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L2+L3 Homeostasis: Principles and Control

Description

Objectives: Define ‘homeostasis’ and explain why extracellular fluid (ECF) composition is regulated in multicellular organisms. • Define ‘osmosis’, ‘osmolarity’ and ‘tonicity’ and understand their relevance to cell volume • Understand the basis of the cell’s ‘resting membrane potential’ and appreciate its physiological significance.
Mer Scott
Quiz by Mer Scott, updated more than 1 year ago
Mer Scott
Created by Mer Scott over 7 years ago
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Resource summary

Question 1

Question
The homeostatic theory states that every [blank_start]regulatory[blank_end] mechanism of the body exists to [blank_start]maintain[blank_end] the constancy of the body's [blank_start]internal[blank_end] fluid environment.
Answer
  • regulatory
  • maintain
  • internal
  • external

Question 2

Question
(Select the correct statements.) ECF composition is regulated in multicellular organisms because:
Answer
  • 1/3 of total body water is in the ECF.
  • Cell membranes are semi-permeable and the concentration of components in the ECF influences the ICF, and so the internal environment of cells.

Question 3

Question
Fill in the normal reference ranges. - Core body temperature = [blank_start]35[blank_end] - [blank_start]38[blank_end] degrees celsius. - Fraction of body water content in ICF = [blank_start]2/3[blank_end], and so ECF = [blank_start]1/3[blank_end]. (4/5 of this is [blank_start]interstitial[blank_end] fluid, 1/5 of this is [blank_start]plasma[blank_end].) - Na+ conc. in ECF = [blank_start]135[blank_end] - [blank_start]145[blank_end] mmol/L. - Ca++ conc. in plasma = [blank_start]2.2[blank_end] - [blank_start]2.6[blank_end] mmol/L - Glucose conc. in blood = [blank_start]3.5[blank_end] - [blank_start]6[blank_end] mmol/L while fasting, 3.5 - [blank_start]8[blank_end] mmol/L non fasting. - K+ conc. in ECF = [blank_start]3.5[blank_end] - [blank_start]5[blank_end] mmol/L.
Answer
  • 35
  • 38
  • 2/3
  • 1/3
  • interstitial
  • plasma
  • 135
  • 145
  • 2.2
  • 2.6
  • 3.5
  • 6
  • 8
  • 3.5
  • 5

Question 4

Question
Osmosis is the movement of water toward a region of [blank_start]high[blank_end] concentration of [blank_start]solute[blank_end], or from a high water concentration to a low water concentration. [blank_start]Osmolarity[blank_end] is a measure of the total number of solute [blank_start]particles[blank_end] per [blank_start]litre[blank_end] of solution. For body cells this is 275 - 300 mosmol/L, in the ECF and ICF. [blank_start]Tonicity[blank_end] refers to the effect that a solution's osmolarity has on cell [blank_start]volume[blank_end].
Answer
  • high
  • low
  • solute
  • particles
  • litre
  • Tonicity
  • volume
  • Osmolarity

Question 5

Question
Normal RMP (resting membrane potential) is:
Answer
  • -70mV, if the outside of the cell is taken as 0.
  • -70mV, if the inside of the cell is taken as 0.

Question 6

Question
The main determinant of RMP (resting membrane potential) is:
Answer
  • K+, as it has the highest permeability of ions.
  • Ca++, as it controls electrical impulses and therefore contractions in muscles.

Question 7

Question
The RMP of cells remains constant.
Answer
  • True
  • False

Question 8

Question
Which statement about reference (normal) ranges is incorrect?
Answer
  • Reference range values are specific to age group, and values within two standard deviations of the mean are considered normal.
  • By chance, 5% of tests outside this range are from healthy people.
  • Intra-individual variation is normal, but inter-individual is not.
  • Both inter-individual and intra-individual variation are normal.

Question 9

Question
Choose the correct statements about feedback systems.
Answer
  • Positive feedback systems are the most helpful to maintaining homeostasis.
  • Negative feedback systems oppose change to regulated variables.
  • Feed-forward system responses can be behavioural or physiological.
  • The sensor and integrator of a system can be the same cell.
  • A good example of a negative feedback system is childbirth, specifically oxytocin release due to stretch which triggers more contractions.

Question 10

Question
Choose the two physiological communication pathways, and their appropriate timings.
Answer
  • Neuronal for quick responses, hormonal for slow responses.
  • Neuronal for slow responses, hormonal for quick responses.
  • Feed-forward for quick responses, feedback for slow responses.

Question 11

Question
Which method of heat loss is still effective when the environment is hotter than the body.
Answer
  • Evaporation
  • Radiation
  • Convection
  • Conduction

Question 12

Question
[blank_start]Vasodilation[blank_end] allows more blood to the skin and so allows more heat [blank_start]loss[blank_end]. [blank_start]Piloerection[blank_end] diverts more blood to the visceral organs and so aids heat [blank_start]retention[blank_end].
Answer
  • Vasodilation
  • Piloerection
  • loss
  • retention

Question 13

Question
In anatomical position the palms face backward.
Answer
  • True
  • False

Question 14

Question
Which statement is false?
Answer
  • Anterior is opposite to superior.
  • Inferior means below something, superior means above something.
  • Medial means closer to the saggital median line, lateral means further away from it.
  • Distal is opposite to proximal.
  • Superficial means closer to the surface.
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