Communication and Homeostasis Flashcards
What conditions do cells need to maintain?
Temperature
pH
Aqueous environment (solute concentrations)
Freedom from toxins and inhibitors
What will happen if conditions are compromised?
Cells will be damaged, become inactive and potentially die.
Why do cells communicate?
Cells all all specialised for a specific purpose
Need to communicate so they can carry out functions smoothly
How do he actions of the cells alter their own external environment?
Some products of metabolic reactions are toxic
They are moved out of the cell into the tissue fluid
Therefore altering the external environment of the cell
How does the body maintain its internal environment?
Moves toxins into tissue fluid
These then move into blood
Moved to excretory organs (kidneys and liver)
Excreted
List features of a good communication system
Cover the whole body
Enable cells to communicate with each other
Enable specific communication
Rapid communication
Enable both long and short term responses
How does cell singanling work?
Cells release a specific chemical
Second cell has a receptor for this chemical which it binds to sending the message
What are the 2 major communication systems?
Neuronal System
Hormonal system
How does the neuronal system work?
network of neurons that signal to each other via synapses
Can send signals very quickly and responses are rapid
How does the emdocrine system work?
Uses the blood to send signals
Endocrine system secretes hormones directly into blood
Response takes longer to come to effect but enables a longer term response
What does homeostasis regulate?
Body temp Blood glucose concentration Blood salt concentration Water potential of blood Blood pressure CO2 Concentration
What are sensory receptors?
Sensory receptors are on the surface of the body
They monitor the external environment and alert the body to change
When stimulated it sends a signal to an effector
What is an Effector?
Cells that bring about a response
such as Muscle (sarcomeres) or liver cells (hepatocytes)
What is negative feedback?
A change is detected
The body responds in opposition to this change
Return the body to optimum
What is positive feedback?
A change is detected
The body reacts to exacerbate this change
This moves the body away from optimum so is usually harmful
Why is positive feedback often harmful?
Because it moves the body away from optimum conditions
Enzymes can become less effective and even become denatured
Impacts metabolic reactions causing harm to the body
What is an example of where positive feedback is beneficial the body?
Cervix dilation during labour
The body detects the stretch of the cervix
The pituitary gland releases oxytocin which increases uterine contractions causing the crevix to stretch more
This is essential for a safe delivery of the baby
What is an endotherm?
An organism that regulates its own internal body temperature
Very strict tolerances
largely independent of external factors
What is an ectotherm?
Can’t control own body temp
rely on external sources
use behavioral mechanisms to maintain body temperature in different conditions
Give examples of how ectotherms maintain body temp
Too hot:
Move to a sunny area/ lie on a warm surface
expose more of their surface area to the sun
Too cold:
Move out the sun
Move underground
reduce surface area exposed to the sun
Give 4 advantages of Ectothermy
Less energy used in respiration
More nutrients gained from food (because less energy is required)
Don’t need to find food as often
Can survive long periods without any food
Give a disadvantage of Ectothermy
Less active in cold environments
so they are more at risk from predators when it is cold
Give 3 advantages of Endothermy
Can maintain fairly constant temperature despite external conditions
Remain active even when environment is cold
Can inhabit colder parts of the planet
Give 4 disadvantages of Endothermy
Use energy in order to maintain body temperature in cold conditions
Require more food
Less energy can be used towards growth
Can overheat in hot conditions
Where are the temperature receptors in the brain?
Hypothalamus
What is the role of periphery temperature receptors?
To give the hypothalamus an early warning that core body temperature could change
