Taste
The tongue is covered with many little bumps called papillae. Taste buds are found in the walls of papillae and the grooves surrounding them. Each taste bud contains anywhere from 50 to 150 taste receptor cells.
Microvilli extend from taste receptor cells
and protrude through an opening (taste pore) into the mouth.
These microvilli come in contact with substances in the mouth that can be tasted, also known as tastants.
Tastants interact with taste receptor cells through a number of different mechanisms to depolarize the cells.
When taste cells are depolarized, they release neurotransmitters that stimulate sensory neurons that travel in cranial nerves VII, IX, and X.
These neurons terminate on neurons in the nucleus of the solitary tract in the medulla then continue on to the thalamus.
Taste information is sent to the gustatory cortex, ( ocated on the border between the anterior insula and the frontal operculum).
This information encodes for basic tastes, such as sweet, salty, sour, bitter, and savory or umami.
However, the actual flavour of a food---which is what we typically define as taste---is created by a combination of taste and olfactory (smell) information.
Sweetness
Produced by the presence of sugars, some proteins, and other substances.
Detected by��G protein-coupled receptors T1R2+3 (heterodimer) and T1R3 (homodimer).
Saltiness
Saltiness is a taste produced best by the presence of cations (such as Na+, K+or Li+)
Directly detected by cation influx into glial like cells via leak channels causing depolarisation of the cell.
Sourness
Sourness is acidity and is also sensed using ion channels.
Undissociated acid diffuses across the plasma membrane of a presynaptic cell, where it dissociates in accordance with Le Chatelier's principle.
The protons that are released then block potassium channels, which depolarise the cell and cause calcium influx.
Bitterness
Current research suggests TAS2Rs (taste receptors, type 2, also known as T2Rs) such as TAS2R38 are responsible tasting bitter substances.
Savouriness
The amino acid glutamic acid is responsible for savouriness, but some nucleotides (inosinic acid and guanylic acid) can act as complements.
Glutamic acid binds to a variant of the G protein-coupled receptor, producing a savoury taste
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E-PORTFOLIO
IN PHYSIOLOGICAL &
BIOLOGICAL PSYCHOLOGY
(PY48)
MRS. ABIGAIL INTERNO (COURSE PROFESSOR) LAIRA ANDREI S. OSIAS (STUDENT)
MIDTERM ASSIGNMENT #2
PHYSIOLOGICAL & BIOLOGICAL PSYCHOLOGY
NAME: OSIAS, LAIRA ANDREI S.
SUBJ CODE: PY48
UNIT 3 TOPIC:
Sensory Physiology
Endocrine Glands
Muscles
SPECIFIC GUIDE QUESTIONS:
A. Sensory Physiology
Discuss the following:
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Sensory receptors are primarily classified as chemoreceptors, thermoreceptors, mechanoreceptors, or photoreceptors.
Broadly, sensory receptors respond to one of four primary stimuli:
Chemicals (chemoreceptors)
Temperature (thermoreceptors)
Pressure (mechanoreceptors)
Light (photoreceptors)
Cutaneous Sensations
Touch, pressure, and temperature receptors are found on the surface of the skin. The connections between receptors and cutaneous sensations are not well understood. Touch sensitive Meissner corpuscles and deep pressure sensitive Pacinian corpuscles Ruffini ends communicate warmth, while Krause's bulbs communicate cold. Information is sent from the receptors to nerve fibers in the spinal cord, which then travel to the brainstem. They are then sent to a cortical area in the parietal lobe. Skin senses are also subjected to sensory adaptation. A hot tub, for example, can be unbearably hot at first, but after a while, one can sit in it without discomfort.
Pain. The majority of pain receptors in the skin are free nerve endings. Information is transmitted by two types of pathways to the brain by way of the thalamus.
The fast (myelinated) route recognizes localized pain and transmits it to the cortex quickly.
The unmyelinated slow route carries less localized, longer acting pain information (such as that concerning chronic aches).
Taste & Smell
Taste and smell are two distinct sensations with independent receptor organs, but they are inextricably linked. Taste buds, which are made up of unique sensory cells, detect tastants, which are substances found in foods. These cells convey messages to specific parts of the brain when activated, making us aware of our taste sense. Similarly, odorants, or airborne odor molecules, are picked up by specific cells in the nose. Odorants trigger a neuronal response by activating receptor proteins present on hairlike cilia at the ends of sensory cells. Taste and smell messages eventually converge, allowing us to detect food flavors. This strong association is most evident in our perception of food flavors. Food "tastes" differently when the sense of smell is impeded, as anyone who has had a head cold will attest. Actually, the flavor of the food, or the combination of taste and smell, is what is being altered. This is because just the taste of the meal is detected, not the scents. Taste is concerned with discriminating between compounds that have a sweet, salty, sour, bitter, or umami flavor (umami means "savory" in Japanese). Taste and smell interactions, on the other hand, improve our perceptions of the meals we eat. Specialized sensory neurons in a small patch of mucus membrane along the roof of the nose detect airborne odor molecules called odorants. These sensory cells' axons flow through perforations in the overlying bone and enter two extended olfactory bulbs on the underside of the frontal lobe.
Vestibular Apparatus and Equilibrium
The vestibular system is the inner ear's sensory equipment that aids in maintaining postural balance. The vestibular system's input is also crucial for coordinating the position of the head and the movement of the eyes.
