Biology 2 Exam 1

Chapter 33

Intro

Symmetry

• Animals exhibit different types of body symmetry

• Asymmetry: no pattern, sponge.

• Radial: up or down orientation no left or right side, sea anemone

• Bilateral symmetry: left and right sides, goat

Apodemes

• Apodemes are ingrowths on arthropod exoskeletons to which muscles attach.

• The apodemes on the crab leg are located above and below the fulcrum of the claw

• Contraction of muscles attached to the apodemes pulls the claw closed

• Exoskeleton is made mostly of chintin

Metabolism

• Anabolism = builds

• Catabolism= breaks

• Basal metabolic rate: measures metabolic rate of endothermic animals

• Standard metabolic rate: measures metabolic rate of exothermic animals

• A mouse has a much higher metabolic rate than a elephant. Smaller animals loose heat at a faster rate than larger animals.

Torpor vs Estivation

• Torpor: process that leads to a decrease in activity and metabolism and allows animals to survive harsh conditions (hibernation)

• Estivation: when torpor occurs during the summer months when high heat and little water

Different planes

• Midsagittal plane: divides body in half (left and right)

• Frontal plane: divides front to back

• Transverse plane: divides body to upper and lower

Different Cavities

• Dorsal cavity is split to spinal and cranial cavity

• Spinal cavity is split to thoracic cavity and abdominopelvic cavity

• Abdominopelvic cavity is split into abdominal cavity and pelvic cavity

• Diaphragm: divides the respiratory tract from the gastrointestinal tract (thoracic and abdominopelvic cavities)

• Abdominal and pelvic cavities are separated by parallel line of pelvic bones

Types of Cells

• Squamous epithelial cells have a slightly irregular shape, small centrally located nuclease.

  • These cells can be stratified into layers like in a human cervix

• Simple cuboidal epithelial cells line tubules in mammalian kidney where they are involved in filtering the blood

• Pseudostratified columnar epithelia line the respiratory tract.

  • They exist only in one layer but the arrangement of nuclei at different levels makes it appear there are more than one layer

  • Goblet cells interspersed between the columnar epithelial cells secrete mucus into the respiratory tract,

Types of Cells Pt 2

• Simple columnar epithelial cells absorb material from the digestive tract.

  • Goblet cells secrete mucous into the digestive tract of the lumen

• Transitional epithelia of the urinary bladder undergo changes in thickness depending on how full the bladder is

• Loose connective tissue is composed of loosely woven collagen and elastic fibers. The fibers and other components of the connective tissues matrix are secreted by fibroblasts.

Types of Cells Pt 3

• Fibrous connective tissue from the tendon has strands of collagen fibers lined up in parallel

• Hyaline cartilage consists of a matrix with cells called chondrocytes exist in cavities in the matrix called lacunae

Bone

• Compact bone: is a dense matric on the outer surface of bone

• Spongy bone: inside the compact bone is porous with web-like trabeculae

• Compact bone is organized into rings called osteons

• Blood vessels, nerves, and lymphatic vessels are found in the central Haversian Canal. Rings of Lamellae surround the Haversian canal.

Bone Pt 2

• Between the lamellae are cavities called lacunae

• Canaliculi are micro-channels connecting the lacunae together

• Osteoblasts surround the exterior of bone. Osteoclasts bore tunnels into the bone. Osteocytes are found in the lacunae

Blood/Fat/Nerves

• Adipose is a connective tissue made up of adipocytes. Adipocytes have a small nuclei localized at the cell edge (does not contain fibroblast or matrix)

• Blood is a connective tissue that has a fluid matrix called plasma and no fibers.

  • Erythrocytes tare the predominate cell type and involved in the transport of oxygen and CO2

Types of Muscle

• Smooth Muscle: Does not have striations, involuntary movement (visceral organs)

• Skeletal muscle: have striation, multinucleated, voluntary movement (skeletal msucle)

• Cardiac muscle: have striations, one nucleus, involuntary (heart)

  • Cardiac muscle also have intercalated discs. Specialized regions running along the plasma membrane that join adjacent cardiac muscle cells and assist in passing of electrical impulse from cell to cell

Neuron

• The neuron has projections called dendrites that receive signals and projections called axons that send signals

• Glial cells are also shown:

  • Astrocytes regulate the chemical environment of the nerve cell.

