BIOL 1720 Exam 1 Review

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Animal Form and Function

• Anatomy: the study of the biological form of an organism

• Physiology: the study of the biological functions an organism performs

• The comparative study of animals reveals that form and function are closely related

Evolution of animal size and shape:

• Physical laws constrain strength, diffusion, movement, and heat exchange

• As animals increase in size, their skeletons must be proportionately larger to support their mass

• Evolutionary convergence reflects different species’ adaptations to a similar environmental challenge

Animal form and function are correlated at all levels of organization

• Size and shape affect the way an animal interacts with its environment

• Many different animal body plans have evolved and are determined by the genome

Adaptation: an environmentally advantageous trait

Exchange with the environment:

• Materials such as nutrients, waste products, and gases must be exchanged across the cell membranes of animal cells

• Rate of exchange is proportional to a cell’s surface area (diffusion)

• Amount of exchange material is proportional to a cell’s volume (metabolism)

  • As a cell gets larger, surface for diffusion drops

Law of diffusion: Dictates the rate at which material diffuse into and out of the tissue

• Calculated

  • Surface area (large)

  • Concentration difference (large)

  • Distance (small)

    • Exists in gas exchange such as the respiratory system

Two environments:

• Internal

  • Regulated via homeostasis

    • Homeostasis: regulation of the internal environment

  • Spaces: 

    • Intracellular: inside the cells

    • Extracellular: outside of the cells

      • Interstitial space: interstitial fluid

      • Plasma space: blood

  • Regulation of the intracellular space

• External

Surface area/Volume relationships:

• As a cell gets larger, its volume increases much faster than its surface area

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Hierarchical Organization of Body Plans

• Most animals are composed of specialized cells organized into tissues that have different functions

• Tissues make up organs, which together make up organ systems

  • Some organs belong to more than one organ system

• Different tissues have different structures that are suited to their functions

• Tissues are classified into four main categories:

  • Epithelial

    • Apical membrane (outside of the animal or lining an organ)

    • Basolateral membrane (connects to other tissues)

    • Contains cells that are closely joined

    • Shape may be cuboidal, columnar, or squamous

    • Function is protective and exchange (skin)

      • Protection from the environment

      • Regulate movement of materials in and out of the body

    • Arrangement may be:

      • Simple (single cell layer)

      • Stratified (multiple tiers of cells)

      • Pseudostratified (a single layer of cells of varying length)

  • Connective

    • Made up of cells that are surrounded by extracellular substance

    • Function is to support and bind other tissues together (bones)

    • Contains sparsely packed cells scattered throughout ECM

      • Matrix consists of fibers in a liquid, jellylike, or solid foundation

        • Can be elastic, collagen, or reticular

    • Examples:

      • Loose connective tissue

      • Fibrous connective tissue

      • Blood

      • Cartilage

  • Muscle

    • Composed of thin cells capable of contraction

    • Function: Movement of materials in the body, and limbs/body

    • Types:

      • Skeletal (striated)

        • Striated fibers; multiple nuclei, long; made up of sarcomeres

        • Attached to the skeleton and is used for movement

        • Under voluntary control

      • Smooth

        • Smaller/single cells; single nuclei; no striations

        • Under involuntary control

        • Common throughout the body

      • Cardiac

        • Single cells; binucleate or single nuclei; connected by intercalated disk (gap junctions) to allow for intercellular communication

        • In the heart; allows the heart to be spontaneously active

  • Nervous

    • Senses stimuli and transmits signals throughout the animal

    • Contains:

      • Neurons (nerve cells) that transmit nerve impulses

        • Made up of dendrites (input), cell body (stores info), and axon (output)

      • Glial cells (glia) that help nourish, insulate, and replenish neurons

Internal Regulation

• Regulators: animals that use internal mechanisms to control internal change, despite external fluctuation

• Conformers: animals that allow their internal condition to change in accordance with external changes

