has cerebral fluid - no blood vessels contains CSF
Pia Mater
- sticks closely to surface of brain and spinal cord
- very tender
- rich supply of blood vessels which provide nutrients to nervous tissue
- helps produce CSF
Where is CSF found and what does it do
Where is CSF found
Occupies space between inner and middle layer of meninges. Circulated through cavities in brain and through a canal in center of spinal
What does Cerebral spinal fluid do?
-protection: acts as shock absorber
Support: brain floats in it
Transport: takes nutrients to brain cells and spinal cord, removing wastes
What is the general function of the autonomic division?
Adjustment of internal environment (homeostasis)
What is the general function of the somatic division?
Response to the external environment
Effector affected in the Autonomic vs somatic division?
Effector affected in the Autonomic division?
Heart muscles, involuntary muscles and glands
Effector affected in the Somatic division?
Skeletal( voluntary) muscles
Efferent outwards pathway for the Autonomic vs somatic division?
Efferent outwards pathway for the Autonomic division?
To nerve fibres from the CNS to the effector with a synapse in a ganglion
Efferent ( outward) pathway for somatic division?
One nerve fibre from the CNS to the effector; no synapse or ganglion
Autonomic division vs somatic division type of neurotransmitters at effector
Autonomic division, type of neurotransmitters at effector
noradrenaline
Somatic division, type of neurotransmitters at effector
Acetylcholine
Is Autonomic division voluntary or involuntary
Usually involuntary
Is somatic division voluntary or involuntary?
Usually voluntary
What type of nerves go to the target organ in Autonomic division vs somatic division ?
What type of nerves go to the target organ in Autonomic division?
sympathetic and parasympathetic
What type of nerves go to the target organ in somatic division?
One set, somatic
What is the effect on the target organ in Autonomic division vs somatic division?
What is the effect on the target organ in Autonomic division?
Excitation or inhibiton
What is the effect on the target organ in somatic division?
Always excitation
Excitation vs inhibition
Excitation:the process by which nerve cells use their “presynaptic terminals” to stimulate the next receiving nerve cell in line to transmit information onward
Inhibition:kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential.
What parts of the brain are responsible for regulating the ANS?
Groups of nerve cells in medulla oblongata, hypothalamus and cerebral cortex
Reflexes?
Reflexes: Rapid and autonomic responses to a change in the environment. They are coordinated by the spinal cord on an involuntary bandits. Once the reflex has occurred, an impulse is sent to the brain and the person becomes aware of the situation.
4 important properties of reflexes
4 important properties of reflexes
- Stimulus
- Involuntary and rapid
- Small no. Of neurons involved
- Stereotyped (same way each time)
Reflex arc route
Reflex arc route
1. Sensory receptor detects stimulus and generates nerve impulse in a sensory neuron (pain= nociceptor)
- Sensory neuron carries impulse into the spinal cord via the dorsal root ganglion and Dordal root
- Impulse transmitted into an interneuron in the grey matter of spinal cord
- Interneuron transmits impulse to a motor neuron. Motor neuron carries impulse out via the ventral root to the effector.
- Effector responds to remove the stimulus
- While reflex is being carried out, an impulse is sent to the brain so an individual becomes aware of the situation. Upper sensory neuron carries the message
Species?
A group of individuals that share many characteristics and are able to interbreed under natural conditions to produce fertile offspring
Alleles?
Alternative forms of a gene. The pairs of alleles each person inherits from their parents control and determine the characteristics of that individuals
Populations?
Populations: A group of organisms of the same species living together in a particular place at a particular time
Geneticists
Geneticist: Scientists who specialise in the study of inheritance; prefer to consider the characteristics of the population as a whole and not those of the individuals that make up the population. They find it convenient to pool genotypes of all the individuals capable of reproducing ‘gene pool’
Gene pools
Gene pool: Sum of all the alleles carried by the members of a populatio
Allele frequencies
Allele frequencies: How often each allele of a gene occurs in a population
Mutations
Mutations: A permanent change in a gene or chromosome leading to new characteristics in an organism, they may occur suddenly or purely by chance. There are 2 main types: gene mutations and chromosomal mutations
Mutant
Mutant: An organism with a characteristic resulting from a mutation
Gene mutation vs Chromosomal mutations?
