Human Responses to the Environment

Stimulus

a signal to which an organism responds

environment

the surroundings or conditions in which a person, animal, or plant lives or operates.

Receptors

structures specialized to detect certain stimuli

Interoceptors

detect internal stimuli, usually chemical stimuli

Exteroceptors

detect external stimuli, are therefore located on the surface of the body.

Propioceptors

Provide information about body position and motion, are located in the inner ear.

sight

the sense through which we detect light stimuli

Photoreceptors

cells in the retina that initially transform light stimuli into nerve impulses

Iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Cornea

The clear tissue that covers the front of the eye. It acts like a lens to focus the light rays into the pupil

crystalline lens

the lens inside the eye, which focuses light onto the back of the eye

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

pupil

the adjustable opening in the center of the eye through which light enters

Retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

optical nerve

something that transmits visual information from the retina to the brain

Rods

Specialized visual receptors that play a key role in night vision and peripheral vision.

Cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.

Sclera

white part of the eye

Hearing

the sense through which we detect sound

Mechanoreceptors

sensory cells that are sensitive to vibrations in the surrounding environment, therefore detection sound waves.

outer ear

the outermost part of the ear, consisting of the pinna and the ear canal

Pinna

the visible part of the ear that intercepts sound waves and focuses them into the ear canal

ear canal

A narrow region leading from the outside of the human ear to the eardrum. The sound waves travel through it

eardrum

a thin membrane that marks the beginning of the middle ear; sound waves cause it to vibrate

ear bones

malleus, incus, stapes

Eustachian tube

A narrow tube between the middle ear and the throat that serves to equalize pressure on both sides of the eardrum

middle ear

the chamber between the eardrum and cochlea containing 3 tiny bones that concentrate the vibrations of the eardrum on the cochlea's oval window

inner ear

the innermost part of the ear, containing the cochlea, Vestibular system and auditory nerve

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

vestibular system

three semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve

auditory nerve

the nerve that carries impulses from the inner ear to the brain, resulting in the perception of sound

aqueous humor

fluid in the eye, found between the cornea and the lens

cilliary muscle

adjusts shape of the lens to focus objects on the retina.

the nervous system

the network of nerve cells and fibers that transmits nerve impulses between parts of the body.

the endocrine system

the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream

reflex

a simple, automatic response to a sensory stimulus, such as the knee-jerk response

Photomotive reflex

when the pupil/iris adjusts to the amount of light in the environment

patellar reflex

The knee-jerk reflex; a spinal reflex in which tapping below the knee produces a reflexive contraction of the quadriceps muscle of the thigh, causing the foot to kick.

nervous reaction

A reaction triggered by the nervous system that has to be processed before causing a reaction

Reaction capacity

The immediacy with which an individual can react to stimuli or a task

Chemoreceptors

Receptors that detect chemicals

taste buds

Tiny bumps covering the upper surface of the tongue. They contain chemoreceptors and nerve endings

taste receptors

chemical receptors on the tongue that detect the presence of substances dissolved in saliva or in liquids inside the oral cavity, then turn these stimuli into electrical impulses

Nerve endings

carry information from the taste buds to the brain. These receive nerve impulses from the taste receptor they're connected to

olfactory mucosa

covers the upper region of the nasal cavity. It holds chemoreceptors that are connected to nerve endings from the olfactory bulb. (3)

olfactory bulb

Collects electrical impulses from the olfactory mucosa and directs them to the olfactory nerve

olfactory nerve

the nerve that carries smell impulses from the nose to the brain (1)

Thermoreceptors

detect changes in temperature

Nocioreceptors

pain receptors

Meissner's corpuscles

detect slight pressure changes

Pacinian corpuscles

respond to deep pressure and vibration

Ruffini's corpuscles

Detect increases in temperature

Krause's corpuscles

detect decreases in temperature

free nerve endings

transmit sensation of pain

central nervous system

A subdivision of the human nervous system comprising the brain and spinal cord. Receives information from the receptors and creates an appropriate response to the stimulus.

