Quiz
Homeostasis
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Questions in this quiz (18)
1[blank_start]Homeostasis[blank_end] is the maintenance of a [blank_start]stable[blank_end] internal environment. It keeps conditions within a narrow range of the cells' optimum conditions.
- AHomeostasis
- Bstable
2Homeostasis is partly achieved by maintaining stable conditions within the [blank_start]blood[blank_end], which in turn gives rise to [blank_start]tissue fluid[blank_end] that bathes the body's cells. In the blood the concentration of [blank_start]glucose[blank_end], ions and CO2 must be kept within narrow limits. In addition, the water potential (determined by the concentration of solutes in the blood), [blank_start]pH[blank_end] and temperature of the blood are tightly regulated.
- Ablood
- Btissue fluid
- Cglucose
- DpH
3Each condition that's controlled has a [blank_start]norm value[blank_end] or set point, usually the [blank_start]optimum[blank_end] for the condition, that the homeostatic control mechanisms are trying to maintain. [blank_start]Receptors[blank_end] detect deviations from the norm. The receptors are connected to a [blank_start]centre[blank_end], which turns on or off [blank_start]effectors[blank_end] to bring the condition back to the norm value. The effectors are usually turned on or off by signals ([blank_start]nerve impulses[blank_end] or hormones) from the control centre. The process is known as [blank_start]negative feedback[blank_end] as a deviation from the norm results in a change in the [blank_start]opposite[blank_end] direction, back to the norm. These corrections mean that the actual value fluctuates in a narrow range around the norm.
- Anorm value
- Boptimum
- CReceptors
- Dcentre
- Eeffectors
- Fnerve impulses
- Gnegative feedback
- Hopposite
4[blank_start]Positive feedback[blank_end] is the opposite of negative feedback: the output from the control centre moves the condition [blank_start]further[blank_end] from the set point.
- APositive feedback
- Bfurther
5[blank_start]Thermoregulation[blank_end] is the control of body temperature. Our core body temperature is very stable at about [blank_start]37.5[blank_end] degrees C; this is about 0.5 degrees C higher than oral temperature, measured with a thermometer under the tongue. This body temperature allows enzyme-controlled reactions to occur at a reasonable rate. At lower temperatures, the reactions would occur too [blank_start]slowly[blank_end] for the body to remain active; at higher temperatures the enzymes would [blank_start]denature[blank_end]. A rise of only 5 degrees C in core body temperature can be fatal.
- AThermoregulation
- BHomeostasis
- C37.5
- D40
- Eslowly
- Fquickly
- Gdenature
- Hdie
6In humans, temperature is maintained by a [blank_start]negative[blank_end] feedback system. This system involves receptors that detect changes in the blood temperature. These receptors are located in the [blank_start]hypothalamus[blank_end]. The [blank_start]hypothalamus[blank_end] is the control mechanism and acts as a thermostat, turning on the effectors necessary to return the temperature to the norm. There are also [blank_start]thermoreceptors[blank_end] in the skin that detect temperature changes. When skin is warm, impulses are sent to the hypothalamus initiating the heat-loss responses and inhibiting heat gain responses. When skin is cold, the opposite happens. These changes help keep the core body temperature near its optimum. There are several ways the skin can help control temperature, including sweating, hair attitude (flat or raised), route of blood flow, and shivering. Shivering is the [blank_start]uncontrolled[blank_end] contraction of normally voluntary muscles and can increase heat production six-fold. Shivering transfers energy to muscle tissue, which helps maintain body temperature.
- Anegative
- Bpositive
- Chypothalamus
- Dmedulla oblongata
- Ehypothalamus
- Fmedulla oblongata
- Gthermoreceptors
- Hchemoreceptors
- Iosmoreceptors
- Juncontrolled
- Kcontrolled
7Sweat released on the skin via the sweat duct [blank_start]evaporates[blank_end], taking [blank_start]heat energy[blank_end] from the skin. Sweat glands are stimulated by nerves from the hypothalamus.
