Anatomy Test #1

Gross Anatomy

Study of body features visible with naked eye

Histology

Study of things that we can’t see with the naked eye, at the microscopic level.

Cytology

• Study of cell structure and function

• We can see function by their form.

Physiology

• Study of bodily functions

• Outcome of interactions of cells, tissues, organs, and organ systems

• Use of Observation

• More Conceptual/Uses methods of experimental science

Comparative Physiology

• Study of different species to learn about bodily functions in humans (or other animals)

• Reflects on ethical and other limitations on experiments.

• I. E. Use animals for experiments before use of humans.

• Uses rats for quicker reproduction, and cannot feel pain unlike primates.

Ultrastructure

Study of structure down to molecular level

Medical Imaging

Permit viewing inside of body without surgery

Comparative Anatomy

Study of more than one species to determine evolutionary patterns

Exploratory Surgery

No anesthetics, probably alcohol was provided

Hippocrates (c.460-c.375 BCE)

• Developer of the hippocratic oath

• Identified natural sources and causes for disease: i.e bad water, bad food.

Metrodora (-200 BCE) and Galen( c. 130-c.200)

• M - created first women medical guidelines/development

• Women specific

• G - Roman anatomist and physician

• G - worked with gladiators, worked with injured gladiators, could not dissect

• G - Was derived from study of animals, dogs, pigs, under the assumption that they related to human beings

• Errors from text persisted because there was little opportunity to fact check it.

• Illegal to dissect corpses and to find more information

• Slow to develop due to social laws and ethics at the time

Robert Hooke (1635- 1703) and Antony van Leeuwenheok (1623-1723)

• Pioneers in microscopy

• Identify to cells and tissues

• Took decades to create

• Was hot and cold due to the idea that it was a fad, believed not true substance to the practice

Theodor Schwann (1810-82)

• Helped develop modern cell theory

• Established human anatomy at the cell

• Allowed to discover by the technology create before him

Charles Darwin (1809-1882)

• Theory of evolution by natural selection (1859)

• Explains how species originate and change over time

• Aids our understanding of human form and function

• How we are related to animals, but not same species

Common Ancestry

• Knowledge of evolutionary relationships crucial to development of A+P

• Power of natural selection

• Helps explain presence of vestigial organs (see deeper insight 1.1)

• Vestigial: retained through evolutionary history but still does not have a significant function

• Helps us choose appropriate animals for biomedical research

Anatomical Variation

• No two humans exactly alike

• Variation in organ number and position

Kidneys

• Filter blood and removal of certain toxins

• A lot of variation in form, i.e Normal, Pelvic Kidney, Horseshoe Kidney

• Attached to posterior side of abdominal midline

Scientific Inquiry: Inductive Method

• Process of making observations, then drawing generalizations and predictions

• Source of knowledge in anatomy

Deductive Method

• Ask a question and formulate hypothesis (educated speculation)

What makes a good hypothesis?

• Consistent with what is already known

• Testable and falsifiable with evidence

What is scientific Proof?

Something is effectively proved in science when:

• Tested repeatedly

• Supported by reliable observations

• Not falsified by any credible observation

Ultimately, science all truth is tentative

• “Proof beyond a reasonable doubt”

Hierarchy of Complexity

• Organism

• Organ system

• Oran

• Tissue

• Cell

• Organelle

• Macromolecule

• Molecule

• Atom

Characteristics of Life

Organization

• Living things have a higher level of organization than nonliving things

Cellular Basis

• Living matter compartmentalized into one or more cells 

Metabolism

• Exhibit internal chemical change: anabolism and catabolism

Responsiveness and movement

Homeostasis

Maintenance of stable internal conditions, regardless of external conditions.

Development

Change in form or function over lifetime

Reproduction

• Produce copies of themselves, be able to pass genetic material onto offspring (at least have the capacity)

Evolution

Populations change in genetic structure

Homeostasis

• Ability to detect change and activate mechanisms to oppose it

• Permits maintenance of stable internal conditions

• Negative feedback allows for dynamic equilibrium within a limited range around a set point

• Loss of homeostatic control causes illness or death

CORE BODY TEMP 97.7-98.6-99.5 degrees F

When too hot:

• Blood vessels in skin dilate, Increase blood flow to the skin, to remove extra heat in body via sweat

• Sweat begins: releasing water onto skin for a breeze to evaporate water which cools us off.

