Special Senses and Endocrine System: Vision, Taste, Smell, Hearing, Hormones

What is the primary function of the special senses?

To convert sensory input from the environment into electrical signals for interpretation by the cerebral cortex.

What is the first structure light passes through in the eye?

The cornea.

What is the role of the lens in vision?

It fine-tunes focus by changing shape to direct light onto the retina.

What are the two types of photoreceptors in the retina?

Rods and cones.

What is the function of rods in vision?

They are sensitive to light, function in dim lighting, and provide peripheral vision.

What is the function of cones in vision?

They require brighter light, provide high visual acuity and color vision.

What happens to retinal in the presence of light?

It changes from a bent shape (11-cis retinal) to a straight shape (all-trans retinal), activating rhodopsin.

What is myopia?

Nearsightedness, where the eye is often too long and corrected with a concave lens.

What is hyperopia?

Farsightedness, where the eye is often too short and corrected with a convex lens.

What is the primary location of taste buds?

On the tongue within structures called papillae.

What type of papillae are cone-shaped and provide friction but have no taste buds?

Filiform papillae.

What cranial nerves are involved in the gustatory pathway?

Cranial Nerves VII (Facial), IX (Glossopharyngeal), and X (Vagus).

What is anosmia?

The complete inability to smell.

What is the mechanism of smell?

An odorant binds to a chemoreceptor, activating a G-protein, which opens Na+ channels and depolarizes the neuron.

What is the role of the cochlea in hearing?

It facilitates the conversion of sound waves into electrical signals.

What is conduction deafness?

Impaired movement of vibrations to the inner ear, usually treatable.

What is tinnitus?

Ringing in the ears.

What do the otolith organs in the vestibule detect?

Gravity and linear acceleration.

What is the function of the semicircular canals?

To detect angular acceleration (rotational movement).

What is macular degeneration?

Deterioration of the macula causing center field vision loss.

What is the role of the tympanic membrane in hearing?

It vibrates in response to sound waves.

What is the significance of the fovea centralis?

It is the area of the retina with the highest concentration of cones, providing the best color vision and visual acuity.

What is the clinical condition associated with the clouding of the lens?

Cataract.

What happens to sodium channels in phototransduction when light hits the retina?

They close, leading to hyperpolarization of the cell and decreased release of glutamate.

What is the role of the vestibulocochlear nerve?

It transmits auditory and balance information to the brain.

What is the function of the basilar membrane in hearing?

It resonates in response to sound waves, bending hair cells to create signals.

What is the condition characterized by the failure of papillae to slough off, leading to a buildup of bacteria?

Hairy tongue.

What are signaling molecules secreted by endocrine cells called?

Hormones

How do hormones reach their target cells?

Through circulation

What is upregulation in the context of hormone signaling?

An increase in receptor number due to the presence of a hormone, making the cell more sensitive to that hormone.

What hormone stimulates the increase in LH receptor number?

FSH (Follicle-Stimulating Hormone)

What is downregulation?

A decrease in receptor numbers due to the presence of a hormone, affecting receptor degradation or production.

What type of signaling involves a molecule acting on a neighboring cell?

Paracrine signaling

What are some examples of locally secreted molecules?

Growth factors, clotting factors, cytokines, histamine

What is the function of neurotransmitters?

To act as signaling molecules released from one cell to act on a neighboring cell, such as at synapses.

What is autocrine signaling?

When a signaling molecule stimulates the same cell that released it.

What are the characteristics of the endocrine system?

Glands secrete chemical messengers (hormones) into the circulatory system.

What is the difference in transport mode between the endocrine and nervous systems?

Endocrine uses blood, while nervous uses axons.

How does the speed of response differ between the endocrine and nervous systems?

Nervous system responses are instant/milliseconds, while endocrine responses are delayed/seconds.

What is the duration of response for the endocrine system compared to the nervous system?

Endocrine responses last minutes/days; nervous responses last milliseconds/seconds.

What is the stability characteristic of hormones?

Hormones can have long or short half-lives, affecting their activity duration.

What is chronic hormone regulation?

A relatively constant concentration of hormone, such as thyroid hormone.

What is acute hormone regulation?

A rapid increase in hormone levels in response to stress, such as epinephrine.

What are the hypothalamic hormones that regulate the anterior pituitary?

GnRH, TRH, CRH, PIH, GHRH, Somatostatin

What hormones are stored in the posterior pituitary?

Oxytocin (OT) and Antidiuretic hormone (ADH)

What triggers the release of ADH from the posterior pituitary?

Hypothalamic osmoreceptors detecting a rise in blood osmolarity.

What is negative feedback inhibition in hormone regulation?

Increased levels of target organ hormones inhibit the release of hypothalamic and/or pituitary hormones.

What is an example of positive feedback in hormone regulation?

