ivyanatomy.com Chapter 1

anatomy - physiology - science of structures (morphology) science of functions ana = up, tome = cutting physis = nature, logy = the study of

Form follows Function Physiology (function) questions of the heart How many chambers does the heart have? Describe the location of the heart. Identify the tissues within the wall of the heart. Anatomy (form) questions of the heart Describe how electrical currents are conducted through the heart. Describe how the heart helps maintain blood pressure. The anatomy (form) of an organ should be based on its intended physiology (function)

Levels of Organization subatomic particles atom molecule macromolecule organelle cell tissue organ organ system organism (protons, neutrons, electrons) (hydrogen, carbon, oxygen) (water, glucose) (proteins, DNA, RNA) (mitochondrion, nucleus) (basic unit of life) (nervous, cardiac muscle) (heart, liver, stomach) (cardiovascular, digestive) (Homo sapien)

Levels of Organization Atom LevelExamples subatomic particlesprotons, neutrons, electrons atomoxygen atom, carbon atom moleculewater molecule, glucose molecule macromoleculeDNA, proteins organellemitochondrion, Golgi apparatus, nucleus cellneuron, red blood cell, muscle cell tissueskeletal muscle tissue, areolar connective tissue organheart, liver, kidney, skin organ systemcardiovascular system, digestive system organism Homo sapiens (us!) Table 1.1

Characteristics of Life Complex Organization Organisms are composed of cells. Cells are composed precise arrangements of large molecules. Responsiveness detect changes in the environment and react to those changes Growth and development increase size and complexity Movementability to change positions or part of an organism

Absorption Assimilation Digestionbreakdown food into simpler forms passage of substances through a membrane converting absorbed molecules into different forms Characteristics of Life Excretionremoving waste forms new cells or new organisms Reproduction

ProcessExamplesProcessExamples Movement Ability to change position of part of organism or entire organism Digestion Breakdown of food into smaller molecules that can be absorbed Responsiveness Ability to detect changes in the environment and respond to them Absorption Transport molecules through membranes Growth Increase size of body or organ Circulation Movement of substances in body fluids Reproduction DNA synthesis, Cell Division, Sexual Reproduction Assimilation Convert one molecule into a different molecule Respiration Converting energy from food into a form the cells can use Excretion Removal of waste products Table 1.2 Characteristics of Life

Water transportation & metabolic processes Food growth and repair required to release sufficient energy from food Oxygen Heat Pressurerequired for breathing and circulation controls the rate of chemical reactions Requirements of an Organism

Homeostasis Homeostasis – is the maintenance of a stable internal environment Examples of homeostatic mechanisms Set-point value (average) Normal Range (estimations) Body Temperature37°C (98.6°F)36.5 – 37.2°C Blood Pressure120/80 mmHg100/70 –140/90 mmHg Heart Rate76 beats per minute60 – 100 bpm pH (whole blood) – 7.45 Table. Examples of homeostatic mechanisms. Each mechanism maintains conditions near a set-point value. The conditions may fluctuate but they mostly remain within a normal range.

Components of a Homeostatic Mechanism Receptor monitors the environment and provides information about changes in the conditions Control Center region in body that sets the normal range Set-Point : target value that is maintained by the control center (e.g. body temperature = 37°C) Effector alters conditions in the environment (muscle or a gland)

Feedback Loops 1.Negative Feedback Loop returns conditions towards the set-point maintains conditions within the normal range for homeostasis 2.Positive Feedback Loop Drives conditions further away from the set-point Causes the system to move away from equilibrium (runaway train) Not involved in homeostasis “As conditions return towards normal, negative feedback gradually shuts down the effectors. This prevents a correction from going to far.”

Receptor control center effectors (muscles or glands) effectors (muscles or glands) Stimulus Response set-point negative feedback diminishes the stimulus

Example of Homeostasis and Negative Feedback Body temperature falls below set-point (37°C) Thermoreceptors transmit impulse to hypothalamus Hypothalamus detects the body temp is falling below normal range skeletal muscles start shivering, producing heat. Body temperature returns towards the set-point. Brrrr! Negative Feedback

Positive feedback cycle child birth Openstax college Uterus contracts, pushing the head of baby against the cervix Stretch receptors signal the hypothalamus Hypothalamus activates pituitary gland Pituitary gland releases Oxytocin Oxytocin is carried through the blood to the uterus Oxytocin triggers uterine contractions Baby stretches the cervix

Positive Feedback & Childbirth Positive feedback continues to increase the strength of contractions. The cycle ends only after the baby is born and the cervix is no longer stretched.

Attribution NIH image of human brain: Childbirth. Openstax College: ch01_05_02 NIH image of human brain: Mitochondrion.. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI: /wjm/ ISSN (Own work) [CC BY 3.0 ( via Wikimedia Commons Animal Cell. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI: /wjm/ ISSN (Own work) [CC BY 3.0 ( via Wikimedia Commons Heart. By Patrick J. Lynch, medical illustrator (Patrick J. Lynch, medical illustrator) [CC BY 2.5 ( via Wikimedia Commons Cardiovascular System. By Bryan Brandenburg ( [CC BY-SA 3.0 ( via Wikimedia Commons David Wiley Photo. Mark A. Philbrick / CC BY BYhttp://farm8.staticflickr.com/7264/ _fc7af56605.jpg