5.1.1 - Communication And Homeostasis

Question 1

What is the purpose of an effective communication system in organisms?

Answer 1

To ensure an organism is able to function effectively.

Question 2

What is a stimulus in the context of cell signaling?

Answer 2

An environmental change like temperature.

Question 3

What is the response in the context of a stimulus?

Answer 3

A change in behaviour or physiology.

Question 4

What is the difference between external and internal stimuli?

Answer 4

External stimuli are environmental changes; internal stimuli are changes to tissue fluid and blood composition.

Question 5

What are the components of the coordinating communication system?

Answer 5

• Stimulus
• Receptor
• Effector
• Response

Question 6

What is the standard response pathway for homeostasis?

Answer 6

Stimulus → Receptor → Communication pathway → Effector → Response.

Question 7

Where are sensory receptors typically found?

Answer 7

On surfaces like the skin and in the brain.

Question 8

What do sensory receptors do when they detect a change?

Answer 8

They send a signal to an effector.

Question 9

What are the two main communication systems in the body?

Answer 9

• Neural system
• Hormonal system

Question 10

What is homeostasis?

Answer 10

The maintenance of a constant internal environment despite changes in external and internal factors.

Question 11

List six examples of homeostatic control systems.

Answer 11

• Blood glucose concentration
• Body temperature
• Blood pressure
• Water potential of the blood
• Blood salt concentration
  *Carbon dioxide concentration

Question 12

What is negative feedback?

Answer 12

A mechanism used to reverse changes to maintain a constant environment.

Question 13

Fill in the blank: The closer the conditions get to optimum, the receptors detect the reduction in stimulus so they reduce the _______.

Answer 13

input that is sent to the coordination centre.

Question 14

True or False: The effector causes a change back to the optimum conditions.(negative feedback)

Answer 14

True.

Question 15

What role do effectors play in the communication system?

Answer 15

They match a response to the stimulus (muscle or gland).

Question 16

What are the main steps of negative feedback?

Answer 16

1. Conditions in the body change from a set point
2. The change is detected by receptors in/out of the body
3. Once the receptor has received a signal a corrective mechanism, is activated
4. Conditions return to a set point
5. Corrective mechanism is switched off

Question 17

What is an example of cell signaling between adjacent cells?

Answer 17

The nervous system secreting neurotransmitters which send signals to other nerve cells or muscle cells

Question 18

What is an example of cell signalling between distant cells?

Answer 18

The hormonal system releases hormones which travel through the blood and are detected by cell surface receptors

Question 19

What is the difference between receptors and effectors?

Answer 19

• Receptors detect specific stimuli, like pressure change
• Effectors are cells that bring about a response to a stimulus, like muscles contracting

Question 20

What is a positive feedback mechanism?

Answer 20

A process that amplifies or increases the effects of a stimulus.

Question 21

True or False: Positive feedback mechanisms are commonly involved in homeostasis.

Answer 21

False
It is not involved as it does not keep the internal environment constant

Question 22

Fill in the blank: In a positive feedback loop, the output enhances the __________.

Answer 22

initial stimulus

Question 23

Which of the following is an example of a positive feedback mechanism? A) Blood sugar regulation B) Childbirth C) Body temperature control

Answer 23

B) Childbirth

Question 24

Short answer: Describe one situation in which a positive feedback mechanism is beneficial.

Answer 24

During childbirth, the release of oxytocin increases contractions, facilitating delivery.

Question 25

Fill in the blank: Positive feedback is useful to ______________ something, eg. blood clots after injuries

Answer 25

Rapidly activate

Question 26

What is the effect of increased temperature on molecular activity?

Answer 26

Increased temperature provides more kinetic energy, leading to faster molecular movement and increased collision rates. ## Footnote This results in a faster rate of chemical reactions.

Question 27

What happens to enzyme-controlled reactions at higher temperatures?

