Human Bio 4

Outer ear structures

Pinna, external auditory canal, tympanic membrane

Function of pinna

Collects and funnels sound waves into ear

Tympanic membrane function

Vibrates in response to sound waves

Middle ear bones

Auditory ossicles (malleus, incus, stapes)

Function of auditory ossicles

Amplify and transmit sound vibrations to inner ear

Oval window function

Transfers vibrations into inner ear fluid

Round window function

Relieves pressure in cochlea

Inner ear structures

Cochlea, semicircular canals, vestibule

Cochlea function

Converts sound vibrations into nerve signals

Hair cells

Sensory mechanoreceptors that detect sound vibrations

Tectorial membrane

Structure that lies over hair cells

Semicircular canals function

Detect rotational movement (balance)

Vestibule function

Detects linear movement and gravity

Path of sound through ear

Pinna → auditory canal → tympanic membrane → ossicles → oval window → cochlea

Photoreceptors in eye

Rods and cones

Rods function

Vision in low light, peripheral vision

Cones function

Color vision and sharp detail

Fovea centralis

Area of highest visual acuity (many cones)

Blind spot

Area with no photoreceptors where optic nerve exits

Path of light through eye

Cornea → aqueous humor → pupil → lens → vitreous humor → retina

Accommodation definition

Adjustment of lens shape to focus light

Lens shape for near vision

Rounded/thicker

Lens shape for distant vision

Flat/thin

Ciliary muscles (near vision)

Contract

Ciliary muscles (far vision)

Relax

Central nervous system (CNS)

Brain and spinal cord

Peripheral nervous system (PNS)

All nerves outside CNS

Sensory neuron function

Carries information to CNS

Interneuron function

Processes information within CNS

Motor neuron function

Carries signals away from CNS to body

Neuron structure

Dendrites, cell body, axon, myelin sheath

Function of myelin sheath

Increases speed of signal transmission

White matter

Myelinated axons

Gray matter

Unmyelinated areas

Resting potential

State when neuron is not sending signal (~ -70 mV)

Depolarization

Na+ enters cell, making inside more positive

Repolarization

K+ leaves cell, restoring negative charge

All-or-none principle

Neuron fires completely or not at all

Synapse

Junction between two neurons

Synaptic cleft

Gap between neurons

Neurotransmitters

Chemicals that transmit signals across synapse

Excitatory signals

Increase likelihood of neuron firing

Inhibitory signals

Decrease likelihood of neuron firing

Synaptic integration

Summing of excitatory and inhibitory signals

Spinal cord function

Main pathway between brain and body

Dorsal root

Carries sensory information into spinal cord

Ventral root

Carries motor information out of spinal cord

Cerebrum

Responsible for thinking, memory, reasoning

Cerebellum

Coordinates movement and balance

Brainstem

Controls vital functions (breathing, heart rate)

Diencephalon

Maintains homeostasis (includes hypothalamus)

Frontal lobe

Decision making, personality, motor control

Parietal lobe

Sensory processing

Occipital lobe

Vision

Temporal lobe

Hearing and memory

Broca’s area

Speech production

Precentral gyrus

Voluntary movement

Angular gyrus

Reading comprehension

Amygdala

Controls emotions like fear and aggression

Hippocampus

Forms long-term memories

Parkinson’s Disease

Damage to basal nuclei, affects movement

Alzheimer’s Disease

Degeneration of hippocampus, affects memory

Sympathetic nervous system

Fight or flight response

Parasympathetic nervous system

Rest and digest response

Hormones

Chemical messengers transported in blood

Target cells

Cells with receptors for specific hormones

Hypothalamus

Links nervous and endocrine systems; controls pituitary

Pituitary gland

Master gland that controls other endocrine glands

Thyroid gland location

Neck, around larynx

T3 and T4 function

Increase metabolism

Calcitonin function

Lowers blood calcium levels

Parathyroid hormone (PTH)

Raises blood calcium levels

Adrenal glands location

On top of kidneys

Epinephrine function

Short-term stress response (fight or flight)

Cortisol function

Long-term stress response

Effects of long-term stress

Decreased immunity, increased blood pressure

Insulin function

Lowers blood glucose levels

Glucagon function

Raises blood glucose levels

Type I diabetes

Little or no insulin production

Type II diabetes

Insulin resistance

Atrial natriuretic hormone (ANH)

Lowers blood pressure

Aldosterone

Increases blood pressure

Pineal gland

Produces melatonin (sleep cycle)

Thymus

Produces immune cells (lymphocytes)

Adipose tissue

Produces leptin (regulates hunger)

Gonads

Reproductive organs that produce sex hormones

Testes

Produce testosterone

Ovaries

Produce estrogen and progesterone

Sensory Receptors

Structures that take in info from external stimulus and internal environment

Chemoreceptors

measure chemicals

Photoreceptors

measure light

Mechanoreceptors

1- Pressure 2- Stretching 3- Vibrations

Thermoreceptors

measure heat

Sensation

arrival of a stimulus

Perception

conscious awareness of the stimulus

Categories of sensation

Somatic and Special Senses

Somatic

scattered throughout the body (skin, muscles, joints, viscera)

Special Senses

found in specific locations (taste, smell, sight, hearing, and balance)

Taste and Smell

chemoreceptors

Taste

4- sweet, salty, sour, bitter