L7 Flashcards
(121 cards)
1
Q
What is homeostasis?
A
Maintaining a constant internal environment
2
Q
How does the internal environment stay stable?
A
Through compensation mechanisms when deviations from the set point occur
3
Q
Is homeostasis the same as equilibrium?
A
No, it’s a dynamic steady state.
4
Q
What is dynamic steady state?
A
Ions can have some movements between the ECF and the ICF, but ultimately, they will reach these levels which we classify as a steady state in our bodies.
5
Q
Are ion concentrations equal in ECF and ICF during homeostasis?
A
No, they are not at equilibrium, and that’s OK. For our bodies, this is homeostasis.
6
Q
What is the set point in the fish tank example?
A
29 degrees.
7
Q
What acts as the stimulus in the fish tank example?
A
Water cooling down.
8
Q
When does a response turn on?
A
When deviating past the normal range.
9
Q
What turns the response loop off?
A
The negative feedback to get back to the set point.
10
Q
What is the purpose of negative feedback?
A
To get the body back to homeostasis
11
Q
What is the initial step in a negative feedback loop?
A
A stimulus that takes you away from a set point
12
Q
What happens after the body elicits a response in negative feedback?
A
It decreases the effect of the stimulus
13
Q
What signals the end of a negative feedback loop?
A
Stabilization
14
Q
What is the main characteristic of positive feedback loops?
A
Reinforcing the response
15
Q
How are positive feedback loops typically stopped?
A
By outside factors
16
Q
What is the primary purpose of positive feedback?
A
To make a change
17
Q
Are positive feedback loops common?
A
No, they don’t happen often
18
Q
What is the opposite of reaching homeostasis?
A
Positive feedback
19
Q
What is the role of the body in negative feedback?
A
To have a response, then decrease the effect or stimulus
20
Q
What stimulates cortisol to be released?
A
Hormones
21
Q
What is the purpose of negative feedback in cortisol secretion?
A
To turn off the process when enough cortisol is present
22
Q
What does cortisol suppress?
A
The release of ACTH and CRH
23
Q
Where is CRH released from?
A
The hypothalamus
24
Q
What happens when the body needs to begin the cortisol release cycle again?
A
The negative feedback disappears.
25
What is the end goal of cortisol regulation?
Getting back to the set point
26
What is the initial step in the cortisol release?
The hypothalamus releases a stimulating hormone
27
What does the anterior pituitary stimulate?
ACTH
28
Where does ACTH travel to?
The adrenal cortex
29
What is the role of the adrenal cortex?
To ultimately release cortisol
30
What triggers the release of oxytocin?
The baby dropping lower in the uterus, stretching the cervix
31
What does oxytocin cause?
Uterine contractions
32
What does the baby pushing against the cervix cause?
More cervical stretch, stimulating more oxytocin release
33
When does the positive feedback loop stop in childbirth?
Once the baby is delivered
34
Is the oxytocin feedback loop homeostatic?
No
35
What is the purpose of positive feedback in childbirth?
To make a change
36
What initiates labor?
The baby dropping lower in the uterus
37
What is the stimulus in the childbirth example?
The stretch of the cervix
38
What is the ultimate change being made?
The child goes from the uterus to the outside environment
39
What is required to maintain homeostasis and other body functions?
Intercellular communication
40
What is the scope of local control in cell communication?
One location
41
How do gap junctions facilitate cell communication?
By allowing small ions and molecules to move through
42
Where are gap junctions commonly found?
Cardiac muscle
43
How does contact-dependent signaling work?
Membrane protein binds to membrane protein
44
What system is contact communication important for?
Immune system
45
How does autocrine signaling work?
A molecule secreted acts on the same or nearby cells
46
Give examples of molecules involved in autocrine signaling.
Some cytokines or histamines
47
What is the range of autocrine signaling?
Short distance
48
What are the two main systems for long-distance communication?
Endocrine and nervous systems
49
How do endocrine cells communicate long distances?
By releasing hormones into the bloodstream
50
What is essential for a hormone to affect a target cell?
The right receptor
51
What are neurohormones?
Chemicals released by neurons that act as hormones
52
Where are neurohormones often secreted from?
Hypothalamus
53
How do neurotransmitters communicate?
They diffuse across a small gap to the target cell
54
What is the role of the endocrine system in long-distance communication?
It's the second major system for this purpose
55
What determines if a cell will respond to a hormone?
The presence of the right receptors
56
What is another name for neurohormones?
Neuroendocrine
57
What mediates simple reflexes?
Either the nervous or endocrine system
58
What mediates complex reflexes?
Both nervous and endocrine systems
59
What do complex reflexes involve?