• Animals may both conform to and regulate environmental variables

Homeostasis allows for internal regulation, regardless of external environment

• In humans, body temperature, blood pH, glucose concentration, etc. are all maintained at a constant level

• Fluctuations above or below a set point serve as a sensor and trigger a stimulus

  • Stimulus is detected by a motor output (response)

  • Response returns the variable to the set point

• Equilibrium is maintained by negative feedback

  • Helps return variable to a normal range

• Positive feedback amplifies a stimulus and does not usually contribute to homeostasis

Thermoregulation: the process by which animals maintain an internal temperature within a tolerable range

• Endothermic: animals that generate heat by metabolism (tend to be homeotherms)

  • Constant

  • Birds and mammals are examples

  • Active at a greater range of external temperatures

  • More energetically expensive

• Ectothermic: animals that gain heat from external sources (tend to be poikilotherms)

  • Include most invertebrates, fish, amphibians, and reptiles

  • Varies with environment

  • Tolerate wider ranges in internal temperature

  • Less energetically expensive

• Poikilotherm: body temperature varies with its environment

• Homeotherm: relatively constant body temperature

Balancing Heat Loss and Gain

• Radiation: Brings heat into the animal

  • Solar, infrared

• Evaporation: Typically cooling

  • Sweating

• Convection: Typically cooling, insulating

  • Standing in front of a fan, wind

• Conduction: Can be cooling or heating

  • Placing body on a warmer or colder surface

Integumentary system: Skin, hair, and nails; allows for heat regulation in mammals

• Adaptations that help animals thermoregulate:

  • Insulation

    • Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment

    • Especially important in marine mammals (whales, walruses)

  • Circulatory adaptations

    • Regulation of blood flow near the body surface

      • In vasodilation, blood flow in the skin increases, facilitating heat loss

      • In vasoconstriction, blood flow in the skin decreases, lowering heat loss

    • Countercurrent exchange: transfer heat between fluids flowing in opposite directions; reduces heat loss

      • Seen in tuna, ducks, dolphins, sharks, endothermic insects

  • Cooling by evaporative heat loss

    • Done by producing water on the surface to reduce heat through evaporation

      • Sweating, bathing, panting

  • Behavioral responses

    • Moving from a warm or cold environment into one more suitable for heat regulation

    • Some terrestrial invertebrates can minimize or maximize absorption of solar heat

      • Huddling with other animals, ball up to reduce surface area

  • Adjusting metabolic heat production

    • Thermogenesis: The adjustment of metabolic heat production to maintain body temperature 

      • Increased by muscle activity such as moving or shivering

      • Nonshivering thermogenesis takes place when hormones cause mitochondria to increase their metabolic activity

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Animal Nutrition

• Digestion and conversion efficiency

Nutrition: Food is taken in, taken apart, and taken up

• Animals fall into three categories:

  • Herbivores (plants and algae)

  • Carnivores (other animals)

  • Omnivores (regularly consume animals as well as plants; take advantage of both sources)

• Most animals are opportunistic in their nutrition

Uses of nutrients:

• Fuel cellular metabolism and activities

• Organic raw materials to make tissues

• Provide essential nutrients not produced by animals

  • Vitamins

Aerobic Respiration:

• Three basic units of food:

  • Carbohydrates

  • Proteins

  • Lipids

• Calorie: The energy produced by the oxidation of 1g of material

  • Lipids 9.5Kcal

  • Proteins and carbohydrates 4.25 Kcal

• Used to maintain BMR

Essential Nutrients

• Essential amino acids

  • Animals require 20

  • Must be obtained from food in preassembled form

  • Meat, eggs, and cheese provide all the essential amino acids; thus classified as ‘complete’ proteins

• Essential fatty acids

  • Must be obtained from the diet and include certain unsaturated fatty acids

  • Deficiencies in fatty acids are rare

• Vitamins

  • Organic molecules required in the diet in small amounts

  • Humans require 14

  • Grouped into two categories: water-soluble and lipid-soluble

• Minerals

  • Simple inorganic nutrients, required in small amounts

  • Ingesting large amounts can upset homeostatic balance

Phases of food processing:

