Anatomy and Physiology 2 Exam 1

Special senses, endocrine system, blood, endocrine pathology

Define sensory receptors

Structures that are specialized to detect and respond to changes in the external or internal environment, generate electrochemical messages

If a stimulus is strong enough, then action potentials are conducted to the brain

Sensation is

awareness of a stimulus, How a sensation is experienced (e.g., as sight or sound) depends on which part of the brain receives the impulses

Perception is

the conscious awareness of sensations, Understanding the stimulus occurs when the cerebral cortex integrates sensory input

explain a sensation from sensory receptor to the brain

1.sensory receptor detects stimulus in internal/external environment,

2.Sensory neurons conduct a nerve impulse to the spinal cord and then brain, or directly to brain

3.brain interprets the info from the sensory receptor

4.The brain’s interpretation of the information is a perception or understanding of the stimulus.

what is Sensory adaptation

Sensory receptors stop responding when continuously stimulated, leading to a decrease in the awareness of the stimulus

Pressure and touch receptors adapt quickly

Receptors in muscles and joints that report on body position never adapt

what are the Classes of Receptors

Mechanoreceptors • Thermoreceptors • Photoreceptors • Chemoreceptors • Pain receptors

General receptors what are they and what do they do

located in skin, muscles, bones, joints, and internal organs

General senses: touch, pressure, vibration, temperature, body and limb position, pain

We are not usually aware of the general senses, but they are still important to Provide information about body position, Help keep internal body conditions within optimal limits

Special receptors what are they and what do they do

-located in the head, often within specific structures

-Special senses Vision, Hearing, Equilibrium, Smell, Taste

-We rely on the special senses to perceive the world

Sharp vision requires

light be focused on the retina

Light is bent (refracted) at four points when it enters the eye

Cornea • Aqueous humor • Lens • Vitreous humor

explain accommodation of vision

Changing the shape of the lens (which is elastic) to change the bending of light

whats a cataract

A lens that has become cloudy, usually due to aging

Two types of photoreceptors

rods -vision in dim light  More numerous than cones  Responsible for black-and-white vision  Contain the pigment rhodopsin, which is broken down in bright light

cones-responsible for color vision red, blue, and green, produce sharp images, A reduced number or lack of one type of cone results in color blindness

Focusing problems • Farsightedness • Nearsightedness • Astigmatism caused by can they be repaired

discrepancies in the thickness or curvature of the lens or the shape of the eyeball, Normal vision can be restored with corrective lenses or laser-assisted surgeries (LASIK)

Olfactory receptors

Sensory neurons with long hairs covered by mucus located in the roof of each nasal cavity

One of the few types of neurons known to be replaced during life

purpose of nasal conchae

to increase surface area of the nasal cavity

describe how we smell

odor molecules dissolve into the mucus layer in the nasal cavity and bind to the receptor cells, stimulating them. if a threshold is reached, message is carried to olfactory bulbs in the brain

what do tastebuds are made of and what do they do

Composed of taste supporting cells that are replaced every ten days, sense five basic tastes: Bitter, Umami (meat/broth taste), Sweet, Salty, Sour

describe how we taste

Taste hairs have receptors for chemicals found in food, When food molecules are dissolved in saliva, they enter the pore and stimulate the taste hairs that generate electrical signals that are sent to sensory neurons wrapped around taste cells

outer ear function

Functions as a receiver

Includes the pinna and external auditory canal

pinna

of the outer ear and Gathers sound and channels it to the external auditory canal, Helps determine sound direction

External auditory canal is of what and leads to

of the outer ear and leads to the tympanic membrane (eardrum)

Tympanic membrane (eardrum) of what and does what

of middle ear and Vibrates at the same frequency as the sound waves and transfers these vibrations to the middle ear

Auditory tube (Eustachian tube) of what and does what

of middle ear and Connects middle ear cavity with the throat; alleviates pressure differences

middle ear function and consists of

Functions as an amplifier

Consists of an air-filled cavity within the temporal bone of the skull and the three auditory bones

 Malleus (hammer)

 Incus (anvil)

 Stapes (stirrup)

inner ear function and consists of

Functions as a transmitter, generates neural messages in response to pressure waves caused by sound waves, Sends these messages to the brain for interpretation

consists of: cochlea (hearing) and vestibular apparatus (body position and movement)

cochlea contains two openings

oval window-stapes fits into

round window-relieves pressure

explain basilar membrane function

supports the spiral organ of corti

vestibular canal vs tympanic canal

The vestibular system includes the semicircular canals and the otolith organs, which detect head movements and balance, respectively. The tympanic canal, on the other hand, is part of the cochlea, which is involved in converting sound vibrations into electrical nerve impulses for hearing.

