Organization Flashcards
Biology hierarchy
Organized from small to large
starts with atom and ends at biosphere
Body’s structural hierarchy
atom to molecule to macromolecule to organelle to cell to tissue to organ to organ system
Basic unit of matter
atom
molecule
2+ atoms together
organelles
molecules that come together
Carry out individual functions and come together to make a cell
Smallest unit of life
Cell
Tissues
group of similar cells that come together and function as a unit
4 classes of tissues in human body
- Epithelial - lining of GI tract organs and other hollow organs, skin surface (epidermis)
- Connective - fat and other soft padding tissue, bone, tendon, blood
- Nervous - brain, spinal cord, nerves
- Muscular - cardiac muscle, smooth muscle, skeletal muscle
Organs
two or more tissue types come together to carry out a particular function
11 organ systems
- Integumentary (hair, skin, and nails) - encloses internal body structures, site of many sensory receptors
- Skeletal (cartilage, bones, joints) - supports the body, enables movement (with muscular system)
- Muscular (skeletal, tendons) - enables movement (with skeletal system), helps maintain body temperature
- Nervous (brain, spinal cord, peripheral nerves) - detects and processes sensory information, activates bodily responses
- Endocrine (pituitary gland, thyroid gland, pancreas, adrenal glands, testes, ovaries) - secretes hormones, regulates bodily processes
- Circulatory (heart, blood vessels) - delivers oxygen and nutrients to tissues, equalizes temperature in the body
- Lymphatic
- Respiratory
- Urinary
- Digestive
- Reproductive
11 organ systems (just names)
Integumentary
Skeletal
Muscular
Nervous
Endocrine
Circulatory
Lymphatic
Respiratory
Urinary
Digestive
Reproductive
System
organs come together as a group to carry out a particular function
Organism
systems come together to form an organism
Reductionism
Large, complex systems can be understood by studying their simpler components
Proposed by Aristotle and essential to scientific thinking.
Important for understanding systems
holism
In order to understand the whole organism you must look at all the parts (holism).
Anatomical variation
No two humans are exactly alike (not even twins)
Anatomy books show most common organization of structures (present in 70% of people)
Some individuals have an atypical number of vertebrae
Some individuals lack certain muscles (plantaris in leg and palmaris longus in forearm).
Some individuals have an atypical number of certain organs (for example, kidneys) or unusual organ placement
Schaeffer’s Test
The first test developed in 1909
Involves maintaining the forearm at 90 degrees first followed by moving the thumb in opposition towards the little finger with the wrist partially flexed
Situs inversus
organs are flip-flopped
Physiological Variation
Sex, age, diet, weight, physical activity, genetics and environment all play a role in how different people, different bodies, may function differently.
Failure to consider variation can lead to overmedication of elderly or medicating women on the basis of research done on men.
Characteristics of life
- Organization—living things exhibit a higher level of organization than nonliving things
- Cellular composition—living matter is always compartmentalized into one or more cells
- Metabolism—internal chemical reactions
- Responsiveness—ability to sense and react to stimuli (irritability or excitability)
- Movement—of organism and/or of substances within the organism
- Development—differentiation and growth
- Reproduction—producing copies of themselves; passing genes to offspring
- Evolution —changes in genes
- Homeostasis—maintaining relatively stable internal conditions
Claude Blagden (1813-78)
physician that did experiments with heat in 1774 and 1775. He created a super sauna and endured temperatures up to 236⁰ F along with colleagues, a dog, and some steak.
Results from sauna experiment - In about twenty minutes the eggs were taken out, roasted quite hard; and in forty-seven minutes the steak was not only dressed, but almost dry. Another beef-steak was rather overdone in thirty-three minutes.
Noted fairly constant internal conditions despite changing external conditions (for example, temperature)
Homeostasis
the ability to detect change, activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions
Walter Cannon (1871–1945)
Coined the term homeostasis
Negative Feedback and Homeostasis
Negative feedback allows for dynamic equilibrium within a limited range around a set point
The body senses a change and “negates” or reverses it
Stimulus (body temp exceeds 37 degrees Celsius) to sensor (nerve cells in skin and brain) to control (temperature regulatory center in brain) to effector (sweat glands throughout body) back to stimulus
Loss of homeostatic control
leads to death
Feedback loops
Because feedback mechanisms alter the original changes that triggered them, they are called feedback loops.
Vasodilation
blood vessels dilate when it is too warm and sweating begins (heat-losing mechanism)
vasoconstriction
vessels in the skin constrict and shivering begins (heat-gaining mechanism)
Negative Feedback in Thermoregulation
- Room temperature falls to 19 degrees Celsius
- Thermostat activates thermos
- heat output
- room temp rises to 20 degrees Celsius
- Thermostat shuts off furnace
- room cools down
fluctuates back and forth
Receptor
structure that senses change in the body (e.g., stretch receptors above heart that monitor blood pressure)
Integrating (control-center) - control center that processes the sensory information, “makes a decision,” and directs the response (e.g., cardiac center of the brain)
Effector - — cell or organ that carries out the final corrective action to restore homeostasis (e.g., the heart)
Positive Feedback and Rapid Change
Self-amplifying cycle
* Leads to greater change in the same direction
* Feedback loop is repeated—change produces more change
* Normal way of producing rapid changes
Examples include: childbirth, blood clotting, protein digestion, and generation of nerve signals
Can sometimes be dangerous
Example: vicious circle of runaway fever
Positive feedback in Childbirth
Nerve impulses from cervix transmitted to brain
brain stimulates pituitary gland o secrete oxytocin
oxytocin carried in bloodstream to uterus
oxytocin stimulates uterine contractions and pushes baby towards cervix
head of baby pushes against cervix
nerve impulses from cervix transmitted to brain
Gradient
a difference in chemical concentration, charge, temperature, or pressure between two points
Matter and energy tend to flow down gradients
Example: blood flows from a place of higher pressure to a place of lower pressure
Movement in the opposite direction is “up the gradient” and requires spending metabolic energy
Chemicals flow down concentration gradients
Charged particles flow down electrical gradients
Heat flows down thermal gradients
