Coordination and control

The five senses

Sense	Stimulus	Receptor Cell	Sensory Organ
Sight	Light	Photoreceptors or light receptors in the retina of the eye	eye
Hearing	Sound (vibrations)	Mechanoreceptors: hair cells in inner ear	Ear
Taste	Chemicals	Chemoreceptors or tastebuds	tongue
Touch	Pressure Temperature Pain	Mechanoreceptors Thermoreceptors Nociceptors (pain receptors)	Skin
Smell	Chemicals	Chemicals  in olfactory cells in nasal cavity	Nose

Eye Eyes

Eyes

Structure : The corneas and lesn focus light onto the retina , which contaons rods and cones

Ears

Structure : The outer ear collects sound waves , the middle ear amplifies them , and the cochlea in the inner ear converts vibrations    into nerve signals . The vestibular system ( Semicucluar canals ) Detects head movement for balance

Stimulus: Detects sound waves and head postiion/movement

nose

Structure : The olfactory recetors in the nasal cavity detect airbore chemcical molecules

Stimulis: Detects chemical molecules in the air

Tongue

Structure - The taste buds on the tounge contain receptors for sweet . Salty , sour , bitter , and unami taste

Stimulus : Detects dissolved chemical in food and drinks

Skin

Structure : Contains different recpetors for pressure ( Mechnorecpetors ) , temperature ( Themoreceptors ) , Pain  ( Noiccieptors )

Stimulus  Detects touvh temperature changes and pain .

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Describe passage of information through a neuron

1. Neuron receives a  stimuls

2. Electical impuse traves throguh the neruom

3. Impulse reaches the axon terminal

4. Nuerotransmitters are relased into the synaoe

5. Neurotransmitters bind to receprots on the nextneuron

6. A new electical impulse is generate int eh nect neuro

mylin Sneath

  A fatty layer that insulates the axon , speeding up impulse transmission

Dendrite

The part of a neuronn that receives a message and sends it to the cell body

Axon

part of a neuron that carries an electrical message away from the cell body to synapse

synapse

A small gap between two neurons that must be crossed by neurtransmitters

Sensory neuron

A nerve cell that carries a message from a receptor to the central nervous system

Interneurons

A nerve cell that carries a message from a receptor to the central nervous system

Motor neurons

A nerve cell thar carries a message from the central nervous system to a muscle cell .

Cell body

the Main part of a cell that contains the nucleus genetic material and processes signals

.

Neurotransmitters

n I A chemical messenger that cross the synapse between rhe axon of the neuron and the dendrite of another neuron

Passage of information through a neuron

• Information travels through a neuron as an electrical impulse , moving from the dendrites to the axon terminasl . when impulse reaches the synapse , neurotransmitters are released , crossin he gap to stimulate the next cell

sensory , motor , interneurons communicate info

Sensory neurons detect stimuli and send signals to internuerons in the central nervous ssytem . Interneurons process the information and relay it to the motr=or neurons , which triggers a respnse in muscles or glands . This process enables the body from something hot ina reflex action .

Scenarios without thinking

• Knee jerk reflex , when the docotr taps the knee it kicks out automatically

• Blinking when something approaches your eye .

• cOUGHING OF SNEEZING

Response order

Stimulus —> recpetor—> sensory neuron—> Internueron —> Brain—> Motor neuron —> Effector —> Response

Central Nervous system (CNS

The CNS is control centre of the body . All messages from your enviroment and responses are processed

Two parts to CNS

Brain that is the processinf centre , where informatioon , is gathered by the interneuron , compares it to past experiences , and controls internal changes and movement .

parts of the brain

Peripheral nervous system ( PNS)

The oerioheral neurvous system connects the body to the central nervous system , transmitting information between the cns and organs , limbs , and tissue

PNS split 1 - SOmatic nervous system

ontrols voluntary skeletal muscle movements , such as waving or reaching out to take an object

PNS split 2 - Autonomic nervous system

controls involuntary actions. This includes heartbeat, digestion, respiration, salivation and perspiration. It maintains a constant internal environment of the body.

Autpnomic system two parts

The autonomic system is further split into two systems, the two divisions have opposite effects, e.g:

 

1. Sympathetic system speeds up heart rate.

 

1. Parasympathetic system slows down heart rate.

The systems work together in the body to maintain a balance.

SOmatic vs automatic

Examples of diseases and problems affecting nervous systek

ALzheimers disease - Affects memeory and thinking due to brain cell damage

Multiple sclerosis - The immune system attacks the mylein sneath , leading to muscle weaknesss and coordination problems

Stroke - occurs when blood flow to the brain is blocked , leading to brai damage .

Endocrine system

Endocrine system – a collection of glands that make and  secrete (release) hormones.

Hormone

– a chemical messenger that travels through blood vessels to target cells.

Target cells

a cell that has a receptor that matches a specific hormone.

Flight or fight

The bodies automatic reaction to danger , drivenby the sympathetic nervous system . It increases heart rate , breathing ,and muscle readiness , while slowing digestion , preparing the body for either fight or escape .

example hormon - adrenalin

Adrenal glands

Produce the hormone adrenaline/ epinephrine.

Normally it stimulates heart rate and enlarges blood vessels.

In danger it floods your system causing the ‘fight or flight’ response:

 

• Increased strength and heart rate

 

• Raises blood pressure

 

• Glycogen converted to glucose faster

 

• Blood diverted to the muscles (for energy).

  

effects

Effects that the relese of adrenalin causes

 

•  Heart beats faster to increase the delivery rate

of fuel and oxygen to muscles and remove their waste

products quickly.

 

• Breathing increases. Active muscles need extra oxygen so they can use more fuel to get more energy.

 

•  Muscles able to work harder .Muscles need to be more

efficient as they prepare for ‘fight or flight’ situations.

 

•  Skin goes pale.  Blood is diverted from the skin to essential organs and muscles.

 

•  Skin starts to sweat. We need to dissipate heat as

our muscles become active.

Type of hormone - Peptide hormone

Made of protein and produced by the anterior pituitary , parathoid gland , placenta , throid glnd and pancrease .

• Travel through bloodstream until they find and interact with specific repetor on surface of their target cell

Steroid hormone

Secreted by the adrenal glands and the ovaries ( women ) and testtes ( men) .

• Produced from cholesterol