• Ingestion

  • Food enters the system

  • Oral cavity: food material is masticated or chewed to mix materials and combine with fluids 

    • Teeth and jaw structure have evolved for specific diets

    • Herbivores:

      • Teeth are flat for grinding/crushing plant matter

      • Jaw is at a 90 degree angle

    • Carnivores:

      • Teeth are sharp pointed

      • Jaw is at a greater angle (>90 degrees)

    • Omnivores:

      • Combination of each

  • Salivary Glands

    • Add saliva (a glycoprotein)

    • An amylase that begins the  breakdown of polysaccharides

    • Contains antibacterial agent; kills most of the bacteria in mouth and food

    • Lingual Lipase

    • Growth factors

  • Tongue shapes food into a bolus (ball) and provides help with swallowing

  • Throat (pharynx) is the junction that opens to both the esophagus and the trachea

    • Esophagus:

      • Striated muscle at top: upper third of the esophagus is voluntary contraction

      • Smooth muscle at the end: lower two thirds are involuntary

• Digestion

  • Intracellular digestion: internalization of the food material into:

    • Food Vacuole: membrane surrounded space

    • Lysosomes: break down the item

  • Extracellular digestion: food material is broken down before it enters the animal

    • Limits self digestion

    • Gastrovascular cavity: digestive sac; one opening to a cavity in which materials are broken down

    • Digestive tract: tube running between two openings with specialization of areas of function

      • Alimentary Canal

    • Allows for the development of feeding on food larger than itself

    • Allows for cellular specialization: all the cells only need to retain the ability to absorb nutrients

    • Separation of digestive processes: proteins can be digested in one section while carbohydrates can be broken down in a second location

  • Vertebrate digestive system:

    • Gastrointestinal tract and accessory glands (saliva glands)

    • Activity of the GI tract

      • Peristalsis: bulk movement of materials through the GI in waves

      • Sphincters: regulation passage

  • Mechanical Digestion: teeth or gizzard grinds material

  • Chemical breakdown: secretion of enzymes that breakdown molecules

  • Stomach: 

    • Stores food and converts the meal to acid chyme; lined by a mucus protective layer

      • Secretes Gastric Juice

        • Parietal cells: create hydrochloric acids

          • Hydrogen ion, positive charge; chloride, negative charge; they come together and create hydrochloric acid within the stomach

          • Can lower pH by adding H+ or reduce pH by slowing H+ pumping

        • Chief cells: create pepsinogen → pepsin → breaks down proteins

          • Low pH environment in the stomach stimulates these cells and activates pepsinogen, allowing pepsin to break down protein and other particles

    • Dynamics of the stomach: 

      • Coordinated contraction/relaxation of stomach muscle churn the stomach’s contents

      • Sphincters prevent chyme from entering the esophagus; regulate its entry into the small intestine

• Absorption

  • Transporting from the digestive tract into the body

  • Small Intestine

    • Villi: fingerlike or threadlike projections from the surface of the small intestine; serves to increase surface area and facilitate the passage of fluid or nutrients

    • Microvilli: increase surface area for absorption

    • Duodenum:

      • Secreted from the Pancreas

        • Bicarbonate increased the pH

        • Amylase: break down sugars

        • Lipase: breaks down fats

        • Protease: breaks down proteins

      • Bile from the liver and gallbladder are also dumped into the small intestine for emulsifying lipids

  • Pancreatic Secretions

    • Pancreas produces proteases trypsin and chymotrypsin

      • Activated in the lumen of the duodenum

      • Solution is alkaline and neutralizes the acidic chyme

    • Bile production by the liver:

      • In the small intestine, bile aids in digestion and absorption of fats

        • Made in the liver and stored in the gallbladder

        • Destroys nonfunctional red blood cells

  • Transportation:

    • Proteins and carbohydrates are actively moved

      • Apical membrane: outside of epithelial cells

      • Basolateral membrane: inside of epithelial cells

        • Connected to the body

        • Moves sodium out of the cell, potassium into the cell

        • Allows for absorption of glucose as a cotransporter with sodium back into the cell across its gradient

      • Taken to the membrane

    • Triglycerides get emulsified by the bile

    • Phospholipids, cholesterol, and proteins are water-soluble and go through the membrane

    • Triglycerides and the water-soluble materials combine to create chylomicrons which are water-soluble; go into the lymphatic system and then the cardiovascular system

  • Large Intestine

    • Colon of the large intestine is connected to the small intestine

    • Cecum aids in the fermentation of plant material; connects where the small and large intestines meet

    • Primary function of the large intestine: recovering water, production of vitamins, eliminating fecal material

  • Accessory Organs

    • Pancreas

    • Liver

    • Gallbladder

  • Regulation of digestion

    • Each step in the digestive system is activated as needed

    • Enteric division of the nervous system helps to regulate the digestive process

    • Endocrine system also regulates digestion through the release and transport of hormones

  • Regulation:

    • Two components:

      • Neural: the site and smell of food can stimulate the release of salive and gastric secretions

      • Hormonal: gastrin release in proteins in the food stretch

        • Causes release of pepsinogen and HCL

        • pH goes down inhibiting further Gastrin release

        • Negative feedback loop

• Elimination

  • Indigestible material is expelled

Feeding Mechanisms:

• Suspension feeder: flamingos and some whales

• Bulk feeder: humans

• Fluid feeder: hummingbirds, vampire bats

• Surface absorption: annelids and parasites

** Digestive strategies are coupled to the evolution of specific digestive structures

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The Nervous System: Control of Function

• All cells have membrane potential

  • Resting potential: cell not transmitting signal, typically -70mV

  • Membrane potential: electrical charge, ranges from -50mV – -100mV

    • Voltage required for the membrane to avoid going down its concentration gradient

    • Not measured, but calculated

• Relative concentration of sodium outside the cell is high; relative potassium concentration inside the cell is high

  • Inside the cell, negatively charged proteins can’t leave; negative charge on the inside of the cell, positive on the outside

• Cells can change their membrane potential

• By adjusting permeability to ions, cells can change their action potential

  • Excitable cell: resting membrane potential (eg. -70 mV)

  • Equilibrium voltage: voltage needed to keep cells from going down in their concentration gradient

  • Hyperpolarization: potassium leaves the cell

    • Pulls away positive charge; inside becomes more negative thus hyperpolarizing the cell

  • Depolarization: sodium enters the cell (across its natural concentration gradient and voltage gradient)

    • Brings positive charge, inside becomes more positive thus depolarizing the cell

• Gates open for sodium/potassium when the cell needs more positive or negative charges; sodium comes in or potassium leaves

Equilibrium Potential: the membrane voltage for a particular ion at equilibrium; can be calculated using the Nernst equation

• The equilibrium potential of K+ (EK) is negative, while the equilibrium potential of Na+ (ENa) is positive

Resting Potential: In a mammalian neuron at resting potential, the concentration of K+ is highest inside the cell, while the concentration of Na+ is highest outside the cell

• Sodium-potassium pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane

• These concentration gradients represent chemical potential energy

If the threshold is reached, it results in an action potential which significantly affects the membrane potential

• Membrane potential goes towards equilibrium for that ion (eg. sodium goes towards +50 during action potential)

• Voltage-gated channels will open, allowing the depleted ion to flow into the cell

• During the rising phase, the threshold is crossed, and the membrane potential increases

• During the falling phase, voltage-gated ion channels become inactivated, and the membrane potential decreases

• Sodium-Potassium ATPase returns to regulating the Na+ and K+ concentration

Refractory period: after an action potential, a second action potential cannot be initiated

