Lectures 16-22

General Senses

Sensory modalities that involve receptors located within multiple organs, including touch, pain, and body movement.

Special Senses

Sensory modalities that involve receptors located within specialized sensory organs, such as taste, smell, hearing, balance, and vision.

Chemoreceptors

Receptors that respond to chemicals and are involved in detecting taste, smell, and blood pH.

Photoreceptors

Sensory receptors that respond to light.

Mechanoreceptors

Receptors that respond to physical forces and are involved in detecting hearing, motion, and touch.

Thermoreceptors

Sensory receptors that detect changes in temperature.

Nociceptors

Receptors that respond to tissue damage and are responsible for the sensation of pain.

Receptive Field

The area of the body served by a single sensory neuron, with precision determined by the size of the field.

First Order Neuron

A sensory neuron that carries signals from sensory receptors to the central nervous system (CNS).

Second Order Neuron

Neuron that crosses over and carries signals to the thalamus.

Third Order Neuron

Neuron that carries signals to the primary somatosensory cortex.

Lingual Papillae

Bumps on the tongue surface that help grip and position food.

Taste Buds

Structures that contain gustatory receptor cells for detecting taste and stimuli, located in lingual papillae.

Five Primary Taste Sensations

1. Salty 2. Sweet 3. Sour 4. Bitter 5. Umami.

Olfaction

The sense of smell.

Olfactory Neurons

Neurons with receptors that bind chemicals in the air to detect smell.

Olfactory Bulb

The structure where olfactory neurons synapse.

Olfactory Tracts

Bilateral bundles of nerve fibers that connect the olfactory bulb to the brain.

Auricle

The visible part of the ear that collects sound waves and determines the direction of sound.

External Acoustic Meatus

The passage through the temporal bone for sound.

Tympanic Membrane

The membrane that transmits sound to the middle ear.

Auditory Ossicles

Three small bones in the middle ear that transmit sound to the inner ear.

Malleus

The hammer-shaped ossicle attached to the tympanic membrane.

Incus

The anvil-shaped middle ossicle in the ear.

Stapes

The stirrup-shaped ossicle attached to the oval window.

Auditory Tube

The passage that connects the middle ear to the throat and equalizes pressure.

Oval Window

The membrane in the vestibule where the stapes attaches.

Vestibule

The central chamber of the inner ear involved in equilibrium.

Semicircular Canals

Three tubes in the inner ear that detect head rotation.

Cochlea

A snail-like structure in the inner ear involved in hearing.

Round Window

The membrane located at the end of the cochlea.

Vestibular Duct

A perilymph-filled cavity behind the oval window in the cochlea.

Vestibular Membrane

The membrane that separates the vestibular and cochlear ducts.

Cochlear Duct

An endolymph-filled cavity containing the spiral organ.

Basilar Membrane

Membrane that separates the cochlear duct from the tympanic duct.

Tympanic Duct

A perilymph-filled cavity located behind the round window.

Spiral Organ

The receptor organ for hearing located in the cochlear duct.

Hair Cells

Cells that convert fluid movements in the cochlea to nerve signals.

Stereocilia

Extensions of hair cells that send signals when bent.

Tectorial Membrane

The membrane that lies over the stereocilia of hair cells.

Sclera

The white fibrous outer layer of the eye.

Cornea

The clear covering that allows light to pass through the anterior eye.

Choroid

The highly vascular middle layer of the eye.

Ciliary Body

Smooth muscle that controls the shape of the lens.

Iris

The colored portion of the anterior eye surrounding the pupil.

Pupil

The open hole at the center of the iris through which light enters the eye.

Retina

The inner, light-sensitive layer of the eye containing photoreceptors.

Optic Disc

The spot on the retina where axons leave and blood vessels enter, containing no photoreceptors.

Macula

An oval-shaped pigmented area in the retina responsible for high resolution, color vision.

Aqueous Humor

Clear watery fluid that fills the space anterior to the lens.

