This document summarizes the key sense organs - eyes, tongue, and skin. It describes the main sensory receptors for each organ, including taste buds, mechanoreceptors, thermoreceptors, and photoreceptors. For the eyes, it outlines the major parts, focusing on the retina containing rods and cones. It also discusses visual disorders like myopia, hypermetropia, and astigmatism. For taste, the document notes the four primary tastes and location of taste buds on the tongue. The skin section lists the different mechanoreceptors and their functions in sensing touch, pressure, and temperature.
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Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
2. INTRODUCTION: SENSE ORGANS
Sensations and perceptions begin with
sensory reception, detection of stimuli by
sensory receptors.
Sensory receptors can detect stimuli
outside and inside the body.
Sensory receptors fall into five categories:
Mechanoreceptors
Chemoreceptors
Electromagnetic receptors
Thermoreceptors
Pain receptors
3. 2. CHEMICAL SENSES: TASTE
The receptors responsible for taste are
called– CHEMORECEPTORS
Gustation (taste) is dependent on the
detection of chemicals called tastants.
4. SENSE OF TASTE
Taste receptors = TASTE BUDS
Taste buds are located on tongue(mainly),
hard palate, pharynx and epiglottis.
5. The tongue very rough, due to
numerous papillae.
4 Types of papillae:
- Fungiform- found on front and
sides of tongue.
- Foliate found on front 2/3 of
tongue
- Circumvallate- found on the
back of the tongue.
• Filliform papillae – in middle of
tongue
The taste buds are located on
the papillae.
9. FUNCTIONS OF TASTE BUDS
Chemical molecules in food, dissolve in the
saliva.
The molecules bind to the receptor proteins in
the microvilli of the taste buds.
This stimulates the taste cells to send an
impulse through the sensory nerve fibers.
Impulse move to the parietal lobe of
cerebrum.
Taste is interpreted
https://www.youtube.com/watch?v=JJyQz0152t
8
10. 5 PRIMARY TASTE PERCEPTIONS
Sweet
Sour
Bitter
Salty
Umami (Japanese
savory taste)
- Certain regions of the
tongue are more sensitive
to particular tastes.
11. 3. SENSE ORGAN: SKIN
Mechanoreceptors sense physical
deformation caused by stimuli such as
pressure, stretch, motion, and sound
The sense of touch in mammals relies on
mechanoreceptors
Thermoreceptors, which respond to heat
or cold, help regulate body temperature by
signalling both surface and body core
temperature.
https://www.youtube.com/watch?v=IZ8WOC
U5jYw
12. Pain receptors, or nociceptors, respond to
excess heat, pressure, or chemicals released
from damaged or inflamed tissues.
The sensory cutaneous mechanoreceptors
in the skin are:
Ruffini's end organ (sustained pressure and
heat – all over body)
Meissner's corpuscle (changes in texture, slow
vibrations – light touch – lips, finger tips)
Pacinian corpuscle (deep pressure, fast
vibrations – visceral organs)
Merkel's disc (sustained touch and pressure)
Free nerve endings (pain – all over body)
End bulbs of Krause – cold – all over body
15. SENSE ORGAN: EYES
SENSE OF VISION
Photoreceptors are sensory receptors
that are sensitive to light.
Animals and humans with 2 eyes facing
forward have 3D or stereoscopic vision,
visual fields overlap and each eye is able
to view and object from a different angle.
16. THE HUMAN EYE
Main parts of the eye found in 3
main layers
1. Outer layer (Cornea, Sclera)
2. Middle layer (Choroid, ciliary body,
iris)
3. Inner layer (Retina – rods, cones,
fovea)
17. THE HUMAN EYE
Other parts of importance:
1. Lens (Attach to suspensory ligaments)
2. Humors (Aqueous humor and vitreous
humor – Transmit light rays and support
eyeball)
3. Optic nerves – Transmits impulses to the
brain
18. OUTER LAYER (STRUCTURE AND
FUNCTION)
The sclera: white outer layer, protects
and supports eyeball
Cornea: Front transparent part of eye.
Refracts light rays
Conjunctiva: Transparent membrane
(front). Moistens eye surface.
19. MIDDLE LAYER STRUCTURE AND FUNCTIONS
Pupil: Hole in middle of eye. Black. Admits
light into eye.
The choroid: Pigmented 2nd layer. Absorb
stray light. Contain blood vessels for
nutrition and oxygen.
The iris: Coloured part of the eye that
regulates the size of the pupil and therefore
light entrance
The lens: Transparent biconvex structure
that refract and focuses light on the retina
20. INNER LAYER, STRUCTURE AND
FUNCTION
The retina: contains photoreceptors (cones
and rods)
- Rods: Make black and white vision
possible/ overview sight
- Cones: Make colour vision possible
- Fovea centralis: Best image possible
- Blind spot: place where nerves and blood
vessels enter and leave the eyeball. No
image can be seen if light is focused on this
point.
21. The eye is divided into two cavities
separated by the lens and ciliary
body:
The anterior cavity is filled with
watery aqueous humor.
The posterior cavity is filled with
jellylike vitreous humor.
The ciliary body produces the
aqueous humor.
22. Fig. 50-18
Optic
nerve
Fovea (center
of visual field)
Lens
Vitreous humor
Optic disk
(blind spot)
Central artery and
vein of the retina
Iris
Retina
Choroid
Sclera
Ciliary body
Suspensory
ligament
Cornea
Pupil
Aqueous
humor
23. PHOTORECEPTORS
Found in the retina of the eye.
2 Types: Rods and Cones
They consist of an outer segment and an inner
segment joined by a stalk.
Visual pigment found in rods, is a deep-purple
pigment called Rhodopsin.
Rods are sensitive to light and are therefore
suited for night vision (black and white) and
peripheral vision.
Rods found on either side of fovea- the further
away from the fovea – the more rods present.
24. The cones, are primary located in the fovea
centralis, the further away from the fovea the
less the cones.
Activated by bright light
Cones allow us to detect fine detail and
colour.
Cones contain 3 pigments –B (blue), G
(green) and R (red)
In colour blindness, a person lack certain of
these pigments.
26. INTEGRATION OF VISUAL SIGNALS IN
THE RETINA
Light enter the eye through the cornea,
aqueous humor, pupil, lens, vitreous humor
and focuses on the retina.
Light stimulates the photoreceptors (rods and
cones) in the retina.
Retina sends an impulse to the optic nerves
Optic nerves send an impulse to the occipital
lobe of the cerebrum
Where sight is integrated.
27. ACCOMMODATION
The ability of the lens to change shape to
enable the eye to focus on near and far
objects.= accommodation
Accomodation in the eye (focussing) for IGCSE
Biology.mp4
29. VISUAL DISORDERS
Nearsightedness/
Myopia
Can see objects closer than
6m, but not far objects.
Have an elongated eyeball.
When looking at a far object,
the image is focused in front
of the retina.
These people can wear
concave lenses, which
diverge the light rays so that
the image can be focused
on the retina.
Farsightedness/
Hypermetropic
Can see objects far but not
near objects.
Have a shortened eyeball.
When looking at a near
object, the image is focused
behind the retina.
These people can wear a
convex lens, to increase the
bending of light rays so that
the image can be focused on
the retina.
32. VISUAL DISORDER: ASTIGMATISM
When the cornea or
lens is uneven and
the image that you see
is fuzzy.
Can be corrected by
wearing glasses with
an unevenly round
lens to compensate for
the uneven cornea.