Unit Senses and Movement: Exploring Sense Organs in Biology

Senses and Movement in Biology and Geology

Unit 06
Senses and movement
Biology and Geology
3º ESO/4°PAI
Dña. Macarena Arechavaleta

Sense Organs and Stimuli

1. Sense organs
· Stimuli: changes that occur in our internal and external environment.
· Sensory receptors: specialised structures that detect stimuli and
generate nerve impulses.
· Depending on their location internal or external in the body can be:
· Interoceptors : distributed throughout the inside of the body, detect
changes such as variations in blood oxigen levels or blood pressure.
· Exteroceptors: near the surface of the body, detect changes in the
external environment ex. T or light.&

Types of Receptors

Interoceptors
Exteroceptors
Interoceptors-or internal receptors-
provide information from the body's outside
environment and are therefore located on
collect information about the human
body's internal conditions. These receptors,
located in the internal environment, mostly the surface of the body. Sense organs are
respond to chemical stimuli.
exteroceptors.
Oxygen levels in the blood is detected
by interoceptors.
The eyes contain receptors that detect
light stimuli from the external envi-
ronment.

Proprioceptors and Body Position

Propioceptors
Proprioceptors provide information concern-
ing body position and body motion, as well
as on the relative position of body parts. These
receptors are located in the inner ear's ves-
tibule and the locomotive system (muscles,
tendons, and articulations), respectively.
Propioceptors inform about the relative
position and condition of each of the body's
muscles.

Sensory Receptor Classification by Stimulus

Sensory
receptors
•
Can also be classified
based on the stimulus they
detect
. There are also nociceptors
that detect painful stimuli.

Receptors	Stimuli	Sense organs	Sense(s)
mechanoreceptors	sound	ears	hearing and balance
mechanoreceptors	pressure contact	skin	touch
photoreceptors	light	eyes	sight
thermoreceptors	changes in temperature	skin	touch
chemoreceptors	chemical substances	nose	smell
chemoreceptors	U	tongue	taste

The Ear: Structure and Function

1.1.The ear

Outer Ear Components

Outer ear
· Auricle (1) cartilaginous
structure covered in skin,
directs sound to the ear canal.
· Ear canal (2) contains small
hairs and glands that secrete
earwax (cerumen).

Middle Ear Components

Middle ear
· Chain of ossicles (3) three tiny bones: malleus, incus and stapes
· Eardrum (4) membrane that vibrates when sound waves reach it.
· Eustachian tube (5) keeps equal pressure on both sides of the
eardrum.

6
3
4
2
7
5
1

Inner Ear Components

Inner ear
· Vestibular system (6), whith utricle
and saccule are responsible for
balance.
· Cochlea (7), spiral tube that
contains sensory cells that detect
sound and transform into nerve
impulses.

Hearing Process

1.1.The ear
HEARING
· Sound waves reach the auricle and are transmitted through the ear
canal to the eardrum, which vibrates.
· The eardrum transmits the sound waves to the chain of ossicles.
· The stapes sends the sound waves to the inner ear, causing the
movement of the fluid (endolymph) in the cochlea, that stimulates
the cells which are sensitive to vibrations. They generate nerve
impulses that are sent to the brain via the auditory nerve.

OUTER EAR
MIDDLE EAR
INNER EAR
AUDITORY NERVE

Balance Mechanisms of the Ear

1.1. The ear
· Dynamic balance: walking, running, cycling, etc.
. Controlled by the semicircular canals, which are full of
endolymph. When we move, the endolymph moves. The sensory
cells detect this movement and generate nerve impulses that are
sent to the brain.
•
Static balance: keep our body in the same position when we
are not moving.
. The utricle and saccule detect if we are sitting down,
standing up, lying face up(to), to lie on the back, etc.

Anterior
Canal
Posterior
Canal
Utricle
Saccule
Cochlea
Horizontal
Canal

The Eye: Structure and Appendages

1.2. The eye: eyeball
The eyeball: Spherical structure located in a cavity in the skull called the orbit.
Three layers:

Retina, Choroid, and Sclera

· Retina (4), internal layer, contains photoreceptor cells:
· Cones (colors)
· Rods (black and white / night vision),
· The fovea is an area with high density of cones, responsible of sharp vision.
· Choroid (5), middle layer, contains many blood vessels that provide the eye
cells with nutrients.
· Sclera (6), opaque, white outer layer: the front part (cornea) is transparent.
Covered by a layer of epithelial cells called the conjunctiva.

3
2
7
4
5
1
6
8

Internal Eye Structures

" Aqueous humour (1): transparent fluid between cornea and crystalline lens.
· Crystalline lens (2): elastic, transparent, biconvex structure
behind the iris.
. Anatomical blind spot (3): optic nerve is connected in this area,
no cones or rods.
· Vitreous humour (7): transparent, gelatinous fluid, fills chamber
between crystalline lens and retina.

3
2
7
4
5
1
6
8
· Iris (8): circular structure. Colour varies from person to person.
Pupil is the hole in it's center. Diameter of pupil changes regulating the amount of light that enters

Eye Appendages

1.2. The eye: appendages
eyelid
eyebrow
lacrimal gland
eyelash

Sight and Accommodation

Sigth
" Depending on where the eye
focusses, pupil and crystalline
lens are adapted.
· Pupil dilates or contracts.
" Crystalline lense undergoes
accommodation, changes it's
thickness.

flat crystalline lens
light from a faraway object
faraway object
dilatedpupil
convex
crystalline lens
close object
light from
a close
object
contracted
pupil

The Skin: Layers and Receptors

1.3.The skin
" Largest organ in our body, responsable for most of our sense of touch.
· Consists of three layers:

Epidermis, Dermis, and Hypodermis

· Epidermis: outer layer, epitelial tissue. Outermost cells are dead.
· Dermis: inner layer, connective tissue. Contains:
· Capillaries
· Hair follicles
· Sweat glands
· Sensory receptors
" Hypodermis: deepest layer, mainly adipose cells, protective and
thermoregulatory function.