  • Oligodendrocytes insulate the axon so the electrical nerve impulse is transferred more efficiently

Feedback systems

• Alteration: changing a set point of homeostats

• Acclimation: changes to a group of body organ system to maintain a set point of another system

• Blood sugar levels are controlled by negative feedback

• Birth of an infant is controlled by positive feedback

• Thermoregulation occurs in the hypothalamus and is how the body is able to regulate temperature in response to signals.

Birth Steps

• The baby pushes against the cervix causing it to stretch → Stretching of the cervix causes neve impulses to be sent to the brain → The brain stimulates the pituitary gland to secrete oxytocin → Oxytocin causes the uterus to contract

Thermoregulation steps

• Body temp rises → Blood vessels dilate, sweat glands secrete fluid as fluid evaporates head is lost from body → Heat is lost to environment → Normal body temp

• Body temp falls → Blood vessels contract so heat is conserved, sweat glands do not secrete fluid, shivering generates heat and warms → Heat is retained → Normal body temp

Heat is exchanged by 4 ways

1. Radiation: electromagnetic heat waves

2. Evaporation: sweat

3. Convection: air removes heat from skin surface

4. Conduction: heat from one surface to another

Chapter 34

Gastric system

Types of Diet

1. Herbivores (deer, monarch caterpillar) eat plants

2. Carnivores (lion and ladybug) eat primarily meat

3. Omnivores (bear and crayfish) eat both plant and animal food

Types of Digestive Systems Pt 1

• A gastrovascular cavity has a single opening through which food is ingested and waste excreted.

  • Hydra and jellyfish medusa

• An alimentary canal has two openings: a mouth to ingest food and an anus for eliminating waste as show by the nematode

Types of Digestive Systems Pt 2

• Humans and herbivores have a monogastric digestive system. However in the rabbit the small intestine and cecum are enlarged to allow more time to digest plant material

  • Enlarged organ provides more surface area for the absorption of nutrients

• Rabbits digest their food twice: first time food passes through the digestive system, it collects in the cecum and then it passes as soft feces called ceccotrophes. The rabbit re-ingests the ceccotrophes to further digest it

Types of Digestive Systems Pt 3

• The Avian esophagus has a pouch called a crop which stores food. Food passes from the crop to the first of two stomachs called the proventriculus which contains digestive juices to break down food.

• From the proventriculus the food enters the second stomach the gizzard that grinds food. Some birds swallow stones, or grit, which are stored in the gizzard to aid in the grinding process

• Birds do not have separate openings to excrete urine and feces. Instead, uric acid from the kidneys is excreted to the large intestine and combines with waste from the digestive process. This waste is excreted through and opening called the cloaca.

Types of Digestive Systems Pt 4

• Ruminant animals, goat and cows, have 4 stomachs. The first 2 stomachs, the rumen and reticulum, contain prokaryotes and protists that are able to digest cellulose fiber

• The ruminant regurgitates cud from the reticulum, chews it, and swallows it into a third stomach, the omasum, which removes water

• The cud then passes onto the 4th stomach, the abomasum, where it is digested by enzymes produced by the ruminant.

• The abomasum is most similar to the monogastric stomach

Types of Digestive Systems Pt 5

• Pseudo-ruminants have a 3 chamber stomach. Their cecum is a pouched organ containing many microorganism to digest plant material

• Have no rumen but have omasum, abomasum, and reticulum

• Camels and alpacas

The Human Digestive Tract

• Digestion of food beings in the oral cavity

• Food is masticated by teeth and moistened by saliva secreted by the salivary glands.

• Enzymes amylase and lipase in the saliva begin to digest starches and fats.

