Содержание

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Receptors provide information about both external and internal environments.
The receptors of the

Receptors provide information about both external and internal environments. The receptors of
human are located in EYES, EARS, NOSE, TONGUE and SKIN.
These organs are called Sense Organs.

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Types of sensory receptors

Types of sensory receptors

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Processing Sites and Lobes of the Cerebral Cortex

Processing Sites and Lobes of the Cerebral Cortex

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It provides more than 80% of the information received about the external

It provides more than 80% of the information received about the external environment. THE EYE
environment.

THE EYE

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STRUCTURE OF EYE

Eyes contain 3 main parts;
Schlerenchyma
Choroid
Retina

STRUCTURE OF EYE Eyes contain 3 main parts; Schlerenchyma Choroid Retina

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Schlerenchyma

It is supportive structure of eye that protects inner structures of the

Schlerenchyma It is supportive structure of eye that protects inner structures of
eye.
In the front, it bulges and becomes the transparent cornea.
Light enters the eye through cornea.

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CHOROID

Just inside the sclera is the choroid.
This layer contains many blood vessels.

CHOROID Just inside the sclera is the choroid. This layer contains many
At the front the eye the choroid layer forms the iris.
It is colored part of eye. In the centre of the iris is an opening called PUPIL.

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The diameter of iris is related to the amount of light.
It narrows

The diameter of iris is related to the amount of light. It
pupil under intense light but widens in dark conditions.
The size of pupil is controlled automatically by central nervous system.

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THE RETINA

Behind the iris is the lens. It focuses the light on

THE RETINA Behind the iris is the lens. It focuses the light
the retina (photoreceptor).
Innermost layer of the eye, the retina contains the light receptors.
At the rear of the eye, the retina is attached to the optic nerve which carries impulses from the light sensitive cells to the brain.

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Light entering the eye passes through the cornea, pupil, lens, and forms

Light entering the eye passes through the cornea, pupil, lens, and forms
an image on the retina.
Retina contains light sensitive cells which they are called cones and rods.

VISION

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Cones are sensitive to color and bright light.
Rods are sensitive to

Cones are sensitive to color and bright light. Rods are sensitive to
dim light but not to color.
The retina contains 125 million rods and 6,5 million cones.

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A severe dificiency of vitamin A leads to a condition called night

A severe dificiency of vitamin A leads to a condition called night
blindnes.
In this condition amount of retinal rods and cones is decreased.

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While at rest, instead of focusing on the retina, the light rays

While at rest, instead of focusing on the retina, the light rays
focus in front of it.
This type of eye defect is called myopia.
This condition can be corrected by concave lenses.

defects of eye

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At rest, the light rays focus behind instead of on the retina.

At rest, the light rays focus behind instead of on the retina.

This type of eye defect is termed hypermetropia.
This condition can be corrected by convex lenses.

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The human ear has 2 sensory functions.
One of them is hearing.
Other

The human ear has 2 sensory functions. One of them is hearing.
is maintaning balance or equilibrium.

THE EARS

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Structure of ears

Ears contains 3 main parts;
Outer ear
The middle ear
Inner ear

Structure of ears Ears contains 3 main parts; Outer ear The middle ear Inner ear

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1. OUTER EAR

Outer ear is composed of 3 parts.
These are pinna, auditory

1. OUTER EAR Outer ear is composed of 3 parts. These are
canal and eardrum.
Pinna is a cartilaginous tissue which collects sound waves and determines the source of voices.

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Auditory canal is a canal which is found between pinna and eardrum.
It

Auditory canal is a canal which is found between pinna and eardrum.
has hairs and produces wax-like substance to filter dust and solid partcicles.
The eardrum separates outer ear from the middle ear.
It is thin half transparent.

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2. MIDDLE EAR

It contains three small bones which are called the hammer-malleus,

2. MIDDLE EAR It contains three small bones which are called the
anvil-incus and stirrup-stapes.
These bones form a chain across the middle ear linking the eardrum (hammer) to another membrane, the oval window(stirrup).

