chpt 9.1-9.3 test Flashcards
(106 cards)
1
Q
what is homeostasis?
A
the physiological state of the body in which internal physical and chemical conditions are kept within a range that is suitable for life processes
2
Q
All organisms have preferred environments, but they can live in a…
A
tolerable range of environmental conditions
3
Q
to control thermal energy, animals do what?
A
sweat, seek shade, or shiver
4
Q
plants open and close stomata in their leaves to control…
A
water loss through transpiration
5
Q
To accommodate less desirable condition, bacteria can…
A
adjust their cell walls
6
Q
Most animals cannot control their surroundings, so they…
A
live in environments with appropriate physical conditions
7
Q
humans have mastered the ability to…
A
change their surroundings
8
Q
an organism’s survival ultimately depends on its ability to…
A
maintain its internal environment
9
Q
for life to continue, body cells must be able to…
A
replicate, communicate, and metabolize effectively
10
Q
one of the most critical factors for maintaining proper cell function is…
A
temperature
(metabolic processes that are carried out by the cells can only successfully occur within a fairly narrow range of temperatures)
11
Q
the cells in the human body require an internal temperature of roughly…
A
37 ̊C (below 35 ̊C or greater than 37.8 ̊C can cause some bodily processes to malfunction)
12
Q
Most animals have – or – adaptations that allow them to maintain a suitable temperature.
A
physiological or behavioural
13
Q
Homeostasis is not a “steady state” or a constant condition, but rather a…
A
dynamic process that is continuously adjusted in response to changes in the internal or external environment
14
Q
The body must maintain its optimal range of conditions during exercise, fatigue, and extremes of temperature. The body has several key parts, fluids, and conditions that must be monitored and adjusted. These include…
A
- internal temp
- hormone levels
- the pressure, pH, and concentration of glucose and other solutes in the blood.
15
Q
The blood pH and internal temperature, the tolerable range is —- whereas blood flow, glucose levels, and hormone levels, the tolerable range is —-
A
narrow, broader (there can be considerable variation without harmful consequences)
16
Q
The purpose of homeostasis is to…
A
maintain internal physical and chemical conditions that are appropriate for the cells to function properly
17
Q
The internal environment is the —–, which consists of —-.
A
extracellular fluid, the fluid that surrounds the cells and tissues in the body and the plasma portion of the blood
18
Q
The interstitial fluid is the fluid that…
A
surrounds the body cells
19
Q
A typical adult has —- of extracellular fluid, which constitutes approximately — of our body’s mass.
A
15 L, 20 %
20
Q
Every cell in the body is surrounded by the extracellular fluid, which acts as a medium for …
A
delivering energy, transporting chemicals, and eliminating waste.
21
Q
The regulated flow of —- into and out of the extracellular fluid allows the cells to function properly.
A
energy, chemicals, and waste (when the cells function properly, the tissues, organs, and organ systems, and thus the whole organism, can thrive)
22
Q
T/F: Volume, temperature, and chemical composition of our internal environment can change quickly.
A
True
23
Q
nervous system main organs
A
brain, spinal cord, peripheral nerves, sensory organs
24
Q
endocrine system main organs
A
pituitary, thyroid, adrenal, pancreas, and another hormone-secreting glands
25
muscular system main organs
skeletal, cardiac and smooth muscle
26
integumentary system main organs
skin, sweat glands, hair, nails
27
excretory system ain organs
kidneys, bladder, ureter, urethra
28
reproductive system main organs (female)
ovaries, oviducts, uterus, vagina, mammary glands
29
reproductive system main organs (male)
testes, sperm ducts, accessory glands, penis
30
Nervous system receives sensory data from the environment, which ...
informs the body of external conditions and transmits signals throughout the body to regulate homeostasis.
31
Excretory system works to rid the body of --- and maintain a --- and regulates the levels of ---
waste, clean internal environment, various hormones that are essential to life processes
32
the circulatory system carries --- throughout the body and distributes thermal energy
these hormones and other chemicals, thermal energy
33
the immune system does what?
protects the body from infection and also fights infection
34
The liver in the digestive system has several roles in maintaining homeostasis such as:
- controlling amino acid levels by breaking down any amino acids that are not used
- detoxifying harmful chemicals
- manufacturing important blood proteins.