• With the help of the tongue the resulting bolus is moved into the esophagus, the trachea is covered by the epiglottis

The Human Digestive Tract Pt 2

• The esophagus transfers food from the mouth to the stomach through peristaltic movements

  • Gastro-esophageal sphincter closes stomach preventing acid going into the esophagus

• The human stomach has an extremely acidic environment where most of the proteins are digested by the enzyme pepsin.

• HCL converts pepsinogen to pepsin, ending liquid of fluid is called chyme

• Pyloric sphincter regulates chyme moving to small intestine

The Human Digestive Tract Pt 3

• Villi are folds on the small intestine lining that increase the surface area to facilitate the absorption of nutrients

• SI: duodenum (bile secretion)→ jejunum (most absorption)→ Ileum (bile salt and vitamin absorption)

• The large intestine reabsorbs water from undigested food and stores waste material until it is eliminated

  • Carnivores have shorter LI than herbivores due to diet

Essential Nutrients

Body cannot make them but must be consumed

Digestion of Carbohydrates

• Is performed by several enzymes. Starch and glycogen are broken down into glucose by amylase and maltase.

• Sucrose and lactose are brown down by sucrase and lactase

Starch glycogen -(amylase)→ Maltose-(maltase)→ Glucose

Sucrose-(sucrase)→ Glucose and Fructose

Lactose -(lactase)→ Glucose and Galactose

Digestion of Proteins

• Are digested by a multi step process that begins in the stomach and continues through the intestine by trypsin, elastase, and chymotrypsin

  • Turn large peptides to small peptides, created by pancreas located in SI

• Carboxy peptidase, dipeptidase, and aminopeptidase reduce peptides to free amino acids in SI

• Pepsin (stomach): proteins broken down to large peptides

Digestions of Lipids

• Are digested and absorbed in the small intestine by pancreatic lipase

• Emulsification: large lipids turned to small lipid globules by bile salts

Sights Triggers Digestion

Seeing a plate of food triggers the secretion of saliva in the mouth and the production of HCL in the stomach

Digestive Phases

1. Cephalic phase: CNS prepares food arrival

2. Gastric Phase: food arrives in stomach

3. Intestinal phase: chyme enters SI

Gastrin and Somatostatin

• Gastrin: released in gastric phase by G cells secreting HCL

• Somatostatin: stops HCL secretion

• Secretin: stimulates pancreas to release alkaline solution in duodenum

Gastrin and somatostatin is a negative feedback system

Mouth

• Mechanical digestion (chewing and swallowing)

• Chemical digestion of carbohydrates (saliva)

Stomach

• Mechanical digestion (peristaltic mixing and propulsion)

• Chemical digestion of proteins

• Absorption of lipid-soluble substances like aspirin

Small Intestine

• Mechanical digestion (mixing and propulsion, primarily by segmentation)

• Chemical digestion of carbohydrates, lipids, proteins, and nucleic acids

• Absorption of peptides, amino acids, glucose, fructose, lipids, water, minerals, and vitamins

Large Intestine

• Mechanical digestion (segmental mixing, mass movement for propulsion)

• No chemical digestion except by bacteria

• Absorption of ions, water, minerals, vitamins, and small organic molecules produced by bacteria

Gastric Inhibitory Peptide

• Secreted by SI to slow down the peristaltic movements of the intestine to allow fatty foods more time to be digested and absorbed

Chapter 35

Nervous System

Nervous System

• Parts of the nervous system are involved in determining how hard to push off and turn as well as controlling the muscles throughout the body that make complicated movements possible

• Neurons: specialized cells that can receive and transmit chemical/electrical signals

• Glia: cells that provide support function for neurons by playing an information processing role that is complementary to neurons

Nervous Systems Vary in Complexity

• In cnidarians: nerve cells form a decentralized nerve net

• In echinoderms: nerve cells are bundled into fibers called neurons

• Planarians: neurons cluster into an anterior brain to process information

Nervous Systems Vary in Complexity Pt 2

• Arthropods: cluster of nerve cells bodies, called peripheral ganglia, located along the ventral nerve cord

• Mollusks (squid and octopi): have complex brains containing millions of neurons