• Vasodilation

When too cold:

• Blood vessels in skin constrict

• Shivering begins, automatic response: muscles contract to generate heat.

• Vasoconstriction

Receptor

• Structure that senses change in the body

• Ex: baroreceptors

Integrator

• Control center that processes sensory information and directs a response

• Ex: cardiac center of the brain (Brain Stem)

Effector

Structures that restore homeostasis

Self-amplifying cycles

• Lead to greater change in same direction

• Feedback loop is repeated; change produces more change

Produce rapid changes

• Examples include childbirth, blood clotting, protein digestion

• Can sometimes be dangerous (e.g., fever)

Anatomical Terminolog

Most medical terms derived from Greek and Latin Roots

• Terminologia Anatomica is standard reference (continually revised)

• Avoids use of non-descriptive eponyms

Crucial to correctly read, write and understand anatomical terminology

• Trapezius (muscle) vs. Trapezium (bone)

• Gustation vs Gestation

Cytology

 is the study of cells

Robert Hooke (17th c.)

• Described empty cell walls of cork as “cellulae”

Later observed living plant cells; liquid inside it termed cytoplasm

Theodor Schwann (19th c.)

Concluded all animals made of cells

Modern Cell Theory

• All organisms made of one or more cells

• Cell is the simplest structural/functional unit of life

• All cells share basic similarities in chemical composition and metabolic mechanisms

• Cell arise only from other living cells

• No spontaneous generation

Human Cell Size

• Usually about 10-15 um diameter

• Egg cells > 100 um Diameter

• Neurons 1 meter long

Cell Size

• Constrained by surface area-to-volume ratio

• Growth increases volume faster than the surface area

• Large cells unable to absorb nutrients or remove waste efficiently

• Longest total length in human body are found in the legs and feet

• As cell grows its surface-to-volume ratio decreases

Plasma Membrane

• Surrounds cell

• Made of lipids and protein

Cytoplasm

• Fluid between cell membrane and nucleus

Contains organelles, cytoskeleton, inclusions, and cytosol (intracellular fluid, ICF)

Plasma Membrane

• Unit membrane of entire cell

• Oily film of lipids with embedded proteins

Functions of Plasma Membrane

• Defines cell boundaries

• Controls interactions with other cells

• Controls passage of materials into/out of cell

• Semipermeable membrane

• 98% molecules are lipids, 2% protein

• But roughly equal % by weight

Phospholipids

• 75% of membrane lipids

• Bilayer with hydrophilic and hydrophobic ends

• Help keep membrane fluid

Cholesterol

• 20% of membrane lipids

• Affect how tightly the phospholipids are packed, and so the degree to which the membrane is relatively fluid or stiff

Transmembrane proteins

• Pass through the membrane

• Stuck all the way through the membrane, both inside and outside of the cell

• Some move freely in phospholipid layer

• Others anchored to cytoskeleton

Peripheral proteins

• Bound to inner face of membrane

• Anchored to cytoskeleton and transmembrane proteins

Receptors

Bind chemical signals

• Includes “first messengers”, compounds that carry commands from one cell type to another

Change shape, causing specific effects inside the cell

Enzymes

Break down excess chemical signals

• Help produce “second messengers”, compounds that carry out instructions encoded by first messenger

Channel Proteins

Passages that allow water, ions to cross the plasma membrane

• Some permanently open, such as channels

Gated channels open only with certain stimuli

Ligand-gated channels

Need chemical messenger to open

Voltage-gated channels

• Open following changes in membrane voltage

• All cells are electric, different charges that cause change

Mechanically-regulated channels

Require physical stress on cell to open

Cell-Identity Markers

• Glycoproteins that contribute to glycocalyx

• Acts as cellular ID tag to tell the body that it is not a foreign cell

Cell-Adhesion Molecules (CAMs)

• Proteins that bind cells to each other and to extracellular material

• Necessary for most cell types to grow

Microvilli

• Increase cell surface area

• Little extensions on plasma membrane

• (More Surface area you have, the faster you can move substances around)

• Highly developed in cells specialized for absorption (brush border) Ex: Small intestine, kidney

• Contraction of actin filaments (=microfilaments) can bring contents into cell rapidly

• Smallest on the surface

• Can be lengthened or shortened

• Actin is important in Muscle Contraction

Cilia

• Hairlike Processes (7-10um long)

Serve variety of sensory and motility functions, Motile vs. primary cilia

Motile Cilia

• Axoneme

• Core of cilium formed of microtubules in 9 + 2 arrangement(9 pairs of microtubules, then 2 microtubules in the middle) 

• Rooted to cell by basal body

• Dynein Arms

• Pincer like extensions

• Crawl up adjacent microtubule, bending cilium

Ciliary Action

• Cilia immersed in saline, with mucus layer on tips

• Mucus moves unidirectionally due to the pattern of power and recovery strokes.

