5.1.1 Communication and homeostasis Flashcards
(32 cards)
What is the need for communication systems in plants so they respond to external environment?
avoid herbivory;
grow towards sunlight/water;
Why do animals need to respond to their environment?
to catch prey;
avoid predation;
What is the need for communication systems in multicellular organisms?
respond to abiotic and biotic factors;
Why do plants and animals need to respond to their internal environment?
enzyme controlled reactions involved in metabolic reactions;
What is a transducer?
a receptor that converts one type of energy into another type of energy
What is the reflex arc?
receptors attached to sensory neurone > CNS where there are relay neurones > brain coordinates a response > motor neurone > effector (muscle or gland)
What are effectors?
muscles or glands that bring a response from a stimulus and produce an effect
What are the two types of hormones?
peptide hormones;
lipid based hormones;
How do lipid based hormones cause an effect to a cell?
as it can diffuse through the phospholipid bilayer;
hormone binds to a receptor in the cytoplasm forming a receptor hormone complex;
RHC enters the nucleus and triggers gene transcription;
transcribed mRNA is translated and proteins are produced to alter cells activity
How do peptide hormones cause an effect to a cell?
they use 1st messengers and a 2nd messenger response;
first messenger is the hormone and it binds to the receptor as it is specific and complementary;
this activates the enzyme adenyl cyclase;
the enzyme activates the 2nd messenger cAMP;
cAMP triggers a response inside the cell;
What is a receptor?
detects a change in the body
What is homeostasis?
maintaining a relatively stable internal environment ;
within narrow limits;
even though the environment is changes
What factors need to be kept constant in the body?
core body temperature
blood pH
blood glucose conc
water potential of blood
Why does core body temperature need to be controlled by homeostasis?
enzymes/other proteins are sensitive to temperature changes;
they function best at their optimum temperature;
at low temperatures they don’t work efficiently and at high temperatures they denature;
Why does blood pH need to be controlled by homeostasis?
enzymes/other proteins are sensitive to pH;
they function best at their optimum pH;
away from optimum, enzymes don’t work efficiently/denature
Why does blood glucose concentration need to be maintained by homeostasis?
glucose is a respiratory substrate;
cells need a constant supply;
needed to make ATP used in muscle contraction via aerobic respiration;
keeping blood glucose conc constant ensures a constant water potential;
What is negative feedback?
the effector causes a change that brings the environment back to ‘normal’ conditions
What is positive feedback?
the situation is amplified until there is a change brought about
What are endotherms?
regulate their own body temperature
What are ectotherms?
doesn’t regulate their own body temperatare as effectively;
as they rely on external sources
How does the hypothalamus regulate body temperature?
there is a thermoregulatory centre in the hypothalamus;
contains thermoreceptors which monitor temp of blood;
sends messages to parts of the body to increase/decrease
What occurs to blood vessels when the body temperature is too high/low?
vasoconstriction; blood vessels narrow near the surface of the skin; more blood travels through shunt vessel; less heat loss through epidermis
vasodilation; the shunt vessel constricts more blood rushes towards the surface of the skin; more heat loss through epidermis
What occurs to the hairs on the skin when body temp is too high/low?
hair erector muscle;
contracts or relaxes
stand on end;
creates insulating layer of air
How is a temperature increase or decrease detected by the skin?
detected by peripheral temperature receptors on the skin