Gene mutation: An alteration to a single gene, occur during replication of DNA before cell division. They are Changes to a single gene so that the traits normally produced by that gene are changed or destroyed
Eg. albinism, duchenne, cystic fibrosis
Chromosomal mutations: A change to the structure and or number of chromosomes in a organism. A mutation in which all or part of a chromosome is affected
(a change to the structure and or number of chromosomes in an organism)
Mutagenic agent/ mutagen?
Mutagenic agent/ mutagen: An environmental agent that increases the rate of mutation Eg, mustard gas, Sulfur dioxide, X-rays and radiation from radioactive waste
Somatic mutations vs germline
Somatic mutations: A change occurring in a gene in a body cell( not gamete), reproductive cells are not affected as mutant body cell divides Eg. Many cancerous growths
Germinal/ germline mutations: occurs in gamates. A change in the hereditary material in the egg or sperm that becomes incorporated into the DNA of every cell in the body of offspring. Eg. Diseases like phenylketonuria (PKU) can arise through mutation during formation of gametes and can be passed in to an offsprin
Point mutations?
- a change in just 1 base in a DNA molecule.
- it could alter a protein, have no effect at all of prevent the protein from being produced = DNA for a particular protein is altered= protein for which it codes may be abnormal of missing = can have an enormous effect on entire body
Eg. Albinism, duchenne dystrophy, cystic fibrosis
Albinism?
Point mutation marked by absence of pigment from hair, skin and eye.
Lethal recessive?
Recessive alleles inherited from homozygous condition resulting in death of embryo, foetus or child.
- some lethal recessive masked by dominant allele
Eg. Tay each disease
How lethal recessives affect the gene pool
affect gene pool as ppl who inherit two such alleles would die before their alleles could be passed onto next generation do proportion of lethal recessive alleles in the gene pool would generally be reduced
Chromosomal mutation types
Deletion: When part of a chromosome is removed eg. cri du chat
Inversion: When a section of DNA breaks and is reattached in reverse order and orientation . This changes the order of genes on a chromosome and may disrupt the pairing of homologous chromosomes during meiosis
Eg. haemophilia A
Translocation:When part of a chromosome breaks of and is rejoined to the wrong chromosome
Nondisjunction: When during meiosis a chromosome pair does not seperate and one daughter cell has an extra chromosome and one daughter cell has one less than not,al number. ( sometimes referred to aneuplody- a change in chromosome number)
Trisomy – extra chromosome
Monosomy – lacking one chromosome
Duplication: When a section of a chromosome occurs twice, this may happen if part of a chromosome breaks of and joins to the wrong chromatid
Eg. Charcot Marie tooth disease
Down syndrome?
Down syndrome: Trisomy 21
- child has 3 of chromosome 21 instead of 2
- non disjunction
Partial trisomy
when extra part of 1 chromosome attached to another chromosome
Define evolution
Evolution: The gradual change in the characteristics of a species over a long period of time.
Define variation
Variation: the differences that exist between individuals or population of species
Gene expression: refers to the ‘switching on’ of a gene and the DNA code is converted into the structures and functions of a cell
Define speciation?
Speciation: The process of new species developing
Mechanisms for evolution
Mechanisms for evolution:
- genetics and inheritance ( sexual reproduction, genetic disease, mutations)
- gene flow and barriers
- random genetic drift ( bottle necking and founder effect)
- natural selection
Mutations vs mutant
Mutations: A change in a gene of chromosome leading to new characteristics
Mutant: An organism with a characteristic resulting from a mutation
Cells affected by mutations:
- All
somatic mutations: change occurring in a gene in a body cell ( not gamete) - Germline mutations: a change in the hereditary material in the egg or sperm that becomes incorporated into the DNA of every cell in the body of offspring eg. Phenylketonuria (PKU)
Types of mutations
Gene mutations and chromosomal mutations
Processes that can affect variation in humans
- random assortment: of chromosomes during meiosis ( lots of possible combos )
- crossing over: of chromatids during meiosis ( changes in sequence, recombination of alleles)
- non disjunction: chromosomes fail to seperate during meiosis
- random fertilisation: sperm can fertilise any egg
Define mutations
mutations: permanent changes in DNA of a chromosome #Mutations are the ultimate source of variation introducing new alleles into a population: new alleles may be favourable or unfavourable to survival#
When does natural selection happen?
