Homeostasis

Question 1

WHat are cells?

Answer 1

Fundamental units of life

Question 2

What are cell contents contained in?

Answer 2

Lipid belayer membrane

Question 3

What are some common basic cellular functions of cells?

Answer 3

Perform specialised functions

Share mechanisms to change nutrients into energy

Deliver metabolism + catabolism products to surrounding fluid

Replicate + regenerate

Question 4

What are cells bathed in?

Answer 4

Extracellular fluid - maintained in appropriate state to enable cells to function

Question 5

Definition of cells:

Answer 5

Basic structural and functional unit

Question 6

Definition of tissues:

Answer 6

Aggregates of cells with particular function

Question 7

Definition of organs:

Answer 7

Specialised tissues plus connective tissue

Question 8

Definition of systems:

Answer 8

Group of integrated organs that collectively perform a function

Question 9

What are all parts of the body linked by?

Answer 9

Fluid

Question 10

What do organ systems create?

Answer 10

Internal environment

Question 11

How much of body is fluid?

Answer 11

60%

Question 12

What is body fluid divided into?

Answer 12

Compartments

Intracellular - 70% fluid within cells

Extracellular - 30% fluid outside cells

Question 13

What does extracellular fluid include?

Answer 13

Plasma

Interstitial fluid

Question 14

What’s interstitial fluid?

Answer 14

Fluid between cells

Question 15

What is regulation of intracellular ad extracellular fluid important for?

Answer 15

Functioning of organelles, cells, tissues, systems, organisms

Question 16

What are fluid compartments separated by?

Answer 16

Membranes

Question 17

How are body fluids balanced?

Answer 17

Need to balance intake and outtake

Question 18

Definition of homeostasis:

Answer 18

Physiological control systems maintain relatively stable internal environment (within safe limits) in a fluctuating environment

Question 19

What is homeostasis the result of?

Answer 19

Organised ‘self-government’

Question 20

How is homeostasis maintained?

Answer 20

By control systems:

Within cells - genetics

Within/between tissues - nervous + endocrine system

Question 21

Characteristics of control systems:

Answer 21

Require multiple elements

Many systems interlinked

Most use negative feedback

Question 22

What may control systems be?

Answer 22

Open loop

Closed loop

Feedforward

Question 23

Open loop control systems:

Answer 23

No feedback

Controller -> controlled component -> output

Question 24

Closed loop control systems:

Answer 24

Output feeds back + influences controller

Controller -> controlled component -> output -> sensor -> feedback -> controller

Question 25

Types of feedback in closed loop control system:

Answer 25

Negative feedback - return to set-point Positive feedback - moves away from set-point

Question 26

Feedforward control systems:

Answer 26

Response generated in anticipation of change

Question 27

What isn’t open loop feedback influenced by?

Answer 27

Not influenced by resulting conditions - not useful for maintaining local homeostasis

Question 28

Example of open loop feedback:

Answer 28

Glucose absorbed into gut epithelial cells

Question 29

What is closed loop feedback influenced by?

Answer 29

Influenced by resulting conditions Return to set point - maintains homeostasis

Question 30

Characteristics of set point:

Answer 30

Dynamic and constantly adjusting

Question 31

Thermoregulation:

Answer 31

Skin and hypothalamus receptors detect increased temperature Effector responses begin to reduce temperature (e.g. by sweating, vasodilation) Receptors detect temperature below set point Effector responses begin to increase temperature (e.g. vasoconstriction)

Question 32

What is hunting?

Answer 32

Overshooting and undershooting

Question 33

What does the depth and extent of hunting depend on?

Answer 33

Properties of elements of feedback system

Question 34

What does negative feedback control?

Answer 34

Controls system within limits

Question 35

Arterial blood pressure: What’s the sensor?

Answer 35

Baroreceptors - send signals to control centre

Question 36

Arterial blood pressure: What’s the control centre?

Answer 36

Solitary nucleus in medulla oblongata (set point) - identifies change in blood pressure

Question 37

Arterial blood pressure: What’s the effector?

Answer 37

Heart + blood vessels respond

Question 38

Arterial blood pressure: What’s the controlled variable?

Answer 38

Rise or fall in arterial blood pressure

Question 39

Arterial blood pressure: What does negative feedback involve?

Answer 39

Returns controlled variable to within safe limits

Question 40

What’s gain?

Answer 40

Degree of effectiveness of negative feedback control system

Question 41

How do you calculate gain?

Answer 41

Correction / error

Question 42

What happens to output in closed loop feedback?

Answer 42

Output continually enhanced and moved further away from homeostasis

Question 43

What would happen if there was no termination mechanism in closed loop feedback?

Answer 43

System would ‘run away’

Question 44

Oxytocin:

Answer 44

Positive feedback Induced uterine contractions in child birth

Question 45

Characteristics of feed forward control:

Answer 45

Infrequent

Question 46

Feed forward control - example

Answer 46

Digestive system Sight/smell - response in GI tract - gut prepared for digestion Local result = ingest a digested + nutrients absorbed Overall result = nutrient levels controlled in blood

Question 47

What’s adaptive control?

Answer 47

Feedforward responses can be changed over time and iterations

Question 48

Summary of negative feedback:

Answer 48

Promotes stability

Question 49

Summary of feed-forward:

Answer 49

Anticipates change

Question 50

Summary of positive feedback:

Answer 50

Promotes change in one direction - instability might result in disease but not always