Sensory Receptors Flashcards
What are sensory receptors?
specialised cells that detect changes in surroundings, energy transducers that convert one form of energy to form of electrical energy: nerve impulse
What are the sensory receptors in the eye?
light sensitive rods and cones in retina, detect light intensity and range of wavelengths
What are the sensory receptors in the nose?
olfactory cells line inner surface in nasal cavity, detect presence of volatile chemicals
Where are taste buds? What do they detect?
in tongue, hard palate, epiglottis and first part of oesophagus, presence of soluble chemicals
What are the sensory receptors in the skin?
pressure receptors (Pacinian corpuscles), detect pressure
What are the sensory receptors in the ear?
sound receptors in inner ear (cochlea), detect vibrations in ear
How are muscle spindles sensory receptors?
proprioceptors, detect length of muscle fibre
What is a polarised membrane?
membrane that has a potential difference across it (the resting potential)
What is depolarisation?
loss of polarisation across membrane, when sodium ions are entering cell making inside less negative
What are sodium/potassium pumps?
actively transport sodium ions out of cell and potassium ions into cell, more Na+ out than K+ in
How are the inside of nerve cells charged?
more negative in respect to outside
How is a nerve impulse created?
altering the permeability of a nerve cell membrane to sodium ions, Na+ channels open and Na+ in down diffusion gradient, movement changes charge
What is a generator potential?
small depolarisation caused by sodium ions entering the cell
How does the size of a stimulus affect movement of sodium ions?
large stimulus (change in energy level) = more gates Na+ channels open
What causes an action potential?
when membrane depolarised to +40mV (threshold level), all or nothing response
What are the 3 different types of neurone?
sensory: carry action potential (AP) from sensory receptor to central nervous system (CNS), motor: carry AP from CNS to effector, relay: connect sensory and motor neurones
What is the general structure of a neurone?
long to transmit AP, membrane lots gated ion channels, Na+/K+ pumps, maintain potential difference, surrounded by myelin sheath: Schwann cells, gaps = nodes of Ranvier, cell body with nucleus, many mitochondria and ribosomes, numerous dendrites
Where do motor neurones have their cell body?
in CNS, long axon which carries AP to effectors, start-shaped cell body at top of neurone, transmission direction = down from cell body
How do sensory neurones look?
long dendron, carries AP from sensory receptor to cell body, just outside CNS, cell body smaller and just to side of axon, direction of transmission direction: up to cell body
