Biology G12 Topic 1 - Coordination and Control

Only includes MQF level 2-3 information

coordination systems working together under fight or flight responses

nerve impulses stimulate adrenal gland to secrete adrenaline, which brings about the changes necessary for a fight or flight response

sensory neurone

carriees impulses from the sense organs to the CNS

endocrine system - hormones secreted by endocrine glands

• slow action

• sustained response

• widespread response

• long-term effects

nervous system - electrical signals along nerve cells

• quick action

• immediate response

• localised response

• short-term control

relay neurone

makes connections between sensory and motor neurones in the CNS

motor neurone

carries nerve impulse from CNS to effector muscles/gland to initiate a response

nerve impulse

travels in one direction only

synapse

a structure that permits a neurone to pass on an impulse to another nerve cell

neurotransmitters

chemical messengers released during synaptic transmission, initiate or inhibit a nerve impulse in the next cell

reflex action

an automatic and rapid response involving effectors, which is essential for survival

reflex actions are essential for survival because

they allow the animal to respond quickly to situations that might endanger it

2 neurone reflex arc (mallet hits tendon, causing it to stretch)

stimulus → receptor → sensory neurone → coordinator (spinal cord) → motor neurone → effector → response

cerebrum structure

2 cerebral hemispheres, each side controlling the opposite side of movement in the body.

inner layer = white matter = myelin sheaths.

outer layer = grey matter = cell bodies of neurones
→ highly folded to inc SA for more neurones + more neurone connections

3 neurone reflex arc (touching fire or pin)

stimulus → receptor →sensory neurone → coordinator (spinal cord) → relay neurone → motor neurone → effector → response

cerebrum functions

• memory

• intelligence

• reasoning

• acquired skills

• consciousness

• movement

cerebellum

coordinates movement

eg. balance (requires coordination between multiple part of body)

medulla oblangata/brain stem

responsible for autonomic (involuntary) actions

• breathing rhythm

• heart rate

• swallowing

• vasiconstriction/dilation

• sneezing/vomiting

→ involve reflex actions influenced by nerve impulses from other parts of the brain

pituitary gland

master gland → controls other endocrine glands in the body, producies hormones that act as chemical messengers which stimulate other glands ie.

• ADH (pituitary gland) targets collecting duct in kidney to absorb more water

• FSH + LH (pituitary gland) target ovaries

hormones

chemicals produces by endocrine glands to bring about a response by a target organ or cells

endocrine/hormone-secreting glands are ductless glands…

hormones are secreted directly into the blood and not through ducts

pancreatic hormones

regulate blood glucose levels (homeostasis)

insulin and glucagon

• are antagonistic hormones

• target the liver

when blood glucose levels aretoo high

Islets of Langerhans produce insulin, targeting the liver and muscle cells to bring down/restore glucose conc.

insulin functions

• stimulates cells to take in glucose from the bloodstream (liver & muscle cells)

• excess glucose is converted into glycogen for storage in liver and muscle cells

• promotes conversion of carbs to fats and slows down conversion of proteins to carbs

when blood glucose levels are too low

Islets of Langerhans produce glucagonto bring back up/restore glucose levels to normal

function of glucagon

• acts on liver cells and causes them to convert stored glycogen into glucosenega

negative feedback

involves detecting that a level of a substance or a condition has gone above/below normal levels, which triggers a response to bring back the level to the set point again through the use of 2 opposing systems (antagonistic hormones)

using regulation of blood glucose levels as an example of negative feedback

glucagon - increases blood glucose levels when conc. is low

insulin - decreases blood glucose levels when conc. is high.