C3.1 Integration of body systems (year 6) Flashcards
What are emergent properties?
those that exsist when the sum of all parts (cell < tissue < organ < body systems) creates features that do not exsist in individual components
- this allows for complexity
Compare and contrast endocrine and nervous system
Nervous:
- involves electric signals to send messages
- specific to animals
- signals are received and transmitted by neurons
- controls voluntary/involuntary
- usually quick response
Endocrine:
- involves hormones to send messages
- found in plants and animals
- hormones travel through the bloodstream
- involuntary
- comparatively slower response
1 example of nervous and endocrine system working together
Release of epinephrine (adrenaline):
- Sensory organs transmit signals to nervous system that adrenaline is needed as part of the fight-or-flight response
- the Autonomic Nervous System (ANS) sends impulses to adrenal glands to release epinephrine
- the hormone is transported through the blood system to the organs, resulting in increased heart rate etc..
Describe the role of the brain
Central information integration organ:
- regulates and monitors unconscious bodily functions e.g. blood pressure, heartbeat, breathing
- continously receives and processes information from sensors and generates responses
- learning and memory activities controlled by FRONTAL LOBE
- CEREBELLUM controls voluntary movements, balance, and equilibrium, muscle memory, coordinating muscle
- medulla (in brainstem) regulates breathing and heart rate
Describe the receptors that relay information to the brain (CHECK IF NEED TO MEMO)
photoreceptors- in retina of eye for visual info
chemoreceptors - tongue for tasting
thermoreceptors - skin for temp
mechanoreceptors - inner ear, sensitive to sound vibrations
osmoreceptors - carotoid arteries and hypothalamus to sense solutes and water content of blood
baroreceptors - carotoid arteries and aorta, sense blood pressure
proprioceptors - muscles and joints, provide a sense of balance and coordination
How does the brain communicate to the body?
Spinal nerves
- 31 paired nerves that emerge from the spinal cord
- composed of WHITE matter (carriers neural impulses to and fro the brain) and GREY MATTER (contains neurons and synapses involved in spinal cord integration process)
- Brain + spinal cord = Central Nervous System
Brainstem
- connects body parts to the brain by using CRANIAL NERVES (e.g. eye to brain)
- relays impulses btwn cerebrum, cerebellum, and spinal cord
- responsible for most functions involving the autonomic nervous system (ANS). The medulla is part of the brainstem
Describe the sensory neural pathway
Receptor cell > Sensory neuron > CNS
Receptor cells are specalisied to TRANSDUCE (convertion of a physical stimulus to an action potential/electrical signal)
Describe how muscles are stimulated to contract
Cerebrum (motor cortex) > motor neurons > muscle fibres
The motor cortex is found in the posterior position of the cerebrum.
The motor neurons form synapses with muscle fibres called motor end plates/NEUROMUSCULAR JUNCTIONS, where acetycholine is released when action potentials reach a motor end plate.
Practice drawing a transverse section of a nerve to show the protected sheat, and myelinated and unmyelinated nerve fibres
Difference between nerve and neuron
Neuron is an individual cell vs nerve is a collection of neurons surrounded by a protective sheath
Difference between myelinated/unmyelinated nerve fibres
- Myelinated have cells called SCHWANN CELLS wrapped around them, with the space inbtwn schwann cells called nodes of Ranvier.
- The action potentials of myelinated axons can skip from one nerve to the next, so transmission of action potential is FASTER compared to unmyelinated axons
- groupings of both types are surrounded by protective sheaths
Describe an example of involutary response
PAIN REFLEX ARC:
nocireceptor > interneuron > motor neuron > effector
- the nocireceptor (pain receptor) intiates action potentials when stimulated
- the action potentials eventually reach the spinal nerves, where an interneuron (in the GREY MATTER of the spinal cord) synapses with it
- the interneuron then synpases a motor neuron and the resulting action potentials go directly to the effector, resulting in the reflex action
= limits damage to body tissue w/o the action potential having to travel all the way to the cerebrum
How is the day/night cycle kept in humans
Humans are diurnal (active in the day)
- the PINEAL gland is a small endocrine gland located near the centre of the brain btwn the cerebrum and brainstem
- it secretes high levels of melatonin (regulates sleep schedule) during the night and low levels during the day
- this is as light striking the eye inhibits melatonin production by the pineal gland
Describe the effects of epinephrine
stressful situation = fight-or-flight response = epinephrine released from adrenal glands (located in kidney)
- increased heart rate and blood pressure
- increased dilation of air pathways = more air received by lungs
- dilation of pupils
- increase blood supply to muscles
- increase glucose conc. by stimulating glucagon to convert glycogen to glucose in the liver
Describe the function of the hypothalamus and pituitary gland + 1 example
To control the endocrine system:
- Hypothalamus (in brain) acts as a link btwn nervous and endocrine system, and is composed of neurons and GLANDULAR CELLS.