When nature favours one set of alleles at the expense of others - causing changes to allele frequencies in a gene pool, it is not random.
Random genetic Drift
Random genetic Drift: The occurrence of characteristics in a population as a result of chance rather than natural selection; only occur in small populations.
it is random/ non directional and only contributes to change in frequencies of alleles in a gene pool
Define founder effect
Founder effect: A type of genetic drift that occurs when a new population is formed by a small number of individuals; the small size of the sample can cause marked deviations in allele frequencies from the original population
Define migration
Migration: gene flow from one popular to another
if immigrants from another country bring alleles not already in population allele frequencies for that gene will be altered
Barriers to gene flow
Barriers to gene flow:
- environmental pressures that inhibit the amount of interbreeding in populations
- isolation results in development f seperate gene pools
Geographical barriers- oceans, mountains, large lake systems, deserts, expansive ice sheets ( most common barriers for early humans)
Sociocultural barriers- people of different religions, who speak different languages, economic statuses, educational backgrounds, social positions
Population bottlenecking?
When populations are reduced to low numbers by disease, predation or periods of climate change. ( population crash is not selective but may affect all phenotypes equally)
- populations may recover ( having squeezed through a ‘bottleneck’ of low numbers) and return to previous levels but with reduced genetic diversity
Organisms can be carried offshore to an island by
Wind, ocean, human interference, animals, swimming, finding their way onto a boat,
Natural selection?
The process by which a species becomes better adapted to its environment; those individuals with favourable characteristics have a survival advantage and so pass those characteristics on to subsequent generations
What influences natural selection
What influences natural selection:
Selective pressures- any phenomena which impacts upon the behaviour and fitness of living organisms within a given environment
Types of selective pressures
Abiotic ( non living) and biotic ( living)
Abiotic pressures examples
Access to water, ability of bodies to use water, access to clothing and shelter, exposure to UV
Biotic pressures examples
Eg. Access to food, availability of mates, predators/ prey relationships, diseases
Darwin’s theory of evolution was based on these 3 theories
- variation: all members of a species may vary. Variations are passed on.
( favourable characteristics suited for environment = survival of the fittest) - birth rate: all organisms reproduce at a rate far greater than that at which their food supply and other resources increase. ( normally resulting in overcrowding)
(Exessive birthrate + limited resources =struggle for existence )
natures balance- although birth rate of organisms is high, each species numbers tended to remain at relatively constant level
Example of natural selection in humans
Ppl with long bodies and short limbs ( eskimos) have smaller SA in relation = lose heat less in very cold environments
Ppl with short bodies and long limbed ( black Africans have larger SA so lose heat more effectively and survive better in hotter environments
also sickle cell Armenia is an example ( presence of malaria acts as a selective agent for sickle cell allele)
Selective agent?
Any factor that causes the death of organisms with certain characteristics but has no effects on individuals without those characteristics
Gene pool?
total sum of all alleles of all the genes of all individuals in a population at any one time. They can be used to compare populations at different times or locations # Gene pools are dynamic, with changes in allele frequency caused by: mutations differing selection pressures random genetic drift, including the founder effect changes in gene flow between adjoining groups #
Review Speciation, isolation, variation and selection worksheet
..
Genetic diseases?
Genetic diseases: Diseases that result in changes to allele frequencies in a gene pool. An allele causing an inherited fatal disease is expected to gradually be eliminated from a population because people with the allele would die and would not pass it on to the next generation.
Eg, tay Sachs, sickle cell amenia ,thassemia
Tay Sachs causes, effects, mode of inheritance, treatment and most affected populations
Tay sachs
Causes: disorder of lipid metabolism that is inherited in an autosomal recessive pattern. Missing enzyme results in accumulation of fatty substance in nervous system.
Effects:
lethal recessive condition, leads to early childhood death
Sufferers deal with muscle weakness, problems with coordination, rhythmic muscle contractions, stiff muscles, feeling faint or wasting away, difficulty swallowing, hearing loss, impaired voice, seizures, or vision loss
Mode of inheritance: autosomal recessive
Populations most likely to be affected: Ashkenazi Jew population due to population being small and isolated while heterozygous form of tay Sachs has increased resistance to tuberculosis.
