Themes 4 + 5 Flashcards
Homeostasis and Environmental Adaptation & The Nervous System
1
Q
Who defined homeostasis? (2 ppl)
A
Claude Bernard, Walter Cannon
2
Q
Homeostasis
A
Process of maintaining a relatively stable internal environment despite changes in the external surroundings.
3
Q
2 types of Homeostatis
A
Conformers and Regulators
4
Q
Conformers
A
maintain same fluid composition as environment
5
Q
Which is energetically cheaper? Conformers or Regulators?
A
Conformers
6
Q
Regulators
A
internal composition of fluids different from environment
7
Q
Thermogenesis
A
Generation of thermal energy in an organism
8
Q
4 types of Thermogenesis?
A
Homeotherms
Poikilotherms
Endotherms
Ectotherms
9
Q
Homeotherms
A
organisms that maintain a stable internal body temperature regardless of external influence.
10
Q
Poikilotherm
A
organisms whose internal temperature varies considerably.
11
Q
Which type(s) of Thermogenesis depends on ambient temperature?
A
Poikilotherm, Ectotherm
12
Q
Endotherms
A
heat primarily generated from internal metabolic processes
13
Q
Ectotherms
A
control body temperature through external means;
14
Q
Example of an Ectotherm?
A
Reptiles; regulate body temperature by basking in the sun.
15
Q
Can Poikilotherms be Ectotherms?
A
Yes, meaning their temperature varies over a wider range than homeotherms.
16
Q
Are physiological functions constant for very long?
A
No
17
Q
After a meal the level of glucose in your blood can…
A
increase rapidly
18
Q
If you skip a meal, your blood sugar level may…
A
drop slightly.
19
Q
4 Variables of Homeostatic Control Systems:
A
Set point
Sensor
Integrator
Effector
20
Q
Set Point
A
normal value for controlled variable
21
Q
Sensor
A
monitors particular variable
22
Q
Integrator
A
compares signals from the sensor to set point
23
Q
Effector
A
compensates for deviations between actual value and set point.
24
Q
Feedback
A
a fundamental feature of homeostasis; major way disturbances are minimized.
25
Negative Feedback
variable being regulated bring about response that moves the variable in the opposite direction.
26
Positive Feedback
Accelerates a process;
Explosive system (rapid)
used in Birth + effect of estrogens in ovulation.
27
Where does negative feedback occur?
organ
cellular
molecular levels
28
What type of Feedback prevents overcompensation?
negative feedback
29
Another name for Positive feedback?
Supra-physiological responses
30
Feedforward Regulation
Animal's body begins preparing for a change in some variable before it occurs.
Speeds up homeostatic responses and minimizes derivation from the set point.
31
What type of regulation is a result from or is modified by learning?
Feedforward Regulation
32
What type of Regulation is Anticipatory?
Feedforward Regulation
33
Pavlov 's experiment demonstrated the relationship between what 2 things?
Learning and Feedforward Processes
34
What chemical communication between cells is essential to homeostasis? (3)
paracrine signals
neurotransmitters
hormones
35
The Nervous system
a network of specialed cell that coordinate functions and transmit signals between different organs.
36
What System regulates internal processes-all while maintaining homeostasis?
The nervous system
37
2 Parts of the Nervous system?
Central Nervous System (CNS)
| Peripheral Nervous System (PNS)
38
Central Nervous System organs?
Brain and spinal cord
39
Peripheral nervous system is composed of ?
all neurons and projections of their plasma membranes that are outside of the CNS.
40
T or F - In Certain invertebrates with a simple nervous system, the distinction between CNS and PNS is less clear or not present.
True
41
Composition of the CNS? (matters)
Grey Matter and White Matter
42
Grey Matter
is the major component of the CNS
43
What does Grey Matter consist of ?
Neuronal Cell bodies, dendrites, and axons
Glial cells
Capillaries
44
the grey-brown color in Grey matter comes from what?
