Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
37 Cards in this Set
- Front
- Back
|
Outline the need for communication systems within multicellular organisms
|
Multicellular organisms have internal cells that are not exposed to the external enviroment. Enzymes are required for cellular activities but they can only work at certain conditions; temp., pH etc.. This has to be maintained in order for the internal cells to be kept alive.
|
|
|
Define stimulus and response
|
Stimulus - Any change in the enviroment that causes a response
Response - A change in behaviour or physiology as result of a change |
|
|
Define the terms negative/positive feedback and homeostasis
|
Negative feedback is the reversal of any change in conditions
Positive feedback is the increase of any change in conditions Homeostasis is the maintenance of a constant internal enviroment despite external changes |
|
|
Explain principles of homeostasis in terms of receptors, effectors and negative feedback
|
1.Stimulus - change away from optimum
2. Sensory receptors detect change 3. Communication system transmits information from receptors to effector cells 4. Effector makes a response to reverse any change |
|
|
Distinguish between ectotherms and endotherms
|
An ectotherm is an organism that relies on external sources of heat
An endotherm use internal sources of heat |
|
|
Outline the advantages and disadvantages of ectotherms
|
Advantages
Use less food for respiration and more food can be used for growth Ability to survive for long without food Disadvantages Less active in cooler temperature e.g. winter |
|
|
Outline the advantages and disadvantages of ectotherms
|
Advantages
Fairly constant body temperature despite external temperature Ability to inhabit colder habitats of the planet Disadvantages Lots of energy is used More food is needed Less food for growth |
|
|
Describe the physiological and behabvioural responses that maintain a constant core body temperature in ectotherms
|
Behaviour:
Expose body to/away from sun Hide in burrow Physiolgical: Alter body shape Increase breathing movements |
|
|
Describe the physiological and behabvioural responses that maintain a constant core body temperature in endotherms
|
Behaviour:
Remain inactive and spread out limps/Move to gain heat from muscles respiring Move into shade/towards sun Physiolgical: Sweat glands and panting remove latent heat as water evaporates Hairs on skin provide insulation Vasodilation dilates capillaries allowing more heat to be radiated Vasoconstriction constricts capillairies - less close to surface Liver cells - Rate of respiration can be increased/decreased Skeletal muscles - spontaneous contractions causes muscles to respire more |
|
|
Describe the mechanism for controlling body temperature
|
1. Stimulus is detected by thermoregulatory in hypthalamus
2. Nervous/hormonal system carry signals to skin, liver and muscles 3. More/less heat is generated so temperature goes back to optimum |
|
|
Outline the roles of sensory receptors in mammals in converting different forms of energy into nerve impulses
|
Sensory receptors are also known as energy transducers that convert one form of energy to another. Each type of transducer is adapted to detect changes in particular form of energy. The stimulus energy is converted into a nerve impulse.
|
|
|
Describe how the structure of the neurones relate to their function
|
Neurones are very long so they can transmit action potential over a long distance
The plasma membrane has gated ion channels and Na/K pumps Myelin Sheath insulates from electrical activities Cell body contains many mitochondria |
|
|
Describe and explain how the resting potential is established and maintained
|
The potential difference inside the cell is -60 mV compared to the outside. ATP is used to pump 3 Na+out and 2 K+in. As a result of this and anions inside the cell, a negative potential is maintained.
|
|
|
Describe how an action potential is generated
|
Na+ diffuse into cell causing a depolarisation. A small depolarisation will have no effect but if it reaches the threshold value at -50 mV an action potential will be generated with a potential difference of +40 mV.
|
|
|
Describe the stages of an action potential
|
1. Resting potential at -60 mV
i.e. 3Na+out & 2K+in using ATP 2. Na+ channels open and Na+ diffuse in causing depolarisation 3. Threshold at -50mV is reached 4. Voltage-gated channels open and Na+ influx occurs 5. Action potential is generated at +40 mV 6. Na+ channels close and K+ channels open 7. K+ influx causes repolarisation 8. Potential difference overshoots slightly - hyperpolarisation 9. Back to resting potential |
|
|
Describe and explain how an action potential is transmitted along a myelinated neurone with reference to voltage-gated Na+ and K+ channels
|
LOCAL CURRENTS
An action potential arrives Na+ channels open and Na+ diffuse across membrane The balance of ionic concentrations is affected at that particular point Na+ ions diffuse sideways The movement is known as a LOCAL CURRENT The movement of these Na+ causes a decrease in potential difference which opens voltage-gated channels and Na+ enters the cell which moves the action potential along the neurone Ionic exchanges can only occur at Nodes of Ranvier -> saltatory conduction |
|
|
Outline the stages during transmission of an action potential across the synapse
|
1. Action potential arrives at synaptic knob
2. The voltage-gated Ca2+ channels open 3. Ca2+ diffuses into synaptic knob 4. Ca2+ cause synaptic vesicles to fuse with presynaptic membrane 5. Neurotransmitter is released by exocytosis and diffuses across cleft 6. They bind to receptor sites on Na+ channels on postsynaptic membrane 7. Na+ channels diffuse into postsynaptic neurone 8. A generator potential is generated 9. If threshold value is reached new action potential is generated |
|
|
Outline the roles of synapses in the nervous system