Treatment: none
Sickle cell amenia cause, effect, mode of inheritance, treatment and most affected populations
Sickle cell amenia
Cause: disorder of the blood caused by an inherited mutation in the gene hemoglobin. The abnormal hemoglobin causes distorted (sickled) red blood cells, red blood cells to become rigid, sticky and misshapen.
effects: amenia - Sickle cells break apart easily and die leaving you without enough red blood cells
Pain- when sickle-shaped red blood cells block blood flow through tiny blood vessels to your chest, abdomen and joints, Pain can also occur in bones
swelling of hands and feet
frequent infections
delayed growth
vision problems
Mode of inheritance: autosomal recessive
Populations which are most likely to be affected by sickle cell amenia?
Africa and India
Thalassemia cause, effect, mode of inheritance, treatment and populations most affected?
Causes: It’s caused by a mutation of either the genes for chromosome 11 or the genes for chromosome 16. There are a number of thalassemia mutations.
Effects:
- fewer haemoglobin and red blood cells, may cause anemia .
- Symptoms include fatigue, weakness, pale or yellowish skin(jaundice), facial bone deformities, slow growth, abdominal swelling and dark urine
Mode of inheritance: autosomal recessive
Populations most likely to be affected:
occurs mostly in African-American populations, people of Mediterranean, particularly Greece and Italy. and in people of southeast Asian ancestry.
Treatment: blood transfusions, bone marrow transplants
Define biotechnology?
Biotechnology: Any technological application that uses biological systems/ living organisms
Define genomics?
Genomics: study of whole sets of genes and their interactions
What are the 11 biotechnological techniques and tools?
Gene probing
DNA profiling
DNA sequencing
Gel electrophoresis
Polymerase chain reaction
Cloning
Genetic engineering (recombinant DNA)
Restriction enzymes
Ligase enzyme
Plasmids
Transgenic organisms
Where do restriction enzymes come from and what is their role there?
They come from in bacteria where they restrict the duplication of infecting viruses by cutting up the invading viral DNA
How are restriction enzymes used by scientists?
Scientists use them to cut DNA at recognition sites and restrict the duplication of bacteriophages
What are the 2 types of ends that restriction enzymes can make?
Blunt ends: Straight cuts made when a restriction enzymes make a clean break across the two strands of DNA. Both strands terminate in a base pair, it is harder to recombinate with them.
sticky ends: Made when restriction enzymes produce a staggers cut resulting in fragments with sticky ends, sticky ends is a stretch of unpaired nucleotides in the DNA molecule that overhang at the break in the strand
What is a ligase enzyme and how is it useful to biotechnology?
a ligase enzyme is an enzyme able to join of recombine, seperate pieces of DNA. It’s found in bacterium.
It’s useful in bio tech because it is only in the presence of ligase that single stranded breaks in phage DNA could be repeated= enables scientists to attempt own recombination experiments recombining DNA from different organisms, including different species
Purpose of identifying genes?
To be able to extract genes for further analysis and processing.
Ie. comparison of code to establish evolutionary relationships and diagnosis of genetic disease-> treatment plans
Genetic probing process
- sample of DNA to be analysed is mixed with radioactive nucleotides and free nucleotides
DNA replication is initiated (in lab conditions)
DNA profiling process
- separation of genes within a genome based in base pair length
- restriction enzymes are used to cut DNA into individual genes
use gel electrophoresis to form a DNA fingerprint
Gel electrophoresis process
The process of using an electric current to seperate DNA across an agarose gel.
- extract DNA from cells
- cut DNA to small pieces w/ restriction enzymes
- DNA is inserted at wells on negative end
- add electric current and strands move towards positive end. Small fragments move further
agarose gel is porous = DNA moves through spa
DNA sequencing ( the Sanger method) process
- Denaturing- DNA sample is collected; specific gene is extracted using restriction enzyme. Heat is used to denature the DNA strand. Template strand is exposed. Copies are made by polymerase chain reaction (PCR)
- Annealing- primer (known segment of DNA) is added. This indicates the site at which DNA polymerase is to attach and begin copying the DNA.
- Elongation- DNA polymerase copies the template strand, adding free nucleotides (complementary to the template)
- Termination- when ddNTP (A,T,C,G) is added, the copying process ends and the new strand of DNA is released .
DNA segments of varying lengths can be then seperate using gel electrophoresis. Each DNA segment is a different length, by reading nucleotide order a sequence can be identified.
