Homeostasis

Question 1

What is homeostasis?

Answer 1

Process of maintaining a relatively constant/stable internal environment (set point) in spite of changing external environments.

Question 2

What is homeostasis important for?

Answer 2

Cell function

Question 3

What is the external environment?

Answer 3

Outside body

Question 4

What is extracellular fluid? (ECF)

Answer 4

Internal environment; inside body, outside cells

Question 5

What are the two components of ECF?

Answer 5

Plasma and interstitial fluid

Question 6

What is plasma?

Answer 6

in blood vessels, but outside cells, fluid portion of blood

Question 7

What is interstitial fluid?

Answer 7

outside blood vessels and cells

Question 8

What is intracellular fluid?

Answer 8

intracellular Environment = inside cells; cytoplasm

Question 9

Is homeostasis dynamic?

Answer 9

Yes, not static

Question 10

What is dynamic constancy?

Answer 10

levels change over short periods of time, but remain relatively constant over long periods of time

Question 11

How often do physiological variables change?

Answer 11

Physiological variables can change dramatically over a 24-hr. period, but the system is still in overall balance

Question 12

What do we call it when homeostasis is maintained?

Answer 12

Physiology

Question 13

What do we call it when homeostasis is NOT maintained?

Answer 13

Pathophysiology

Question 14

What are examples of cellular homeostasis?

Answer 14

Function of each cell
Cytoplasm of single cell
Necessary for normal cell function
Relies on components of extracellular fluid

Question 15

What are the two types of extracellular fluid?

Answer 15

Local and systemic

Question 16

What is local extracellular fluid?

Answer 16

Restricted to one tissue space
Utilizes Paracrines and Autocrines
Maintain Function of Tissue

Question 17

What is systemic extracellular fluid?

Answer 17

Involves entire body
Utilizes Nervous System and Endocrine system
Maintain Function of Heart and Brain

Question 18

What is set point?

Answer 18

The level the body tries to maintain (for example 98.6 degrees)

Question 19

What is considered external environment?

Answer 19

GI Tract, lungs, urinary tract (post vascular system, once filtered into kidney)

Question 20

What do homeostatic processes do following a disturbance?

Answer 20

Restore balance

Question 21

What does steady state require?

Answer 21

Energy input; ex. Na gradient across cell membrane

Question 22

Is equilibrium equivalent with homeostasis?

Answer 22

NO

Question 23

What are the levels of homeostasis?

Answer 23

Cellular homeostasis and extracellular fluid

Question 24

What is does the level of extracellular fluid consist of?

Answer 24

Environment outside of the cell
Necessary for normal cell function
Two types: Local vs. Systemic

Question 25

What does local homeostasis utilize?

Answer 25

Paracrines and autocrines

Question 26

What does systemic homeostasis utilize?

Answer 26

Nervous system and endocrine system

Question 27

What do autocrines do?

Answer 27

Autocrine substance acts on same cell that secreted the substance

Question 28

What do paracrines do?

Answer 28

Target cells in close proximity to site of release of paracrine substance

Question 29

What do nerve cells do?

Answer 29

Neuron of effector cell in close proximity to site of neurotransmitter release

Question 30

What do endocrines (hormones) do?

Answer 30

Target cells in one of more distant places in the body

Question 31

What is a stimulus?

Answer 31

First domino, could be a change in ECF Composition, Body Temperature, BP, etc.

Question 32

What is the stimulus flow for a systemic process?

Answer 32

Stimulus to Reflex Receptor to Afferent Pathway to Integrating Center to Efferent Pathway to Effector to Effector Response (Possible feedback regulation)

Question 33

What is the reflex receptor?

Answer 33

Detects changes in [substance] Has threshold stimulus

Question 34

What is threshold stimulus?

Answer 34

(Sensitivity) - Determines amplitude of the normal range

Question 35

What happens if the threshold stimulus is high?

Answer 35

Takes more stimulus to signal the reflex receptor

Question 36

What can be a reflex receptor?

Answer 36

Cluster of cells, individual cells, cell parts or molecules in membrane or cytoplasm of cell

Question 37

What does reflex receptor determine?

Answer 37

Normal range (more sensitive= narrow range; less sensitive= wider range)

Question 38

What is the afferent pathway?

Answer 38

Carries information from Reflex Receptors to Integrating Center NS reflexes ONLY Sensory neurons

Question 39

Where do we not have an afferent pathway?

Answer 39

Endocrine system

Question 40

What is the integrating center?

Answer 40

Receives stimulus, analyzes information and generates appropriate response ES = Endocrine Gland NS = Brain/Spinal Cord

Question 41

What is the integrating center in the endocrine system?

Answer 41

Endocrine gland

Question 42

What is the integrating center in the nervous system?

Answer 42

Brain/spinal cord

Question 43

What is the efferent pathway?

Answer 43

Carries commands from integrating center to effectors ES = Hormones (travel via blood) NS = Motor neurons

Question 44

What is the efferent pathway in the endocrine system?

Answer 44

Hormones; travel via blood

Question 45

What is the efferent pathway in the nervous system?

Answer 45

Motor neurons

Question 46

What is the effector?

Answer 46

Any cell affected by Efferent Pathway (change in function)

Question 47

What are the two levels of the effector response?

Answer 47

Local and systemic effector response

Question 48

What is the local effector response?

Answer 48

how cell (effector) function is changed by the Efferent Pathway (ex. GLUT4 receptors to surface of cells)

Question 49

What is the systemic effector response?

Answer 49

how ECF (whole body) changed by local effector response (ex. fall of blood glucose levels)

Question 50

T/F: Different Efferent Pathways can create the same systemic effector response while having different local effector responses

Answer 50

T

Question 51

What is feedback regulation?

Answer 51

How Systemic Effector Response changes the function of the Reflex Receptor

Question 52

What are the two types of feedback regulation?

Answer 52

Negative and positive

Question 53

What is a negative feedback response?

Answer 53

Decreases activity shutting off pathway (homeostatic; most common) Keeps variable fluctuating around the setpoint

Question 54

What is positive feedback response?

Answer 54

Increases activity further activating pathway (non-homeostatic)

Question 55

Which feedback response is homeostatic?

Answer 55

Negative; NOT positive

Question 56

What is the tonic level of activity?

Answer 56

At rest, a homeostatic pathway is neither completely shut off or fully active

Question 57

What does tonic control regulate?

Answer 57

Physiological parameters in an up-down fashion

Question 58

Are homeostatic pathways either on or off?

Answer 58

No, usually always some level of activity

Question 59

What is antagonistic control?

Answer 59

a single systemic effector response is controlled by two different efferent pathways but in opposite directions.

Question 60

What is a mechanistic explanation?

Answer 60

Describes how something happens

Question 61

What is a telological explanation?

Answer 61

Describes why something happens