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Biology midterm #2


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4 types of tissues:
Epithelial, Connective, Muscle, Nervous
Lines the body’s surface, cavities, ducts, and tubes
-One free surface faces a body fluid or the environment
Simple epithelium consists of a single layer of cells
-Cell shapes: squamous, cuboidal, columnar
-Stratified epithelium is two or more layers thick
-Functions in protection, as in skin
-Cells in the layers may be
-support: Most abundant tissue in the body
Cells are scattered in an extracellular matrix
-Matrix is composed of collagen and/or elastin fibers in a polysaccharide ground substance
-Two major categories:
Soft connective tissues: loose; dense irregular; dense regular
-Specialized: cartilage, bone, adipose, blood
movement: smooth, skeletal, and cardiac.
Muscles contract/shorten and then relax/lengthen; in this way they control movement of the body and its parts
sensory: Detects stimuli, integrates information, and relays commands for response
Consists of excitable neurons and supporting neuroglial cells
Neurons: Excitable cells
Motor neurons relay messages from the brain to muscles or glands
Arrival of the impulse at the neuron endings triggers events that stimulate or inhibit adjacent neurons or other cells
Neuroglia: Constitute more than half of the nervous tissue; Protect and support the neurons, both structurally and metabolically
What do Tight junctions do?
prevent leaks
What do Gap junctions do?
connect adjacent cytoplasms
Adhering junctions
cement cells together
Epithelial tissue membranes
(epithelium + underlying connective tissues together)
Mucous membranes
Serous membranes
Cutaneous membrane (skin)
Connective tissue membranes
(no epithelium included in the membrane)
Synovial membranes (joints)
ORGAN SYSTEMS: integumentary system
protect body from injury, dehydration, and some pathogens: control its temperature, excrete some wastes; receive some external stimuli
ORGAN SYSTEMS: muscular system
move body and its internal parts; maintain structure. generate heat (by increases in metabolic activities)
ORGAN SYSTEMS: skeletal system
support and protect body parts, provide muscle attachment sites, produce red blood cells, store calcium and phosphorous
ORGAN SYSTEMS: nervous system
detect both external and internal stimuli, control and coordinate responses to stimuli, integrate all organ system activities
ORGAN SYSTEMS: endocrine system
hormonally control body function, work with nervous system to integrate short-term and long term activities.
Organ systems: lymphatic
collect and return somae tissue fluid to the blood stream. defend the body against infection and tissue damage
Organ systems: respiratory
rapidly deliver oxygen to tissue fluid that bathes all living cells. remove carbon dioxide wastes from cells. help regulate pH.
Organ systems: digestive
ingest food and water. mechanically/chemically break down food and absorb small molecules into environment. eliminate food residues.
Organ systems: urinary
maintain the volume and composition of the internal environment. excrete excess fluid and blood-borne wastes.
Organ systems: reproductive
female: produce eggs. after fertilization, afford a protective, nutritive environment of new individual.
male: produce and transfer sperm to the female.
for both, hormones influence other systems.
Stable operating conditions in the internal environment (maintain stability in the volume and composition of extracellular fluid)
Brought about by coordinated activities of cells, tissues, organs, and organ systems
Requires the interaction of sensors, integrators, and effectors
NEGATIVE system: cancels or reverses an effect/response

POSITIVE system: intensifies the response by the system

The regulation of the amounts of water and minerals in the body. This is known as osmoregulation. This happens in the kidneys.
The removal of metabolic waste. This is known as excretion. This is done by the excretory organs such as the kidneys and lungs.
The regulation of body temperature. This is mainly done by the skin.
The regulation of blood glucose level. This is mainly done by the liver and the insulin secreted by the pancreas.
process of homeostasis
receptor (free nerve-ending skin)--->integrator (ie. brain)---->effector(muscle or gland)--->(response to stimulus leads to change. change fed back to receptor. in negative system, response to feedback cancels out/ counteracts effect of original stimulus)--->back to beginning
5 microbes important to disease: bacteria
Unicellular and much smaller than eukaryotic cells; simpler in construction; haploid
Have complex cell walls that are important to the disease causing process and their resistance to antibiotics
Reproduce by binary fission (double contents and then split); some “sex” is possible
Metabolically bacteria are tremendously diverse (capable of metabolizing all natural compounds and many synthetic ones)
-very adaptable.