Answer 27

Enzymes can denature due to increased temperature, disrupting the complementarity between the substrate and active site. ## Footnote Denaturation affects the enzyme's functionality.

Question 28

Define ectotherms.

Answer 28

Organisms that rely on external sources to maintain body temperature. ## Footnote Examples include fish, reptiles, and amphibians.

Question 29

Define endotherms.

Answer 29

Organisms that use heat from metabolic reactions to maintain body temperature. ## Footnote Examples include mammals and birds.

Question 30

How do ectotherms generally regulate their temperature?

Answer 30

Through behavioral means such as: * Moving out of direct sunlight * Going underground * Orientating their body away from the sun * Moving into the sun * Lying on warm surfaces * Orientating their body towards the sun ## Footnote These behaviors help maintain optimal body temperatures.

Question 31

How do endotherms regulate their body temperature?

Answer 31

Through both behavioral and physiological mechanisms. ## Footnote They do not rely on external heat sources.

Question 32

What are the three mechanisms endotherms do to reduce body temperature?

Answer 32

* Sweating * Hairs lie flat * Vasodilation

Question 33

What mechanisms do endotherms use to increase body temperature?

Answer 33

* Shivering * Much less sweat * Hairs stand up * Vasoconstriction * Hormones

Question 34

How does sweating reduce body temperature?

Answer 34

* More sweat is secreted from the sweat glands * The water in the sweat evaporates from the surface of the skin to take heat from the body * This cools the skin

Question 35

How does hairs laying flat reduce body temperature?

Answer 35

* Erect pili muscles relax causing the hairs to lie flat * This traps less air, so the skin is less insulated * Heat can be lost more easily

Question 36

How does vasodilation reduce body temperature?

Answer 36

* Arterioles near the skin surface dilate * This means more blood flows through the capillaries in the dermis * This cause more heat to be lost from the skin by radiation lowering the temperature

Question 37

How does shivering increase body temperature?

Answer 37

* When it is cold the muscles contract in spasms * This makes the body shiver producing more heat from respiration

Question 38

How does sweating less increase body temperature?

Answer 38

* Less sweat is screamed from the gland which reduces heat loss

Question 39

How does hairs standing up increase body temperature?

Answer 39

* Erector pili muscles contract when it’s cold * This causes the hairs to stand up and trap more hair * This prevents heat loss

Question 40

Fill in the blanks: Vasoconstriction is when _______ near the surface constrict, so less blood flows through the _________ in the dermis.

Answer 40

1. Arterioles 2. Cappilaries

Question 41

Fill in the blanks: The body releases ___________ and ___________ (hormones) to increase metabolism so less heat is produced

Answer 41

1. Adrenaline 2. Thyroxine

Question 42

What part of the brain is primarily responsible for regulating body temperature?

Answer 42

The hypothalamus.

Question 43

True or False: The hypothalamus can induce sweating to help cool the body.

Answer 43

True.

Question 44

Fill in the blank: The hypothalamus maintains body temperature by balancing heat production and _____ .

Answer 44

heat loss.

Question 45

Which physiological response is initiated by the hypothalamus when body temperature rises?

Answer 45

Vasodilation and sweating.

Question 46

Multiple Choice: What is the set point temperature for the human body that the hypothalamus typically maintains? A) 36.5°C B) 37.0°C C) 38.5°C D) 39.0°C

Answer 46

B) 37.0°C.

Question 47

What are the receptors in the hypothalamus?

Answer 47

Thermoreceptors

Question 48

What happens after the thermoreceptros detect a change in temperature?

Answer 48

1. Send an impulse along the sensory neurones to the hypothalamus 2. This sends an impulse along the motor neurones to the effectors

Question 49

How do plants increase their chance of survival?

Answer 49

Responding to changes in the environment

Question 50

How do animals increase their chance of survival?

Answer 50

By responding to their external environment (avoiding harmful environments) and responding to their internal environment changing so that their conditions are optimal for their metabolism