Capillary blood vessels and neuronal cell bodies.
45
White matter
mostly contains myelinated axon tracts
46
What does the white color in White matter come from?
whiteness of myelin.
47
Myelin
an electrically insulating material that forms a layer around axons.
48
What is Myelin composed of?
80% lipids(primarily glycolipids galactocerebroside)
| 20% protein
49
What is the protein portion of Myelin is made up of?
Myelin basic protein (MBP)
Myelin oligodendrocyte glycoprotein (MOG)
Proteolipid Protein (PLP)
50
What is the lipid portion of Myelin is made up of ?
glycolipids galactocerebroside
51
Neurons
cells that send and receive electrical and chemical signals.
52
What type of animal does not have neurons?
sponges
53
The number of Neurons present is a function of what?
size and behavioural complexity
54
Transmission of Electrical and chemical signals occur in the form of?
action potentials
55
action potentials
a short lasting event in which the electrical voltage of the cell memebrane rapidly rises and falls. (consistent trajectory)
56
Cells that action potentials occur in:
excitable cells
57
excitable cells include:
neurons, muscle cells, endocrine cells, as well as some plant cells.
58
What plays a central role in cell-to-cell communication?
action potentials
59
"nerve impulse" or "spike" or "fire"
action potential
60
In muscle cells, action potentials are the first step in a chain leading to:
contraction of muscles
61
In B-cells of the pancreas action potentials lead to:
release of insulin
62
Neuron Structure includes:
Soma
Dendrites
Axons
63
Soma
Cell body; contains nucleus and organelles
64
Dendrites
branched projections of a neuron that conduct the electrochemical stimulation received from other cells. (RECEIVE SIGNALS)
65
Axons -
Long slender projection of neurons; Conducts electrical impulses away from the soma. (SENDS SIGNALS)
66
Axons are distinguished from dendrites by:
Length : dendrites are restricted to a small region around the cell body, while axons can be much longer
Function: dendrites usually receive signals while axons usually transmit them.
67
Synapses
electrical stimulation transmitted onto dendrites by upstream neurons; located throughout the dendrite arbor.
68
Another name for Glial cells:
Neuroglia
69
Glial Cells
non nervous cells; commonly known as the glue of the Nervous system.
70
In the human brain, what is the ratio of glia:neuron?
1:1
71
In cerebral gray matter, what is the ratio of glia:neuron?
3:2
72
What are the 6 types of Glial cells?
```
SOMEAS
Schwann cells
Oligodendrocytes
Microglia
Ependymal cells
Astrocytes
Satellite cells
```
73
Astrocytes
"Star" shaped
1. provision of nutrients
2. maintenance of extracellular ion balance
3. repair and scarring process of the brain and spinal cord
* 4.biochemical support of endothelial cells which form the blood-Brain barrier
74
Another name for Astrocyte?
Astroglia
75
Blood-Brain-Barrier (BBB)
a separation between the circulating blood and brain extracellular fluid.
Consists fo tight junctions around the capillaries that do not exist in normal circulation.
76
Functions of the Blood brain barrier?
1. Restrict the diffusion of microscopic objects (tight junctions)
2. Actively transport metabolic products such as glucose.
77
Microglia
Macrophages of the brain and spinal cord;
Main active immune defence
Scavenges for damaged neurons, plaques, and infectious agents.
78
The main active immune defence of the CNS?
Microglia
79
~20% of all glial cells are?
Microglia
80
Ependymal Cells
thin epithelial membrane lining the ventricular system of the brain and the spinal cord.
Involved in the function of cerebrospinal fluid.(CSF)
81
What is the Function of Ependymal Glial Cells?
production of cerebrospinal fluid.
82
Cerebrospinal Fluid (CNS)
clear colorless bodily fluid produced by ependymal cells of the brain.
Fill the ventricles and cisterns of the brain and the central canal of the spinal cord.
