5 - MZH - Animal responses - Nervous response, Fight or flight response and Control of HR Flashcards
What type of response does the nervous system provide?
Rapid responses to changes in both the internal and external environment
What is it made up of?
- Central nervous system (CNS)
- Peripheral nervous system (PNS)
CNS:
- Brain + Spinal cord
- Act as control centre
PNS:
- Cranial nerves + Spinal nerves (nerves connecting the receptors to the CNS (sensory neurones) and CNS to the effectors (motor neurones)
Define receptor and effector
Receptor = Specialised cells in the sense organ that detect specific stimui and convert them into action potentials.
Effector = Parts of the body that produce responses i.e. muscles which contract and produce movement or glands which secrete a product
How is the PNS divided up?
Somatic nervous system - concious control
- Includes all the sensory neurones (afferent division) and also the motor neurones that connect to skeletal muscles.
Autonomic nervous system - subconcious control
- Includes 2 sets of motor neurones (efferent division) carrying action potentials to effectors other than skeletal muscles e.g. glands and muscles in the gut and heart.
How is the autonomic nervous system divided up?
SYMPATHETIC NERVOUS SYSTEM - Fight or flight
- Neurones of the sympathetic nervous system have a stimulatory effect and they use the neurotransmitter noradrenaline (NA)
- Speeds up the body processes involved in stress/ fight or flight:
- Increased HR and force of contraction
- Increasing breathing rate and deapth of breaths
- Increased sweating and vasodilation of skin arterioles
- Stops digestion
PARASYMPATHETIC NERVOUS SYSTEM - Rest and digest
- Uses ACh neurotransmitter only
- Slows down body processes allowing rest, recovery and digestion:
- Descreased HR and force of contractions
- Decreased breathing rate and depth of breaths
- Increased secretion of saliva and gastric juice
Fill in the blanks:
Lable the brain
Structure + Function:
Cerebrum
- Largest part of brain
- Formed of 2 cerebral hemispheres linked by the corpus callosum
- Controls:
- Concious thought, reasoning, problem solving, emotional responses, memory, language and the ability to override some reflexes
- Cerebrum has a thin outer layer called the cerebral cortex which is highly folded.
- This is split into 3 areas: sensory, association and motor areas.
Structure + Function:
Cerebral cortex
Outer layer that surrounds the cerebrum.
Divided into 3 different areas:
Sensory areas - Recieves impulses from receptors in the sense organs via sensory neurones.
- The size of the sensory area in the cortex is proportional to the number of receptors in the sense organ.
Association areas - Interpret information from sensory areas based on memory from past experinences. They also coordinate information from other sensory areas.
Motor areas - Sends out impulses via motor neurones to the voluntary muscles to bring about movement.
- The size of a particular motor area is in proportion to the complexity of movements possible e.g. the motor area controlling hand moment is large
Structure + Function:
Medulla Oblongata
- Swollen region located at the base of the brain/ top of spinal cord. Also called the brain stem.
- It’s the main control centre of the autonomic nervous system which carries unconcious control of vital processes e.g. breathing rate, HR and temperature control.
- Controls non-skeletal muscles - cardiac & involuntary muscles
Structure + Function:
Cerebellum
- Highly folded region at the back of the head, below the cerebrum.
- Recieves impulses from the retina of the eyes, the balance organs of the inner ears, spindle fibres in muscles (stretch receptors) and the joints.
- It carries out unconcious control of learned sequences of muscle contraction:
- Maintanance of body posture and balance to remain upright
- Coordination of movements e.g. walking and writing
- Hand-eye coordination
Structure + Function:
Hypothalamus
- Small area above the pituitary gland below the cerebrum.
- Involved in homeostatic control.
- Sensory input from thermoreceptors and osmoreceptors is recieved by the hypothalamus and leads to the initiation of automatic responses that regulate body temperature and the water potential of the blood.
- Produces ADH hormone which is stored in the posterior pituitary and then released into the blood as required.
Structure + Function:
Pituitary gland
- Endocrine gland attached to the underside of the hypothalamus.
- Controlled by hypothalamus.
Structure is split into 2 sections:
- Anterior pituitary - produces 6 hormones including FSH and pituitary growth hormone.
