Muscles, nerves and hormones
- Created by: Steff06
- Created on: 15-02-16 18:39
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- Muscles, nerves and hormones
- Responding to environmental stimuli:
- Responses of mammals to environmental stimuli are coordinated and balanced to ensure survival.
- Coordination of responses to stimuli from external environment is mainly the result of brain activity to assess the most appropriate response.
- Brain also regulates endocrine responses through action of the hypothalamus and its control on the pituitary gland.
- Fight or flight response
- Threat to safety of a mammal leads to physiological changes to prepare the organism to deal with the threat, escaping or challenging it.
- Aterioles to digestive system + skin are constricted whilst those to muscles and liver are dilated.
- Pupils dilate.
- Heart rate & blood pressure increase.
- Blood glucose levels increase.
- Metabolic rate increases.
- Erector pili muscles in skin contract, making hairs stand up.
- Ventilation rate and depth increase.
- Endorphins (natural painkillers) are released in the brain.
- Sweat production increases.
- Coordination of the physiological changes:
- Cerebral understanding of a threat activates hypothalamus which stimulates increased activity in sympathetic nervous system + triggers release of adrenaline from adrenal medulla into blood.
- Hypothalamus releases corticotropin-releasing factor (CRF) into pituitary gland, stimulating release of adreno-corticotropic hormoone (ACTH) from pituitary gland. Stimulates release of hormones from adrenal cortex which help body to resist stressors.
- Effects of sympathetic nervous system + adrenaline release and hormones into blood is responsible for physiological changes of fight or flight response.
- Timing of fight/flight response:
- On perception of threat, there is a period of heightened awareness.
- The threatened animal assess the threat which is an autonomic assessment.
- Responding to environmental stimuli:
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