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Biology > Homeostasis > Flashcards

Homeostasis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Homeostasis

A

Maintenance of constant internal environment irrespective of changes in the external environment
Keeps set point within narrow limits

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2
Q

Negative feedback mechanism

A

Restoration of norm or set point

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3
Q

Stimulus

A

Internal or external change in environment away from set point

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4
Q

Receptors

A

Cells or tissues that detects a stimuli

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5
Q

Coordinating center

A

Tissues which receives messages from receptors and determines appropriate response

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6
Q

Effectors

A

Tissues organs which receives message from coordinating center and carry out corrective response

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7
Q

Response

A

Reaction carried out by effector

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8
Q

Negative feedback

A

Fluctuates around norm or set point
Corrective actions

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9
Q

Positive vs negative

A

Positive: reinforces
Uncommon
Intensifies
Labour pain

Negative: counteracts
Common
Maintains homeostasis
Blood glucose concentration

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10
Q

Excretion

A

Removal of unwanted productS of metabolism
Toxic, poisonous, damage tissues

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11
Q

Main excretory products

A

. Carbon dioxide:
From aerobic respiration
Through blood stream
. Urea:
Produced in liver
From excess amino acid
Via kidney
. Creatinine:
Energy store in muscle
. Uric acid:
From excess purines

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12
Q

Deamination

A

Removal of amine group and h aTom from amino acid
Produces ammonia (NH3)
Toxic if allowed to accumulate

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13
Q

Urea cycle ( ornithine cycle)

A

NH3 + carbon dioxide → urea
Urea excreted through kidneys

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14
Q

Blood vessels in kidney

A

Renal artery (in)
Renal vein (out)

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15
Q

Ureter

A

Brings urine out from kidney to urinary bladder

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16
Q

Urethra

A

Takes urine out from urinary bladder

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17
Q

Capsule

A

Tough, protective layer

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18
Q

3 major regions of kidney

A

Cortex, medulla, pelvis

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19
Q

Nephrons

A

Structural and functional unit of kidneys
Tiny tube like structures in cortex and medulla

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20
Q

Structure of nephron

A

I) bowman’s capsule @ cortex
Ii) proximal convoluted tube @cortex
Iii) loop of hence @ medulla
Iv) distal convoluted tube @ cortex
V) collecting duct @ medulla connected to pelvis

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21
Q

Afferent arteriole

A

Branches out into tangle of capillaries: glomerulus

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22
Q

Efferent arteriole

A

Goes into network of capillaries surrounding the rest of nephron
A) nutrients a useful substances from urine can be returned
B) whatever waste that have not been filtered out can enter nephron and be excited via kidney

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23
Q

Mechanism of excretion in kidneys

A

Ultrafiltration
Selective reabsorption

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24
Q

Ultrafiltration

A

Filtering of small molecules including urea out of blood
A) glomerular filtrate is produced
B) flows along entire nephron
C) into ureter

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25
Q

Structure of bowman’s capsule wall

A

Endothelium: with many gaps so that substance can pass through (60-80 nm)
Basement membrane: made of collagen and glycoprotein
Acts as main selective barrier
Epithelial cells (podocytes):
Inner lining of bowman’s capsule
Many finger like projections that forms gaps (filtration slit )

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26
Q

Adaptations of bowman’s capsule

A
  • Large gaps or filtration slits: allows movement of substance into blood plasma easily
  • diameter a afferent arteriole is larger than efferent: high blood pressure in glomerulus than bowman’s capsule thus fluid is forced out
  • basement membrane acts as main filter: prevents WBC, RBC and large plasma protein
27
Q

Glomerular filtrate contains

A
  • no large proteins and cells.
  • soluble molecules (water, amino acid, creatinine, glucose, vitamin, urea)
28
Q

Selective reabsorption

A

Reabsorb essential material/ substances back into blood from filtrate
After bowman’s capsule glomerular enter antes pct

29
Q

Proximal convoluted tube:

A

Main site for selective reabsorption of amino acid, glucose, vitamins etc.)
Walls made a single layer of cuboidal epithelial cells

30
Q

Proximal convoluted tube steps

A

I) active transport of Na + ions: from pct cells to blood capillaries
Ii) Na + ions in pct lumen diffuse into cells lining pct: facilitated diffusion via co-transporter protein down the concentration gradient along with glucose and amino acid
Iii) glucose, amino acid diffuse into capillaries into blood

31
Q

Reabsorption

A

Glucose, vitamin, amino acid, chloride ions: actively reabsorbed
Water, urea: passively reabsorbed
Uris acid, and creatinine: not reabsorbed

32
Q

Adaptations of pct cells:

A

Microvilli
Mitochondria
Infolding of basal membrane
Transport protein
Tight junctions

33
Q

Loop of henle structure:

A

Ascending limb: permeable to No and cl only
Descending limb: partneable to both Na, Cl and water

