Module 5 - Keywords Flashcards
Generator potential
Small depolarisation caused by sodium ions entering the cell
Resting potential
When neurone is at rest (no stimulus), -70mV. Sodium/potassium ion pumps [3 out/2 in], K+ leakage
Depolarisation
Loss of polarisation due to entry of Na+ entering the cell. Potential difference across membrane becomes less negative
Threshold potential
Creates an action potential. There is a big enough stimulus for enough Na+ to enter the cell for the potential difference to exceed -50mV
Action potential
Membrane is depolarised to +50mV. All or nothing response. Transmitted along axon membrane
Repolarisation
Membrane becomes polarised again due to loss of K+ through v-g channels. Potential difference across membrane becomes more negative
Hyperpolarisation
Too many K+ diffuse out - potential difference under -70mV
Refractory Period
Following an action potential, there is a need to redistribute sodium and potassium ions and restore resting potential. During this time another impulse cannot be generated. Ensured impulses are separated, determines maximum frequency of impulse transmission, ensure impulse passes in one direction only along axon
Local Currents
Movements of ions along the neurone
Saltatory conduction
How the action potential ‘jumps’ from one Node of Ranvier to the next
Excretion
Removal of unwanted/toxic/waste products of metabolism
Deamination
Removes the amine group from amino acid, produces keto acid (can be respired) + also produces ammonia (soluble + highly toxic). Occurs in the liver
Ornithine cycle
Ammonia is converted into urea
Ultrafiltration
Filtration at molecular level in glomerulus by the basement membrane; smaller molecules (urea, water, glucose, amino acids, ions) are filtered out of the blood into the lumen of the Bowman’s capsule
Selective Reabsorption
Useful substances are reabsorbed from the nephron (most happens in the PCT) into the blood e.g. glucose. Excretory substances remain in the nephron e.g. urea
Hairpin countercurrent multiplier
Arrangement of a tubule in a sharp U shape so one part passes close to another with the fluid in opposite directions. Allows exchange between the contents + can be used to create a high concentration of solutes
Osmoregulation
Control and regulation of water potential of the blood and bodily fluids. Controlled by the kidney (particularly the collecting duct)
Osmoreceptors
Monitor changes in water potential of the blood. Found in the hypothalamus
Neurosecretory cells
Make ADH in the hypothalamus in response to low water potential in the blood. This collect in the terminal bulb found in the posterior pituitary gland where ADH is released
ADH
Anti diuretic hormone. Increases reabsorption of water
Dialysis
Use of a partially permeable membrane to filter the blood
Endocrine glands
Produce and secrete hormones directly into the blood - they have no ducts
Exocrine glands
Do not produce hormones - they secrete molecules into a duct which carries them to where they are needed
Hormones
Molecules released by endocrine lands into the blood and act as messengers carrying a signal from the endocrine gland to the target tissue
Target cells/tissue
Possess specific receptors on their cell surface membrane which is complementary in shape to a hormone molecule
Hepatocytes
Liver cells
Diabetes mellitus
A disease in which you can’t control your blood glucose concentrations effectively
Hyperglycemia
Blood glucose levels are too high
Hypoglycemia
Blood glucose levels are too low
Glycogenolysis
Glycogen being converted into glucose. Occurs in the liver.
Gluconeogenesis
Fatty acids/amino acids –> glucose. Occurs in the liver
Glycogenesis
Glucose being converted into glycogen. Occurs in the liver
Myogenic
Muscle can initiate its own contractions