35
Integumentary system, or skin, is important for maintaining a constant body temperature, since it is...
in constant contact with the external environment
36
All of the organ systems are coordinated to carry out the tasks necessary for the survival of the organism, which are:
1. taking in nutrients and other required chemicals (ex.oxygen) from the environment, processing/ distributing them throughout the body, disposing of the waste
2. synthesizing proteins, fats, carbohydrates, and other essential molecules for cellular function and structure
3. sensing and responding to changes in external environment
4. protecting the body from injury or from infection by viruses, bacteria, and other disease- causing agents
5. reproducing, and protecting and feeding offspring
37
the most important systems for maintaining homeostasis:
endocrine and nervous
38
A homeostatic mechanism is...
a system that monitors internal and external conditions and changes bodily functions to maintain homeostasis
39
regulation of body temperature: internal temperature is too high
- sweat is produced and the evaporation of sweat from our skin (endothermic process), the body experiences a net loss of thermal energy
40
regulation of body temperature: when low
shiver when cold so the tiny muscle contractions generate thermal energy and raise the internal temperature
41
Negative feedback:
the response of a system that acts to maintain equilibrium by compensating for any changes made to the system
42
The primary mechanism of homeostasis is :
negative feedback
43
The primary mechanism of homeostasis is negative feedback, in which a stimulus resulting from a change in the external or internal environment triggers a response that compensates for the change. What is stimulus and response?
Stimulus- the internal or external environmental change
Response- the system’s output
44
Homeostatic mechanisms include three elements (+explain each) :
- SENSOR (tissues/organs) (nervous and endocrine system) = element of a feedback system that detects changes in the environment (ex. pH, temperature, or concentration of molecules)
- INTEGRATOR (nervous and endocrine system) = element that compares existing conditions with optimal functioning (ideal) conditions called set points.
- EFFECTOR (organs and tissues) = the elements that act to return the system to its optimal state
45
To bring internal conditions back into balance, negative feedback mechanisms use ---.
antagonistic effectors (act to produce the opposite effect of the change recorded by the sensor)
46
Mammals and birds also have a homeostatic mechanism that maintains body temperature within a relatively narrow range around a set point. The integrator in this mechanism is located in ----.
a brain center called the hypothalamus. (portions of the hypothalamus act like a thermostat for the body)
47
Groups of neurons in the preoptic region of the anterior hypothalamus receive...
information from thermoreceptors in various locations, including the skin, the spinal cord, and the hypothalamus itself
48
homeostasis: body temp high
a) Sensor = thermoreceptors signal an increase in temperature
b) Integrator = hypothalamus turns on cooling system
c) Effector = skin blood vessels dilate and an increase of blood flow to skin results. Thermal energy is lost from skin.
d) Result = body temperature decreases, the hypothalamus turns off cooling system
49
homeostasis: body temp low
a) Sensor = thermoreceptors signal decrease in temperature
b) Integrator = hypothalamus turns on warming system
c) Effector = skin blood vessels constrict and a decrease of blood flow to skin results. Reduced thermal energy is lost from skin. Skeletal muscles contract and shivering generates energy production. The body hair becomes erect to conserve thermal energy.
d) Result = body temperature increases, the hypothalamus turns off warming system.
50
an infection caused by a virus or bacteria will cause...
the homeostatic effectors to increase your temperature (causes a fever which fight off infection)
51
T/F: All mammals use similar homeostatic mechanisms to maintain their body temperature set point.
True
52
Mammals and birds are able to regulate their internal temperature within a narrow range, but other vertebrates can thrive within a much broader range.
True
53
Reptiles alter their behavior in response to changes in body temperature. They absorb thermal energy how?
basking
54
Tuna and hunting sharks are able to generate enough thermal energy by ----- to maintain a body temperature many degrees above the surrounding water.
contraction of the swimming muscles
55
Insects use ---- to maintain their body temperature. Flight muscles operate best at higher temperatures, so some insects bask in the sunlight to warm their muscles before taking off
feedback mechanisms
56
Dragonflies, bees, and moths contract their flight muscles in a process similar to shivering in mammals. During the cold winter months, hives of honeybees form --- to maintain body temperature and contract their flight muscles to generate thermal energy.
large masses
57
Plants have --- which often aid in their development and to attract pollinators. The lotus plant minimizes transpiration to stay cool and breaks down carbohydrates to increase thermal energy.
thermal energy control mechanisms
58
positive feedback is the...
response of a system that acts to increase the effect of any changes made to the system
59
Positive feedback mechanisms usually (with some exceptions) do not result in ---, since they cause the system to become ---. They almost always operate when a ---.
homeostasis, unstable, continuous increase in some internal variable is required
60
examples of positive feedback
- an animal is attacked, the body releases adrenaline and hormones into the blood to prime the muscles and organ systems for the “flight or fight” reactions. The release of these chemicals stimulates further release, in a positive feedback cycle, making the animal even more fit to survive the attack.