Cystic Fibrosis

• Disease caused by failure of chloride channels ( pumps to instal properly in plasma membrane

• Mucus becomes sticky and dry, clogging ducts and inhibiting ciliary action

Primary Cilia

• Single, not motile cilium found on most cells

• Cellular antenna, monitoring conditions

Ex: inner ear, nose, eye

• 9+0 structure of microtubules

Flagella

• Much longer than cilia

• Sperm are only cells that have a flagella in humans

• Beat in snakelike or corkscrew pattern

• No power/recover strokes

• Have 9 + 2 arrangement (Like Motile Cilia)

Filtration

Passive Non-carrier mediated (does not involve a channel protein)

• Particles driven through membrane by hydrostatic pressure

• No ATP required

• Ex: Coffee maker; blood capillaries

• By product of the action of the heart

Simple Diffusion

• Net movement of particles from high to low concentration

• Due to constant motion of particles

• No ATP required

• Sugar cubes in tea; O2 from lungs into blood

• Only small nonpolar, hydrophobic materials diffuse through phospholipid bilayer

• Water, other charged small hydrophilic solutes

Factors affecting Diffusion Rate

• Temperature

• ^Temperature, ^Diffusion

• Molecular weight

• ^ Molecule size, slower the rate of diffusion

• Concentration Gradient

• ^Difference, ^Diffusion

• Membrane Surface area

• ^Area, ^Diffusion

• Membrane permeability

• ^ permeability, ^diffusion

Facilitated Diffusion

• Solute transported down concentration gradient

• Solute binds to carrier, which changes shape

• Carrier releases solute on other side of membrane

• Ex: glucose

PUMPS

• Requires ATP

• Ex: Na+/K+ (sodium/potassium) Pump

• Carrier Mediated, active

• Each cycle exchanges 3 NA+ for 2 K

• Keeps K+ concentration higher and Na+ lower wit

VESICULAR TRANSPORT

• Moves large particles or quantities through the plasma membrane in enclosed vesicles

• Requires ATP 

• Endocytosis: brings material into the cell

• 3 major forms

• - Phagocytosis (eating)

• - Pinocytosis (drinking)

• - Receptor-mediated endocytosis

• Exocytosis: removes material from cell

Transcytosis: transfers material across cell, releasing it on other side

Exocytosis

• Process of discharging material from cell

• Wall is formed by phospholipid bilayer

• Helps replace plasma membrane

Receptor-Mediated Endocytosis

• More selective; only certain molecules bind to receptors on cell surface

When discharged internally, becomes clathrin-coated vesicles

Cytoskeleton

• Network of internal cellular proteins

• Provide structure support

• Determine cell shape

• Organize cell contents

• Direct movements of cellular materials

• Help cell Move

3 major components: actin filaments, microtubules, intermediate filaments

Microfilaments

• Thin filaments or actin filaments

• 6 nm thick

• Retract, extend to microvilli

• Forms terminal web

• Keeps membrane bilayer intact

Intermediate Filaments

• Thicker, more rigid than microfilaments

• - 8-10 nm thick; made of keratin 

• Provide support, strength, structure

Contribute to cell adhesion (desmosomes)

Microtubules

• Formed of multiple strands of protein (tubulin) arranged to form a tube

• About 25 nm thick

• Responsible for movement of cilia, flagella

• Control aspects of cell division

• Maintain cell shape and rigidity, and hold organelles in place

Organelles

• Internal cell structures that carry out specific tasks

• Perform most major aspects of cellular physiology

• Some surrounded by unit membrane

Nucleus

Largest cell organelle

• Site of nuclear DNA

• Usually one/cell but some have many (muscle fibers) and RBCs have none (Mature RBCs do not have a nucleus)

• Filled with nucleoplasm

• DNA and protein (chromatin)

Nucleoli

produce ribosomes

• Surrounded by nuclear envelope

• Double membrane

Perforated by nuclear pores

• Controlled traffic through nuclear envelope

• Hold two membranes together

Endoplasmic Reticulum

System of connected channels (cisternae)