5 microbes important to disease:Fungi
Yeast or mold forms;
haploid or diploid
Reproduce by budding or sexually via spore production
In nature, fungi are decomposers, responsible for most “turn-over” of organic material
Present in most warm environments; only 4 species are pathogenic for humans, the rest are opportunists
5 microbes important to disease: Helminthes
Parasitic worms with complex life cycles that encompass adult feeding “worm” forms, eggs, and larval stages. Life cycles generally utilize more than one host and are acquired by humans from water, soil or food.
Reproduce via fertilization and release of eggs.
Environmentally restricted based on range of host species; usually not a problem for humans in the United States
5 microbes important to disease: Protozoa
Unicellular eukaryotic microbes
larger than yeast cells,
lack cell walls,
Reproduce by binary fission or through complex life cycles involving different developmental forms
They are very diverse and are found in a variety of habitats, often preying on other microbes for food
5 microbes important to disease: Viruses
Simplest microbes
Genome + protein
Genome can be DNA or RNA
Protein = capsid (helical or icosahedral)
Sometimes enveloped (with “spike” proteins)
Reproduce by parasitizing cells and forcing those cells to manufacture and assemble new viral particles. Can be very destructive – generally use the host cell up until it dies and lyses
ALL are parasites (obligate). Parasitize essentially every living cellular form on earth.
Viruses are not considered to be alive.
the genetic ability to inflict damage to a host
a quantitative assessment of pathogenicity (severity of symptoms)
the ability of the host to prevent the establishment of the parasite/pathogen; highly variable
growth of microbes on/in the host
damage or injury to the host that impairs normal function
Mode of transmission
the method or process by which a pathogen moves from reservoir to host or from host to host
major modes of transmission
Respiratory (droplets)
Airborne/Inhalation (particles)
Physical Contact
Contact with fomites (everyday objects)
Vector-borne from animals or insects
Vehicle-borne from water or food
microbe invasion
Animal bodies provide favorable environments for microbial growth (nutrients, protection, etc.)
Body is not a uniform “place”; differs chemically and physically within any one individual and between individuals
Microbes must therefore be flexible to some extent to adapt but in the end microbes can’t colonize every place within us or every individual encountered
To have a shot at using the animal host, the microbe must first invade it – generally does this through one of the body surfaces exposed to the environment (internally or externally)
Where microbes enter is important, so is how many enter
Often stay near where they enter (local infections)
Systemic infections always bad news
Direct host to host transmission
(involves actual direct contact): respiratory, direct contact, sexual, fecal-oral, biological vectors in vector-borne transmission
Indirect host to host transmission
(involves an intermediary between infected and uninfected): airborne/inhalation, fecal-oral in conjunction with fomites, vehicle-borne, mechanical vectors in vector-borne transmission
Common Source pandemic
infect large number from a single contaminated and commonly encountered source (often food or water); rapid rise to peak incidence, rapid decline; no host to host transmission
propogated source pandemic
one infected individual introduces infection to population; incidence shows slow rise to peak because transmission is from person to person following a chain defined by the microbe itself; can involve direct or indirect modes of transmission; not everyone traceable to same initial person
Controlling Infectious Diseases
Increase the general health of ALL populations to increase overall community health; must be global venture
Control vectors and reservoirs to reduce potential exposure
Vaccinate or destroy domestic vectors, prevent wild to domestic transmission, eliminate insects, immunization, insecticides
Control general transmission of diseases through sanitation or reducing contact between infected and uninfected
Immunization to protect the susceptible; need to offer to adults and children globally (limited by technology and cost)
Surveillance and reporting to recognize early and cut down on transmission if at all possible (reportable diseases)
Eradication of pathogens
Functions of Bone
Interacts with muscle to enable movement
Supports and anchors muscles
Encloses and protects internal organs
Stores calcium and phosphorus
Produces blood cells
Long-Bone Development
Cartilage “model” of the bone provides a template for true bone formation
Growth occurs at the bone ends (epiphyses)
