D - option Flashcards
discuss high altitude training for athletes (6)
benefits:
- improved performance at lower oxygen levels
- due to higher concentration of red blood cells cells
- more oxygen being transported due to increase in RBC numbers
- improved lung efficiency
- increase in number of mitochondria
risks:
- altitude sickness
- increased muscle breakdown
- effects are not immediate/ not permanent
- may be unfair to competitors who cannot train at high altitudes
describe the unique properties of cardiac muscle cells (4)
- cells are myogenic
- cells are joined end to end
- intercalated discs allow for faster propagation of signals
- cells contract together for coordinated contraction
- contains many mitochondria
- cells are branching
- controlled by SA and AV nodes
explain how the normal production of bile pigments changes with the development of jaundice (4)
normal production:
- red blood cells broken down in liver
- hemoglobin is converted to bilirubin
- bilirubin transferred to bile and eliminated in the feces
jaundice
- liver does not eliminate bilirubin
- caused by immaturity/ dysfunction/ disease of the liver
- therefore bilirubin accumulates in the blood
describe the action of steroid hormones (3)
- steroid hormone passes through cell/ plasma membrane
- binds to receptor in cytoplasm
- receptor hormone complex travels to nucleus
- binds to DNA
- promotes/ inhibits the transcription of specific genes
- codes for specific proteins
outline the treatment of stomach ulcers (3)
- proton pump inhibitors reduce stomach acid production
- medication to neutralise acidity
- lower acidity allows ulcers to heal
- take antibiotics for bacterial infection
- lifestyle changes
- surgery
explain the role of receptors in mediating the action of both steroid and protein hormones (6)
- receptors are proteins
steroid hormones
- steroid hormones cross plasma membrane
- bind to receptor proteins in the cytoplasm of the target cell
- to form a receptor-hormone complex
- promotes the transcription of specific genes
peptide hormones
- peptide hormones bind to receptors in the plasma membrane of the target cell
- binding of hormones to receptors activates a cascade of reactions
- mediated by a second messengers inside the cell
outline how infection by vibrio cholerae can lead to dehydration (3)
- V. cholerae produces toxin
- toxin causes ions to be pumped into small intestine
- drawing water into the intestine
- through osmosis
- leading to dehydration
explain how low blood pH causes hyperventilation (3)
- increased CO2 lowers blood pH
- chemoreceptors in carotid/ aorta detect lower pH
- signal/ impulses to medulla
- to intercostal muscles/ diaphragm
- ventilation rate increase occurs to expel CO2
explain the process of erythrocyte and hemoglobin breakdown in the liver (6)
- erythrocytes rupture when they reach the end of their life span
- absorbed by phagocytosis
- kupffer cells ingest erythrocytes
- kupffer cells in sinusoids in the liver
- hemoglobin split into globin and heme groups
amino acids from the globin are recycled - heme groups are further broken down into iron and bilirubin
- iron stored in liver
- bilirubin released into alimentary canal
explain how the increase in CO2 concentration affects the release of oxygen to respiring cells (2)
- increased levels of CO2 lower the pH of the blood
- which results in decreased affinity of the hemoglobin for oxygen
- this shifts the oxygen dissociation curve to the right
outline the need for iodine in the endocrine system (2)
- iodine is absorbed by the thyroid
- to synthesise thyroxin
- lack of iodine causes swelling of thyroid gland
describe how the structure of cardiac muscle cells allows them to transmit impulses (3)
- cardiac muscle cells are branched
- intercalated discs are special regions between plasma membranes
- enable rapid transmission of impulses between cells
- ion channels in membranes
- flow of ions allows action potentials to spread between cardiac cells
- trigger action potentials without nervous input
explain the reason for the delay between contacts of the atria and the ventricles (2)
- impulses from atria do not pass directly to ventricles due to layer of fibrous material
- travel to ventricle via AV node in wall of right atrium
- impulses from AV node sent along bundle of His/ purkinje fibres
- ensures that the atria have ejected their blood into the ventricles first before the ventricles contract
explain how hemoglobin supplies oxygen to respiring tissues and how the Bohr shift increases the supply (6)
- tissues use O2 for cellular respiration, thus lowering pO2 at tissue level/ repairing tissues produce CO2
- O2 dissociates more at lower pO2 from Hb thus providing O2 to respiring tissues
- Co2 is converted to hydrogen carbonate ions
- increase in H+ lowers blood pH
- H+ combines with Hb, freeing some O2
- shifts the oxygen dissociation curve to the right
- oxygen dissociation curve steeper at lower pO2
- lowers affinity of hemoglobin for oxygen
- means less oxygen can be carried for same pO2
describe how the liver regulates nutrient levels (3)
- storage of glucose as glycogen
- deamination of excess amino acids
- storage/ recycling of iron
- produces/ eliminates cholesterol
- storage of fat soluble vitamins
explain the importance of bilirubin in the onset of jaundice (4)
- jaundice is a yellowish pigmentation of the skin/ whites of eyes
- caused by high levels of bilirubin in blood tissues
- comes from breakdown of red blood cells
- results form the breakdown of the heme group of hemoglobin
- released into blood when excess produced
- released into blood when bile ducts blocked
- normally excreted with bile
- jaundice is often seen in liver disease
outline the ways in which the liver regulates the chemical and cellular composition of the blood (6)
- stores glucose as glycogen
- under influence of insulin
- some nutrients in excess can be stored in the liver
- the liver detoxifies blood/ removes toxins/ alcohol/ drugs
- kupffer cells engulf bacteria
- kupffer cells breakdown red blood cells by phagocytosis
- hemoglobin is split into heme and globin
- iron from heme is carried to the bone marrow or excess iron is stored in liver
- surplus cholesterol is converted to bile salts
- produce plasma proteins
explain the mechanism of action of a second messenger (3)
- peptide hormones bind to receptors in plasma membrane
- involves activation of second messenger
- triggers cascade of events
- leads to promotion of enzymes
- causes the hormone effect
explain the role of chemoreceptors in the regulation of ventilation rate (3)
- high CO2 levels lead to decrease in pH
- chemoreceptors found in the aorta
- they are able to detect a change in blood pH
- chemoreceptors send message to the respiratory centre
- respiratory centre controls ventilation rate
- triggers an increase in the ventilation rate to get rid for the body of CO2
outline the control of milk secretion by oxytocin and prolactin (3)
prolactin:
- produced by the anterior pituitary
- stimulates mammary glands to grow
- stimulates the production of milk
oxytocin:
- produced in neurosecretory cells in hypothalamus and secreted by posterior pituitary
- suckling stimulates oxytocin release
- contractions cause ejection of milk from mammary glands
explain the role of the liver in regulating and storing nutrients (6)
- all nutrients arrive at the liver via hepatic portal vein
- liver stores excess glucose as glycogen and releases it as needed
- process is under the control of insulin/ glucagon
- controlled by negative feedback
- amino acids are delaminated in the liver
- liver produces plasma proteins/ fibrinogen
- synthesises and stores cholesterol
- liver stores iron from the breakdown of hemoglobin in red blood cells
- liver stores vitamin A and D
outline the function of gastrin (2)
- gastrin controls the release of digestive juices
- when there is a presence of food in the stomach
explain the causes and consequences of PKU
- mutation of gene
- defective enzyme
- Phe not broke down to Tyr
- Phe accumulates
- symptoms mental retardation/ seizures
- diet free of Phe to avoid symptoms
