Homeostasis And Response (part 1) Flashcards
Homeostasis
Maintaining a stable internal environment
Automatic control systems such as nervous and hormonal
Receptors, coordination centres and effectors
Negative feedback
Automatic cycle
Receptor detects a level too high, coordination centre organises a response, effector counteracts
Level now too low, coordination centre organises a response, effector counteracts
Continues happening
CNS
Central nervous system, the brain and spinal cord in vertebrates
Sensory and motor neurones
Sensory receptor —> CNS
Motor CNS —> effector
Receptors and effectors
Receptors- the cells which detect stimuli, can form part of larger organs e.g. retina
Effectors respond to nervous impulses- muscles and glands
Synapses
The connection between two neurones
Chemicals diffuse across the gap
Set off a new electrical signal in the next neurone
Reflexes
- instant response
- don’t involve the conscious part of the brain
Reflex arc
- receptor detects a stimulus
- travels along the sensory neurone
- diffuses across a synapse
- relay neurone in the CNS
- diffuses across a synapse
- travel along a motor neurone
- effector brings about a response
Brain
Part of CNS
Billions of interconnected neurones
In charge of all complex behaviours
Cerebral cortex
Big, wrinkly big
Consciousness, intelligence, memory, language
Cerebellum
Back and base
Muscle coordination
Medulla
Above spinal cord
Controls unconscious activities
Studying patients with brain damage
The effect can tell you what part has been damaged if only a small part has been impacted
Electronically stimulating the brain
Pushing a tiny electrodes, a small zap of electricity. Stimulating different parts allow us to see what each does
MRI scans
Magnetic resonance imaging
Gives a detailed picture of the brain’s structures
Use it to see which parts are active when doing things e.g. listening to music or trying to recall a memory
Consequences of messing with the brain
Electrical stimulation decreased muscle tremors due to nervous system disorders e.g. Parkinson’s disease
Incredibly complex and delicate, risks such as physical damage or increased problems with brain function
Body temperature
Must be kept around 37 degrees
Uses negative feedback
When too hot:
Sweat evaporates from skin
Blood vessels vasodilate to expand lumen and move blood closer to the surface, helps transfer energy to environment
When too cold:
Hairs stand up- trap insulating lager of air
No sweat
Blood vessels constrict- low transfer of energy
Shiver- needs respiration
Hormones
Chemical messages sent in blood
Produced and secreted by glands in endocrine system
Pituitary gland
Bottom of brain
Produces several hormones which act on other glands- release hormones to bring about change
Thyroid
Bottom of neck
Produces thyroxine, regulates metabolism, heart rate, temperature
Adrenal glands
Either side of pancreas
Produce adrenaline- “fight or flight”
Pancreas
Produces insulin, regulates blood glucose level
Hyper vs hypoglycemia
Hyper - too hot
Hypo- too low
Ovaries
Females only Produces oestrogen (menstrual cycle)
Testes
Males only
Produces testosterone, controls puberty and sperm production
Nerves vs hormones
Nerves: fast, act for a short time on a precise area
Hormones: slower, long time, more general area
Thermoregulatory centre
In the brain- maintains body temperature