- the glandular cells produce hormones that either stimulate or inhibit the release of hormones by the pituitary gland.
e.g. Antidueretic Hormone (ADH) production is controlled by the hypothalamus, and produced and secreted by the pituitary gland.
- this is as hypothalamus has osmoreceptors that monitor water conc. in blood. If water level is too low then hypothalamus sends action potentials to pituitary gland to secrete ADH to bloodstream.
- the collecting tubules of nephrons in the kidneys become more absorbent, reabsorbing more water that is lost as urine.
this is an example of NEGATIVE FEEDBACK
Diff btwn + location of baro/chemo receptors
Baroreceptors are located in the blood vessels (e.g. carotid arteries but Chemoreceptors are located in tissue near baroreceptors but not in blood vessel.
(In diagram>V shape>Baro below>Chem above)
Baroreceptors:
- monitor blood pressure
- blood pressure increases > walls are streched outwards > baroreceptors send increased action potentials to MEDULLA > medulla sends impulses to Sinoatrial node (SA) to decrease HR/stroke volume and force of contraction > BP falls to normal > decrease in action potentials sent to medulla
Chemoreceptors:
- monitor blood pH, CO2, O2
- each chemical change has its own chemorecptor w the same general process as above
- O2 and pH (as CO2 combines with water in blood to form carbonic acid which produce h+ ions) drops during HR increase
- CO2 increase during HR increase
both are examples of FEEDBACK CONTROL MECHANISM and are part of the AUTONOMIC NERVOUS SYSTEM
describe feedback control of ventilation rate
groups of cells called respiratory centres in medulla spontaneously release action potentials to diaphram and intercostal muscles to maintain breathing
- strenuous excercise > CO2 conc increase > carbonic acid produced catalysed by carbonic anhydrase > bicarbonic acid and H+ ION produced > chemoreceptors in the medulla sense high H+ conc and send action potential to muscles associated with lung ventilation e.g. diaphram and intercostal muscles > rate of ventilation and volume of air moving in and out increases
Diff btwn CNS and ENS
Swallowing food and excretion of waste is VOLUNTARY and so controlled by CNS.
Movement of food through the digestive system (peristalsis) is INVOLUNTARY and controlled by the Enteric nervous system (ENS)
Describe the process of peristaltic reflex
- Whenever a bolus is located in the gastrointestinal tract, that area becomes DISTENDED, stimulating STRECH RECEPTORS in the ENS.
- the streach receptors synapse with nearby relay neurons, which synapse with 2 types of motor neurons
- 1 type of motor neuron releases an EXCITATORY neurotransmitter to the area of smooth muscle behind the bolus to contract and push the bolus
- 1 type of motor neuron release INHIBITORY neurotransmitter ahead of the bolus to relax the smooth muscle, opening the lumen for the bolus to slide through.
What is phototropism?
phenomenon of plants growing towards a light source and is a POSITIVE TROPHIC RESPONSE
Describe the purpose of the phytohormone Auxin in plants
Promote cell growth:
- promotes H+ secretion into the apoplast, acidifying the cell wall
- the H+ ions also activate a protein called EXPANSIN to loosen the cross links btwn cell walls = facilitating cell elongation.
- absorbtion of water also creates high turgor pressure to create force necessary for the fibres to slide past one another
Transport of Auxin:
- Auxin requires the presence of Auxin efflux carriers to exit a cell, to control the conc. of Auxin for differntial growth.
Describe example of positive feedback of phytohormones in plants
ETHYLENE:
- during ripening, fruits produce a gas called ethylene.
- the gas is exposed to adjacent fruit who ripen quickly and do the same.
this is a SELF PERPETUATING event and so is positive feedback