Epiphysis is separated from the bone shaft by a plate of cartilage
Plates are replaced by bone when growth ends
Bones held together by ligaments (joints) and tendons (muscle to bone)
deposit bone
secrete enzymes that degrade bone
The Axial Skeleton
Composed of:
Skull (cranial and facial bones, sinuses); protection of brain
12 pairs of ribs + sternum; protection organs, breathing, upper body scaffold
26 vertebrae (cervical, thoracic, lumbar, sacrum, coccyx); support and weight distribution
Intervertebral disks; shock absorbers and flex points
The Appendicular Skeleton
Composed of:
Pectoral girdle (scapula, clavicle); highly flexible
Arm, hand bones (30 separate bones total)
Pelvic girdle (6 fused bones); less flexible than pectoral girdle, meant to support weight of body
Leg, foot bones (femur, patella, tibia, fibula + 28 bones in the normal foot)
Fibrous joints
short connecting fibers join bones
Synovial joints
move freely; ligaments connect bones
Cartilaginous joints
straps of cartilage enable slight movement
Osteoarthritis (loss of cartilage covering ends of bones in joints); joint replacement possible
Rheumatoid arthritis (immunological self-attack)
inflammation tendons, synovial membranes)
Carpal tunnel syndrome common in technology professions
stretch/twist too far
bones out of the joint
simple fracture
complete fracture
compound fracture
fragmentation plus protrusion of bone through skin
muscle fiber
single muscle cell
make up muscle fiber
Muscle Contraction
Sliding filament model
Myosin heads attach to actin filaments
Myosin heads tilt toward the sarcomere center, pulling actin with them
The concentration of calcium ions in the muscle determines whether myosin can bind actin
no ATP= muscle fatigue
Muscle tension
the mechanical force a contracting muscle exerts on an object
For a muscle to shorten, muscle tension must exceed the load that opposes it. The load may be the weight of an object or gravity’s pull on the muscle.
Isotonic contraction
muscle visibly shortens; moves a load. Tension remains constant as the muscle changes length
Isometric contraction
Muscle does not change length. Tension is insufficient to move load
Slow/Red muscle
give example
Many capillaries, high myoglobin
Contracts fairly slowly
Can sustain contraction
Example: back muscles
Fast/White muscle
Fewer capillaries, less myoglobin
Contracts quickly
Cannot sustain contraction
Example: muscles in the hand
Myopathies: Diseases of Muscle: Muscular Dystrophies
several genetic based muscle-wasting diseases
Myopathies: Diseases of Muscle:Metabolic
endocrine or inflammatory myopathies
Myopathies: Diseases of Muscle:Myositis
inflammation and pain
Myopathies: Diseases of Muscle:Neuromuscular diseases
paralysis and others involving nerve damage and subsequent loss of muscle function
Myopathies: Diseases of Muscle:trauma
strains, bruising, etc. can lead to muscle stiffness or bleeding into the muscles
Human Skin
Protects the body from injury, dehydration, UV radiation, and some pathogens
Helps control temperature
Receives some external stimuli
Produces vitamin D
Composed of epidermis and dermis overlying the hypodermis
Essentially forms the body “sack” containing bones, muscle and organs
stratified epithelium that grows from bottom upward
dense connective tissue with many elastin and collagen fibers
Includes blood vessels, lymph vessels, and receptor endings of sensory nerves
derived from epidermal cells)
Sweat glands are controlled by sympathetic nerves and produce sweat (99% water, with dissolved salts, trace of ammonia)
Oil glands (sebaceous glands) produce secretions that lubricate and soften hair and skin; also kill many surface bacteria
Skin Infections:Bacterial diseases
acne, necrotizing fasciitis, cutaneous anthrax, scalded skin syndrome
Skin Infections:Fungal diseases
cutaneous candidiasis, athlete’s foot, sporotrichosis, ringworm
Skin Infections:Viral diseases
herpes simplex, chickenpox (varicella and shingles), measles, rubella, smallpox, monkeypox, warts
Skin Infections:Parasitic diseases
leishmaniasis (protozoa), scabies (mites), lice
The Digestive System/Gastrointestinal (GI) Tract
long tube (~ 6.5 to 9 meters long if extended), lined with mucus-secreting epithelium, that moves materials one way – from the mouth to the anus
functions of digestive system
Break up, mix, and move food material
Secrete enzymes to facilitate digestion
Digest (break down) food particles into smaller molecules
Absorb nutrients and fluids
Eliminate wastes and residues
Process of digestion
-teeth tear the food into small bits and mix the bits with saliva to start digestion
Food moves down the esophagus to the stomach: the stomach stores food, initiates protein digestion, controls food release to the small intestine
The small intestine further digests food and facilitates absorption.
