Senses

Vestibular apparatus

Made up of two structures in the inner ear, the semicircular canals, and the utricule and saccule

Semicircular canals

sense acceleration

Utricule and saccule

sense body position relative to gravity and constant motion

Nociceptors

transmit impulses that are perceived as pain. Some of these are free nerve endings in the skin and other tissues and respond to actual or perceived tissue damage

Overstimulation of heat and cold receptors can also be felt as

pain

Thermoreceptors

Unspecialized sensory receptors (free nerve endings) that detect warmth or cold and are meant to detect harmless changes in temperature.

Endothermic creatures also have thermoreceptors in their \_________. These monitor the temperature of the blood to ensure that the core body temperature remains within a narrow homeostatic range.

hypothalamus

Electroreceptors

Found only in vertebrates, in aquatic and semi-aquatic animals (various fish, dolphins and platypuses). Animals generate electrical currents from their muscular activity

Electrolocation

is used to detect prey and avoid predators, and may be passive or active

Active electrolocation

is used by electric fish, such as electric eels. They give off an electrical field, and their receptors can distinguish between conductive (living) and resistant (inanimate) objects. They can also produce shocks that are capable of stunning prey and discouraging predators

Magnetoreceptors

The ability to detect magnetic fields. Has been demonstrated by several invertebrates, migratory birds, bats, bees, sea turtles and salmon

Exteroreceptors

Gather information about the external environment

Interoreceptors

Gathered information about what is happening within the body

Stimulation

A neuron in a sensory receptor revives a stimulus

Transduction

The stimulus is changed into electrical signals in the dendrites of the sensory neuron

Transmission

The signal is sent to the CNS

Interpretation

The brain intercepts the signal and tells you what you are perceiving

Photoreceptors

Most animals have the ability to detect light through a photopigment (opsion) that detects changes in the wavelength of light

Image forming eyes occur in

annelids, molluscs, arthropods, and chlordates

Compound eyes

Found in many arthropods, made up of thousands of individual units called ommatidia

Simple eyes

Found in spiders and annelids, called ocelli

In vertebrates light enters

through the cornea, passes through the lens, and produces an upside down image on the retina

Cones

Form sharp images in bright light, responsible for colour vision. There are three types of cones each with sensitivities to different portions of the visible light spectrum

Rods

Form black and white images in dim light

What creates the blind spot in mammal eyes?

Where the optic nerve leaves the eye.

Lizards and birds are primarily diurnal and their retinas are composed almost entirely of

cones

Mammals evolved as primarily nocturnal creatures and their retinas are composed mostly of

rods

Eyeshine

Occurs in nocturnal animals because of the thin layer of tapetum lucdium (reflective coating) at the back of their eye.

Binocular vision gives good.....?

Depth perception

Chemoreceptors

Respond to chemical stimuli, categorized based on their location, ex taste and smell

Insect olfactory receptors

Found on antenna and feet

Vertebrate olfactory recpetors

Located in the nasal passage and connected directly to the olfactory bulb in the brain.

The amount of olfactory epithelium relates to

how strong the sense of smell is

Taste receptors are a type of chemorecptor but are not directly linked to the \_______

brain

Internal chemosensors

detect chemical characteristics of blood and fluids derived from the blood, and they help maintain homeostasis

Mechanorecptors

Involved with touch, hearing, body positioning, and balance.

Pressure receptors

Are associated with hairs and vibriassae

Touch receptors

are often clustered together in more sensitive areas of the body

Proprioceptors

monitor the state of muscle contraction and provide information about the body’s position which is necessary for coordinated movement

Lateral line system

Is present in the skin of most fish and aquatic amphibians. Changes in water movements provide information about the animal’s direction of movement and other disturbances in the water.

Hearing

Involves the sensation of vibrations in air or water.

How do fish hear?

Using otoliths in their labyrinth organs

Why do fish not need ears?

Sound travels through water better than it travels through the air, and a fish’s body is composed mostly of water.

In terrestrial animals, vibrations are picked up by the \_________, transmitted by the \________ of the middle ear, and into the \______ of the inner ear

tympanum, ossicles, cochlea

The hair cells in the neuromasts are tuned to

a narrow range of frequencies and are located in different areas.

Statocysts

Used to orient themselves with respect to gravity, movement of the body moves the statocysts and stimulates the applicable hair cells.