Ch 2 Control of the Internal Environment

Question 1

What are control mechanisms?

Answer 1

Allows the human body to maintain a relatively constant internal environment in spite of stressors

Question 2

What is homeostasis?

Answer 2

the maintenance of a relatively constant internal environment

Question 3

What is a steady state (in contrast to homeostasis)?

Answer 3

a steady state represents physiological variables that are unchanging and constant

Question 4

T or F
The French physiologist Claude Bernard observed that the internal environment of the body constantly varied with change in the external environment.

Answer 4

FALSE; Claude Bernard observed that the internal environment of the body remained REMARKABLY CONSTANT DESPITEEE a changing external environment

Question 5

Give an example of steady state

Answer 5

• Heart rate; although it changes constantly (80-90bpm for one heart beat), it still maintains a constant rate within the beat

IN CONTRAST TO HOMEOSTASIS LIKE SWEATING WHEN THE WEATHER IS HOT

Question 6

T or F

Homeostasis is generally reserved for describing normal resting conditions

Answer 6

True

Question 7

Where does the most intricate of the control systems in the body reside in?

Answer 7

the cells

Question 8

What are the elements of a biological control system?

Answer 8

1) a sensor or receptor
2) a control center (i.e. center to integrate response)
3) effectors (i.e. organs that produce the desired effect)

Question 9

A biological control system is composed of how many elements?

Answer 9

3; three

Question 10

The sensor, upon excitation by a stimulus, sends a message to the

a) efferent nervous system
b) receptor
c) control center
d) effector

Answer 10

c) control center

Question 11

The control center signals the __ to bring about an appropriate response to correct a disturbance

a) isotope
b) receptor
c) sensor
d) effector

Answer 11

d) effector

Question 12

Identify the cell activities that are regulated by cellular control systems

Answer 12

breakdown of proteins and energy production

Question 13

What is a biological control system?

Answer 13

a series of interconnected components that maintain a chemical or physical parameter of the body near a constant value

Question 14

A type of feedback loop that is the primary method responsible for maintaining homeostasis

Answer 14

negative feedback loop

Question 15

This excites a sensor and is the signal to begin the operation of a control system, thus representing a change in the internal environment

Answer 15

stimulus

Question 16

T or F

A majority of the control systems of the body operate via positive feedback

Answer 16

FALSE; mostly operate via negative feedback

Question 17

What is negative feedback?

Answer 17

an important class of biological control systems in the body that serves to restore normal values of a variable to maintain homeostasis

Question 18

The __ integrates the strength of an incoming signal from the sensor

Answer 18

control center

Question 19

When homeostasis is established via the negative feedback mechanism, physiological events result in

Answer 19

negating the initiating stimulus;

giving an opposite response from the initial stimulus to maintain homeostasis

Question 20

Give an example of positive feedback control system

Answer 20

• enhancement of labor contractions when a woman gives birth

Question 21

Give an example of a negative feedback control system

Answer 21

• low body temp leads to shivering to increase body heat
• high body temp leads to sweating to decrease body heat
• increasing blood glucose levels triggering the release of insulin to metabolize (decrease) sugar

Question 22

During labor, increased pressure on the cervix stimulates sensory receptors that trigger the release of oxytocin. Oxytocin in turn promotes increased contractions. This is a classic example of _____.

Answer 22

positive feedback

Question 23

What is the gain of a control system?

Answer 23

the precision with which a control system maintains homeostasis

Question 24

In thermoregulation, the hypothalamus receives information about the changes in body temperature and establishes homeostasis by directing appropriate responses. In this instance of negative feedback, the hypothalamus functions as the _____.

Answer 24

control center;

hypothalamus RECEIVES information, NOT TRIGGERED. If hypothalamus was TRIGGERED then it would be sensor but since it is RECEIVING information and DIRECTING appropriate responses (probably to the effectors) then it is a control center

Question 25

control systems that deal with life-and-death issues a) maintain true homeostasis b) are capable of establishing new set points c) have large gains d) have small gains

Answer 25

have large gains

Question 26

When body temperature increases above normal, homeostatic control via negative feedback is triggered by the _____.

Answer 26

thermal receptors in the body

Question 27

A control system with a large gain is ___. a) slower in returning to homeostasis b) more prone to homeostatic disturbances c) more capable of correcting homeostatic disturbances d) less capable of returning the system to homeostasis

Answer 27

c) more capable of correcting homeostatic disturbances

Question 28

The eight major endocrine glands synthesize and secrete blood-borne chemical substances called what?