• Vertebrates: the brain and spinal cord comprise the central nervous system while neurons extending into the rest of the body comprise the peripheral nervous system

Neurons

• Neurons contain organelles common to many other cells, such as a nucleus and mitochondria

• They also have more specialized structures including dendrites and axons

Look at picture in notes to know parts of neuron

4 Types of Neurons

• Unipolar neuron: found in insects, stimulate muscles or glands

• Bipolar neuron: retinal biopolarcey

• Multipolar neuron” most common type of neuron found in CNS, ex: Purkinje cell in cerebellum

• Pseudouniplolar neuron: have traits of unipolar and multipolar neurons, found as most sensory neurons

Look at pictures in notebook to know shapes

Fluorescence of Neuron and Division

• Cells that are actively dividing have bromicdoxyuridine (BrdU) incorporated into their DNA and are labeled RED

• Cells that express glial fibrillary acidic protein (GFAP) are labeled GREEN

• Astrocytes, not neurons, express GFAP. Thus cells that are labeled both red and green are actively dividing astrocytes, cells only red are dividing neurons

Glial Cells

• Support neurons and maintain their environment

• Most brain tumors are caused by mutations of the glia

• 10x more glia cells in the nervous system than neurons

Glial Cells of the Central Nervous System

• Oligodendrocytes: from myelin sheath around axons

• Astrocytes: form blood brain barrier, provide nutrients to neurons, maintain their extracellular environment, provide structural support

• Microglia: scavege pathogens and dead cells

• Ependymal cells: produce cerebral spinal fluid that cushion neurons

• Radial glia: scaffolds for developing neurons as they migrate to their end destinations

Glial Cells of the Peripheral Nervous System

• Schwann cells: form the myelin sheath

• Satellite cells: provide nutrients and structural support to neurons

Voltage-gated ion channels

• Open in response to changes in membrane voltage

• After activation they become inactivated for a brief period and will no longer open in response to a signal

Steps of the Voltage gated ion channel

1. Closed: at resting potential the channel is closed

2. Open: In response to the nerve impulse the gate opens and Na+ enters the cell

3. Inactivated: For a brief period following activation the channel does not open in response to a new signal

Resting Membrane Potential

• Is a result of different concentrations of Na= and K= ions inside and outside the cells

• A nerve impulse causes Na= to enter the cell resulting in depolarization (+10mV)

• At the peak action potential (+40mV) K+ channels open and the cell becomes hyperpolarized.

  • -70mV is the resting potential for most neurons maintained by the sodium-potassium pump (2K in 3Na out)

  • Threshold of excitation is -55mV

Formation of an Action Potential

1. A stimulus from a sensory cell or another neuron causes the target cell to depolarize toward the threshold potential (-55mV)

2. If the threshold of excitation is reached all the Na+ channels open and the membrane depolarizes

3. At peak potential (+40mV) K+ channels open and K+ begins to leave the cell at the same time the Na+ channels close

4. The membrane becomes hyperpolarized as K+ ions continue to leave the cell. The hyperpolarized membrane is in a refractory period and cannot fire

5. The K+ channels close and the Na+/K+ transporter restore the resting potential

Speed of Conduction

• Speed of conduction of an action potential along an axon is influenced by both diameter of the axon and the axon’s resistance to current leak

• Myelin acts as an insulator that prevents current from leaving the axon increasing the speed of action potential conduction

• The jumping of the action potential from one node to the next is called saltatory conduction

Nodes of Ranvier

• Are gaps in myelin coverage along axons

• Nodes contain voltage-gated K+ and Na+ channels.

• Action potentials travel down the axon by jumping from one node to the next

Communication at Chemical Synapses that Requires Neurotransmitters

1. When the presynaptic membrane is depolarized, voltage-gated Ca2+ channels open and allow calcium to enter the cell

2. The calcium entry causes synaptic vesicles to fuse with membrane and release neurotransmitter molecules to the synaptic cleft

3. The neurotransmitter diffuses across the synaptic cleft and bins to ligand-gated ion channels in the postsynaptic membrane, result8ing in a localized depolarization or hyperpolarization of the postsynaptic neuron.