83
Functions of the Cerebrospinal Fluid (CNS)
1. It acts as a cushion or buffer for the cortex
2. Provide Mechanical or immunological protection to the brain
3. play a vital function in regulation of cerebral blood flow.
84
Oligodendrocytes
Insulate axons in the CNS, mainly in the brain and spinal cord
*relatively few branches
85
another name for Oligodendrocytes
Oligodendroglia
86
Schwann Cell
the principal glia cells of the CNS; Wrap around the axons of motor and sensory neurons to form the myelin sheath.
87
What is the principal Glia cell of the PNS?
Schwann Cell
88
Myelination
The production of the myelin sheath.
89
What cells myelinate the PNS?
Schwann cells
90
What cell myelinate the CNS?
Oligodendrocytes
91
During what week of fetal development does myelination begin ?
14th week
92
T or F: During infancy myelination occurs slowly and does not stop until the adolescent stages of life
false : occurs rapidly.
| During infancy myelination occurs RAPIDLY and does not stop until the adolescent stages of life
93
Children under the age of two should receive a diet higher in _____ ?
Fats
94
Myelin sheath is interrupted by:
Nodes of Ranvier
95
Nodes of Ranvier
uninsulated gap (~1um) formed between the myelin sheaths;
96
Nodes of Ranvier are unmyelinated to promote...
exchange of ions faster.
97
Satellite glial cells (SGCs)
line the exterior surface of neurons in the PNS.
98
Which two types of Glial cells share similar embryolgical origin of the neural crest of an embryo in the PNS?
Schwann cells, Satellite glial cells (S&S)
99
Function of the Satellite Glial Cells:
1. Control over the microenvironment of sympathetic ganglia
* thought to be similar to Astrocytes of CNS
2. supply nutrients to the surrounding neurons and also supply structural function
3. act as protective cushioning cells
4. Express a variety of receptors that allows for a range of interactions with neuro-active signalling chemicals.
100
What cell of the PNS shares a similar role to Astrocytes in the CNS?
SGC - satellite glial cells
101
3 main types of Neurons?
1. Sensory Neurons
2. Motor Neurons
3. Interneurons (or association Neurons)
102
Sensory Neurons
*Afferents* - detect information from the outside world or internal body conditions and transmits to the CNS
Usually a large axon that bypasses the cell body and goes directly to CNS
*automatic - not controlled
X==={o}====8
103
What type of Neuron is Afferent?
Sensory Neurons
104
What type of Neuron is Automatic; Involuntary?
Sensory Neurons
105
Which type of Neuron has a cell body that has a bypassing axon?
Sensory Neurons
106
Motor Neurons
* Efferent* - sends signals away from CNS to elicit response.
* controlled; voluntary
X{o}=======8
107
Afferent
brings in;
108
Efferent
sends away
109
Which type of Neuron is Voluntary; controlled?
Motor neurons
110
Which type of Neuron has the soma located within the network of dendrites ?
Motor neuron
111
Interneurons
form interconnections between other neurons in the CNS.
tend to have many dendrites
axons are typically short and highly branched allowing to form complex connections with other cells.
112
What type of Neuron has many dendrites?
Interneuron
113
What type of Neuron typically has short, highly branched axons?
interneuron
114
another name for interneuron
Association Neuron
115
Reflex Circuit
a series of connections where neurons transmit information to each other.
116
A Reflex arc
a simple circuit; allows an organism to repsond rapidly to inputs from sensory neurons and consists of only a FEW neurons.
117
T or F: many neurons are involved in a reflex arc.
False; few are involved.
118
What are the oldest and most importnat features of the nervous system? (they exist in simple animals as well as complex)
Reflexes
119
Pathway of a Reflex Circuit:
1. stimulus from sensory neurons
2. sent to CNS and there is little to no interpretation
3. signal is then transmitted to motor neurons
4. Reflex action
120
Infant primates have a strong grasp that help them hold onto their others as they move, this is an example of?
reflex arcs