61
Positive feedback mechanisms often operate within...
a larger negative feedback mechanism, which ultimately works over the long term to bring the body back into balance
62
thermoregulation is the...
regulation of internal temperature by negative feedback mechanisms
63
Temperature receptors, called thermoreceptors, detect what?
any deviations in the external and internal temperatures from set point and then trigger behavioural and physiological responses that act to maintain the set internal temperature
64
Almost all thermal energy exchange occurs at the ---
surface where the body comes in contact with the external environment.
65
This exchange (thermal energy) occurs through one of four mechanisms:
- Conduction
- Convection
- Radiation
- Evaporation
66
Conduction
- flow of thermal energy between molecules that are in direct contact, lose thermal energy when in contact with a colder body, gain when in contact with a warmer body
67
Convection
the transfer of thermal energy within a fluid (liquid or gas)
68
Radiation
- transfer of thermal energy in the form of electromagnetic radiation, all objects radiate thermal energy, radiation increases with the temp of the object.
- animals constantly losing thermal energy to the environment through radiation.
- animals gain thermal energy through radiation, usually by absorbing it from the Sun.
69
Evaporation
- transfer of thermal energy, water on the surface of the skin (sweat) evaporates, absorbing thermal energy from the skin and causing it to cool.
70
All animals can be categorized into two groups based on the stability of their body temperature:
homeotherm, poikilotherm
71
A homeotherm is...
an animal that maintains a stable body temperature regardless of the temperature of the external environment. Birds and mammals are homeotherms because they can maintain a body temperature that is often above the ambient environmental temperature
72
A poikilotherm is...
an animal whose body temperature varies with, and often matches, the temperature of the external environment. Fish, amphibians, reptiles, and most invertebrates are poikilotherms because their body temperature varies with, and sometimes matches, the temperature of their external environment. Although the body temperature of poikilotherms can vary considerably, these organisms have some degree of control over their body temperature
73
There are two general types of mechanisms that animals use to regulate their body temperature:
Internal physiological, Behavioural
74
Internal physiological mechanisms that generate thermal energy to regulate body temperature are referred to as...
endothermy (an endotherm is an animal that maintains its body temperature by internal mechanisms)
75
Behavioural mechanisms that involve using external sources of energy are considered...
ectothermy (ectotherm is an animal that maintains its body temperature by absorbing thermal energy from the environment, regulate their body temperature by absorbing thermal energy from their environment)
76
--- are more successful than --- at maintaining a stable body temperature.
Endotherms, ectotherms
77
The difference between endotherms and ectotherms is determined by their...
metabolic responses to the environmental temperature
78
ectotherms generate...
at least some thermal energy from internal reactions
79
ectotherms body temperature tends to...
fluctuate with the environmental temperature, so ectotherms are usually less active in cold weather. When the environmental temperature drops too low, they become inactive and as a result move slowly and are unable to capture food or escape from predators. Their food needs are lower under these circumstances because their metabolic rates are reduced, so they do not have to look actively for food and expose themselves to predators.
80
ectotherms: some live in a habitat with a stable temperature and maintain a fairly constant body temperature and are considered ---
homeotherms
81
ectotherms do not use their metabolism to heat or cool themselves, and their energy requirements are ---
much lower than those of endotherms
82
ectotherms include...
a diverse group of animals with different abilities to maintain a stable internal temperature.
invertebrates, fish, amphibians, and reptiles are ectotherms, and each has its own method of thermoregulation.
83
--- have poor thermoregulation abilities
Aquatic Invertebrates
84
aquatic invertebrates: body temperature rarely varies from the ---
external temperature of the water
85
aquatic invertebrates: live in or seek warm or temperate environments where ...
the temperature allows them to have optimal physiological performance.
86
aquatic invertebrates: most fish have a body temperature that is similar to their surroundings, but they are able to use ---to regulate their internal temperature.
behavioural adaptations
87
Amphibians and Lizards recap:
- rely heavily on conduction and radiation to regulate body temp
- most common thermoregulatory behaviour for many lizards is moving between sunny and shady areas. A lizard will sun itself on a hot rock and this makes use of both mechanisms of thermal energy transfer and allows the lizard to reach its temperature set point quickly. The lizard will retreat to a cooler area to lower its temperature if it becomes too hot.