EPSP and IPSP

• A single neuron can receive both excitatory and inhibitory inputs from multiple neurons resulting in local membrane depolarization input (ESPS) and hyperpolarization (IPSP) input

• All of these inputs are added together at the axon hillock

• If the EPSPs are strong enough to overcome the IPSPs and reach the threshold of excitation the neuron will fire

  • This occurs in axon hillock, called summation

Examples of EPSPs and IPSPs

• acetylcholine is EPSP for nerve→ muscle action potential

• GABA (gamma-aminobutyric acid opens Cl- channels, Cl- causes hyperpolarization and is a IPSP

Neurotransmitters Leave the Synapse By

1. Diffusion from the cleft

2. Degradation by enzymes in the cleft

3. Recycled (reuptake) by the presynaptic neuron

Chemical Synapse

• Need neurotransmitters to pass signal

• Unidirectional signaling

• Millisecond delay for action potential to go from presynaptic neuron to postsynaptic neuron

Electrical Synapse

• Instantaneous

• Bidirectional

• More reliable, less likely to be blocked

• Pre and post synaptic membranes close together

Long-term Potentiation (LTP)

• Strengthening of synaptic connection, Hebbian principle

• Arises when a single synapse is repeatedly stimulated

• This stimulation causes calcium and CaMKII-dependent cellular cascade, which results in the insertion of more AMPA receptors into the postsynaptic membrane

• The next time glutamate is released from the presynaptic cell it will bind to NMDA and the newly inserted AMPA receptors, this depolarizing the membrane more efficiently

Longpterm Depression

• Long term weakening of synaptic connection

• Occurs when few glutamate molecules bind to NMDA receptors at a synapse (due to low firing rate of the presynaptic neuron)

• The calcium that does flow through NMDA receptors initiates a different calcineurin and protein phosphatase I-dependent cascade, which results in the endocytosis of AMA receptors

• This makes the postsynaptic neuron less responsive to glutamate released from the presynaptic neuron

The Brain

• The cerebral cortex is covered by 3 layers of meninges:

  • Dua mater: protection

  • Arachnoid mater:

  • Pia mater: cerebral spinal fluid is between arachnoid and pia maters

The Brain Pt 2

• The human cortex includes

  • Frontal: motor cortex, attention, speech, decision making

  • Parietal: speech, reading, somatosensation, cold/hit

  • Temporal: processing and interpreting, memory formation

  • Occipital: vision, seeing, recognizing

The Brain Pt 3

• Different parts of the motor cortex control different muscle groups.

• Muscle groups that are neighbors in the body are generally controlled by neighboring regions of the motor cortex

  • Ex neurons that control finger movement are close to neurons that control hand movement

• Mammals have larger brain-to-body ratios than other vertebrates. Within mammals increased cortical folding and surface area is correlated with complex behavior

Limbic System

• The limbic system regulates emotion and other behaviors

• It includes parts of the cerebral cortex located near the center of the brain

• Includes: cingulate gyrus (regulates emotion and pain), hippocampus, thalamus, hypothalamus, and amygdala (sensation of fear in temporal lobe)

Parts of the Brain

• Basal Ganglia: important in movement control and posture, regulate motivation (Parkinson’s damages basal ganglia)

• Thalamus: Receives sensory and motor input from the body and receives feedback from the cortex. Regulates consciousness, arousal, and sleep states

• Hypothalamus: controls endocrine system. Body’s thermostat. Neurons regulate cardiac rhythms and sometimes sleep schedules

Parts of the Brain Pt 2

• Cerebellum: Controls balance, learning new motor skills, aid in coordinating movement

• Brainstem: Made up of midbrain, pons, and medulla oblongata

  • Alertness, arousal, breathing, blood pressure, digestion, heart rate, swallowing, walking, sensory motor information integration

• Spinal Cord: Controls motor reflexes, unconscious movements, does not regenerate