DNA sequencing uses
- identify location of a specific mutation
- genetic counselling
establishes evolutionary trends/ relationships
Recognition site?
A specific sequence of nucleotides at which an enzyme cuts a strand of D
How plasmids are used to make proteins?
- plasmid is selected based in whether or not DNA can be easily inserted into it.
-cut using the same restriction enzyme used to extract desired gene (ie human insulin)
-DNA segment is inserted into plasmid- DNA ligase bonds to form = recombinant DNA - recombinant DNA is inserted into a transgenic organism
transgenic organism capable of transcribing the recombinant DNA and thus performs protein synthesis to manufacture the desired gene
Importance of 3’ and 5’ Prime ends?
3 and 5 prime indicate the carbon number in the DNA sugar backbone, it gives DNA strand a direction.
Formula for finding how many strands after a certain number of cycles?
2^(no. Of cycles)
Two to the power of (Number of cycles)
Why are primers added to the DNA strand before DNA polymerase extends the strand?
It acts binding site for DNA polymerase so DNA replication can happen.
What advantages does PCR have over gene cloning?
PCR clones just DNA. Cloning is whole cell. PCR is more efficient and less costly
How is recombinant insulin made?
recombinant insulin made by….: Gene for human insulin is isolated from pancreatic cells. Human gene is inserted into vectors such as plasmid which is then inserted into bacteria or yeast. Insulin gene is then cloned in the bacteria or yeast. Resulting insulin percusor formed from the gene is extracted from the bacteria or yeast and purified for pharmaceutical use by diabetes patients.#
Steps of polymerase chain reaction process?
Denaturing- hydrogen bonds of the two strands of the target sequence seperate after being heated to 90°c.
Annealing- mixture cools to allow short primer to attach/ anneal to each of the two DNA strands at the 3’ ends to act as starting points for elongation.
Elongation- sample is heated to 75°c and starting at primer DNA polymerase copies and extends the strands adding complementary nucleotides to the template.
Cycle is repeated multiple times to reproduce many copies of original templates.
Stages of cloning
Stages of cloning?
- Grow human growth cell in culture Eg. Nerve cell for myelin sheath or pancreatic cells for the insulin gene. Human cells contain the gene of interest gene X
- Isolate DNA from cultures human cell. Cut gene x from rest of DNA, at recognition site, using a restriction enzyme to create sticky ends
- Isolate suitable plasmid vector from bacterial cell
- Cut plasmid with same restriction enzyme used to cut gene x. Producing a plasmid with matching sticky end to the gene
- Gene x is inserted into the plasmid by mixing the gene and the plasmids together. Some plasmids take up gene x. The sticky ends of the plasmid base pair with the sticky ends of gene x.
- DNA ligase joins together, the sticky ends of the plasmid and the gene by covalent bonds
- Recombinant plasmid is put back in bacteria. Plasmid added to growing bacterial culture. Some bacteria will take up the plasmid by the process of transformation.
- Recombinant bacteria grown on an agar plate. Bacteria multiply and reproduce many copies of gene x. Gene has been cloned. Colonies of bacteria containing blonde gene can be identified and gene can be isolated for scientific or medical use.
Genome?
Complete set of genetic information of an organism
What is phage?
Phage: Bacteriophage; virus that infects bacteria
Vector?
Bacterial plasmid, viral phage or other such agent used to transfer generic material from one cell to another
Gene therapy involves….
replacing faulty genes with functional genes and is being used for:
Cystic fibrosis
Huntington’s disease
Gene therapy can be administered…
In vivo: genes are transferred to the body using vectors such as viruses, plasmids or liposomes
Ex vivo:cells with faulty genes are removed from the body and the fictional genes are inserted in the laboratory. Cells grow containing the functional gene and are injected back into the body.
Stem cell?
a cell that can differentiate into different cell types and proliferate ( reproduce itself)
Totipotent?
can differentiate into any cell type including placental. Is found in zygote.
Pleuripotent: can differentiate into embryonic cell types. Found in embryo blastocyst.
Multipotent
can differentiate into several cell cell types- adult stem cells
Cell replacement therapy vs tissue engineering
Cell replacement therapy: The replacement of damaged cells with healthy ones
Tissue engineering: the rebuilding of damaged tissues by the use of biology, medicine and engineering
Synthetic hormones?
