Homeostasis Flashcards

1
Q

Homeostasis

A

The tendency of the body to seek/maintain a condition of balance/equilibrium within its internal environment, even when faced with external changes

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2
Q

What 3 Systems Does it Effect?

A

Nervous System - vasodilation, vasoconstriction, shivering, sweating Endocrine - adrenaline, cortisol, thyroxine Behavioural - clothes change

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3
Q

What Happens when Fluids are too High?

A
  1. Osmoreceptors send signal to hypothalamus
  2. Hypothalamus tells pituitary gland to release less ADH
  3. Less ADH means kidney (effector) so less urine output
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4
Q

Baroreceptor

A

sensory neurones detecting pressure changes found in the blood vessels

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5
Q

Definition of Blood Pressure

A

The Force exerted as it presses against the walls of the blood vessels

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6
Q

Oncotic Pressure

A

the pulling force which draws fluid into the capillaries from surrounding tissue

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7
Q

Hydrostatic Pressure

A

the pushing force exerted on the walls of the capillaries out onto the surrounding tissue

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8
Q

Negative Feedback System

A
  1. Change detected by specialised receptors
  2. Receptor informs control centre
  3. Control centre sends signal to effector
  4. Effector Initiates response
  5. Response reinstates normal physiological range
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9
Q

Positive Feedback System

A

body continues to move away from optimum range, less common. Eg. Hormone production in birth

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10
Q

Temperature Regulation

A
  1. Thermoreceptors in skin, aorta, arteries detect change
  2. Signal sent to hypothalamus (control centre) in brain
  3. Hypothalamus sends signal to effectors
  4. Effector informs control centre when to stop
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11
Q

What Causes Temperature Change?

A

Conduction ie lying on cold concrete, convection ie jumping into sea, metabolic changes, environment

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12
Q

What Happens if Blood Sugar is too High?

A

beta cells detect ‘hyperglycaemia’ so pancreas releases insulin

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13
Q

What Happens if Blood Sugar is too Low?

A

Alpha cells detect ‘hypoglycaemia’ so pancreas releases glucagon

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14
Q

How Does Insulin and Glucagon Raise/Lower Blood Sugar Lvl’s?

A

Insulin converts glucose -> glycogen stored in the liver Glucagon is broken down to glucose for blood to cells

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15
Q

Hypoglycaemic Event

A

Blood Sugar >4mmol/L. Assess LOC. Glucogel = 40%. Glucose = 10%. IV, Glucagon1M, when alert make them eat carbs

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16
Q

Hyperglycaemic Event

A

IV Fluids to dilute conc. DKA/HONK fluids, rapid transfer

17
Q

Blood Pressure Negative Feedback

A
  1. Baroreceptors detect change in blood pressure
  2. Send impulse to medulla oblongata (control centre)
  3. Medulla oblongata sends correct signal to effectors
18
Q

How the Endocrine System Works as an Effector in BP?

A

Epinephrine is released which increases heart rate & contractility causing vasoconstriction, increasing BP OR ADH released stimulating H2O retention, so blood is less diluted, so BP is increased

19
Q

The Renin-Angiotensin-Aldosterone System (R.A.A.S)

A
  1. Liver regurlary secretes a pre-enzyme Angiotensinogen into the blood
  2. In response to lowered blood pressure, the juxtaglomerular cells in the Kidney secrete the ‘Renin’ enzyme
  3. Renin converts Angiotensinogen -> Angiotnesin 1 before being converted to Angiotensin 2 by Angiotensis Converting Enzyme (ACE) as it passes through the lungs
  4. Angiotensin 2 actis upon the adrenal gland, to release Aldosterone (steroid hormone) which reduces H2O retention
  5. Angiotensin 2 also does vasoconstriction, reducing vol of blood to kidney, so reducing the potential to excrete H2O
20
Q

Difference between intracellular/extracellular fluid

A

intracellular fluid is found within cells and extracellular is found outside of cells in various places throughout the body

21
Q

5 Places where extracellular fluid is found

A

ECF - Fluid outside cells
ECF in Blood- plasma
ECF in lymph vessels - lymph
ECF in spinal/brain - CSF cerebrospinal fluid
ECF in eye - aqueous humour

22
Q

What Effects Fluid Composition?

A

Composition changes when going into/out cells eg drops of glucose and picks up waste products Exercise, temp, electrolyte conc

23
Q

Osmoregulation Negative Feedback System

A
  1. Osmoreceptors detect change, sends signal to hypothalamus
  2. Hypothalamus tells pituitary gland to release more ADH
  3. Effectors secrete ADH, makes kidney retain H2O, lowering urine output
  4. Hypothalamus also triggers ‘thirst’ signal