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EUSTACHIAN TUBE

It is located between pharynx and the middle ear.
It equalizes air

EUSTACHIAN TUBE It is located between pharynx and the middle ear. It
pressure between the middle ear and the atmosphere.

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3. THE INNER EAR

It consists of the cochlea and semicircular canals.
Cochlea is

3. THE INNER EAR It consists of the cochlea and semicircular canals.
organ of hearing which consists of coiled, liquid-filled tubes.

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They are separated from another by membranes.
Lining of the membranes are specialized

They are separated from another by membranes. Lining of the membranes are
hair cells that are sensitive to vibration.

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Semicircular canals enable the body to maintain balance.
These canals contain fluid and

Semicircular canals enable the body to maintain balance. These canals contain fluid
hairlike projenctions that detect changes in body and head position.

Semicircular canals

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Sound waves collected by outer ear pass down the auditory canal to

Sound waves collected by outer ear pass down the auditory canal to
the eardrum.
They cause the eardrum to vibrate.
The vibrations are transmitted across the middle ear by the hammer, anvil and stirrup.

HEARING

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Vibration of stirrup cause vibrations in the oval window which in turn

Vibration of stirrup cause vibrations in the oval window which in turn
cause the fluid within the cochlea.
The initiates in nerve endings around the hair cells.
These impulses are carried to the cerebral cortex, where their meaning is interpreted.

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All multicellular organisms have a skin composed of one or more layers.

THE

All multicellular organisms have a skin composed of one or more layers. THE SKIN
SKIN

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Functions of Skin

It protects the inner layers of the body from physical

Functions of Skin It protects the inner layers of the body from
and chemical effects.
It prevents body from microbes
It prevents water loss in terrestial organisms.
It prevents body cells from ultraviolet light.

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Skin is composed of 3 tissue layers:
Epidermis
Dermis
Hypodermis

Skin Structure

Skin is composed of 3 tissue layers: Epidermis Dermis Hypodermis Skin Structure

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EPIDERMIS is outermost layer of skin.
This layer composed of keratinised epithelial cells.
Epidermis

EPIDERMIS is outermost layer of skin. This layer composed of keratinised epithelial
do not contain blood vessels.
Upper section of epidermis is composed of non-living cells.
The color of skin is conferred by melanin pigment.
DERMIS is rich in blood vessels and nerve endings.
The receptors located in the skin are connected to these nerve ending.
Dermis also contain smooth muscle, sweat glands, hair follicles and lymph vessels.
HYPODERMIS innermost layer of skin

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RECEPTORS

Meisner corpuscles: They are involved in reception of touch of the palm

RECEPTORS Meisner corpuscles: They are involved in reception of touch of the
sole and lips.
Paccinian corpuscles: They are involved in reception of mechanical stimuli.
Krouse corpuscles: They are involved in reception of cold and pressure.
Ruffini corpuscles: They are involved in reception of heat, touch and pressure.

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Sweat glands:
They are present in all regions of the skin. They

Sweat glands: They are present in all regions of the skin. They
open onto the surface of skin by pores.
They are involved in removal of water, minerals, urea and other substances.
The main function of sweat glands is the regulation of body temperature by evaporation of water.

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Nose is the organ of the body involved in both respiration and

Nose is the organ of the body involved in both respiration and
smell.
The reception of smell takes place in chemoreceptors located in nasal cavity.
These chemoreceptors are called as olfactory receptors
Nose also provides the control of temperature
And the control of humidity and the elimination of infectious microbes

THE NOSE

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The surface of the tongue is covered with small projections called papillae.
There

The surface of the tongue is covered with small projections called papillae.
are the taste receptors or taste buds within the papillae.
Nerve fibers branch among the cells of the taste bud and each cell is in contact with one or more neurons.

THE TASTE

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Only substances that are in solution can stimulate the taste buds.
The taste

Only substances that are in solution can stimulate the taste buds. The
buds are sensitive to only four basic tastes;
SWEET, SOUR, SALT AND BITTER
Each taste bud is particularly sensitive to one of these tastes.

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When taste buds are stimulated, impulses are initiated by the sensory cells

When taste buds are stimulated, impulses are initiated by the sensory cells
of the structure and carried to the brain.
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