Synthetic hormone: a hormone produced artificially which is similar to those produced naturally in a living organism.
Hormone replacement therapy?
Hormone replacement therapy: giving hormones to replace those which are manufacturing or insufficient.
Evidences for evolution:
-Comparative studies: Biochemistry (DNA & proteins), Embryology, Anatomy (homologous structures)
- vestigial organs
- biogeography
fossils
Phylogenetic trees?
A diagram showing evolutionary relationships between organisms; also called a dendogram
How is biochemistry used in compariative studies?
mtdna is used in comparative studies as it mutates faster than nuclear DNA
EVRs: Endogenous retrovirus, Junk DNA. It is a viral sequences hat has become part of an organisms genome. Comparing humans and chimps, same evrs are found in the same locations on chromosomes.
Mitochondrial DNA: Human mtDNA has been slowly diverging from the mtDNA from our original female ancestors and the amount of mutation is roughly proportional to the amount of time that has passed.
Protein sequences: can be compared, the more differences the less related. The less differences the more related.
Bioinformatics?
Multidisciplinary field that combines all areas of biological science with computer science, statistics and applied mathematics to help understand biological processes
In practical terms is use of computers to describe molecular components
Comparative genomics?
Comparative geomatics: Is a field of biological research in which the genome sequence of different species are compared. It allows researchers to identify regions of similarity and difference,
What are the 2 main categories of dating methods? ( for fossils)
Absolute dating and relative dating
What does relative dating Find?
The actual age
What does absolute dating find?
Tells you if one sample is older or younger than other fossil
Half life?
Time it takes for radioactive elements to decompose by half
1 half life of carbon is 5730
Potassium argon dating?
Potassium argon dating: Measures the rate of radioactive potassium decay to form calcium and argon
Limitations of potassium argon dating
can only date volcanic rocks older than 100000 to 200000
not all rock types are suitable for this method can only be used for volcanic rocks
Carbon 14 dating
: carbon 14 ( radioactive) decays to nitrogen, half life is 5730 years and ratio of C14:c12 provides an absolute date for the fossil
Limitations of carbon 14 dating
- amount of carbon 14 in air varies
- material to be dated must contain organic compounds
- requires at least 3 grams of organic material
can not be used to date back more than about 60000
Dendrochronology
Dendrochronology: Ring dating, counting the centric rings of surface of cut tree trunk.
Each ring= one year of growth
Difference in width= indicates how favourable the growing season was
Limitations of dendrochronology
timber rarely preserved for more that a few thousand years
particular conditions necessary for the method do not occur often
Stratigraphy?
- Study of layers of strata. They use two principles to do this
- principle of superposition
correlation of rock strata
Principle of superposition?
Layer on top younger than the ones below
Correlation of rock strata?
Matching layers of rock from different layers
Index fossils
Fossils or organisms that were on the earth for only a short period of time and are therefore useful in relative dating of rock strata
What are index fossils used for?
Index fossils allow for more precise relative dating. They are used to define and identify geological time periods as they were only in existence for a specific time.
Eg, fossilised pollen grains
Fluorine dating
Relative dating method, when a bone is left in the soil fluorine ions which are present m water in the soil replace some of the ions in the bones
So the older the fossil= more fluorine
Limitations of fluorine dating
- fluorine levels in water differs from area to area
can only compare fossils from the same location
How can PCR be used in evidence for evolution?
PCR can be used to amplify minute amounts of DNA so that can be used to facilitate the sequencing of the genome.
Can be Useful with fossils where sometimes only small amounts of DNA may be available
How can DNA profiling be used in evidence for evolution?
Can be invaluable in tracing ancestry and relationships btwn individuals and groups
Ubiquitous proteins?
One of a group of proteins that appear to be in all species from bacteria to humans.
Eg. cytochromes
Embryology?
Comparing the very early stages of the development of organisms
Vestigial organs?
Organs that may have once been important but have lost or changed their functions.
Examples: Nicitating membrane Muscles to move ears Wisdom teeth + pointed canines Nipples on males Hair on body Appendix Coccyx
Fossil?
Evidence of or remains of an organism that lived long ago
Eg. footprints, burrows, faeces or impressions of an animal or plant
Factors that increase rate of fossilisation?