Answer 28

hormones

Question 29

Identify a process that is controlled by systems with large gains

Answer 29

regulation of body temp, breathing, and delivery of blood throughout the body

Question 30

Where is the control center located in the context of regulation of body temperature?

Answer 30

in the brain

Question 31

When the thermoregulatory control center directs the blood vessels in the skin to constrict, _____.

Answer 31

body heat is conserved; shivering occurs

Question 32

When the thermoregulatory control center directs the blood vessels in the skin to dilate, _____.

Answer 32

sweating occurs; to promote heat loss

Question 33

The endocrine system regulates blood glucose concentration by the hormone _____.

Answer 33

insulin

Question 34

The failure of a blood glucose control system to correct disturbances in homeostasis results in _____. a) a steady state b) disease c) autoimmunity d) a new set point

Answer 34

b) disease

Question 35

the maintenance and control of blood glucose levels for homeostasis is a function of what system?

Answer 35

endocrine system

Question 36

Muscular exercise presents a dramatic test of the body's homeostatic control systems because it results in large a) amounts of heat production b) increases in muscle O2 production c) increases in muscle CO2 requirements d) amounts of O2 accumulation

Answer 36

a) amounts of heat production

Question 37

What are the sensors and control centers for change in body temp (either increase of decrease above normal)?

Answer 37

sensors -> thermal receptors in the body control center -> hypothalamus in the brain THIS WASN'T ASKED FOR BUT effectors -> IF COLD = shiver and IF HOT = sweat

Question 38

The cell's ability to respond to a challenge can be a) improved by prolonged exposure to a specific stress b) can become severely limited on prolonged exposure to a specific stress

Answer 38

a) improved by prolonged exposure to a specific stress

Question 39

What is acclimation?

Answer 39

- the improved function of an existing homeostatic system - the change that occurs in response to repeated environmental stresses and results in the improved function of an existing homeostatic system - ex: cells can adapt to heat stress due to a hot environment by the production of heat shock proteins.

Question 40

What is adaptation?

Answer 40

a change in the structure and function of a cell or an organ system that results in an improved ability to maintain homeostasis during stressful conditions

Question 41

Intracrine signaling is a form of cell signaling mechanism wherein a chemical messenger _____. a) moves from one cell to the neighboring cell b )acts on nearby cells to bring about a coordinated response c) triggers a signaling pathway within the same cell d) travels by the blood stream throughout the body to target cells

Answer 41

c) triggers a signaling pathway within the same cell

Question 42

What is intracrine signaling?

Answer 42

occurs when a chemical messenger is produced inside a cell that triggers a signaling pathway within the same cell that leads to a specific response

Question 43

What is juxtacrine signaling?

Answer 43

occurs when the cells communicate by cell-to-cell contact, in which the cytoplasm of one cell is in contact with the cytoplasm of another through small junctions that connect the two cell membranes i.e. the method by which one heart cell signals to an adjacent cell to contract

Question 44

What is autocrine signaling?

Answer 44

occurs when a cell produces and releases a chemical messenger into the extracellular fluid that acts upon the cell producing the signal i.e. resistance training; muscle cell triggers the DNA in the nucleus to produce more contractile protein which in turn increases the size of that muscle cell

Question 45

What is paracrine signaling?

Answer 45

occurs when cells produce signals that act locally on nearby cells to bring about a coordinated response i. e. how immune cells communicate with each other to generate a coordinated attack to protect the body from infection and injury. ex2: synaptic signaling

Question 46

What is endocrine signaling?

Answer 46

occurs when cells release chemical signals (hormones) into the blood and these hormones are then carried throughout the body

Question 47

The signaling mechanism in which a cell contacts another cell through small junctions that connect the two cell membranes is called _____ _______.

Answer 47

juxtacrine signaling

Question 48

In autocrine signaling, the chemical messenger is _____. a) sent to nearby cells to bring about a coordinated response b) released into the extracellular fluid c) used to trigger a signaling pathway within the same cell d) carried by the blood stream throughout the body to target cells

Answer 48

b) released into the extracellular fluid

Question 49

In paracrine signaling, chemical messengers are released _____. a) to trigger pathways within the same cell b) via junctions into the adjacent cell c) into the blood to travel to remote target cells d) to act on nearby cells

Answer 49

d) to act on nearby cells

Question 50

Identify the cell signaling mechanism that occurs when a chemical messenger is produced inside a cell that triggers a signaling pathway within the same cell.

Answer 50

intracrine signaling

Question 51

The cell signaling mechanism that acts locally to bring about a coordinated response is called _____ signaling.

Answer 51

paracrine signaling