ABSORPTION:carbohydrates and proteins are digested and then [B] absorbed. Fats are emulsified [C] and mixed with bile salts. Micelles form [D] which pass through the plasma membrane [E] into the cell where the move through into the internal environment of the body [F].
Major Enzymes Needed for digestion: Carbohydrate Digestion
salivary amylase (active in mouth and stomach), pancreatic amylase, disaccharidases (both active in small intestine)
Major Enzymes Needed for digestion:Protein Digestion
pepsins (stomach), trypsin and chymotrypsin, carboxypeptidase, aminopeptidase (rest active in small intestine)
Major Enzymes Needed for digestion:Fat Digestion
lipase (small intestine)
Major Enzymes Needed for digestion:Nucleic Acid Digestion
pancreatic nucleases, intestinal nucleases (both active in small intestine)
Importance of the Liver in Digestion
Role in carbohydrate metabolism
Role in protein synthesis, disassembly
Forms urea from nitrogen-containing wastes
Assembles and stores some fats; forms bile to aid in fat digestion
Inactivates many chemicals (hormones, some drugs)
Detoxifies many poisons
Breaks down worn-out red blood cells
Aids immune response (removes some foreign particles)
Importance of Large Intestine (Colon) in digestion
absorbs some nutrients not absorbed by the small intestine (generally salts and water) and concentrates undigested materials for elimination as waste (feces)
-Proper movement of material through the colon is necessary for proper GI tract functioning
Constipation: feces remains “trapped”, water is absorbed, and the feces becomes hard and difficult to eliminate
Diarrhea: small intestine secretes more water and salts than the colon can absorb; feces is watery and hard to control
Nutritional Requirements for digestion:Complex Carbohydrates
(body’s main energy source)
Foods high in complex carbs usually high in fiber; promote colon health
Nutritional Requirements for digestion:Lipids
(should be ~30% of diet)
Most fats can be synthesized but essential fatty acids must be obtained from food
Excess saturated fats can raise cholesterol level and contribute to heart disease
Nutritional Requirements for digestion:Proteins
Essential amino acids must be obtained from diet (8 out of 20)
Animal proteins are complete; supply all essential amino acids
Plant proteins are incomplete; must be combined
dietary essentials:vitamins
Fat soluble (excess accumulates in tissue): Vitamins A, D, E, K
Fat insoluble: B vitamins, Pantothenic acid, Folate, Biotin, Vitamin C
dietary essentials:Minerals
Calcium, chlroide, copper, fluorine, iodine, iron, magnesium, phosphorus, potassium, sodium, sulfur, zinc
body mass index-BMI
one indicator of obesity-related health risk as well as under-nutrition:
BMI = Weight (lbs) X 700
Height (inches)2
body functions or development suffers due to inadequate or unbalanced food intake
lack of food
Obesity-related conditions
Type 2 diabetes, Breast cancer, Heart disease, Colon cancer, Hypertension, Gout, Gallstones, Osteoarthritis
Dietary Diseases and Disorders:Malabsorption Diseases
Lactose intolerance, Cystic fibrosis, Crohn’s disease, Food allergies
Dietary Diseases and Disorders:Eating disorders
anorexia nervosa, bulimia

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