Chapters on Immune System, Sensory Systems, and Development

Innate immunity

A type of immunity that is nonspecific and rapid.

Adaptive immunity

A type of immunity that is specific and slower initially.

First line defenses in innate immunity

Physical barriers like skin and mucous membranes.

Phagocytic cells

Cells that engulf and destroy pathogens.

Types of phagocytic cells

Macrophages and neutrophils.

Antimicrobial peptides

Substances that disrupt microbial membranes.

Toll-like receptors (TLRs)

Receptors that recognize pathogens by binding to pathogen-associated molecular patterns (PAMPs).

Inflammatory response

A defense mechanism that involves redness, swelling, heat, and pain at infection sites.

Mast cells

Cells that release histamine to increase blood flow and permeability during inflammation.

Fever

A response that raises body temperature to inhibit pathogen growth.

Complement system

A group of proteins that enhance phagocytosis and can lyse pathogens.

Natural killer (NK) cells

Cells that destroy infected or cancerous host cells.

Humoral immunity

An adaptive immune response mediated by B cells.

Cell-mediated immunity

An adaptive immune response mediated by T cells.

Antigen

Any substance that can trigger an adaptive immune response.

B and T cells recognition of antigens

They recognize specific antigens through antigen receptors unique to each lymphocyte.

Clonal selection

The process by which an antigen selects and activates specific lymphocytes to proliferate.

Memory cells

Long-lived lymphocytes that respond quickly upon re-exposure to an antigen.

Helper T cells

Cells that activate B cells and cytotoxic T cells.

B cells maturation site

Bone marrow.

T cells maturation site

Thymus.

Antigen receptors of B and T cells

B cell receptors bind directly to antigens; T cell receptors bind to antigen fragments presented by MHC molecules.

Classes of MHC molecules

Class I and Class II.

Allergy

An exaggerated response to harmless antigens.

Autoimmune diseases

Conditions where the immune system attacks the body's own cells.

Immunodeficiency

A condition in which the immune system's ability to fight infectious disease is compromised.

Example of an immunodeficiency disease

AIDS.

Vaccines

Substances that stimulate production of memory cells without causing disease.

Herd immunity

When a large portion of a population is immune, reducing spread.

Sensory transduction

Conversion of stimulus energy into a change in membrane potential.

Types of sensory receptors

Mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors.

Receptor potential vs action potential

Receptor potential is a graded response; action potential is an all-or-nothing signal.

Mechanoreceptors

Receptors that detect touch and pressure.

Chemoreceptors

Receptors that detect chemicals.

Photoreceptors

Receptors that detect light.

Sensory adaptation

A decrease in response to a continuous stimulus.

Intensity of a stimulus encoding

Encoded by the frequency of action potentials.

Thalamus role in sensory processing

It relays sensory information to the appropriate region of the cerebral cortex.

Somatosensory cortex

Responsible for processing touch, pressure, pain, and temperature signals.

Lateral inhibition

The process that sharpens sensory perception by inhibiting neighboring neurons.

Location coding of a stimulus

Coded by which neurons are activated.

Hair cells in the cochlea

Structures in the ear that detect sound.

Vestibular system

Structure responsible for balance.

Sensation of hearing

Caused by movement of hair cells bending in response to fluid vibrations.

Lateral line system in fish

Detects water movement.

Statocyst

A structure used for equilibrium in some invertebrates.

Stretch receptors

Detect muscle stretching and tension.

Pacinian corpuscles

Detect pressure and vibration.

Detection of smell

Chemoreceptors in the nose bind to odor molecules.

Difference between taste and smell receptors

Taste receptors respond to molecules dissolved in saliva; smell receptors respond to airborne molecules.

Five basic tastes

Sweet, sour, salty, bitter, umami.

Photoreceptors function

Detect light.

Function of thermoreceptors

Detect temperature changes.

Hormones

Chemical signals secreted into the bloodstream that regulate physiology and behavior.

Endocrine vs exocrine signaling

Endocrine signals travel through the blood; exocrine signals are released into ducts.

Types of hormones based on chemical structure

Peptide, steroid, and amine hormones.

Role of the hypothalamus

It regulates the pituitary gland and links nervous and endocrine systems.

Target cells

Cells with specific receptors for a hormone.

Hormone receptor

A protein that binds to a specific hormone.

Steroid hormones

By entering the cell and binding to intracellular receptors to regulate gene expression.

Peptide hormones

By binding to surface receptors and triggering signal transduction pathways.

Negative feedback in hormone regulation

When a hormone's effect reduces its own production.

Positive feedback

When a hormone's effect increases its own production.

Hormone regulating blood glucose levels

Insulin and glucagon.

Hormones produced by the adrenal glands

Epinephrine, norepinephrine, cortisol, aldosterone.

Role of thyroid hormones

Regulate metabolism.

Hormone controlling water balance

Antidiuretic hormone (ADH).

Hormone stimulating milk production

Prolactin.

Hormones regulating reproduction

Estrogens, androgens, progesterone.

Function of growth hormone

Stimulates growth and metabolism.

Hormone triggering fight-or-flight response

Epinephrine.

Hormone lowering blood calcium levels

Calcitonin.

Hormone raising blood calcium levels

Parathyroid hormone.

Hypothalamic-pituitary axis

A system where the hypothalamus controls pituitary hormone release.

Tropic hormone

A hormone that regulates the function of other endocrine glands.

Homeostasis using hormones

Through feedback loops regulating hormone levels.

Releasing and inhibiting hormones

They regulate pituitary hormone secretion.

Main parts of a neuron

Dendrites, cell body, axon, axon terminals.

Function of myelin

To insulate axons and speed up nerve impulses.

Cells producing myelin in the CNS

Oligodendrocytes.

Cells producing myelin in the PNS

Schwann cells.

Resting membrane potential

The voltage difference across the membrane of a resting neuron (~ -70 mV).

Ion channels opening during an action potential

Voltage-gated sodium and potassium channels.

Role of the sodium-potassium pump

To maintain resting potential by pumping Na⁺ out and K⁺ in.

All-or-none principle

Action potentials either happen fully or not at all.

Synapse

A junction where a neuron communicates with another cell.

Common excitatory neurotransmitter in the CNS

Glutamate.

Inhibitory neurotransmitter

GABA or glycine.

Temporal summation

Multiple signals arriving at one synapse in quick succession.

Spatial summation

Signals from multiple synapses combine.

Role of the postsynaptic receptor

To receive neurotransmitters and initiate a response.

neurotransmitters

To bind neurotransmitters and generate a postsynaptic potential.

postsynaptic potentials

Excitatory and inhibitory postsynaptic potentials.

plasticity in the nervous system

The ability of synapses to strengthen or weaken over time.

reflex arc

A simple neural pathway controlling reflexes.

medulla oblongata

The brain region that controls vital functions like heartbeat.

hippocampus

The brain structure responsible for memory.

blood-brain barrier

A selective barrier protecting the brain from harmful substances.

cerebral cortex

Higher brain functions like thought, language, and consciousness.

cerebellum

Coordination and balance.