• Refractory period is a result of a temporary inactivation of the Na+ channels

• Inactivated Na+ channels behind the zone of depolarization prevent the action potential from travelling backwards

Axon Structure: 

• Speed of an action potential increases with the axon’s diameter

• In vertebrates, axons are insulated by a myelin sheath, which causes an action potential’s speed to increase

• Myelin sheaths are made by glia; oligodendrocytes in the CNS, and Schwann cells in the PNS

• Action potentials are formed only at nodes of Ranvier (depolarized region), gaps in the myelin sheath where voltage-gated Na+ channels are found

• Action potentials in myelinated axons jump between the nodes of Ranvier in a process called saltatory conduction

Transmission of Information: 

• Neurons communicate with other cells at synapses

  • At electrical synapses, the electrical current flows from one neuron to another

  • At chemical synapses, a chemical neurotransmitter carries information across the gap junction

  • Most synapses are chemical synapses

• Neurotransmitters are contained within the vesicles on each synapse

• Two type of synapses:

  • Electrical

  • Chemical

• Within the presynaptic neuron:

  • Synaptic vesicles

  • Conversion

  • Depolarization channel

    • Synaptic vesicle fusion

    • Bind to receptors

• Neurotransmitter binding causes ion channels to open, generating a postsynaptic potential

  • Excitatory postsynaptic potentials (EPSPs) are depolarizations that bring the membrane potential toward threshold

  • Inhibitory postsynaptic potentials (IPSPs) are hyperpolarizations that move the membrane potential farther from threshold

• After release, the neurotransmitter:

  • May diffuse out of the synaptic cleft

  • May be taken up by surrounding cells

  • May be degraded by enzymes

• Summation of Postsynaptic Potential:

  • Most neurons have many synapses on their dendrites and cell body

• Types of summation:

  • Subthreshold (no summation)

  • Temporal summation

  • Spatial summation

    • EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron add together

  • Spatial summation of EPSP and IPSP

• Modulated Signaling at Synapses

  • In some synapses, a neurotransmitter binds to a receptor that is metabotropic

  • Movement of ions through a channel depends on one or more metabolic steps

  • Effects of second-messenger systems have a slower onset but last longer than ligand-gated channels

Neurotransmitters:

• 5 main groups:

  • Acetylcholine

    • Important for cardiac muscles and skeletal muscles

  • Biogenic

    • Epinephrine, norepinephrine, serotonin, dopamine

  • Amines

    • GABA: produce IPSP; inhibit neural activity

    • Alcohol, barbiturates, etc. bind to channel increasing the GABA action

  • Amino acids

  • Neuropeptides

    • Endorphins; opioids bind to this receptor

  • Gases

• A single neurotransmitter may have tens of different functions

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Sensory Systems

Sensory Receptors: transduce stimulus energy and transmit signals to the central nervous system

• All stimuli represent forms of energy

• Sensory receptor converts stimulus energy into a change in the membrane potential

• When a stimulus is received and processed by the nervous system, a motor response may be generated

  • May involve a simple reflex or more elaborate processing

4 basic functions in common with all sensory pathways:

• Sensory reception

  • Detection of stimuli by sensory receptors

  • Sensory receptors are sensory cells or organs

• Transduction

  • Conversion of stimulus energy into a change in the membrane potential of a sensory receptor

  • Called a receptor potential

    • Graded potentials; their magnitude varies with the strength of the stimulus

• Transmission

  • Receptors may be neurons or non-neuronal receptors

  • Size of a receptor potential increases with the intensity of the stimulus

• Perception

  • The brain’s construction of stimuli

  • Brain distinguishes stimuli from different receptors based on the path by which the action potentials arrive

Amplification and adaptation:

• Amplification: the strengthening of a sensory signal during transduction

• Sensory adaptation: a decrease in responsiveness to continued stimulation

Types of sensory receptors:

• Mechanoreceptors

  • Sense physical deformation caused by forms of mechanical energy

  • Consist of ion channels linked to structures that end outside the cell (such as hairs/cilia)

    • Mammalian sense of touch relies on mechanoreceptors that are dendrites of sensory neurons

• Chemoreceptors

  • Taste, smell

  • Can transmit information about the total solute concentration of a solution

  • When a stimulus molecule binds to a chemoreceptor, the chemoreceptor becomes more or less permeable ions

• Electromagnetic receptors

  • Detect electromagnetic energy such as light, electricity, and magnetism

    • Platypus has electroreceptors on its bill that can detect the electric field generated by prey

    • Some organisms migrate using Earth’s magnetic field to orient themselves

• Thermoreceptors

  • Temperature measuring

  • Detect heat and cold

  • Receptors that respond to capsaicin (in jalapeno and cayenne peppers) respond to high temperatures also, by opening a calcium channel

  • Mammals have a variety of thermoreceptors

• Pain receptors

  • (aka nociceptors); detect stimuli that reflect harmful conditions

  • Respond to excess heat, pressure, or chemicals released from damaged or inflamed tissues

  • Chemicals produced in an animal’s body sometimes enhance the perception of pain

  • Condocireceptors 

Hearing and equilibrium:

• Hearing and perception of body equilibrium are related in most animals

• For both senses, settling particles or moving fluid is detected by mechanoreceptors

• In most terrestrial vertebrates, sensory organs for hearing and equilibrium are closely associated in the ear

  • Fish and aquatic amphibians also have a lateral line system along both sides of their body

  • Lateral line system contains mechanoreceptors with hair cells that detect and respond to water movement

Sound:

• Sound comes into the auditory canal and hits the tympanic membrane; travels through the malleus, incus, and stapes into the oval window en route to the cochlea

• Organ of Corti within the cochlea is made up of hair cells and axons of sensory neurons

  • At rest, hair cells dump a certain amount of neurotransmitter; when bent due to stimuli, there is an increase in action potential

  • The more action potentials you get, the higher the intensity

    • Decrease in action potential if there is a weak intensity; increase with higher intensity

• Basilar membrane allows for detection of high and low frequencies based on the distance from oval window

Equilibrium:

• Several organs in the inner ear detect body movement, position, and balance

• Utricle and saccule contain hair cells projecting into a gelatinous material

• Embedded in the gel are granules called otoliths that allow us to perceive position relative to gravity/movement

• Three semicircular canals contain fluid and can detect angular movement in any direction

Vision:

• The underlying mechanism for capturing light is photoreceptors

  • Photoreceptors: cells that contain light-absorbing pigment molecules

• Light hits the retina, transmits through tissue prior to touching photoreceptors

  • Rods: pick up intensity of light

  • Cones: pick up colors in light

• Vertebrate pigments consist of retinal, a light-absorbing pigment bound to a membrane protein called an opsin

  • One such pigment is called rhodopsin

  • Absorption of light causes a shape change in retinal

Taste:

• Gustation (taste) is dependent on the detection of chemicals called tastants

• Olfaction (smell) is dependent on the detection of odorant molecules

• Five taste perceptions:

  • Sweet, sour, salty, bitter, and umami

• Receptors exist for all five tastes

  • Located in taste buds; associated with projections called papillae

• Three types of taste receptors

  • G protein-coupled receptors (sweet, bitter)

  • TRP family (similar to the capsaicin and other thermoreceptor proteins); (sour)

  • Sodium channel (salt)

Smell:

• Olfactory receptor cells are neurons that line the upper portion of the nasal cavity

• Binding of odorant molecules triggers a signal transduction pathway, generating action potentials

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Endocrine System

• Hormones:

  • Chemical signals that are secreted into the circulatory system and communicate with body systems

  • Composed of two systems:

• Endocrine system: secretes hormones that coordinate slower but longer-acting responses