- Posterior pituitary - Stores and released hormones produced in the hypothalamus including ADH
What is a Reflex
What is the altered pathway for reflexes?
Reflex = Rapid automatic responses that doesn’t require concious coordination.
- They’re achieved by bypassing the brain between sensation and reaction. The is informed afterwards about the stimulus/reflex.
Sensory neurone → Relay neurone in spinal cord → Motor neurone
Summarise the reflex arc
What is this a diagram of?
Lable it
What type of reflex is this an example of?
The an example of a spinal reflex.
The reflex of muscle contraction due to pain.
The knee-jerk reflex:
- What type of reflex is this?
- Purpose of reflex + how it works (5)
- Lable on the diagram which synapses are exitatory and inhibitory and fill in the key
- Spinal reflex - passes through spinal cord
- Purpose - Coordination when walking and posture when standing to prevent falling over.
- Stimulus - Tendons connecting quadriceps with patella are tapped.
- Receptors - Strech receptors in the quadricepts muscle detect that the muscle is being stretched. Nerve impulse is passed along a sensory neurone.
- CNS - Sensory neurone communicates directly with a motor neurone in spinal cord.
- Effectors - Motor neurone carries the nerve impulse to the quadricepes muscle.
- Response - Quadriceps muscle contracts so lower leg moves forward quickly
NOTE: Muscle spindles detect any over stretching of the quadriceps muscle
The blinking reflex:
- What type of reflex is this?
- Purpose of reflex + how it works (5)
- Cranial reflex - Passes through part of the brain
- Purpose - Avoid damage to eye
-
Stimulus
- Foreign body touches eye - corneal reflex (example)
- Sudden increase in light intensity - optical reflex
- Sudden movemnts to close eye
- Loud noise
- Receptors - Sensory nerve endings in the cornea detect the touch from the stimulus. A nerve impulse is sent along the sensory neurone to a relay neurone in the CNS.
- CNS - Impulse is passed from the relay neurone to motor neurones.
- Effectors - Motor neurones send impulses to the orbicularis oculi muscles that move your eyelids.
- Response - Muscles contract causing eyelid to close quickly.
NOTE: The receptor and effector are in the same place ∴ it’s called a reflex arc.
Sequence of events involved in the coordination of the fight or flight response in mammals
- This is a range of coordinated responses to the perception of danger.
- It involves both the endocrine and nervous systems coordinating the body to make it ready to confront danger or escape from it.
Controlling of the HR through nervous system:
High/low blood pressure
HIGH BLOOD PRESSURE:
- Baroreceptors in aorta and carotid arteries detect high blood pressure and sends impulses along sensory neurones to the cardiovascular centre
- Cardiovascular centre sends impulses along parasympathetic neurones which then secretes ACh
- ACh binds to receptors on the SAN
- ∴ Causes HR to slow down in order to reduce blood pressure back to normal
LOW BLOOD PRESSURE:
- Baroreceptors in aorta and carotid arteries detect low pressure and sends impulses to cardiovascular centre
- Cardiovascular centre sends impulses along sympathetic neurones which secrete noradrenaline
- Noradrenaline binds to receptors on SAN
- ∴ Causes HR to speed up in order to increase blood pressure back to normal
Controlling of the HR:
High [O2] low [CO2] or high pH levels
OR
Low [O2], high [CO2] or low pH levels
High [O2] low [CO2] or high pH levels:
- Chemoreceptors in aorta, carotid arteries and medulla oblongata detect chemical changes in the blood and send impulses along sensory neurones to the cardiovascular centre
- Cardiovascular centre sends impulses along parasympathetic neurones which then secrete ACh
- ACh binds to receptors on SAN and decreases HR in order to return O2, CO2 and pH levels back to normal
Low [O2], high [CO2] or low pH levels:
- Chemoreceptors in aorta, carotid arteries and medulla oblongata detect chemical changes in the blood and send impulses along sensory neurones to the cardiovascular centre
- Cardiovascular centre sends impulses down sympathetic neurones which secrete noradrenaline
- Noradrenaline binds to receptors on SAN, causes HR to increase in order to return O2, CO2 and pH levels back to normal