Spinal Cord

• A cross section of the spinal cord shows grey matter (containing cell bodies and interneurons) and white matter (containing axons)

Autonomic Nervous System

• In the autonomic nervous system a preganglionic neuron of the CNS synapses with a postganglionic neuron of the PNS

• The postganglionic neuron in turn acts on a targeted organ

• Autonomic responses are mediated by the sympathetic and parasympathetic systems

  • Sympathetic = flight or flight

  • Parasympathetic = rest and digest

• The sympathetic and parasympathetic nervous systems often have opposing effects on target organs

Steps of Sympathetic Neurons

• Preganglionic neuron: soma is usually in spine

• Neurotransmitter released

• Postganglionic neuron: soma is a sympathetic ganglion, located next to the spinal cord

• Neurotransmitters released from postganglionic synapse: acetylcholine or nitric acid

• Fight or flight response activated

Steps of Parasympathetic Neuron

• Preganglionic neuron: Soma is usually in brain stem or sacral (bottom of spinal cord)

• Neurotransmitter released

• Postganglionic neuron: soma is usually in a ganglion near the target organ

• Neurotransmitters released from postganglionic synapse: acetylcholine or nitric acid

Disorders of the Brain

• The human brain contains 12 cranial nerves that receive sensory input and control motor output from the head and neck

• Sensory somatic system main neurotransmitter is acetylcholine and only has one synapse unlike autonomic system

Spinal Nerves

• Spinal nerves contain both sensory and motor axons, 31 spinal nerves.

• The somas of sensory neurons are located in the dorsal root ganglia

• The somas of motor neurons are found in the ventral portion of the gray matter of the spinal cord

Alzheimer’s Disease

• Compared to a normal brain the brain of a patient with Alzheimer’s disease shows a dramatic neurodegeneration. Particularly within the ventricles and hippocampus

• Alzheimer’s disease is the most common cause of dementia in elderly

  • Amyloid plaques, neurofibrillary fibers, shrinking of brain volume are symptoms

  • apolipoprotein E (APOE) E4 variant common gene

  • decreases activity of cholinergic neurons (decreases acetylcholine)

Parkinson’s Disease

• Loss of dopamine neurons in substantia nigra

• tremor, slow movement, speech changes

• Caused by genetic and environment

• Lewy bodies in dopaminergic neurons (increase is more severe)

• L-DOPA helps treat, no cure

• Patient often have a characteristic hunched walk

Diseases of Brain

• Stroke: 3rd cause of death in US, smoking 2x increases risk of stroke

• Schizophrenia: increased dopamine

• Depression: decreased serotonin/norepinephrine/dopamine

• Many people with ADHD have one or more other neurological disorders

Chapter 36

Sensory Systems

Sharks

• Sharks use their sense of sight, vibration (lateral-line system) and smell to hunt, but it also relies on its ability to sense the electric fields of pray, a sense not present in most land animals

Definitions

• Reception: activation of sensory receptors, first step of sensation

• Receptive field": region space receptors responds to stimulus

• Perception: Individuals interpretation of a sensation. Occurs in brain

  • All sensory signals (except olfactory) transmit through the CNS to the hypothalamus

Definitions Pt 2

• Vestibular sensation: an organism’s sense of spatial orientation and balance, proprioception (position of bones and joints), and sense of limb position.

  • Is used to tract Kinesthesia (limb movement)

• Sensory transduction: converting stimulus to electrical signal in nervous system

Intensity of Stimulus is affected by

1. More rapid train of axon potentials

2. Number of receptors activated

Two Ways to do Sensory Transduction

1. Neuron works with a sensory receptor (cell or cell process specialized to engage with a stimulus)

2. Sensory nere ending responds to a stimulus in the internal or external environment

Mechanosensitive Ion Channels

• Are gated ion channels that respond to mechanical deformation of the plasma membrane

• A mechanosensitive channel is connected to the plasma membrane and the cytoskeleton by hair like tethers

• When pressure causes the extracellular matrix to move, the channel opens allowing ions to enter or exit the cell