- continuous and frequent raising and lowering of body temperature allows lizards and some amphibians to keep an almost constant temperature comparable to endotherms.
- Galapagos marine iguanas (use physiological responses) can increase the blood flow to areas of the skin exposed to infrared radiation. The blood warms quickly, and thermal energy is carried to the organs in the core of the body. When the skin is cooled, the blood flow to the skin is restricted, thereby preventing the loss of thermal energy to the external environment.
88
Many ectotherms undergo seasonal physiological changes. ---allows them to adjust gradually to changes in external temperature and usually accounts for seasonal variations. It is a process by which an animal gradually adjusts to temperature changes in its environment.
Thermal acclimatization
89
Wood frog (Rana sylvatica) recap...
- lives in temperate forests where winter temperatures typically drop below freezing.
- spends the winter in a frozen state, with no heartbeat, breathing, or brain activity.
- release of glucose from glycogen stores in the liver and a suspension of the function of insulin, resulting in an accumulation of glucose in the frog’s cells.
- extremely high concentration of glucose within the cells lowers the freezing point of water and creates a “slurry” of ice crystals and sugar that prevents the cells from being damaged.
- When the ice melts, the wood frog thaws and shows little sign of cellular damage.
90
Endotherms allow their body temperature to vary considerably during certain times of day or in different seasons and are considered --.
poikilotherms
91
The dependence on thermal energy generated by metabolic processes makes endotherms use about --- of the energy from their food to maintain their body temperature. Endotherms keep their bodies at an optimal temperature by regulating the amount of thermal energy that is generated by internal reactions and the amount of thermal energy that is exchanged with the environment.
80 %
92
Endotherms can therefore remain fully active over a wider range of temperatures than ectotherms, but they require a nearly constant supply of energy. Cold weather does not prevent them from foraging, mating, or escaping from predators, but it does increase their ---.
energy and food needs
93
Scientists have estimated that up to ---- of the basal metabolic rate of most endotherms can be attributed to the energy that is consumed to offset this loss of thermal energy.
25 %
94
Body cells of -- contain far more mitochondria, and they are proportionately larger than the body cells of --.
endotherms, ectotherms
95
- - make up the majority of endotherms. They have the most elaborate thermoregulatory mechanisms of all animals.
Birds and mammals
96
-- is a (sheeplike) short-term state of reduced metabolic rate and body temperature that reduces the demand for energy during the night or day.
Torpor
97
An animal may enter into torpor nightly or even daily, as in the case of some bats and other nocturnal animals. Metabolic rate, heart rate, respiration rate and other functions are ...
greatly reduced to conserve energy and heat.
98
In cold climates, many endotherms enter a prolonged state of ...
torpor tied to the seasons (This change is usually triggered by a change in the length of the day, which signals the transition between summer and winter)
99
Hibernation is a state of ...
greatly reduced metabolic rate and activity
that enables an animal to survive the winter by reducing the demand for energy when food is unavailable.
100
Extended torpor of small mammals during the winter is called ---
hibernation: a state of inactivity and significantly decreased metabolic rate
101
Brumation:
- the hibernation-like state that cold-blooded animals such as reptiles and amphibians enter during very cold weather
- triggered by the onset of colder temperatures and shorter daylight hours and can last for months.
102
Estivation:
- a state of torpor that enables an animal to survive the summer by reducing the demand for energy
103
Many insects can use exercise to maintain a core body temperature above the environmental temperature and are referred to as --
exercise endotherms (ex.honeybees)
104
Dogs have an uneven distribution of fur that aids --.
thermoregulation (fur is thickest over the back and sides of the body and the tail, and thinnest over the belly and the legs. In cold weather, a dog curls up, pulls in its limbs, wraps its tail around its body, and buries its nose in its tail so that only the best-insulated surfaces are exposed to the air)
105
Elephants and jackrabbits dissipate thermal energy from the large surface area of their ears. The ears have a large surface area with blood vessels close to the skin and thermal energy --.
dissipates easily
106
organ systems, other than the excretory system, that are involved in homeostasis, and describe the role of each system
The nervous system- receives sensory data from the environment, which informs the body of external conditions, and transmits signals in the body to regulate homeostasis
The endocrine system- regulates the levels of various hormones that are essential to life processes
The immune system- protects the body from and fights infection