The Ears and Hearing
The ear is the organ of hearing and balance. The parts of the ear include:
External or outer ear, consisting of:
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Tympanic membrane (eardrum). The tympanic membrane divides the external ear from the middle ear.
Middle ear (tympanic cavity), consisting of:
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Inner ear, consisting of:
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The ability to see the world around you is determined by your vision. Several components within your eye and brain work together to give you vision. These components are:
Lens
Retina
Optic nerve
Many different parts of your eye and brain work together to assist you in seeing. The following are the primary elements of your vision:
Cornea: The front layer of your eye is called the cornea. The cornea is a dome-shaped structure that bends light entering your eye.
The pupil is the black dot in the middle of your eye that serves as a light gateway. In dark light, it extends, and in brilliant light, it contracts. The iris is in charge of it.
Iris: Your eye color is usually attributed to this area. The iris is a muscle in your eye that regulates the size of your pupil and the amount of light that enters it.
The lens is located behind the iris and pupil. Like a camera, it works with your cornea to concentrate the light that enters your eye. The lens sharpens the image in front of you, allowing you to see all of the details clearly.
The retina is a layer of tissue located in the back of the eye that converts the light that enters your eye into electrical signals. These signals are transmitted to the brain, which recognizes them as images.
Optic nerve: This aspect of your vision serves as a link between the retina and the brain. The electrical signals created in the retina are transmitted to the brain via the optic nerve. The brain then generates visuals.
Tears: Tears are supposed to keep your eyes moist and help you focus effectively, despite the fact that they are most usually associated with sobbing. They also aid in the prevention of eye discomfort and infection.
Endocrine Glands
Discuss the following:
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The endocrine system is made up of hormone-secreting endocrine glands. Despite the fact that there are eight primary endocrine glands spread throughout the body, they are nevertheless considered one system since they have comparable functions, influence mechanisms, and interrelationships.
Non-endocrine portions of certain glands serve purposes other than hormone release. The pancreas, for example, includes both an exocrine and an endocrine part that secretes digestion enzymes and hormones. Hormones are secreted by the ovaries and testes, which also create eggs and sperm. Although several organs, such as the stomach, intestines, and heart, create hormones, this is not their major role.
Mechanisms of Hormone Action
Hormones activate target cells by diffusing through the target cell's plasma membrane (lipid-soluble hormones) to bind a receptor protein in the cell's cytoplasm, or by binding a particular receptor protein in the target cell's cell membrane (water-soluble proteins).
Pituitary Gland
The pituitary gland is a small pea-sized gland that plays a major role in regulating vital body functions and general wellbeing. It is referred to as the body's 'master gland' because it controls the activity of most other hormone-secreting glands.
Adrenal Glands
Adrenal glands are small, triangular-shaped glands that sit on top of both kidneys. Hormones produced by the adrenal glands serve to regulate your metabolism, immunological system, blood pressure, stress response, and other vital activities.
Thyroid and Parathyroid Glands
Iodine from meals is used by the thyroid gland to produce two thyroid hormones that control how the body uses energy. The parathyroid glands are a group of four small glands that sit behind the thyroid gland. The parathyroid glands make a hormone (parathyroid hormone) that helps regulate calcium levels in the blood.
Pancreas and Other Endocrine Glands
Glands are organs in the body that generate and release chemicals. The pancreas has two primary functions: exocrine and endocrine. Exocrine function: produces chemicals (enzymes) that aid digesting. Endocrine function: releases hormones that regulate the quantity of sugar in your blood.
Paracrine & Autocrine Regulation
(Autocrine glands generate hormones that operate on their own glandular cells, such as prostaglandins; paracrine glands create hormones that are released into the extracellular matrix and diffuse to neighboring cells, such as islets of Langerhans - somatostatin.) Diffusible chemicals bind to receptors on the same cell from which they were released in autocrine signaling. Insulin was the first transmitter to be implicated in the autocrine regulation of -cell function.
Muscles
Discuss the following:
Skeletal Muscles
Skeletal muscles make up 30 to 40% of your total body weight. They're the muscles that attach to your bones and allow you to move and operate in a variety of ways. Skeletal muscles are voluntary, which means you may choose when and how they perform.
Mechanisms of Contraction
Abstract. When the thin actin and thick myosin filaments slip past each other, muscle contraction occurs. Cross-bridges that stretch from myosin filaments and cyclically engage with actin filaments when ATP is hydrolyzed are thought to be the driving force behind this activity.
Contractions of Skeletal Muscles
The neuromuscular junction, which is the synapse between a motoneuron and a muscle fiber, is where skeletal muscle contraction begins. The presynaptic membrane's voltage-gated calcium (Ca2+) channels open when action potentials are sent to the motoneuron and then depolarized.
Energy Requirements of Skeletal Muscles
The breakdown of ATP provides the energy required for muscle contraction, but the amount of ATP in muscle cells is only enough to fuel a brief contraction.
Neural Control of Skeletal Muscles
Concentric, eccentric, and isometric contractions, muscle fiber recruitment, and muscle tone are all controlled by neural control. The role of motor units in nervous system control of skeletal muscles is critical.
Cardiac & Smooth Muscles
Cardiac muscle cells are found in the heart's walls, appear striped (striated), and are controlled involuntarily. Except for the heart, smooth muscle fibers are found in the walls of hollow visceral organs (such as the liver, pancreas, and intestines), are spindle-shaped, and are controlled involuntarily.
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