• Stereocilia in the human ear are connected to mechanosensitive ion channels. When a sound causes the stereocilia to move mechanosentivie ion channels transduce the signal to the cochlear nerve

Touch (Somatosensation)

Mammalian skin has 3 layers:

1. Epidermis

2. Dermis (hair follicles)

3. Hypodermis (holds 50% of body fat)

• Free nerve ending: unencapsulated dendrite of sensory neuron. Is the most common nerve ending in skin. Located in epidermis

Five of the Primary Mechanoreceptors in the Skin

1. Merkel’s disk: unencapsulated, respond to light touch. Found in skin, hair, glabrous skin (hairless) like fingers

2. Meissner’s corpuscles: Capsulated, respond to touch and low-frequency vibration. Found in fingertips and eyelids

3. Ruffini-endings: capsulated, detect stretch, deformation with joints, and warmth. Found in glabrous skin, and hairy skin

   1. Warm receptors are placed lower than cold so humans detect cold first

Five of the Primary Mechanoreceptors in the Skin Pt 2

4. Pacinian corpuscles: Capsulated, detect transient pressure and high frequency vibration. Found in dermis of glabrous and hairy skin, joint capsules, pancreas, genitals, breasts

5. Krause end bulb: capsulated, detects cold

Extra Facts of Touch

• There are less Pacinian corpuscles and Ruffini endings in the skin than Merkle’s discs and Meissner’s corpuscles

• Muscle spindles: Stretch receptors that detect the amount of stretch or lengthening of muscles

• Golgi tendon organs: tension receptors that detect force of muscle contraction

Extra Facts of Touch Pt 2

• Baroreceptors: detect pressure change in organ. Found in carotid artery, aorta, and lungs

• Meissner corpuscles in the fingertips allow for touch discrimination of detail

• Pacinian corpuscles detect pressure (touch) and high frequency vibration

Nociceptive Receptors

• Pain receptor

• Most pathways go through thalamus however some pathways go to the hypothalamus and stimulate the sympathetic nervous system

Taste Receptors

1. Salty: Na+ excretion

2. Sour: acid binds and H+ concentration depolarizes

3. Sweet and bitter: G-protein couples receptors

4. Umami: taste of L-glutamate

Gustation is taste while olfaction is smell

Smell and Taste

• In the human olfactory system, bipolar olfactory neurons extend from the olfactory epithelium where olfactory receptors are located in the olfactory bulb

• Bipolar neuron receptors are specialized detect specific tastes/smells but they can overlap odorants

• Sensations go directory to the cerebral cortex unlike most other sensations which go through the thalamus

Pheromones

• A chemical released by an animal that affects the behavior or physiology of animals of the same species

• Vomeronasal organ (VNO) is a tubular fluid filled organ in the nasal cavity of most vertebrates that are sensitive to pheromones

• A pheromone signal goes to amygdala then hypothalamus

• The flehman response in a tiger results in the curling of the upper lip and helps airborne pheromone molecules enter the vomeronasal organ

Parts of Tongue

• Foliate, circumvallate, and fungiform papillae are located on different regions of the tongue

• Pores in the tongue allow tastes to enter taste pores in the tongue

• Primary organ of taste is the taste bud which is a cluster of gustatory receptors located on bumps on tongue called papillae

• Taste buds replaced every 10-14 days

Types of Papillae

• Filiform papillae: tactile, provide friction to help tongue move substances, contain no taste cells

• Fungiform papillae: contain 1-8 taste buds and have pressure and temperature

• Folate papillae: contain 3k taste buds in folds

• Circumagitate papillae: V shape surrounded by groove with 250 taste buds

Pathways of Taste

1. olfactory bulb (contain glomeruli) → olfactory cortex → frontal cortex and thalamus

2. Signal → amygdala → hypothalamus → hypothalamus/thalamus/cortex

3. Olfactory signal → cortical center → in temporal for memory

Sound

• For sound waves, wavelength corresponds to pith. Amplitude of the wave corresponds to volume

• Speed of sound is dependent on altitude, temp, and medium

• Frequencies above human range are called ultrasound