NERVOUS AND ENDOCRINE Flashcards
What are the 3 main functions of nervous system
- sensory input - monitoring stimuli
- integration - interpreting sensory input
- motor output - response to stimuli via effector organs
basic steps of nervous system
- sensory input
- integration
- motor output
Two sections of nervous system
- Central Nervous Sytem = brain and spinal cord
- Peripheral nervous system =
- paired spinal and cranial nerves (messages to and from spinal cord and brain)
first divisions of peripheral system
- Sensory (afferent) division
- somatic afferent nerves carry impulses from skin, skeletal muscles and joints to the brain
- visceral afferent fibres - transmit impulses from visceral organs to the brain - Motor (efferent) division
- impulses from CNS to effector organs, muscles and glands
divisions of Motor division
- somatic (voluntary)
- conscious control of skeletal muscles
- somatic motor nerve fibres conduct impulse from CNS to skeletal muscles - Autonomic (involuntary)
- regulates smooth muscle, cardiac muscle, glands
divisions of autonomic (involuntary) motor division
- sympathetic - fight or flight
- parasympathetic - rest and digest
*antagonisitic, keep us in a state of dynamic balance
what are Somatic reflexes
- fast, involuntary sequence of acions in response to stimulus
- inborn
- involves skeletal muscle
what are vibrissae
- an organ of touch
- hair follicle suspended in expanded sinus of fluid - maximise response to hair movement (whiskers)
label the eye
- eyelid
- sclera
- conjunctiva
- iris
- pupil
-retina - cornea
- lens
difference between monocular and binocular vision
monocular - see separate scenes with eye
- detect predators
- can’t judge height and distance
Binocular - one scene in both eyes
- best for judging distance
- best for hunted
what are the chemical sense
- taste
- smell
- flehmen
explain taste
- tongue has chemoreceptors (taste buds)
- excited by food molecules dissolved in saliva
- mostly found on tongue in papillae (bumps)
explain smell
- olfaction receptors excited by airbone chemicals that dissolve in fluids coating nasal membranes
- organ of smell = 5cm squared patch olfactory epithelium on roof of nasal cavity
what is the flehmen
curling of the lips allows odorant chemicals into vomeronasal organ - detects pheromones for breeding
how does hearing work
sound through ear canal. eardrum vibrates, ossicles amplify and deliver vibrations to cochlear = receptor organ
how do organisms balance
- equilbrium receptors in ear = vestibular aparatus - measures gravity with cilia of hair cells in semi-circular canals
series of homeostasis
- stimuli
- receptor - detect stimuli
- integrating centre - assess input, initiates response
- effector - corrects stimuli
Types of control systems of homeostasis
- Autoregulation - cells, tissue, organs change automatically in response to signals inside e.g. blood supply to active muscles
- Extrinsic conrol by nervoous and endorcrine systems - changes stimulated by signals from outside body
define nervous and endocrine control
nervous - brain and spinal cord signals cause change; rapid but short term
endocrine - glands produce hormones cause changes; response is slower but long effects (making chemicals and travelling to target cells)
types of chemical communication
- direct via gap junctions
- chemical messengers (endocrine)
what are gap junctions - simplest form of chemical communication
- link adjacent cells
- connexons form channels to link cytosol of cells
Explain 6 chemical messenger classifications
- classic endocrine - diffuse to distant cell (usually via bloodstreams) e.g. growth hormones
- Paracrine - diffuse to nearby target cell e.g. histamine
- Autocrines - bind to receptors on the secretory cell e.g growth factors
- cytokines - either act locally, diffuse to nearby cell or diffuse to far cell * interferons*
- neurotransmitters - secreted from neurons at axon terminal, binds to target cell (synaptic signalling), e.g. ACh to contract skeletal muscle
- Neurohormones - hormones secreted by neurons, diffuse in bloodstream to far target cell. e.eg ADH from pituitary gland.
How do nervous and endocrine system work in the face of stress
- CNS sends nerve signal through soinal cords to adrenal gland where adrenaline is produced in response by adrenal medulla.
- Hypothalamus releases hormones which stimulates pituitary gland to release ACTH. hormone to adrenal cortex, releases cortisol
Neg vs pos feedback and examples
Neg: reverse stimulus/disturbance to homeostasis e.g. blood pressure increase, baroreceptors send info to brain, brain signals heart to contract more slowly to decreased pressure, blood pressure decreased
Pos: reinforces stimulus. e.g. cut causes clotting by palates, palates relese chemical to attract more palates, increases clotting
what is homeorhesis
coordinated control of metabolism for homeostasis