34
Q

Ascending limb

A

I) Na and cl ions more into tissue fluid in medulla space
Ii) higher concentration of Na and Cl in medulla space: renal fluid becomes more dilute and enters distal convoluted tube

35
Q

Descending limb

A

I) due to high concentration of solute in medulla water moves into medulla space via osmosis
Ii) urea, Na, cl diffuses into descending limb, fluid becomes concentrated

36
Q

Distal convoluted tube

A

1) Na and cl actively transported into blood
2) wate is reabsorbed into blood
K, h and urea secreted into lumen from blood

37
Q

Collecting duct

A

Tissue fluid or medulla has high concentration of solute
Water moves out collecting duct
High reabsorption water back into blood
Urine formation

38
Q

ADH

A

Antidiuretic hormone controls rate of water absorbed

39
Q

osmoregulation

A

Control of water potential oF body fluids
Starts at hypothalamus

40
Q

Water potential is low:

A

Osmoreceptors detects
Neurosecretory cells of hypothalamus detects
Sends nervous impulse to posterior pituitary glands
ADH releases enters blood stream

41
Q

In kidney (response)

A

ADH binds to receptors on plasma membrane of collecting duct
Activates series of enzyme - controlled reaction
Production of active phosphorylase enzyme
Vesicles containing aquaporine fuses with plasma membrane
Increases permeability of membrane
Increases water reabsorption
Smaller volume a more concentrated urine

42
Q

Increase in water potential

A

Neurons stop secreting ADH
Aquaporine moves out of cell membrane of collecting duct
Collecting duct is les permeable to water
More volume of less concentrated urine

43
Q

Endocrine glands

A

Secretory glands
Releases secretions to blood capillaries
Hormones
Pituitary glands, ovary

44
Q

Exocrine glands

A

Secretory gland
Releases secretions into ducts
Not hormones
Salivary glands

45
Q

Hormones

A

Small
Short life span
Transported in blood
Needed in small quantities

46
Q

Protein hormones

A

Wate soluble, cannot pass through plasma membrane

47
Q

Steroid hormones

A

Lipid soluble, can pass through plasma membrane

48
Q

Pancreas

A

Acts as both endocrine and exocrine gland
Exocrine: secretes pancreatic juice
Endocrine: secretes glucagon and insulin
Islets of langerhans
A cell, b cell

49
Q

Insulin

A

In liver, muscle and adipose cells:
Insulin binds to receptors on surface
Increases permeability to glucose
Uptake of glucose from blood into cells
Glycogenesis
Respiration
Inhibits production of glucose / glucagon

50
Q

Glucagon

A

Binds to receptors on cell surface
Activates G protein
Activates adenyl cyclase
Produces camp
Acts as a second messenger activating series of enzyme controlled reaction
Glycogen phosphorylase→ glycogenolysis
fatty acid and protein: protein substrates
Glucose diffuse from glut to liver to blood

51
Q

Adrenaline

A

Fight or flight hormone
Produced during exercise or stress
By adrenal gland

52
Q

Diabetes mellitus type 1

A

Develops during childhood
Body not producing insulin
Destruction of b-cells
Injections (insulin)

53
Q

Diabetes mellitus type 2

A

Develops during adult hood
Body not responding to insulin
Down regulations of insulin receptors
Improve life style

54
Q

Symptoms of diabetes

A

High blood glucose concentration in urine
Dehydration
Weight loss

55
Q

Urine analysis

A

Presence of glucose and keto acid in urine
Not accurate as not all glucose is absorbed in pct
Fever, pregnancy, kidney diseases

56
Q

Dip stick test

A

Dip stick contains enzymes oxidase and peroxidase
Darker color = more glucose concentration

57
Q

Bio sensor

A

Glucose concentration in blood
Oxidase on pad
More glucose concentration = more current generated

58
Q

Guard cells characteristics

A

Unevenly thickened cell walls
Bundles of cellulose microfibrils arranged as hoops around guard cells

59
Q

Opening mechanism of stomata

A

1) H+ ions pumped out of guard cells
2) more -ve charge inside cells
3) K+ channel opens
4) cl ions diffuses in
5) more concentrated, water potential decrease
6) water moves in via osmosis
7) guard cells become thicker, due to uneven thickness opens

60
Q

Stomata opens in response to:

A
  • Increase in light intensity
  • low C 02 concentration
61
Q

Stomata closes in response to

A

Low light intensity
High co 2 concentration
Low humidity
High temperature

62
Q

Aba

A

Absisic acid
Stress hormone
Regulates stomata closure: reduce co2 uptake
Reduce water loss

63
Q

Role of Aba

A

Binds to Aba receptors
Stimulates ca 2 + influx into cytoplasm
Acts as second messenger
Inhibits proton pump and k+ reflux
-Vely charged ions leave the guard cells
Increases water potential
Cell becomes flaccid
Stomata closes

Biology (5 decks)

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