Several integrating systems
60
What is a key characteristic of reflexes?
Long-distance communication in the body
61
What initiates the response in local control?
Cells in the vicinity of the change
62
What type of change does local control typically address?
Vasodilation or constriction of a specific blood vessel
63
Where is a systemic change in blood pressure sensed?
Number of different areas in the body
64
What acts as the integrating center in a long reflex for blood pressure?
The brain
65
What is the key difference between local and reflex control regarding the response site?
Local is at the site; reflex is at a distant site
66
What is the stimulus in the context of local control?
A change in the immediate environment of the cells
67
What is the integrating center in reflex control?
The brain, which evaluates the change
68
What does the brain do in response to a systemic change?
Initiates a response to fix the change
69
What is the overall purpose of both local and long-distance responses?
To fix a change and maintain homeostasis
70
What is an example of a systemic change that requires reflex control?
A big change in blood pressure
71
What do specialized cells or structures convert stimuli into?
Electrical signals
72
What are examples of special sense receptors?
Vision and hearing (all senses)
73
Where can receptors be located besides the brain?
Outside of the brain, detecting temperature, pressure, and pain
74
Where else can sensors be located?
Directly on the cell
75
What is the role of sensors in homeostatic reflex pathways?
To detect changes and convert them into electrical signals
76
What can a stimulus be?
Anything from the external environment or inside the body
77
What are the two main categories of receptors discussed for reflex pathways?
Special sense receptors and receptors outside the brain
78
What is a simple neural reflex?
A stimulus sensed by a sensory neuron in the CNS
79
What does the CNS do with the sensory input?
Integrates it to have a response
80
What is released by the efferent neuron?
A neurotransmitter
81
What is an example of a simple neural reflex?
Knee-jerk reflex
82
What is the role of the sensory neuron in a simple neural reflex?
To sense the stimulus and transmit the signal to the CNS
83
What is the role of the integrating center in complex reflexes?
To release a neurohormone that travels to an endocrine cell
84
What is the final step in the complex neuroendocrine reflex?
A target tissue response
85
What is the key difference between simple and complex reflexes?
Simple reflexes involve fewer steps and organs, while complex reflexes involve multiple layers and organs
86
What initiates an endocrine reflex?
Internal or external change
87
What is the role of the endocrine cell?
To release a hormone
88
What is an example of an endocrine reflex?
Insulin release when blood glucose increases
89
What is the integrating center in a simple endocrine reflex?
Endocrine cell
90
What is the speed of neural reflexes?
Very rapid
91
What is the speed of endocrine reflexes?
Slower
92
What is the duration of action for neural reflexes?
Usually very short
93
What is the duration of action for endocrine reflexes?
Usually last longer
94
What mediates neural reflexes?
Neurons
95
What mediates endocrine reflexes?
Hormones
96
How is stimulus intensity coded in neural reflexes?
Increased frequency of signaling
97
How is stimulus intensity coded in endocrine reflexes?
Amount of hormone secreted
98
Why do we need different control systems?
To do different things
99
What do exocrine glands secrete into?
Ducts
100
What do endocrine glands secrete into?
Bloodstream
101
What is secreted by exocrine glands?
Substances to the external environment
102
What is secreted by endocrine glands?
Hormones
103
What is the function of exocrine glands?
Secrete chemicals to the external environment
104
What is the function of endocrine glands?
Secrete chemicals directly into the bloodstream
105
Give an example of an exocrine secretion.
Sweat
106
Give an example of an endocrine secretion.
Hormones
107
What is the main function of primary endocrine organs?
To release hormones
108
Name three primary endocrine organs located near the brain.
Hypothalamus, pineal gland, pituitary gland
- All have cells to secrete hormones
109
What is a key characteristic of secondary endocrine organs?
They release hormones and perform other functions
110
Name three secondary endocrine organs.
Heart, liver, kidneys
111
Where are hormones made?
Specific endocrine glands or other tissues
112
How are hormones transported?
In the blood to distant targets
113
What do hormones bind to?
Specific receptors
114
Can a hormone act on multiple tissues?
Yes, if the tissues have the right receptors
115
What must happen to a hormone's action?
It must be terminated
- Signal needs to be turned off (neg feedback loop)- return to homeostasis
116
What processes do hormones maintain or precipitate?
Homeostasis or change in physiological processes
- Pos feedback can precipitate a change
117
What is key to maintaining homeostasis?
Interplay between different hormones at different times and places
118
What was a basic method to identify hormones?
Remove gland & observe results
119
What is done after removing the gland?
Replace gland and see if those results are restored
120
What is another method besides replacing the whole gland?
Replace extract from gland
121
What is done with the extract today?
Purify extract & test in biological assay