- Aevaporates
- Bheat energy
8Hairs are [blank_start]raised[blank_end] in cold weather by contractions of the [blank_start]erector muscles[blank_end]. This is a [blank_start]reflex[blank_end] that we have no control over. It produces goose pimples on the flesh. The aim is to trap a layer of [blank_start]air[blank_end] that insulates the body. Due to the shortage of hair in humans, this isn't very [blank_start]effective[blank_end].
- Araised
- Berector muscles
- Creflex
- Dair
- Eeffective
9In colder conditions, the muscles in the arteriole walls [blank_start]contract[blank_end], causing the arterioles to constrict, [blank_start]reducing[blank_end] blood supply to the surface capillaries. Blood is diverted through the shunt vessel which [blank_start]dilates[blank_end] as more blood flows through it. Blood flows [blank_start]further[blank_end] from the skin surface so less energy is lost. This is known as [blank_start]vasoconstriction[blank_end]. In warm conditions, the shunt vessel [blank_start]constricts[blank_end] and muscles in the walls of the arterioles relax. Blood flows through the arterioles, making them dilate. More blood flows closer to the surface so more energy is lost through radiation. This is known as [blank_start]vasodilation[blank_end].
- Acontract
- Brelax
- Creducing
- Dincreasing
- Edilates
- Fconstricts
- Gvasoconstriction
- Hvasodilation
- Ifurther
- Jcloser
- Kconstricts
- Lrelaxes
- Mvasodilation
- Nvasoconstriction
10During exercise, core body temperature rises.
- ATrue
- BFalse
11Once the hypothalamus detects a deviation from the norm in core temperature, it starts a chain of actions, including the release of [blank_start]sweat[blank_end] from sweat glands in the skin. These actions counteract the deviation and bring body temperature back to the [blank_start]norm[blank_end]. [blank_start]Evaporation[blank_end] from the skin surface is very important in temperature regulation in humans, people born without sweat glands can experience severe problems when they undertake exercise.
- Asweat
- Bnorm
- CEvaporation
12Evaporation from moist surfaces of lungs decreases energy loss.
- ATrue
- BFalse
13Which type of energy transfer is this? Energy can be ... from one object to another through air, or even through a vacuum as EM radiation.
- ARadiation
- BConduction
- CConvection
- DEvaporation
14Which type of energy transfer is this? Energy loss by ... involves direct contact between objects and energy transfer from one to another.
- AConvection
- BConduction
- CEvaporation
- DRadiation
15What type of energy transfer is this? Energy is needed to convert water from liquid to vapour.
- AEvaporation
- BConvection
- CConduction
- DRadiation
16What type of energy transfer is this? Air lying next to the skin will be warmed by the body. As the air expands and rises, or is moved away by air currents, it will be replaced by cooler air, which is then warmed by the body.
- AConvection
- BConduction
- CEvaporation
- DRadiation
17The energy required to evaporate sweat is drawn from the [blank_start]body[blank_end], cooling it. However the process of sweating only has this cooling effect when the water [blank_start]evaporates[blank_end]. Mammals, birds and reptiles may also [blank_start]pant[blank_end] to keep cool, by evaporation of water from the [blank_start]gas exchange surfaces[blank_end]. In conditions of high [blank_start]humidity[blank_end], evaporation becomes virutally impossible. Controlling body temperature becomes much more difficult when the air is saturated with water vapour.
- Abody
- Bevaporates
- Cpant
- Dgas exchange surfaces
- Ehumidity
18At around 37.5 degrees C human core body temperature is normally [blank_start]higher[blank_end] than the surroundings, so energy will be transferred to the environment. In very cold environments, excessive cooling may occur and the body can lose thermal balance - the core body temperature starts to [blank_start]fall[blank_end]. The hypothalamus detects this and immediately does its best to regulate the internal temperature by increasing [blank_start]metabolic rate[blank_end] and slowing energy loss.
- Ahigher
- Bfall
- Cmetabolic rate
Information
- Description
- 18 questions
- Author
- Ella Middlemiss
- Language
- English
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- 6
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