  • Growth, metabolism, reproduction, behavior, development

• Nervous system: conveys high speed electrical signals along neurons

Intercellular Communication

• Endocrine signaling: hormones secreted into extracellular fluids by endocrine cells reach their targets via the bloodstream

  • Maintains homeostasis, mediates responses to stimuli, regulates growth and development

• Paracrine/Autocrine signaling systems

  • Local regulators: molecules that act over short distances, recahing target cells solely by diffusion

    • Paracrine signaling: target cells lie near the secreting cells

    • Autocrine signaling: target cell is also the secreting cell

• Synaptic and Neuroendocrine Signaling

  • Synapses terminal end of the neuron

    • Secrete neurotransmitters that diffuse short distances and bind to receptors on target cells

• Pheromones:

  • Chemicals that are released into the environment to communicate with members of the same animal species

    • Mark trails to food, define territories, attract mates

Endocrine tissues and organs

• Endocrine glands: Ductless organs that contain groups of endocrine cells

  • Secrete hormones directly into the surrounding fluid

• Three major classes of molecules function as hormones in vertebrates:

  • Polypeptides

  • Amines

  • Steroid hormones

• Water-soluble (polypeptides and amines):

  • Do not go into the cell; usually reside outside the cell

  • Secreted by exocytosis; travel freely in the bloodstream, and bind to cell-surface receptors

  • Bind to G protein-coupled receptors

• Lipid-soluble (steroids):

  • Pass through cell membranes (reside in the cell)

  • Diffuse across cell membranes; travel in the bloodstream bound to transport proteins (that allow them to go into solution with water); diffuse through the membrane of target cells

  • Last longer but take longer to incur; cause gene expression

• One hormone can have multiple effects

  • Type of receptor, secondary messenger, or hormone all affect the outcome of the operation

• Local Regulators

  • Secreted molecules that link neighboring cells or directly regulate the secreting cells

  • eg. Cytokines and growth factors, nitric oxide, prostaglandins

    • Prostaglandins help regulate aggregation of platelets to form blood clots

• Coordination of Neuroendocrine and Endocrine signaling

• Utilize feedback loops to regulate cell function (positive and negative)

• Level of hormones are not monitored; hormones simply respond to stimuli 

• Hypothalamus: receives information from the nervous system and initiates responses through the endocrine system

  • Attached to the pituitary gland

    • Posterior pituitary: stores and secretes hormones made in the hypothalamus

      •  release ADH and Oxytocin

    • Anterior pituitary: makes and releases hormones under regulation of the hypothalamus

      • Release dozens of hormones

• Tropic hormones: have an effect or stimulus on other endocrine cells

  • eg. FSH, LH, ACTH

  • Cause endocrine target cells to release other hormones

  • Nontropic hormones: have an effect on regular tissues but not endocrine cells

  • Growth hormones have tropic and nontropic actions

• Adrenal Hormones: Response to stress

  • Adjacent to the kidneys

  • Produce adrenaline and norepinephrine

    • Mediate fight-or-flight

  • Steroid hormones from the adrenal cortex are also released in response to stress (corticosteroids)

    • Triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary

    • Glucocorticoids influence metabolism and the immune system

Exam 1 Review: 2/11

• Study through chapter 32

Neuron Function:

• Depolarization: small rise in resting potential

  • Sodium into the cell

• Hyperpolarization: small decrease in resting potential

*Both depolarizing and hyperpolarizing are lithium-gated ion channels

• Strong depolarizing stimulus leads to action potential (voltage gated channel)

  • Potassium leaves the cell and sodium comes into the cell

Potassium has a negative charge and requires a negative value in the cell to keep it in (maintain equilibrium)

Sodium has a positive charge and requires a positive value to keep it in (maintain equilibrium)

Neuron makeup:

• Dendrites, axon hillock, nucleus, cell body

Heat gaining and loss:

• Radiation: warming

• Evaporation: cooling

• Convection: generally cooling

• Conduction: cooling or warming