Encephalon

another word for brain

Cerebrum

Part of the brain that initiates movement, interprets information from the senses, and enables complex cognitive skills (speaking, thinking, memory and emotions etc.)

Cerebellum

an area at the base of the brain that coordinates muscle movement in the body, but doesn't initiate it.

Brainstem

central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions (heartbeat, breathing, sleep-wake cycles, etc.)

circumvolutions

The "rugouseness" on the brain that is there to increase surface area

spinal cord

a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain, is protected by the vertebral column

peripheral nervous system

the sensory and motor neurons that connect the central nervous system to the rest of the body

autonomic peripheral nervous system

The group of nerves in the PNS that innervates smooth muscle, cardiac muscle, and glands. It controls the body's involuntary processes such as heartbeat or bowel movement

somatic peripheral nervous system

part of the peripheral nervous system that controls voluntary actions such as moving your arms

sympathetic autonomic peripheral nervous system

directs the body's rapid involuntary response to dangerous or stressful situations. It is your "fight or flight" response and prepares all your organs to face a treat.

parasympathetic autonomic peripheral nervous system

works to calm your body down after a SAPNS response, and encourages your body to "rest and digest". Settles the body back into homeostasis or equilibrium after a stressful event.

nerve impulse

the message carried by a neuron

sensory nerves

Nerves that carry information from the sense receptors to the spinal cord and brain.

motor nerves

Nerves that carry information from the central nervous system to the muscles of the body.

relay neuron (interneuron)

nerve cells linked to other neurons that form networks within the CNS. They take part in producing responses

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Soma

cell body of a neuron

Ranvier nodes

breaks in the myelin sheath; places where action potentials are generated

myelin sheath

covers the axon of some neurons and helps speed neural impulses

sysnapse

Location at which a neuron can transfer an impulse to another cell

Schwann cell

Section of myelin sheath on the cell

Axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

Hypothalamus

brain region connecting the nervous system and endocrine system and also controls the pituitary gland

pituitary gland

endocrine gland at the base of the brain that secretes hormones that activate other endocrine glands

pineal gland

endocrine gland that secretes melatonin

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness.

thyroid gland

endocrine gland surrounding the neck that produces hormones that regulate metabolism, body heat, and bone growth

Tyroxin

hormone released by the thyroid gland that controls your cells metabolic rate

parathyroid glands

small pea-like organs that regulate calcium and phosphate balance in blood, bones, and other tissues through the parathyroid hormone

parathyroid hormone

A hormone of the parathyroid gland that regulates the metabolism of calcium and phosphorus in the body.

adrenal glands

a pair of endocrine glands that sit just above the kidneys and secrete hormones (adrenaline and corticosteroids) that help arouse the body in times of stress.

Corticosteroids

A group of hormones, including cortisol, released by the adrenal glands at times of stress

Adrenaline

a hormone secreted by the adrenal glands, especially in conditions of stress, increasing rates of blood circulation, breathing, and carbohydrate metabolism and preparing muscles for exertion.

Pancreas

endocrine gland; controls the levels of glucose in the blood, secretes insulin and glucagon

Glucagon

A protein hormone secreted by pancreatic endocrine cells that raises blood glucose levels; an antagonistic hormone to insulin.

Insulin

A protein hormone synthesized in the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues (decreases blood glucose levels)

Ovaries

The female sex glands that store the ova and produce female sex hormones (estrogens and progesterone)

Testes

Male sex glands or gonads that produce the male sex hormone, testosterone.

Estrogen

female sex hormone secreted by the ovaries. In charge of female secondary sex characteristics during puberty

Progesterone

A hormone produced by the ovaries which acts with estrogen to bring about the menstral cycle and participates in pregnancy.

Testosterone

Male sex hormone that controls the development of male secondary sex characteristics

addiction

A physiological and/or psychological dependence on a drug

Depressants

drugs (such as alcohol, sedatives, and heroin) that reduce neural activity and slow body functions

Narcotics

drugs that inhibit the transmission of nerve impulses associated with pain and in addition to dulling pain, they also induce drowsiness and sleep. Cause extreme addiction (morphine, heroin)