Stretching of the uterus increases OT release, causing contractions and further stretching.

What is the role of the pituitary gland?

To release hormones that govern puberty, sexual development, and reproductive function.

What is the function of the hypothalamus in the endocrine system?

It regulates the release of hormones from the pituitary gland.

What hormone increases water retention by the kidneys?

Antidiuretic hormone (ADH)

What is another name for antidiuretic hormone?

Arginine vasopressin (AVP)

What hormone promotes feelings of sexual satisfaction and emotional bonding?

Oxytocin (OT)

What hormone stimulates labor contractions during childbirth?

Oxytocin (OT)

What condition is caused by a deficiency in ADH?

Diabetes insipidus

What are the main symptoms of diabetes insipidus?

Polyuria and polydipsia

What hormone stimulates the secretion of ovarian sex hormones?

Follicle-stimulating hormone (FSH)

What hormone stimulates ovulation and secretion of progesterone?

Luteinizing hormone (LH)

What hormone stimulates the adrenal cortex to secrete glucocorticoids?

Adrenocorticotropic hormone (ACTH)

What hormone stimulates mammary glands to synthesize milk after birth?

Prolactin (PRL)

What hormone stimulates mitosis and cellular differentiation?

Growth hormone (GH)

What hormone stimulates secretion of thyroid hormone from the thyroid gland?

Thyroid-stimulating hormone (TSH)

What is the primary function of growth hormone (GH)?

Stimulates growth in cartilage, bone, muscle, and fat

What hormone is produced by the pineal gland?

Melatonin

What is the role of the thymus in the immune system?

Site of maturation of T cells

What hormone does the thyroid gland secrete in response to TSH?

Thyroid hormone (TH), primarily in the form of T4 and T3

What condition is characterized by low thyroid production?

Hypothyroidism (Myxedema)

What are the symptoms of hyperthyroidism?

Hyperactivity, high heart rate, exophthalmos

What hormone is secreted by the parathyroid glands?

Parathyroid hormone (PTH)

What is the effect of parathyroid hormone (PTH) on blood calcium levels?

Increases blood calcium levels

What is the most significant mineralocorticoid?

Aldosterone

What hormone is secreted by the adrenal medulla?

Catecholamines (epinephrine and norepinephrine)

What is Cushing's disease characterized by?

Increased cortisol levels

What is Addison's disease?

Hyposecretion of adrenal cortex hormones

What is the primary function of insulin?

Lowers blood glucose levels by promoting nutrient absorption

What hormone is secreted by alpha cells in the pancreas?

Glucagon

What is the role of somatostatin in the pancreas?

Regulates glucagon and insulin secretion

What is the main difference between Type I and Type II diabetes?

Type I is due to destruction of beta cells; Type II involves faulty insulin receptors

What is the role of atrial natriuretic factor (ANF)?

Blocks aldosterone secretion to reduce blood pressure

What is the effect of aldosterone on the kidneys?

Causes retention of sodium and water, maintaining blood volume and pressure

What is the primary adrenal sex steroid?

Androgens

What is the role of ghrelin in growth hormone secretion?

Activates growth hormone secretion

What is the significance of insulin-like growth factors (IGF-I)?

Prolongs the action of growth hormone

What are the symptoms of hypoparathyroidism?

Muscle twitches, convulsions, respiratory paralysis

What is a key similarity between the nervous and endocrine systems?

Both may use the same chemical messenger, such as epinephrine.

How does the nervous system communicate with the body?

It secretes neuroendocrine peptides into the circulatory system.

What is the primary mode of transport for the nervous system?

Axons.

What is the primary mode of transport for the endocrine system?

Blood.

How quickly does the nervous system respond?

Instantly, in milliseconds.

How quickly does the endocrine system respond?

With a delay, in seconds.

What is the duration of response for the nervous system?

Milliseconds to seconds.

What is the duration of response for the endocrine system?

Minutes to days.

How does the nervous system adapt to long-term stimuli?

The response declines quickly (adapts quickly).

How does the endocrine system adapt to long-term stimuli?

The response persists (adapts slowly).

What are the characteristics of hormones related to stability?

Hormones can have long or short half-lives; long half-life hormones regulate constant activities, while short half-life hormones have rapid onset and short duration.

How are hormones transported in the blood?

Hormones dissolve in blood plasma and can be unbound or reversibly bound to plasma proteins.

What is episodic (cyclic) hormone regulation?

Hormone regulation that occurs in cycles, such as female reproductive hormones.

How many hypothalamic hormones regulate the anterior pituitary?

Six.

What does Gonadotropin-releasing hormone (GnRH) do?

Stimulates the release of gonadotropins (FSH, LH) from the anterior pituitary.

What does Thyrotropin-releasing hormone (TRH) do?

Stimulates the release of thyroid-stimulating hormone (TSH) from the anterior pituitary.