» Sometimes soft tissues are preserved but it is mostly hard tissues such as bones that are fossilised. Therefore, for ideal conditions of fossilisation, there will still be hard body parts present.
» Rapid burial by sediments protects the remains from scavengers and mechanical damage
» Absence of decay:
» An alkaline environment favours the preservation of hard tissues
» An acidic environment favours the preservation of soft tissue, as long as there is no oxygen
present, e.g. a bog
Artefacts?
Objects that have been deliberately made by humans eg. stone heads, carvings and charcoal from cooking fires
accelerator mass spectrometry (ams) radiocarbon dating?
A more refined technique that can be used to date a sample as small as 100 micrograms
Absolute dating methods?
Absolute dating methods Dendrochronology Carbon 14 Protactinium Uranium thorium Potassium argon Electron spin resonance Fission tracks Thermoluminescence
Brachiator?
Brachiator: Brachiators a type of primate mostly from the family they use their arms to move from tree branch to tree branch, through a process called brachiation. Their arms are longer than their legs, and are much more powerful. All primates except hominins
Half life of potassium
1.3 billion years
Can only be dated between 100 000- 200000
Example of bacteriostatic and bactericidal antibiotics?
Examples:
Bactericidal- penicillin treats several bacterial infections, some being skin , ear, throat infections
Bacteriostatic- tetracycline treats bacterial infections of the skin, intestines, respiratory tract etc.
How are they made?:
….
Natural passive immunity?
Natural passive: immediate, temporary immunity with no human intervention. When pathogens are passed from 1 person to another
( mother to foetus across placenta and amniotic fluid)
Natural active immunity?
Natural active: takes time and is prolonged immunity with nohuman intervention. When Natural exposure to antigens occurs. ( chicken pox, flu virus)
Artificial passive immunity?
Artificial passive:immediate, temporary immunity with human intervention. When antibodies are injected into the blood stream. ( serious illness where immediate action is required eg, tetanus, diphtheria or if someone has a poor immune system )
Artificial active immunity?
Artificial active:takes time and is prolonged immunity with human intervention. Occurs when antigen injected into the body initiates an immune response to produce antibodies. ( vaccines, eg. Measles, mumps) it is preventative
Gene probing
Gene probing: A single stranded DNA or DNA used in genetic engineering to search for a particular gene or other DNA sequence
DNA profiling?
DNA profiling: a technique that uses the banding patterns of DNA fragments as means of identification; a DNA fingerprint is unique to a particular individual; also called DNA fingerprinting
DNA sequencing?
DNA sequencing: The determination of the precise order of nucleotides (nucleotide sequence) in a sample of DNA. Separation based on length of DNA.
Gel electrophoresis ?
Gel electrophoresis: The process of using an electric current to seperate DNA across an agarose gel
Polymerase chain reaction?
Polymerase chain reaction: (PCR) A technique used in molecular biology for producing multiple copies of DNA from a sample; used in DNA fingerprinting and in identifying diseases. ( amplifys small amounts of DNA)
Cloning?
Cloning: Process of producing clones of organisms or clones of organisms or copies of cells or DNA fragments (molecular cloning)
Genetic engineering?
Genetic engineering (recombinant DNA): (Recombinant DNA) , the procedures used to produce recombinant DNA; involve introducing DNA into a cell from a different type of organism or DNA that has been modified in someway
Restriction enzymes vs ligase enzymes
Restriction enzymes:An enzyme that cuts strands of DNA at a specific sequence of nucleotides
Ligase enzyme:An enzyme that can catalyse process of joining short strands of DNA during replication ( ligation?)
Plasmids?
Plasmids: In bacterial cell, small circular double stranded DNAs distinct from the main bacterial genome, composed of only a few genes and able to replicate independently within cells, apart form chromosomal DNA.
Transgenic organism?
Transgenic organisms: An organism that has had DNA from another species introduced into it artificially
Homologous organs?
Organs that are similar in structure but are used in different ways
Role of helper T cells?
helper T cells- Release chemicals to sensitise and attract b and T cells. Chemicals released attract phagocytes which enhance the response
Role of suppressor T cells?
suppressor T cells- They release chemicals which reduce b and T cell activity. Reducing also excessive activity when antigen has been removed
What do memory T cells do?
Recognise antigen in further exposures; initiate secondary response
