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CTR 2015 > CTR - 10 - Homeostasis > Flashcards

CTR - 10 - Homeostasis Flashcards

1
Q

What is a set point?

A

The desired value of a variable

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2
Q

What is a stimulus?

A

Deviation from a set point

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3
Q

What is negative feedback?

A

To reduce or correct a deviation from the set point (negate the stimulus)

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4
Q

Why is there oscillation?

A

Due to large between receptor and response (slight overcorrections)

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5
Q

What happens to oscillations in a more efficient homeostatic system?

A

Less oscillation (but this requires energy = costly)

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6
Q

Homesotasis is concerned with the ______ but changes are often detected ________.

A

ECF, but changes are often detected in the blood

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7
Q

Who said this:
Organ systems create and control composition of the internal milieu, and constantly is required for body cells to operate

A

Claude Bernard

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8
Q

Who said this:

Numerous agents/processes act together to control particular variables

A

Walter Cannon

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9
Q

Gain = ?

A

correction / error

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10
Q

What is the importance of maintaining body temperature?

A

Enzymatic reaction rates are temperature dependent.

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11
Q

T or F? Shell temperature and rectal temperature are accurate representations of core temperature.

A 
Shell = NO
Retal = YES
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12
Q

A fever results in ____________

A

A shift (increase) in the hypothalamic set point (greater than 37 degrees celsius)

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13
Q

How do you know when a fever is broken? What does this mean?

A

Set point returns to normal. Sweating to cool the body back down to regular set point.

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14
Q

What temperatures does heat stress occur at? What is another name for heat stress? Symptoms

A

Heat exhaustion. 37.5 - 39

Elevated core body temp
Mental confusion
Fainting
Dehydration
Headache
Heat loss mechanisms ARE functional

Corrective responses

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15
Q

What temperatures does heat stroke occur at? What is another name for heat stress? Symptoms

A

Hyperpyrexia. Greater than 40

Brain and hypothalamic activity is depressed - thermoregulatory mechanisms work less effectively –> POSITIVE FEEDBACK

Elevated core body temp
Behave/speak inappropriately
Confused
Clammy/dry skin
Not request shade or fluids
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16
Q

What is positive feedback? 2 physiological examples

A

Error in signalling - acceleration into catastrophe.

Blood clotting
Childbirth (oxytcoin)

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17
Q

What is the primary excretory organ?

A

Kidneys

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18
Q

What % of blood flow goes to the kidneys?

A

25%

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19
Q

The nephrons filter a total of _____

A

180 L of blood per day

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20
Q

How many nephrons?

A

2 million (1 million per kidney)

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21
Q

How much of the filtered blood is reabsorbed?

A

99%

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22
Q

What is reabsorbed in the PCT?

A

Glucose, water, Na+, Cl-, amino acids

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23
Q

How is glucose reabsorbed in the PCT?

A

secondary active transport

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24
Q

How are amino acids reabsorbed in the PCT?

A

secondary active transport

25
Q

What is the osmolarity of the medulla?

A

1200 mOsm

26
Q

How does ADH affect the kidney?

A

Inserts aquaporins into the collecting duct –> increases water reabsorption

27
Q

What are eryhtrocytes?

A

Red blood cells

28
Q

How many red blood cells are produced?

A

2 million per second (and removed)

29
Q

How many haemoglobin molecules per RBC?

A

300 million

30
Q

What is a hypoxic tissue?

A

Tissue getting insufficient oxygen

31
Q

What is an anoxic tissue>

A

Tissue getting NO Oyxgen

32
Q

What is another name for a RBC?

A

Erythrocyte

33
Q

What does the ________ release to regulate RBC concentration?

A

Kidney, releases erythropoietin (EPO)

34
Q

What does EPO do (broadly)?

A

Increases RBC count

35
Q

Where does EPO act?

A

On red bone barrow - releasing RBC

36
Q

What is acclimatisation?

A

Change in set point instigated by environmental change

37
Q

Change in set point instigated by environmental change. What is this?

A

Acclimatisation

38
Q

What happens if there is too little/much calcium?

A 
Too little:
Heart and muscle contraction
Nerve action (APs)
Blood coagulation
Cell division

Too much
- precipitates out in blood (with phosphate) forming clots

39
Q

Why is blood glucose regulation important?

A 
Too high (diabetes)
Too low (decreased CNS activity)
40
Q

What are the roles of insulin?

A

Conversion of glucose to glycogen in liver (if stores filled up, sorted as fat)

Uptake of glucose into tissue cells (by binding to receptors, increasing facilitated diffusion of glucose into cells)

41
Q

Stimulus for insulin release?

A

High blood glucose (amino aids, and fatty acids too)!

42
Q

glucose enters beta cells via ________?

A

GLUT (glucose transporters)

43
Q

How does glucose affect beta cells?

A

eneters via GLUT, increases ATP production, causes K+ channels to close, depolarisation, opens Ca2+ channels, insulin released from vesicles via exostosis

44
Q

How is glucose reabsorbed from the kidney (BG)? Structures?

A

lumen of nephron –> tubular cell
- secondary active transport against concentration gradient (with sodium) - via co-transport carrier

  • facilitated diffusion out of tubular cell to interstitial fluid via glucose carrier
45
Q

What are signs of diabetes mellitus?

A

Sweet urine

Wake up many times to urinate (osmosis)

46
Q

What is the real threshold?

A

300 mg / 100 mL

Greater than this, glucose is excreted, as transporters are maxed out.

47
Q

What does diabetes mellitus mean?

A

Sweet urine

48
Q

Type II accounts for _____

A

90%

49
Q

Type II accounts for _____

A

10%

50
Q

What are some consequences of diabetes mellitus?

A 
Blindness
Amputation of lower limbs
Kind failure
Impotence
Cardiovascular disease
Acidosis
Metabolic anomalies
51
Q

What are the first and second actions of glucagon?

A

Firstly - glycogenolysis (glucogen –> glucose in liver)

Gluconeogenesis - formation of new glucose from fat cells

52
Q

Why is chronic stress diabetogenic?

A

Chornic stress -> increases cartels levels
Which is a stimulus for glucagon release
Increases blood glucose –> can lead to diabetes mellitus

53
Q

What is diabetes insipidus?

A

Inability to concentrate urine

Diuresis can be 3-15 L per day

54
Q

What are the causes of diabetes insipidus?

A

Neurogenic (insufficient production or release of ADH from posterior pituitary - tumours)

Nephrogenic (end stage kidney disease - no receptors for ADH = cannot retain water)

Pscyhogenic = vastly increase water intake

55
Q

What is cardiac output?

A

Volume of blood pumped from heart per minute

CO = SV x HR

56
Q

What three factors maintain blood pressure? Structures?

A

Adequate Cardiac output - heart
Sufficient peripheral resistance = smooth muscle in small arteries
Adequate blood volume = kidneys

57
Q

Baroreceptors are _______ receptors

A

Stretch

Falling BP = less stretch
Rising BP = more stretch

58
Q

Baroreceptors signal the ___________

A

Sympathetic nervous system

59
Q

What does angiotensin II do?

A

Vasocontrstion

Increase ADH release from post pituitary

Increase aldosterone from adrenal cortex

CTR 2015 (6 decks)

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