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Homeostasis 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
Structure of bowman's capsule wall
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 )
26
Adaptations of bowman's capsule
- 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
Glomerular filtrate contains
- no large proteins and cells. - soluble molecules (water, amino acid, creatinine, glucose, vitamin, urea)
28
Selective reabsorption
Reabsorb essential material/ substances back into blood from filtrate After bowman's capsule glomerular enter antes pct
29
Proximal convoluted tube:
Main site for selective reabsorption of amino acid, glucose, vitamins etc.) Walls made a single layer of cuboidal epithelial cells
30
Proximal convoluted tube steps
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
Reabsorption
Glucose, vitamin, amino acid, chloride ions: actively reabsorbed Water, urea: passively reabsorbed Uris acid, and creatinine: not reabsorbed
32
Adaptations of pct cells:
Microvilli Mitochondria Infolding of basal membrane Transport protein Tight junctions
33
Loop of henle structure:
Ascending limb: permeable to No and cl only Descending limb: partneable to both Na, Cl and water
34
Ascending limb
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
Descending limb
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
Distal convoluted tube
1) Na and cl actively transported into blood 2) wate is reabsorbed into blood K, h and urea secreted into lumen from blood
37
Collecting duct
Tissue fluid or medulla has high concentration of solute Water moves out collecting duct High reabsorption water back into blood Urine formation
38
ADH
Antidiuretic hormone controls rate of water absorbed
39
osmoregulation
Control of water potential oF body fluids Starts at hypothalamus
40
Water potential is low:
Osmoreceptors detects Neurosecretory cells of hypothalamus detects Sends nervous impulse to posterior pituitary glands ADH releases enters blood stream
41
In kidney (response)
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
Increase in water potential
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
Endocrine glands
Secretory glands Releases secretions to blood capillaries Hormones Pituitary glands, ovary
44
Exocrine glands
Secretory gland Releases secretions into ducts Not hormones Salivary glands
45
Hormones
Small Short life span Transported in blood Needed in small quantities
46
Protein hormones
Wate soluble, cannot pass through plasma membrane
47
Steroid hormones
Lipid soluble, can pass through plasma membrane
48
Pancreas
Acts as both endocrine and exocrine gland Exocrine: secretes pancreatic juice Endocrine: secretes glucagon and insulin Islets of langerhans A cell, b cell
49
Insulin
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
Glucagon
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
Adrenaline
Fight or flight hormone Produced during exercise or stress By adrenal gland
52
Diabetes mellitus type 1
Develops during childhood Body not producing insulin Destruction of b-cells Injections (insulin)
53
Diabetes mellitus type 2
Develops during adult hood Body not responding to insulin Down regulations of insulin receptors Improve life style
54
Symptoms of diabetes
High blood glucose concentration in urine Dehydration Weight loss
55
Urine analysis
Presence of glucose and keto acid in urine Not accurate as not all glucose is absorbed in pct Fever, pregnancy, kidney diseases
56
Dip stick test
Dip stick contains enzymes oxidase and peroxidase Darker color = more glucose concentration
57
Bio sensor
Glucose concentration in blood Oxidase on pad More glucose concentration = more current generated
58
Guard cells characteristics
Unevenly thickened cell walls Bundles of cellulose microfibrils arranged as hoops around guard cells
59
Opening mechanism of stomata
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
Stomata opens in response to:
- Increase in light intensity - low C 02 concentration
61
Stomata closes in response to
Low light intensity High co 2 concentration Low humidity High temperature
62
Aba
Absisic acid Stress hormone Regulates stomata closure: reduce co2 uptake Reduce water loss
63
Role of Aba
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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