Flashcards
Communication and Homeostasis
Cards in this deck (44)
- 1What conditions do all living thing need to maintain their cells• suitable temperature
•suitable pH
•aqueous environment that keeps substrates and products in solution
•freedom from toxins and excess inhibitors - 2What happens to cells if they do not have the correct conditionsCells will die and become inactive
- 3Why do cells in multicellular organisms communicateCells are specialised and rely upon each other to coordinate their activites
- 4What is the external environment for living organisms and what happens if it changes•Air, water or soil around them
•If it changes it may place stress on the living organisms - 5Give an example of a change in the external environement•Environment becomes cooler
•Leads to greater heat loss
•The organsisms must monitor changes in the environemtn and change its behaviour or physiology in order to survive - 6Define stimulusA change in the environment that brings about a response
- 7Define responseThe way in which the organisms changes its behaviour or physiology
- 8What is the environment of cellsTissue fluid bathes internal cells and tissues, not exposed to external environemtn
- 9How do the activities of cells alter their own environment•Cells undergo metabolic activities and create new products
•These compounds can be unwanted or toxic and move out of cells into the surrounding tissue fluid
•It would reduce the cell's activities so less waste is made - 10How is the tissue fluid maintained•It is maintained by the blood
•Blood flows throughout the body and transport substances to and from cells, waste products would be carried away and removed from the body by excretion - 11Why is it important to monitor the concentrations of waste products and substances•So the body does not excrete too much of a useful substance
•So the body removes enough of the waste products
•So cells in the body are supplied with the substrates they need - 12Why is a good communication system required?•So different parts of the body work together effectively
•Cells that monitor blood may be in a different part of the body away from the source of the waste product - 13What will a good communication system do (5 points)•cover the whole body
•enable cells to communicate with each other
•enable specific communication
•enable rapid communication
•enable both short-term and long-term response - 14Name the two major systems of communication• Neuronal system
•Hormonal system - 15What is the neuronal system•Interconnected network of neurones that signal to each other across synapse junctions
•Neurones can conduct a signal quickly and enable rapid responses to a stimuli - 16What is the hormonal system?•System that uses blood to transport its signals
•Cells in an endocrine organ releases the signal directly into the blood and is recognised by a specific target cells
•Enables long term responses - 17Define homeostasisMaintaining a constant internal environment despite changes in the external and internal factors
- 18What is maintained by homeostasis? (6)•Body temperature
•Blood glucose concentration
•Blood salt concentration
•Blood Ψ
•Blood pressure
•Carbon dioxide concentration - 19What is the response pathwayStimulus → receptor → communication pathway (cell signalling) → effector →response
- 20What is the function of sensory receptors? Give an exampleSensory nerve endings that monitor changes in the internal or external environment of an organism and create action potentials
Temperature receptors on the skin or in the brain - 21What is an effector? Give an example•A cell, tissue or organ that brings about a response
Liver cells or muscle cells - 22What is cell signalling?•Can occur in adjacent or distant cells
•Cells in the nervous system communicate via neurotransmitters
•Cells in the hormonal system communicate via hormones - 23What are receptors?•They detect stimuli and are specific
•Different types of receptors detect different types of stimulus - 24What is negative feedback?The mechanism that reverses a change, bringing the system back to the optimum
- 25What is the mechanism for negative feedback1) Receptor detects stimulus and sends input to coordination centre
2)Coordination centre sends a output to the effectors
3)Effectors respond and brings about a change to bring system closer to optimum
4)As the system gets closer to optimum, the response is reduced - 26What are the limitations of negative feedback?Only works within certain limits, there is variation around the optimum condition
If the change is too big, the effectors cannot counteract it - 27How is temperature control maintained by negative feedbackThe mechanism that increases a change, taking the system further away from the optimum
Is less common and usually harmful - 28What is positive feedback?The mechanism that increases a change, taking the system further away from the optimum
Is less common and usually harmful - 29What is the mechanism of positive feedback?1)Receptor detects change and sends input to communication system
2)Communication system sends output to effector
3)Effector brings about a response that increases the change - 30Give an example of positive feedback•Positive feedback is used for the dilation of the cervix at the end of a pregnancy
•Cervix stretch causes PPG to secrete oxytocin
•Oyxtocin increases uterine contraction which stretches cervix more
•Birth ends the production of oxytocin - 31Why do we need to control body temperature?•Too high can lead to enzymes denaturing
•Too low can slow chemical reactions down
•Too low can affect the individual's health (chemical reactions slow down etc) - 32Define EctothermAn organism that relies on external sources of heat to maintain body temperature
- 33How do ectotherms regulate their temperature?They rely on behavioural responses to alter that amount of eat exchanged with the environment
When they are active muscle contraction will generate heat from increased respiration
Can't control their temperature internally - 34How do ectotherms increase their temperature?•Move into a sunny area
•Lie on a warm surface
•Expose a larger surface area to the sun - 35Give an example of an ectotherm trying to increase their temperature•Snake can be found lying down exposed to the sun
•Locust expose a large surface area to the sun in the morning but less at midday - 36How do ectotherms decrease their temperature?•Move out of the sun
•Move underground
•Reduce body surface exposed to the sun - 37Give an example of an ectotherm trying to decrease their temperature•A Locust increase the rate and depth of breathing when it is hot to cool the body
•A lizard uses burrows to hide in during the hottest part of day and during the night
•A horned lizard can change its shape by contracting/expanding its ribcage - 38What are the advantages of ectothermy?•Do not use up energy to keep warm
•Less of their food is used in respiration
•More energy and nutrients gained from food can be converted to growth
•Need to find less food
•Can survive for long periods without food - 39What are the disadvantages of ectothermy?•Less active in cooler temperatures
•So at risk from predators while they are cold and unable to escape
•Cannot take advantage of food that is available while they are cold - 40Define endothermAn organism that uses heat from metabolic reactions to maintain body temperature
- 41How do endotherms regulate their temperature?Largely independent of external temperatures and controls their temperature to strict limits
Use a variety of temperature regulation mechanisms (physiological and behavioural) - 42What physiological mechanisms are used by endotherms to maintain body temperature when hot and cold (5)
- 43What behavioural adaptations are used by endotherm to maintain body temperature?
- 44What are the advantages of