• Membrane continuous with nuclear envelope

Two major types: Rough and Smooth Er

• Flattened sacs covered with ribosomes

• Help produce proteins lipids for plasma membrane for secretion from cell

Abundant in cells that produce much protein

• Digestive gland organ (pancreas)

Smooth ER

Lack of ribosomes

Produce certain steroids

Detoxify drugs, alcohol

• Tolerance linked to more extensive smooth ER

• Abundant in liver, kidney, and gonads

Golgi Complex

• System of cisternae with unit membrane

• Makes carbohydrates and completes protein synthesis

• Receives proteins from rough ER

• Ships products in Golgi vesicles, which may:

• Become lysosomes

• Become secretory vesicles

• Fuse with plasma membrane

Mitochondria

• Specialized for ATP synthesis

• Cristae (inner folds) surrounded by matrix containing ribosomes

• Derived from endosymbiotic bacteria

• Has own DNA (mtDNA)

• Small circular DNA that replicates independently of (linear) nuclear DNA

• Two unit membranes

• Inner membrane (cristae) and outer membrane

• Produce own ribosomes

Ribosomes

• Makes proteins from instructions in RNA

- Free ribosomes (cytosol) make proteins for use within cell

- Attached ribosomes (rough ER) make proteins for secretion or for lysosomes

• No unit membrane

Centrioles

Short cylindrical sets of microtubules

• Nine groups of three with no spindle pair

• Give rise to mitotic spindle

• Others form basal bodies

• - Anchor cilia/flagella

Inclusions

• All other cell materials

• Not essential for survival, never enclosed in membrane

• Stored products

• - Pigments, oil, vacuoles

• Foreign Bodies

• - Viruses, bacteria, dust

DNA

Deoxyribonucleic acid

• Molecule of heredity

• Found in all living organisms

• Codes for synthesis of proteins

• Distinctive double-helix structure

• See deeper insight 4.1

• Composed of genes: segments of DNA coding for proteins

• -genome: sum of all genes

• Humans have about 22,000-23,000 genes

• Perhaps only about 2% DNA

• Remainder helps regulate activity of other genes or performs other functions

Nucleic Acid Structure

Nucleic Acids are polymers of nucleotides

Each nucleotide consists of:

• One sugar

• One phosphate group

One nitrogen base

DNA Structure

• Purines: Adenine (A), Guanine (G)

• Pyrimidines : Cytosine (C ), Thymine, (T)

• A binds to T

• C binds to G

• Law of complementary base-pairing

• Phosphate and sugar form backbone of double helix

• Nitrogenous bases held in middle by hydrogen bonds

Chromatin

• DNA and Protein

46 pieces, (chromosomes) per cell

RNA

Ribonucleic Acid

• Much smaller than DNA

• Single-stranded molecule

• Use ribose sugar for deoxyribose

Uses uracil for thymine

Messenger RNA (mRNA)

• Transcribed region of DNA

Template for protein synthesis in translation

Transfer RNA (tRNA)

• Small RNAs found in cytosol

• Play key role in protein assembly

Ribosomal RNA (rRNA)

Special RNA that forms part of ribosome

Transcription

• Copying genetic instructions from DNA to RNA

• Occurs in nucleus since DNA is too big to leave

Translation

• Conversion from language of nucleotides to language of amino acids

• Mostly occur in cytoplasm

• Results in construction of proteins

Transcription (continued)

Messenger RNA (mRNA)

• Mirror image of gene copied directly from DNA

• Original base triplets of DNA (e.g., TAC)...

• …now converted to mRNA codons (e.g., AUG)

• After splicing, mRNA leaves nucleus

- Can be read by ribosomes

Transcription: Splicing

• Secondary cutting of pre-mRNA that removes introns and keeps exons

• Multiple proteins from single gene

Translations: RIbosomes

• Organelles of rRNA and protein

• Assemble amino acids in order determined by mRNA codons

- mRNa passes through channel between large and small subunits

Translations: tRNA

Transfer RNA:

• VIDEO ON CANVAS

• One end has anticodon

- 3 nucleotide sequence complementary to mRNA codon binds it with

• Other end has amino acid

-Corresponds to own anticodon and therefore to mRNA codon being read

Translation

• Each mRNA can be translated by about 20 ribosomes at the same time (polyribosome)

-  Cell may have 300,000 identical mRNAs undergoing translation at same time, producing over 100,00 protein molecules/second