3.4 comparing the nervous and endocrine system Flashcards
The nervous system and endocrine system function independently or together to maintain homeostasis. Compare the action of the endocrine and nervous systems. Explain how the nervous and endocrine systems work independently or together to: control body temperature enable osmoregulation maintain blood sugar levels monitor carbon dioxide levels to maintain constant pH of blood.
What two systems are involved in homeostatic control?
Nervous system and endocrine system work together as two systems of communication that combine to bring about the required response.
Which function independently or together to maintain homeostasis.
What is the response for stress (for animals)
Fight or fligt is the response and has evolved as a protective mechanism enabling organisms to react quickly and be able to respond to life threatening situations, allowing organisms to be prepared for:
- fight for survival
- take flight (quickly move away from the danger)
freeze can also sometimes be a factor.
What hormones are the fight or flight response controlled by?
Adrenaline found in the adrenal glands.
How does the hypothalamus initiate the reaction?
The hypothalamus initiates its reaction through the automatic nervous system (controls breathing, blood pressure, heart rate and other involuntary reactions). It is then the sympathetic component which is activated and prepares the body to respond to danger.
Describe the main actions fight or flight.
- Nerve impulses stimulate adrenal glands to release adrenaline to the blood
- Adrenline then goes on to initate a number of physiological changes:
increase in heart rate, increase in blood pressure, dilates bronchial tubes in lungs, dialation of pupils, increased blood flow to muscles, increased metabolic rate etc. - The hypothalamus also activates the adrenal-cortical system by releasing corticotrophin-releasing-factor (CRF)
- The adrenal cortex releasues up to 30 different hormones to further enhance the effects of adrenaline: as well a higher perception (vision and hearing) and an increase in blood glucose levels.
once the threat has passed the parasympthatic component tends to reduce the effects of the sympathetic component and reverses the above effects to restore the body to normal (rest and digest).
Describe the adrenaline fight-or-flight response?
- In response to a threat the hypothalamus activates the sympathetic nervous system and the adrenal-cortical system by releasing CRF.
- In activating the sympathetic nervous system the adrenal medulla is activated which releases norepinephrine (increases alertness,arousal and attention and epinepherine(adrenaline) into the bloodstream. It also leads to glands and smooth muscles being activated.
- On the other hand by the hypothalamus recieving the stimuli it activates the adrenal-cortical system by releasing CRF. This leads to the pituitary glands secreting hormone ACTH, which arrives to the adrenal cortex and releases approx 30 hormones
**All of these hormones going into the bloodstream leads to neural activity; combining hormones in the bloodstream to constitute the fight-or-flight response. **Coordinates system between the nervous and endocrine system.
How do the nervous system and endocrine system work together to maintain human body temperature?
Human body temperature must be maintained around 37 degrees for most efficient function, and is done so through the nervous and endocrine system:
To help conserve heat:
- body hair or feathers stand uo
- blood flow to the skin (vasoconstriction)
- shivering
- metabolic rate(increase thyroxine)
To help lose heat:
- blood flow to the skin(vasodilation)
- flattened hair of feathers
- sweating
What happens when body temperature rises?
When body temperature rises:
- Blood vessles dilate;resulting in heat loss to the enviornment.
- Sweat glands secrete fluid, as the fluid evaporates, heat is lost from the body.
Through this heat is lost to the enviorment and the body returns to its normal temperature.
Describe the homeostatic processes and their mode of transmission.
Hair/feather erection - nervous
Sweating - nervous
Shivering - nervous
metabolc rate (thyroxine) - hormonal
Heart rate (adrenaline) - hormonal
Vasoconstriction/Vasodilation - nervous/hormonal (result of external stimuli e.g. body too hot or cold. which is recieved by receptors in the nervous system which are acted upon by a combination of the nervous and endocrine system)
Pre-capillary sphincters - nervous and hormonal.
What happens when body temperature is too low?
When body temperature falls:
- Blood vessles constrict;so the heat is conserved.
- Sweat glands do not secrete fluid.
- Shivering (involuntary contraction of muscles) generates heat which warms the body.
Through this heat is retained and body returns to normal temperature.
What are pre-capillary sphincters?
Help to regulate body temperature:
essentially specific small muslces located at the entrance of capillary beds, controlling blood flow to capillaries by tightening or relaxing to help maintain a stable body temperature.
- When its too hot, they relax allowing more blood to flow to the skins surface, this increased blood flow helps to dissipate heat from the body into the enviornment cooling you down.
- When its too cold, they contract, reducing blood flow to the skins surface, by limiting blood flow the body retains more heat helping you stay warm.
Whats vasoconstriction and vasodilation?
Vasoconstricion reduces blood flow to the surface of the skin by narrowing the blood vessels it helps keep heat inside the body where you may look paler or feel cooler when your cold.
Vasodilation is when blood flow increases by widening the blood vessles, bringing heat to the skins surface allowing you to release heat into the enviornement.
Compare aspects of the nervous and hormonal system
-Speed of transmission: nerves (fast/fraction of a second) and hormones (slow seconds to years)
-Mode of transmission: nerves (electrical impulses) and hormonal (chemical dissolved in the blood plasma)
-Specificity: nerves (specific, a single gland or muslce) and hormonal (general, usually several organs to cause widespread effects)
Duration: nerves (very brief {seconds}) and hormonal (longer{minutes to years}).
