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CCEA A2 Biology Unit 1 > U1T1 - Keywords > Flashcards

U1T1 - Keywords Flashcards

The principles of homeostasis

1
Q

Homeostasis

A

Maintenance of constant conditions in an internal environment such as the body. e.g. pH, temp, blood glucose, bp + osmotic balance.

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2
Q

Osmotic Balance

A

Controlling the conc of body fluids.

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3
Q

Negative Feedback

A

All homeostatic organisms rely on this. Change from set level detected + triggers response opposing change + restoring set level. Return to set level detected + corrective response switched off.

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4
Q

Kidneys

A

Osmoregulation + excretion of toxic mechanisms.

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5
Q

Renal Artery

A

Takes blood to kidneys.

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6
Q

Renal Vein

A

Removes blood from kidneys.

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7
Q

Ureters

A

Carries urine to bladder.

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8
Q

Bladder

A

Stores urine.

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9
Q

Urethra

A

Takes urine outside body.

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10
Q

Urea

A

Product of breakdown of excess amino acids + nucleic acids.

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11
Q

Osmoregulation

A

Homeostatic process responsible for controlling water potential of blood + conc of other body fluids.

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12
Q

Pelvis

A

Cavity which receives urine from nephrons.

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13
Q

Nephron

A

Over 1 million of these in kidney. Highly specialised to carry out dual function of excretory system. Straddle boundary between cortex + medulla. Functional unit of kidney. Originates as cup shaped Bowman’s capsule.

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14
Q

Glomerulus

A

Knot of capillaries in Bowman’s Capsule. Originates from afferent arteriole + blood leaves via efferent arteriole.

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15
Q

Vasa Recta

A

Blood capillaries branching off efferent arteriole, associated with parts of nephron in medulla.

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16
Q

Ultrafiltration

A

Filtering blood contents with assistance of high pressure. Takes place at boundary between glomerular capillaries + Bowman’s capsule. Blood in glomerulus under high pressure. Forces small molecules out of capillaries (urea, glucose, sodium ions, salts, amino acids, other molecules with RMM <68000). Blood cells + plasma proteins remain suspended in blood plasma.

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17
Q

Glomerular Filtrate

A

Liquid forced out of glomerulus + into Bowman’s capsule through capillaries.

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18
Q

Plasma Proteins

A

Large proteins such as clotting factors + albumin.

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19
Q

Capillary Endothelium of Glomerulus

A

Composed of squamous endothelium with pores between them. More permeable than normal capillaries.

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20
Q

Basement Membrane

A

The effective filter. Extracellular gel like matrix which acts as molecular sieve.

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21
Q

Inner wall of Bowman’s capsule

A

Composed of podocytes.

22
Q

Podocytes

A

Highly specialised cells. Have structure which allows any substances which have passed through basement membrane to flow freely into capsular space.

23
Q

Capsular Space

A

Cavity inside Bowman’s Capsule

24
Q

Hydrostatic Pressure

A

Blood pressure caused by differing diameters of aff + eff arterioles.

25
Q

Colloidal Osmotic Pressure

A

Pressure created by remaining plasma proteins in blood which pulls fluid back into blood by osmosis.

26
Q

Glomerular Filtrate Pressure

A

Pressure built up in capsular space which forces blood back into glomerulus.

27
Q

Proximal Convoluted Tubule

A

Lined with cuboidal epithelial cells with numerous microvilli on lumen side of tubule. (Near Twisty Tube)

28
Q

Selective Reabsorption

A

Glucose, ions + amino acids diffuse into cuboidal epithelium cells of tubule, transported by active transport into extracellular spaces + basal channels. Energy provided by mitochondria. Substances in extracellular space diffuse into blood capillaries + are circulated. Low conc of AAs as continuously removed so more diffusion from PCT. When remaining GF reaches end of PCT, it’s isotonic with blood in surrounding capillaries. Glucose + AA’s can be absorbed by facilitated diffusion if conc gradient but AT ensures all glucose reabsorbed.

29
Q

Loop of Henle

A

Responsible for reabsorption of more water from filtrate. Amount varies depending on hydration. Allows mammals to produce urine hypertonic to blood. Acts as counter current multiplier. Longer loop, more concentrated urine can be.

30
Q

Isotonic Solution

A

Same osmotic pressure/same solute concs.

31
Q

Hypertonic Solution

A

Higher osmotic pressure/higher solute conc.

32
Q

Loop of Henle - Ascending Limb

A

Secretes sodium + chloride ions into surrounding interstitial space of medulla as cells lining this part of loop have high mitochondria nums. Due to solute loss to M tissue, remaining filtrate becomes more dilute + at loop top/start of DCT, filtrate is hypertonic to blood. Impermeable to water.

33
Q

Medulla

A

Salty tissue as has v.negative solute potential. Inner lighter region. Subdivided into pyramids whose apices extend down into large central cavity called pelvis.

34
Q

Loop of Henle - Descending Limb

A

Due to v.negative solute potential surrounding it + high permeability to water, water moves from filtrate into surrounding slow moving vessels of vasa recta. By time filtrate reaches tip, it’s hypertonic (osmotic removel of water from filtrate + diffusion of Na + Cl ions into descending limb) Permeable to water.

35
Q

Distal Convoluted Tubule

A

Further regulates urine content through varying pH + ionic conc of filtrate + absorbing other excretory waste products (creatinine) from blood.

36
Q

Hypotonic Solution

A

Lower osmotic pressure/lower solute conc.

37
Q

ADH

A

Anti diuretic hormone. Made in hypothalamus + stored in posterior lobe of pituitary gland. Solute potential of blood monitored by osmoreceptors in hypothalamus.

38
Q

Diuretic

A

A substance which causes increased passing of urine. Less ADH released, body loses more water. e.g. caffeine

39
Q

Anti diuretic

A

Helps to control fluid balance in body by reducing passing of urine. More ADH released, more water retained. e.g. licorice.

40
Q

Endothelium

A

Inner surface

41
Q

Epithelium

A

Outer surface

42
Q

Effective Filtrate Pressure

A

EFP = HP - (GFP + CoP) In kPa probably.

43
Q

Excretion

A

Removal of toxic metabolic waste e.g. urea.

44
Q

Egestion

A

To remove waste matter which is of no use + cannot be broken down e.g. faeces.

45
Q

Cortex

A

Outer dark region immediately under thin covering layer (capsule).

46
Q

Bowman’s Capsule

A

aka. Renal capsule/glomerular capsule. Capsule surrounding glomerulus. Supplied with blood from afferent arteriole + blood leaves via efferent.

47
Q

Collecting Duct

A

DCT joins this. Converges at pelvis base + empties contents (urine) into ureter. Where water regulation takes place. Reabsorption controlled by varying wall permeability. ADH crucial.

48
Q

Countercurrent Multiplier Effect

A

Osmotic diffs between ascending + descending limbs at any level are small but cumulative effect over length of limbs/depth of medulla is significant. Together with filtrates in limbs travelling in opp directions, process described as so.

49
Q

Afferent Arteriole

A

Wider. Group of blood vessels which supply nephrons with blood.

50
Q

Efferent Arteriole

A

Narrower. Group of blood vessels which are part of urinary tract.

51
Q

Creatinine

A

Waste product produced by breakdown of creatinine phosphate (molecule involved in ATP synthesis) in muscles.

CCEA A2 Biology Unit 1 (15 decks)

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