Lens

The transparent structure that focuses light onto the retina.

Vitreous Body

Clear gel that fills the space posterior to the lens.

Rod Cells

Photoreceptors specialized for low-light vision, using rhodopsin as a photopigment.

Cone Cells

Photoreceptors specialized for color vision, using photopsins as photopigments.

Bipolar Cells

Cells connecting rod and cone cells to retinal ganglion cells.

Retinal Ganglion Cells

Cells that transmit image-forming and non-image information to the brain.

Endocrine System

System that produces hormones to change the activity of organ systems.

Hormones

Signal molecules that induce response in target cells by binding to hormone receptors.

Feedback Loops

Processes where outputs are routed back as inputs to form a loop, which may be positive or negative.

Amino Acid-derived Hormones

Hormones that are derived from amino acids.

Steroid-derived Hormones

Hormones that are derived from steroids.

Hypothalamus

Brain region that regulates the pituitary gland.

Pituitary Gland

Gland attached to the inferior aspect of the hypothalamus, controlling various hormonal functions.

Follicle Stimulating Hormone (FSH)

A hormone that stimulates gamete production.

Luteinizing Hormone (LH)

Hormone that stimulates the production of sex hormones and triggers ovulation in females.

Thyroid Stimulating Hormone

Hormone that stimulates the release of thyroid hormones.

Adrenocorticotropic Hormone (ACTH)

Hormone that causes secretion from the adrenal cortex.

Growth Hormone (GH)

Hormone that promotes the growth of body tissues.

Prolactin (PRL)

Hormone that promotes milk production.

Anti-diuretic Hormone (ADH)

Hormone that stimulates water reabsorption by the kidneys.

Oxytocin (OT)

Hormone that stimulates uterine contractions during labor and is involved in bonding.

Pineal Gland

Gland that produces melatonin, regulating sleep cycles and production in darkness.

Melatonin

Hormone that regulates sleep cycles.

Calcitonin

Hormone that reduces blood calcium levels.

Thyroid Hormone

Hormones that increase basal metabolic rate and heat production, requires iodine.

Parathyroid Hormone

Hormone that increases blood calcium levels.

Pancreas

Organ located posterior to the stomach that has both endocrine and exocrine functions.

Glucagon

Hormone that increases blood glucose levels.

Insulin

Hormone that decreases blood glucose levels.

Adrenal Glands

Glands located at the top of each kidney.

Adrenal Cortex

The outer layer of the adrenal glands.

Adrenal Medulla

The inner layer of the adrenal glands.

Aldosterone

Hormone that increases blood sodium levels and decreases potassium levels.

Cortisol

Hormone that increases blood glucose and inhibits inflammation, released due to long-term stress.

Androgens

Hormones that supplement sex hormones produced by gonads.

Epinephrine

Hormone that promotes fight or flight response to acute stress.

Norepinephrine

Hormone that also promotes fight or flight response to stress.

Testes

Male gonads that produce sperm and sex hormones.

Testosterone

Hormone that stimulates male secondary sex characteristics and sperm production.

Cardiovascular System

System providing transportation for blood materials and dissolved materials, including O2 and waste products.

Blood

Liquid connective tissue of the cardiovascular system.

Blood Plasma

Liquid matrix of blood that carries cells and dissolved materials.

Hematocrit

Measure of the percentage of blood that is made up of red blood cells.

Hemoglobin

Protein found in RBCs that carries oxygen.

Antigens

Molecules capable of stimulating an immune response.

Antibodies

Y-shaped proteins produced by the immune system to bind specific antigens.

ABO Blood Group

Blood type determined by the presence of A and B antigens on red blood cells.

Rh Blood Group

Blood type determined by the presence of the Rh D antigen on red blood cells.

Leukocytes (White Blood Cells)

Blood cells that protect the body from disease.

Granular Leukocytes

Type of leukocytes containing abundant visible granules within the cytoplasm.