|
Ensure signals only transmit in one direction
Persistent low-level signals can be combined to generate action potential - Summation After repeated stimulation a synapse may run out of neurotransmitter and the synapse is fatigued - Acclimatisation |
|
|
Define endocrine gland, hormone and target tissue
|
Endocrine Gland
A gland that secretes hormones directly into the blood - no ducts Hormone Released by endocrine glands and acts as messengers carrying a signal from the endocrine gland ti a specific target organ or tissue Target tissue consist of many target cells which contain specific receptor for a complemtary hormone |
|
|
State the two types of hormones
|
Two main types
Protein hormones Stereoid hormones |
|
|
Describe the functions of the andrenal glands
|
Andrenaline binds to complementary receptor site (first messenger)
This activates adenyl cyclase This then converts ATP to cAMP (second messenger which activates other enzymes Andrenaline: Increases heart rate Dilates pupils Increases mental awareness |
|
|
Outline the pancreas' role as an endocrine and exocrine gland
|
Exocrine Gland
Releases digestive enzymes into pancreatic duct that carries it to the first part of the small intestine Endocrine gland Islet of Langerhans contain alpha cells that secrete glucagon and beta cells secrete insulin into the blood. |
|
|
Explain how glucose concentration is regulated
|
If blood glucose is too high
Beta cells secrete insulin Target cells are hepatocytes, muscle cells and other cells ATP -> cAMP More glucose enters More glucose channels open More respiration of glucose More glucose to fats Glycogenesis If blood glucose is too low Alpha cells secrete glucagon Target cells are hepatocytes More fatty acids are respired Glycogenolysis Gluconeogenesis |
|
|
Outline how insulin secretion is controlled
|
Beta cell membranes consist of Ca2+ and K+ channels
1. K+ channel open and K+ diffuse out 2. Glucose move into cell 3. Glucose is respired to produce ATP 4. K+ channels close by ATP 5. The potential difference inside becomes less negative 6. This opens Ca2+ channels 7. Ca2+ cause vesicles with insulin to fuse with membrane, releasing insulin by exocytosis |
|
|
Compare and contrast causes of type 1 and type 2 diabetes mellitus
|
Type 1 - Insulin-dependent
Hypoglycaemia Auto-immune response Viral attack Type 2 - Insulin-independent Hyperglycaemia Obesity Diet - high in sugars Asian or afro-carribean origin Family history |
|
|
Discuss two relatively new way to treat diabetes
|
Advantages of genetically manufactured insulin
Faster and more affective Lower risk of infection Less chance of rejection Cheaper No animal welfare issues More adaptable to demand |
|
|
Outline the hormonal and nervous mechanisms involved in the control of heart rate in humans
|
Accelerator nerve increases heart rate
Vagus nerve decreases heart rate Adrenaline is secreted to increase heart rate |
|
|
Define excretion
|
Removal of metabolic waste from the body
|
|
|
Explain importance of removing waste from body including co2 and nitrogenous waste
|
Carbon dioxide compete with oxygen to bind to haemoglobin
It can also cause respiratory acidosis It is therfore breathed out from alveoli as we breathe Deamination Excess amino acid is toxic Amino acid + oxygen -> keto acid + ammonia Ammonia + co2 -> urea + water |
|
|
Describe the formation of urea in the liver
|
Orithine to Citrulline
Addition of Co2 and ammonia Forms H2O Citrulline to Arginine Addition of ammonia Forms H2O Arginine to Ornithine Addition of H2O Forms Urea |
|
|
Describe the roles of the liver in detoxification
|
In hepatocytes
Ethanol ---> Ethanal NAD is reduced Ethanal ---> Ethanoic acid NAD is reduced Ethanoic acid ---> coA |
|
|
Describe and explain the processes of ultrafiltration
|
Endothelium has narrow gaps between its cells that blood plasma and substances can pass through
Basement membrane acts as a filter and prevent the passage of molecules woth a relative molecular mass greater than 69,000 Podocytes have major processes. Fluid can pass between these cells. |
|
|
Describe and explain the process of selective reabsorbtion
|
1. Sodium ions are actively transported out of cells into tissue fluid
2. Glucose or amino acids enter cells with Na+ by facilitated diffusion 3. Water potential is reduced so water will diffuse in by osmosis 4. Glucose and amino acids diffuse into blood capillary 5. Water moves by osmosis into blood |
|
|
Explain the control of water content of the blood
|
Loop of Henle
Descending limp Water is lost by osmosis Na+ and Cl- are diffused out At the base Na+ and Cl- diffuse out No water movement Thick ascending limp Na+ and Cl- are actively transported out The Collecting Duct Water moves out by osmosis The water potential of the blood is monitored by osmoreceptors in the hypthalamus. When the water potential is low the osmoreceptor cells will lose water and shrink which releases neurosecretory cells. They release ADH which is stored at the posterior pituitary gland until needed. ADH makes collecting duct walls more permable to water. |
|
|
Outline the problems that arise from kidney failure
|
Unable to remove excess water and waste products
Leads to death |
|
|
Discuss the use of renal dialysis and transplants for the treatment of kidney failure
|
Dialysis
Exchange of substances between dialysis fluid and blood Advantages of kidney transplant Diet is less limited Feeling better physically A better quality of life Disadvantages Need immunosuppressants Need major surgery Risks of surgery e.g infection |
|
|
Describe how urine samples can be used to test for pregnancy and detect misuse of anabolic stereoids
|
Pregnancy
Human chorionic gonadotrophin (hormone) is released Specific antibody bind to hCG and moves up strip till it reaches immobilised antibodies. They carry a blue bead forming a blue line Testing for anabolic stereoids involves mass spec and gas chromotography |