Epidermis
Dermis
Hair Follicle
Hypodermis
Sweat Gland
Fat
Connective Tissue
Blood
Vessels

Sensory Receptors in the Dermis

Sensory receptors in dermis layer
Can be:
· Free nerve endings (nociceptors): detects pain.
· Groups that form corpuscles :
" (1) Krause's corpuscle: detects cold.
" (2) Pacinian corpuscle: detects pressure and
vibrations.
" (3) Meissner's cospuscles: detects textures.
· (4) Merkel's discs: detects pressure.
" (5) Ruffini corpuscle: detects heat.

sweat gland
epidermis
sebaceous
dermis
4
3
hypodermis
1
arrector
2
5

The Nose: Olfaction

1.4. The nose
. The olfatory cells, which are located in the upper lining of the nasal cavity form the olfactory epithelium.
"It contains glands that secrete the mucus. We can only smell
substances if they are disolved in mucus and present in
sufficient concentration.
"When olfactory cells are stimulated, they send nerve
impulses from the olfactory bulb through the olfactory
nerve to the brain, which interprets the information and
identifies the smell.

olfactory
nerve
olfactory
epithelium
olfactory
bulb
nasal
cavity
=10 classes of smells
"woody/resinous, Fragrant, Fruity (non-citrus), Chemical, Minty/peppermint, Sweet, Lemon, Popcorn, Pungent and decayed.

The Tongue: Taste

1.5. The tongue
v Responsible for our sense of taste.
v Its surface is covered in taste buds to form papillae.
v The taste buds contain chemoreceptors that detect
substances in foods that are dissolved in saliva. They
send nerve impulses through the gustatory nerve to
the brain, which interprets and identifies tastes.
-4 basic tastes:
· Sweet, salty, sour and bitter.

tongue
taste buds
papillae
bitter
areawithfew
taste buds
sour
salty
sweet
chemoreceptor
1
2
epithelium
50 um
lamina propria
of papilla
taste
buds
lamina propria
of papilla

The Musculoskeletal System

2. The
musculoskeletal
system

The Skeletal System: Bones and Cartilage

2.1. The skeletal system
. Made up of BONES, to which muscles are attached, as well as cartilage.
· BONES: Hard structures formed of collagen, a protein, as well as phosphorus and
calcium salts.
· An adult human has 206 bones.
. Composed mainly of:
v compact bone tissue on the outside and
v spongy bone tissue at the core.

Spongy bone
(inner bone and porous)
Compact bone
(outer bone and rigid)

Axial and Appendicular Skeleton

2.1. The skeletal system
· Together the bones form the skeleton, two sections:
Appendicular Skeleton
Axial Skeleton
Axial skeleton
made up of the skull,
thorax and spinal column
Appendicular skeleton
made up of the upper and
lower limbs.

Types of Bones by Shape

· Depending on their shape, there are three types of bones:
1. Long (ex. femur)
2. Short (ex. vertebrae, wrist, hand)
3. Flat (ex. skull, scapula)

Humerus
(Long bone)
Frontal bone
(Flat bone)
Vertebra
(Irregular bone)
Carpals
(Short bone)
Patella
(Sesamoid bone)

Long Bone Structure

The bones
epiphysis
spongy bone
periosteum
periosteum
compact bone
- diaphysis
· The structure of a long bone is made up of
marrow cavity
epiphysis

Components of Long Bones

The bones
· The long bones are made up of
· Cartilage, a cartilaginous tissue that surrounds the epiphysis at the
joint.
· Epiphysis , thick end of long bone, spongy bone tissue filled with
red bone marrow (in which blood cells are produced).
· Endosteum, layer of connective tissue lining internal cavity of
diaphysis.
· Diaphysis ,long middle section, compact bone tissue filled with
yellow bone marrow (made up of adipossse tissue)
· Periosteum, layer of connective tissue that surrounds the bone.

Articular cartilage
Epiphysis
Spongy bone
- Red marrow cavities
-
Compact bone
-
Medullary cavity
Endosteum
Diaphysis
Yellow marrow
- Periosteum
Epiphysis

Functions of Bones

The bones
1
Bones have several functions:
v Provide a framework for the body.
v Provide structures to which muscles are attached.
v Protect organs, (such as brain and spinal cord).
/ Contain red bone marrow, produces red blood cells.
Store calcium, which is released into the blood if it is required.

Cartilage Composition and Flexibility

Cartilage
Cartilage cells
Cartilage is softer than bone and formed of cartilaginous tissue:
· Nose
· Ears
.Intervertebral discs (between the vertebrae)
Cartilage also forms the embryonic skeleton.
Because cartilage is softer than bone, it is more flexible.

Joints: Connecting Bones

Joints
Structures that connect two bones.
· Three types
1. Immovable joints (in the skull).
2. Slightly movable joints (in spinal column).
3. Movable joints (knee, elbow, shoulder, etc.), consist of
. Ligaments, groups of fibres that connect the bones.
· Cartilage, covers the surface to prevent friction.
· Synovial cavity, space between the bones, filled with
viscous fluid (lubricant).

ligament
cartilage
synovial
cavity

Joint Classification by Mobility

Immovable
Slightly
movable
Freely
movable
A joint is the place where two or
more bones meet. Depending on the
mobility they permit, joints are clas-
sified into freely movable, slight-
ly movable, and immovable.
Joints