Spiral organ of corti function and consists of

Most directly responsible for hearing

• Consists of hair cells and overhanging tectorial membrane

Summary of How We Hear

Acoustic energy, in the form of sound waves, is channeled into the ear canal by the pinna. Sound waves hit the tympanic membrane and cause it to vibrate, like a drum, changing it into mechanical energy. The malleus, which is attached to the tympanic membrane, starts the ossicles into motion. The stapes moves in and out of the oval window of the cochlea creating a fluid motion, or hydraulic energy. The fluid movement causes membranes in the Organ of Corti to shear against the hair cells. This creates an electrical signal which is sent up the Auditory Nerve to the brain. The brain interprets it as sound!

Vestibular apparatus what is it and consists of what

A fluid-filled maze of chambers and canals within the inner ear

• Consists of Semicircular canals (Help with balance when we are moving)

Vestibule (Helps with balance when we are not moving)

Our sense of dynamic equilibrium—attributed to

equilibrium when the body or head is moving—is due to the semicircular canals, and cupula at the base of those canals which report rotational movements of the head, including those caused by acceleration or deceleration based on if the fluid in the ears pushes the cupula which stimulates the hair cells

Our sense of static equilibrium—attributed to

—position of the head with respect to gravity—is due to the receptors in the vestibule, utricle and the saccule, two fluid-filled cavities that contain hair cells with overlaying gelatinous material. Embedded in the gelatinous material are granules of calcium carbonate called otoliths, When the head is tilted, otoliths in the gelatinous material slide “downhill” over the hair cells, stimulating them. The hair cells send signals to the brain and those are interpreted to know position of the head

nervous system know

initiates responses rapidly

short-duration responses

acts via potentials and neurotransmitters

act @ specific locations determined by axon pathways

neurotransmitters act over very short distances

endocrine system know

initiates responses slowly

long-duration responses

acts via hormones released into the blood

act @ diffuse locations, anywhere blood reaches

hormones act over very long distances

Exocrine glands..what do they do?

Produce nonhormonal substances (examples: sweat, saliva)

– Have ducts to carry secretion to membrane surface

Endocrine system controls and integrates

-Reproduction

– Growth and development

– Maintenance of electrolyte, water, and nutrient balance of blood

– Regulation of cellular metabolism and energy balance

– Mobilization of body defense

Endocrine glands what are they and what do they do

thyroid, adrenal, pituitary, parathyroid, and pineal glands

Produce and secrete chemical compounds called hormones into the blood system, Lack ducts

neuroendocrine organ

hypothalamus

Hormones

proteins (or steroids) that are secreted from a secretory cell in a gland and act on a target cell at another part of the body

Target cells

must have receptors for the specific hormone.

how does Cyclic AMP (cAMP) Second-Messenger System function

1. Hormone (first messenger) binds to receptor

2. Receptor activates a G protein

3. G protein activates or inhibits the effector enzyme adenylate cyclase

4. Adenylate cyclase then converts ATP to cAMP (second messenger)

5. cAMP activates protein kinases that phosphorylate (add a phosphate) other proteins

cAMP is rapidly degraded by enzyme___ which does what

phosphodiesterase, stopping cascade (Cascades have huge amplification effect, ‘cascade of events’)

types of endocrine gland stimuli: Humoral stimuli

altered blood levels of ions and nutrients directly stimulate secretion of hormones (ex, too little ca²+ in blood concentration stimulates parathyroid glands to secrete PTH (parathyroid hormone)—> PTH causes Ca2+ concentrations to rise, and stimulus is removed)

types of endocrine gland stimuli: Neural Stimulus

Nerve fibers stimulate hormone release (ex, Sympathetic nervous system fibers stimulate adrenal medulla to secrete catecholamines)

types of endocrine gland stimuli: Hormonal Stimulus

Hormones stimulate other endocrine organs to release their hormones