Chapter 1: Homeostasis Flashcards
(18 cards)
What percentage does water constitute of the human body?
60%
Describe the difference in percentages of intra vs extracellular fluids, along with divisions of extracellular fluids.
Intracellular: 67%
Extracellular:
- Plasma: 20-25%
- Interstitial Fluid: 75-80%
What is the purpose of body compartmentalization?
Create barriers and regulate movement of substances between difference compartments
True or False: Extracellular fluids are in a state of homogeneous solute composition.
False. All fluids are except for protein, which is higher in plasma than interstitial fluid.
True or False: Homeostasis is a static process of maintaining a stable internal environment within a normal range.
False, it is a DYNAMIC process
Describe thermoregulation in terms of “set point”, “feedback systems”, “reset set points, and “feedforward regulation.”
- A set point is the physiological value around which the normal range fluctuates, for ex: 37 degrees for body temp.
- Feedback systems are changes to return back to set point. Can be positive (amplification of process of sweating to decrease high body temp), or negative (reducing heat loss through shivering).
- Set points can differ, for example: fever, based on “clashing demands” (keeping one property stable by shifting others from set point) and hierarchy of importance.
- Feedforward regulation is anticipation of change in variable and prepared for before it happens. Example: neurons on skin detect temperature change and body begins heat conservation and production regulation before internal body temp decreases.
What are four types of intercellular chemical messengers?
Hormones, Paracrine substances, Autocrine substances, Neurotransmitters
What chemical messenger uses blood as delivery system?
Hormones
What chemical messenger can be considered Intracellular, and why?
Autocrine, as it acts upon its own chemical secretion
True or False: Different chemical messengers always secrete difference chemicals.
False. They can secrete same chemical. Example: norepinephrine
What kind of intercellular communication does not happen in extracellular fluid?
False. Two communications can occur outside extracellular: Gap junctions, and juxtracrine (cell membrance)
Which of the following is incorrect?
a. Equilibrium requires a constant input of energy.
b. Positive feedback is less common in nature than negative feedback.
c. Homeostasis does not imply that a given variable is unchanging.
d. Fever is an example of resetting a set point.
a. Equilibrium requires a constant input of energy.
Most of the water in the human body is found in
a. the interstitial fluid compartment.
b. the intracellular fluid compartment.
c. the plasma compartment.
d. the total extracellular fluid compartment.
b. the intracellular fluid compartment.
All the fluid found outside cells is collectively called_(a)___ fluid, and consists of___(b)__ and__(c)__ fluid.
(a) Extracellular fluid
(b) Blood
(c) intersititual fluid
Physiological changes that occur in anticipation of a future change to a homeostatic variable are called _____processes.
Feedforward processes
A ____is a chemical factor released by cells that acts on neighboring cells without having to first enter the blood.
Paracrine
When loss of a substance from the body exceeds its gain, a person is said to be in____ balance for that substance
Negative
What fraction of total-body water is extracellular? Assume that water constitutes 60% of a person’s body weight. What fraction of a person’s body weight is due to extracellular body water?
Approximately one-third of total-body water is in the
extracellular compartments. If water makes up 60% of a person’s body
weight, then the water in extracellular fluid makes up approximately 20%
of body weight (because 0.33 × 0.60 = 0.20).
