Module 5-Animal responses Flashcards
(52 cards)
State and define the structure of the mammalian nervous system
The Mammalian nervous system is made up of the peripheral nervous system and central nervous system
PNS-includes receptors, sensory and motor neurones. Has 2 different components somatic and autonomic
CNS-coordination centres such as the brain and spinal cord (coordinates reflex axons). Sensory info passes through the CNS to effect a motor response
-SNS-consciously controlled, voluntary e.g when you decide to move
-ANS-works constantly, subconsciously using effectors e.g digestion
-ANS responses are grouped into sympathetic (fight or flight) and parasympathetic (rest and digest)
What are nerves?
groups of axons
What are ganglia?
groups of neurones
What are the key structures in the brain?
cerebrum, cerebellum, medulla oblongata, hypothalamus and the pituitary gland
Structure and function of cerebrum
-largest part of the brain
-Outer layer is known as the cerebral cortex
-Made up of many folds and is split into 2 hemispheres which are connected by corpus callosum
-Functions range from controlling conscious thoughts, language, intelligence, personality, high level functions and memory
-Has 4 lobes- frontal (problem solving, planning), temporal (memory formation, language), occipital (visual processing) and parietal (integrating sensory info)
What is the cerebellum responsible for?
responsible for coordinating movement, posture and balance
Structure and function of medulla oblongata
above the spinal cord and connects it to higher brain regions, is the centre of control for unconscious activities such as breathing and HR
Structure and function of hypothalamus
small part of the brain is responsible for homeostasis including thermoregulation and osmoregulation, secretion of ADH
Structure and function of pituitary gland?
a small lobed structure known as the master gland because it secretes many hormones to coordinate several responses including osmoregulation
-Controls other endocrine glands such as testes, ovaries, thyroid and adrenal glands
Define reflex
rapid, automatic response to protect from danger
What is the reflex arc made up of?
made up of 3 neurones-sensory, relay, motor
What are the steps in the reflex arc?
detection by receptors, sensory neurone carries impulse from receptors to relay neurone in spinal cord, relay neurone carries impulse to motor neurone, motor neurone carries impulse to effectors (muscles/glands), response
What makes reflexes rapid?
as no conscious decision is involved so prevents the brain from being overloaded with situations to decide responses to as the info isn’t processed in the brain
What response does the sympathetic nervous system bring about?
fight or flight
Whats systems does the sympathetic nervous system involve?
involves both endocrine system and nervous system
What is the process of the fight/flight response
-the ANS detects potential threat sending an impulse to the hypothalamus
-this results in more impulses being transmitted along the sympathetic nervous system or the adrenal cortical system
-the effectors are the adrenal glands which will release more adrenaline and noradrenaline
-the release of these hormones triggers the hypothalamus to stimulate the release of adrenocorticotropic hormone from the pituitary gland
Describe the action of adrenaline
-adrenaline is the primary messenger and attached to receptors on the surfaces of target cells which causes a protein (G protein) to be activated and adenylyl cyclase converts ATP into cAMP
-cAMP activates an enzyme that can hydrolyse glycogen into glucose (glycogenolysis) which is known as the second messenger model of adrenaline and glucagon action because the process results in the formation of cAMP which acts as a second messenger
Role and example of primary messenger
-don’t enter the cell
-exert an action on the cell membrane by binding the receptors and triggering a change within the cell
-this change can be activation of another molecule (secondary messenger) or it may initiate a reaction
-e.g include adrenaline and glucagon
Role and example of secondary messenger
-initiate and coordinate responses that take place inside a cell
-usually activated by the binding of a primary messenger to a cell surface receptor
-cAMP is an example of a secondary messenger
What systems have an effect on HR
endocrine and nervous systems
How does adrenaline affect the heart
it increases HR, increases stroke volume, increases cardiac output
How is HR controlled?
-the cardiovascular centre in the medulla oblongata controls the HR via the ANS
-the heart and the medulla oblongata are connected via 2 nerves that are connected to the SAN
-increase in HR are caused by impulses sent via the accelerator nerve in the sympathetic nervous system
-decrease in the HR are caused by impulses sent via the vagus nerve in the parasympathetic nervous system
What is the response if the pH of blood is too low/high
-the pH of the blood will decrease during times of high respiratory rate due to the production of CO2 or lactic acid and this is detected by chemoreceptors
-excess acid must be removed from the blood rapidly to prevent enzymes denaturing. -This is achieved by increasing the HR more impulses via sympathetic nervous system to SAN noradrenaline is released and carbon dioxide can diffuse out into the alveoli more rapidly.
-If co2 is too low impulses are sent from the medulla along the parasympathetic nervous system to the SAN where acetylcholine is released
What is the response if blood pressure is too high?
-barorecpetors detect blood pressure and are found in the carotid arteries and aorta
-if the blood pressure is too high this can cause damage to the walls of the arteries and it is important to put mechanisms in place to reduce the blood pressure.
-This results in more impulses via the parasympathetic nervous system to the SAN to decrease the HR.
-If the blood pressure is too low there may be an insufficient supply of oxygenated blood to respiring cells and removal of waste.
-This results in more impulses from medulla via the sympathetic nervous system to the SAN to increase the HR
