Homeostasis Flashcards
Homeostasis uses what system to maintain a stable internal state?
Negative feedback.
What does the effector do in a negative feedback system?
It induces a physiological response in the opposite direction to the change.
In negative feedback systems, what detects change?
The sensor.
The integrator of a negative feedback system compares what?
It compares the change to the ‘set point’.
In negative feedback control, what happens when the set point is reached?
The physiological response is shut off.
What type of control can control change in both directions?
Antagonistic control.
e.g. too cold = shiver, too hot = sweat.
True or false? Negative feedback can only control unconscious behaviours.
False. Negative feedback can control both unconscious and conscious behaviours.
Name three disadvantages of a negative feedback system.
- There can be a delay between detection and response.
- There can be a delay in shutting off the response.
- It might not function correctly at extremes.
1. and 2. can mean that the set-point range increases.
What is the name for mechanisms that can improve negative feedback? Name two types of this mechanism.
Adaptations.
- Anticipation - predicts external changes before they occur.
- Acclimitisation - negative feedback alters gradually in a new environment.
What is adaptation?
A mechnism for improving negative feedback which predicts external changes before they occur.
What is acclimitisation?
Negative feedback altering gradually in a new environment.
Changes in a set point can be one of three things:
a. T…………………. .
b. P…………………. .
c. C…………………. .
a. Temporary.
b. Permanent.
C. Cyclical.
Give an example of a temporary change in set point.
In a fever.
Give an example of a permanent change in set point.
Sex hormones increasing at puberty.
Give an example of a cyclical change in set point.
Nightly fall in body temperature, monthly reproductive cycle, annual hibernation.
Is disruption of set points a problem?
Yes, ongoing disruption of set points can cause ill or even death!
What is positive feedback? Give an example.
Positive feedback is a mechanism which creates rapid, temporary change from a set point in the SAME direction.
e.g. oxytocin in childbirth.
What is the enantostasis?
The change in one variable to compensate for a change in another variable, in order to maintain homeostasis.
Animals are classified into three groups, dependent on how they deal with changes in their external environment. Name these classes.
- Conformers - internal state matches the external environment.
- Regulators - maintain a constant internal state.
- Avoiders - maintain their internal state by avoiding extreme changes.
What is the smallest unit of organisation capable of processes associated with life?
Cell.
All living things MUST:
a. Self- ?
b. Self- ?
c. Self- ?
d. Self- ?
a. Self-organise by obtaining nutrients and oxygen and producing energy.
b. Self-support by synthesising proteins for shape.
c. Self-replicate in cell division.
d. Self-regulate by maintaining a constant internal state, controlling exchange of molecules and repairing damage.
What are tissues?
Groups of cells with a specialised function.
Epithelial cells are a tissue, a group of cells with a specialised function. What do epithelial cells do?
Epithelial cells are tightly joined to form epithelial sheets which cover or line organs to form boundaries with the external environment.
Epithelial cells allow for the transfer of selected materials and cells specialised for secretion make up glands.
Connective tissue is a group of specialised cells. Where is it found and what is its function?
Connective tissue is a few cells in abundant extracellular material. It can be found as loose connective tissue, tendons, ligaments, bones and blood.
Its function is to connect, support and anchor.
What are the three types of muscular tissue?
Skeletal, cardiac and smooth.
What type of movement does skeletal muscle tissue produce?
Voluntary movement.
What type of movement does cardiac muscle tissue produce?
Involuntary, continuous movement.
What type of movement does smooth muscle tissue produce?
Involuntary movement of hollow tissues and organs.
Which tissue is made from cells specialised for electrical conductivity. Electrical impulses relay information from the external and internal environment.
Nervous tissue.
Different tissues working together form an…?
…organ.
Which tissues make up the stomach?
Epithelial tissue, muscular tissue, connective tissue and nervous tissue.
What is a body system?
Two or more organs working together.
What is a collection of body systems, separate from the external environment?
Organism.
In multicellular organisms, cells are surrounded by …………… …………….. and …………….. .
Interstitial fluid and plasma.
Where do cells exchange materials with surrounding interstitial fluid and plasma?
In the cell membrane’s lipid bilayer and protein channels.
True or false? The levels of materials contained in extracellular fluid can vary.
False. The levels of materials contained within extracellular fluid is tightly controlled within narrow limits.
What is the name given to fast, local control of extracellular fluid by one tissue?
Intrinsic regulation.
What is the name of slower control of extracellular fluid, at different levels with interactions between different systems?
Extrinsic regulation.
Which system provide slow, longer lasting responses to change and which provides rapid coorndination of body systems in response to change?
a. Nervous system.
b. Endocrine system.
The NERVOUS system provides rapid cooordination of body systems in response to external change.
The ENDOCRINE system provides, slower, longer lasting responses.
Which body system not only provides support and enables movement but maintains Ca2+ homeostasis?
Support and movement system / skeleton.
Which body system is responsible for movement, in coordination with the skeleton?
Musculature.
Name the SIX regulatory systems which maintain homeostasis directly.
Respiratory.
Circulatory.
Excretory.
Digestive.
Immune.
Intergumentary (skin).
