Senses

Question 1

Why do we have senses

Answer 1

To get all our knowledge and experience of the world
They inform on external environment in which the organisms is located and on the internal environment I. Which organs tissues and cells reside

Question 2

What are our senses

Answer 2

Vision hearing touch taste and smell
Pain temperature balance body position and movement

Question 3

Transduction sending the sensory information to the nervous system

Answer 3

Specialised sensory cells detect specific stimuli and transducer them into Acton potentials that the nervous system will interperate
Eg vision photoreceptors detect light waves
Touch hearing and balance by mechanoreceptors
Taste and smell by chemoreceptors

Question 4

What are the chemical senses

Answer 4

Gustation and olfaction

Question 5

The chemical senses

Answer 5

The sesnses detect environmental chemicals they act as a quality control and. Heck substances if they are safe of toxic for ingestion
They have unusual strong and direct connection with most basic internal needs
The neural information from each system is processed in parallel and is ,edged at rather high levels in ceeebral cortex

Question 6

The olfactory epithelium

Answer 6

When sniffing the odourus substance in air enters nasal cavity and gets caught on the mucus of epithiulim where they are dissolved and bind to receptors cells

Question 7

Structure of the olfactory epithelium

Answer 7

Olfactory receptors are neurons have cilia and unmylinated axon penetrating cns
Supporting cells produce mucus basal cells are source of olfactory cells
Mucus flow replaced constantly every 10 mins presence of operant binding proteins which helps to concentrate the mucus

Question 8

Structure of olfactory bulb

Answer 8

2 olfactory bulbs left and right located above the cribriform plate in forebrain
Olfactory cell axons enter bulb where endings contact with dentrites of second order olfactory neurones
Points of contact are called glomeruli

Question 9

Olfactory transduction

Answer 9

Binding of operant molecule to operant receptor protein stimulates G protein activates camp which binds to cyclic nucleotide gates cation channel which then allows an+ and ca2+ influx which causes opening of ca2+ activated cl- channels
Leas to membrane depoarisation generate action potentials propagate up to cns

Question 10

Termination of olfactory response

Answer 10

OderAnts diffuse away or are broken down camp activation of other signalling pathways end transduction

Question 11

Olfaction receptor proteins

Answer 11

Express one or few of olfactory gpcrs
These have binding sit for the oderants on cel membrane an bind to different oderants

Question 12

The zones of epithelium olfactory

Answer 12

Large zones each express specific olfactory GPCR group of genes
Within the zones cell types are randomly scattered however a particular kind of olfactory cell is only found in one zone
Olfactory bulb divided into 4 each typ of olfactory cell which from its epithelium sends its axon to only one or two glomerli in the olfactory bulb

Question 13

Central olfactory pathways

Answer 13

Range of interactions between bulbs and glomerli
The second order of olfactory neurones project directly to different targets or indirectly through thalamus pathways are complex

Question 14

Spatial and temporal representation of olfactory information.

Answer 14

Paradox- each olfactory receptor cell is sensitive to range of oderants
Humans can discriminate at least 10 to the power of 12 different combinations of odour stimuli

Question 15

Olfactory population coding

Answer 15

Each odour is represented by large population of neurons
The higher number number of receptor cells the more accurate is odour discrimination

Question 16

Temporal coding in olfactory system

Answer 16

Timing of action potentials

Question 17

Sensation of touch

Answer 17

Somatic- refers to the body
If something touches your finger can accurately determine place and pressure sharpness and texture a single stimulus usually activists many receptors

Question 18

Sensation of touch begins at skin

Answer 18

Two major types of skin hairy top of hand glabrous or hairless lips hand palm
Epidermis outer layer dermis hand palm
Largest sensory organ
Highly sensitive
Mechanoreceptors cells and the hairs hair grows from folliclesninvated by free nerve endings

Question 19

Mechanoreceptors

Answer 19

Are sensitive to physical distortion

Question 20

Types of skin mechanoreceptors

Answer 20

Pacinian corpuscle (pc)
Ruffinis endings
Meissnerz corpuscle
Merkels disk
Krause end bulbs

Question 21

Mechanoreceptor cells field receptivity

Answer 21

Mechanoreceptors cells respond to specific frequencies pressures and receptive field sizes

Question 22

Pacinian corpuscle compression

Answer 22

Capsule compression
Energy transferred to nerve terminal
Membrane deformation
Opening of mechanosesntive ion channels
Current causes local depolarisation
If threshold reached an action potential is generated
If prolonged pressure onion layers slip past each other due due to presence of viscous fluid between them transfer the energy which nullify the deformation and stop receptor potential

Question 23

Mechanosensitive ion channels

Answer 23

Mechanoreceptor of the skin have all unmylinated axon terminals
Mechanosensitve ion channels are present in the axon membranes where convert mechanical force into ionic currents

Question 24

Primary afferent axons

Answer 24

Skin is highly innervated by axons that follow vast network of perishable nerves going to the CNSaxons bring info to spinal cord or brain system