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Summary Alevel OCR Biology A Notes on Communication and Homeostasis
Alevel OCR Biology A Notes on Communication and Homeostasis from an A* Biology student
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communication + Homeostasis-
physical coune
systems maintain the internal environment within restricted limits.
of
-
ensure maintanance optimal condition for enzyme action cell function
+
-nervous system:CNS (braint spinal cord) + PNS (all verves a body
endocrine system:endocrine glands par of organism
-
release formoves into blood tream, transmit into from are to
another bring
to about a change.
-gland:group of cells that produce and releases are or more substance (secretions
-optimum pH hydogen =
and icric bands broken:
allers active site shape
-blood glucose b lood
conc=glue in alters water potential
+
availability of respiritory substrate
for all
temperature is
-
temp of tissue find around all it
s oo
high/low regatively
=
affect rate of enzyme contoced
reactions.
↳
Low temps prevent reactions/slow them down:Ifrequency of successful collision
↳
as temp continues 4,
to at
rate which an enzyme catalpes a reaction, denatles, bands break, tertiary
structure changes, permanately damaged active site
(transfers inco),
-
negative feedback loop receptor, coordination system elector.
-
↳
reduces initial elect a stimulus, uses two corrective rechariors
positive of original
-
feedback loop- enhance elect stimulus
-cell signalling:
allows multicellular organism to control + coordinate their bodies respond
+
to emiroment.
↳
stimulus recieved by receptor cel -> converted signal
to (transduction) -> transmitted target
to all leftector) response.
=
-animals:
paracrine signalling (culls close together)
+
endocrine signalling (cell for apart
-signalling molecules
vry
=
small-
easy transport across membrane
Thermoregulation:c or ner of
-
internal body temp
-Endotherms: count can body temp (hear generated in body tissues
-Ectotherms:b ehavioral adaptations:internal temp stay comerant (absab leal from environment
-Endotherms=peripheral receptors communicate
w/ hypothalamus
=cooking:vasodilation, sweating, flatter hairs
=heating:vasoconstriction, metabolic rate, slivering, erection of hairs
-Ectotherms:avoid extremes of temps, bask in sun/seen shade
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