True or false? the spectrum of health care delivery refers to the various types of care.

The nervous system must receive and process information about the world outside in order to react, communicate, and keep the body healthy and safe. Much of this information comes through the sensory organs: the eyes, ears, nose, tongue, and skin. Specialized cells and tissues within these organs receive raw stimuli and translate them into signals the nervous system can use. Nerves relay the signals to the brain, which interprets them as sight (vision), sound (hearing), smell (olfaction), taste (gustation), and touch (tactile perception).

1. The Eyes Translate Light into Image Signals for the Brain to Process

The eyes sit in the orbits of the skull, protected by bone and fat. The white part of the eye is the sclera. It protects interior structures and surrounds a circular portal formed by the cornea, iris, and pupil. The cornea is transparent to allow light to enter the eye, and curved to direct it through the pupil behind it. The pupil is actually an opening in the colored disk of the iris. The iris dilates or constricts, adjusting how much light passes through the pupil and onto the lens. The curved lens then focuses the image onto the retina, the eye’s interior layer. The retina is a delicate membrane of nervous tissue containing photoreceptor cells. These cells, the rods and cones, translate light into nervous signals. The optic nerve carries the signals from the eye to the brain, which interprets them to form visual images.

2. The Ear Uses Bones and Fluid to Transform Sound Waves into Sound Signals

Music, laughter, car honks — all reach the ears as sound waves in the air. The outer ear funnels the waves down the ear canal (the external acoustic meatus) to the tympanic membrane (the “ear drum”). The sound waves beat against the tympanic membrane, creating mechanical vibrations in the membrane. The tympanic membrane transfers these vibrations to three small bones, known as auditory ossicles, found in the air-filled cavity of the middle ear. These bones – the malleus, incus, and stapes – carry the vibrations and knock against the opening to the inner ear. The inner ear consists of fluid-filled canals, including the spiral-shaped cochlea. As the ossicles pound away, specialized hair cells in the cochlea detect pressure waves in the fluid. They activate nervous receptors, sending signals through the cochlear nerve toward the brain, which interprets the signals as sounds.

3. Specialized Receptors in the Skin Send Touch Signals to the Brain

Skin consists of three major tissue layers: the outer epidermis, middle dermis, and inner hypodermis. Specialized receptor cells within these layers detect tactile sensations and relay signals through peripheral nerves toward the brain. The presence and location of the different types of receptors make certain body parts more sensitive. Merkel cells, for example, are found in the lower epidermis of lips, hands, and external genitalia. Meissner corpuscles are found in the upper dermis of hairless skin — fingertips, nipples, the soles of the feet. Both of these receptors detect touch, pressure, and vibration. Other touch receptors include Pacinian corpuscles, which also register pressure and vibration, and the free endings of specialized nerves that feel pain, itch, and tickle.

4. Olfaction: Chemicals in the Air Stimulate Signals the Brain Interprets as Smells

The sense of smell is called olfaction. It starts with specialized nerve receptors located on hairlike cilia in the epithelium at the top of the nasal cavity. When we sniff or inhale through the nose, some chemicals in the air bind to these receptors. That triggers a signal that travels up a nerve fiber, through the epithelium and the skull bone above, to the olfactory bulbs. The olfactory bulbs contain neuron cell bodies that transmit information along the cranial nerves, which are extensions of the olfactory bulbs. They send the signal down the olfactory nerves, toward the olfactory area of the cerebral cortex.

5. Home of the Taste Buds: The Tongue Is the Principal Organ of Gustation

What are all those small bumps on the top of the tongue? They’re called papillae. Many of them, including circumvallate papillae and fungiform papillae, contain taste buds. When we eat, chemicals from food enter the papillae and reach the taste buds. These chemicals (or tastants) stimulate specialized gustatory cells inside the taste buds, activating nervous receptors. The receptors send signals to fibers of the facial, glossopharyngeal, and vagus nerves. Those nerves carry the signals to the medulla oblongata, which relays them to the thalamus and cerebral cortex of the brain.

4 0

3 years ago

Michelle was curious about her mother's blood type. Michelle knew that her own blood type was o,

babymother [125]

Blood type is determined by the I gene. IAIA and IAi determines A blood type. IBIB and IBi determines B blood type. ii determines 0 blood type. Michelle's mother must at least carry one recessive allele i.

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The blood type is determined by a gene, which is triallelic.

IA dominant over i. The person presents A type of antigens.

IB dominant over i. The person presents B type of antigens.

IA and IB are codominant. The person presents both types of antigens, A and B.

i is the recessive allele. The person does not present any antigen.

⇒ H0m0zyg0us dominant individuals IAIA, or heter0zyg0us Individuals IAi, will express the A blood type.

⇒ H0m0zyg0us dominant individuals IBIB, or heter0zyg0us Individuals IBi, will express the B blood type.

⇒ Individuals with h0m0zyg0us recessive genotype, ii will express the 0 blood type.

⇒ Individuals carrying IA and IB alleles will express the AB blood type.

To solve the problem, we will use this information.

We know that

Michelle is blood type 0

Father is blood type A

Brother and sister are blood type A

Mother??

⇒ If Michelle is blood type 0, then her genotype is ii. She must have received one recessive allele from her father and one from her mother.

⇒ This suggests that Michelle's father, who is blood type A, is heter0zyg0us IAi. He must have at least one dominant allele IA that determines his phenotype, and one i allele.

⇒ Michelle's brother and sisters are also type A. They might be either h0m0zyg0us dominant IAIA or heter0zyg0us IAi.

⇒ Michelle's mother should have at least one recessive allele i. She could be either IAi or IBi, or ii. There are three possible option for her genotype.

Let us make the Punnet squares to understand it better. We know the genotype of the father, but there are three options for the mother.

Option 1

Cross) father x mother

Parentals) IAi x IAi

Gametes) IA i IA i

Punnett square) IA i

IA IAIA IAi

i IAi ii

F1) 25% of the progeny is expected to be h0m0zyg0us dominant IAIA

50% of the progeny is expected to be heter0zygus IAi

25% of the progeny is expected to be h0m0zyg0us recessive ii

75% of the progeny is expected to be blood type A ⇒ IAIA and IAi ⇒ Sisters and brother

25% of the progeny is expected to be blood tye 0 ⇒ ii ⇒ Michelle

Option 2

Cross) father x mother

Parentals) IAi x IBi

Gametes) IA i IB i

Punnett square) IA i

IB IBIA IBi

i IAi ii

F1) 25% of the progeny is expected to be IAIB

25% of the progeny is expected to be heter0zygus IAi

25% of the progeny is expected to be heter0zygus IBi

25% of the progeny is expected to be h0m0zyg0us recessive ii

25% of the progeny is expected to be blood type AB ⇒ IAIB

25% of the progeny is expected to be blood type A ⇒ IAi ⇒ Sisters and brother

25% of the progeny is expected to be blood type B ⇒ IBi

25% of the progeny is expected to be blood tye 0 ⇒ ii ⇒ Michelle

Option 3

Cross) father x mother

Parentals) IAi x ii

Gametes) IA i i i

Punnett square) IA i

i IAi ii

F1) 50% of the progeny is expected to be heter0zygus IAi

25% of the progeny is expected to be h0m0zyg0us recessive ii

50% of the progeny is expected to be blood type A ⇒ IAi ⇒ Sisters and brother

50% of the progeny is expected to be blood tye 0 ⇒ ii ⇒ Michelle

Despite the fact we can not determine for sure the mother's genotype, we know that she carries at least one recessive allele, which is why Michelle's blood type is 0.

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8 0

2 years ago