Terminology & Homeostasis Chapter 1 Terminology & Homeostasis Anatomy & Physiology ivyanatomy.com

Terminology Most anatomical terms have Greek or Latin origins Anatomy: science of structures of the body (morphology) Greek: ana = up, tome = cutting Physiology: science of functions of the organs Greek: physis = nature, logy = the study of

Form follows Function Anatomical questions of the heart The anatomy (form) of an organ should be based on its intended physiology (function) Anatomical questions of the heart How many chambers does the heart have? Describe the location of the heart. Physiological questions of the heart How are electrical impulses generated within the heart? How does the heart help maintain blood pressure?

Levels of Organization All matter, including the human body, is composed of tiny particles called atoms. subatomic particles (protons, neutrons, electrons) atom molecule organism macromolecule organ system organelle organ tissue cell

Levels of Organization Subatomic Particles: electrons, protons, and neutrons Atom: smallest unit of an element (eg. hydrogen atom, lithium atom, etc.) Molecule: particle of 2 or more atoms chemically joined together (eg. water molecule, glucose molecule, etc.) Macromolecule: A very large molecule (eg. protein, DNA, etc.) Organelle: Carries on specific activities within a cell (eg. mitochondrion, Golgi apparatus, nucleus, etc.) Continued…

Levels of Organization Cell: the cell is the basic unit of life Humans are composed of about 40 trillion cells (muscle cell, nerve cell, etc.) Tissue: group of similar cells that perform a specialized function (epithelia, connective, muscle and nerve) Organ: groups of different tissue (skin, femur, heart, kidney, etc. ) Organ System: Group of organs that function together (skeletal system, digestive system, etc.) Organism: Homo sapiens (i.e. human)

Levels of Organization Examples subatomic particles protons, neutrons, electrons atom oxygen atom, carbon atom molecule water molecule, glucose molecule macromolecule DNA, proteins organelle mitochondrion, Golgi apparatus, nucleus cell neuron, red blood cell, muscle cell tissue skeletal muscle tissue, areolar connective tissue organ heart, liver, kidney, skin organ system cardiovascular system, digestive system organism Homo sapiens (us!) Atom 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 Movement ability to change positions or part of an organism Growth and development increase size and complexity

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

Characteristics of Life Process Examples 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

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

Homeostasis Homeostasis: the maintenance of a stable internal environment Table 1.3 Examples of homeostatic mechanisms. Examples of homeostatic mechanisms Set-point value (average) Normal Range (estimations) Body Temperature 37°C (98.6°F) 36.5 – 37.2°C Blood Pressure 120/80 mmHg 100/70 –140/90 mmHg Heart Rate 76 beats per minute 60 – 100 bpm pH (whole blood) 7.4 7.35 – 7.45 Each mechanism maintains conditions near a set-point value. The conditions may fluctuate but they mostly remain within a normal range.

3 Components of a Homeostatic Mechanism Receptor : monitors the environment and provides information about changes in the conditions Control Center: region in body that maintains the set-point value Set-Point: target value that is maintained by the control center (e.g. body temperature = 98.6°F or 37°C) Effector: alters conditions in the environment (muscle or a gland)

Feedback Loops Negative Feedback Loop returns conditions towards the set-point maintains conditions within the normal range for homeostasis “As conditions return towards normal, negative feedback gradually shuts down the effectors. This prevents a correction from going to far.” 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

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

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

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

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: http://upload.wikimedia.org/wikipedia/commons/0/0a/Human_brain_NIH.png Childbirth. Openstax College: http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@7.16:7/Anatomy_&_Physiology#fig-ch01_05_02 Mitochondrion. . "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/f/f2/Blausen_0644_Mitochondria.png Animal Cell. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/4/4e/Blausen_0208_CellAnatomy.png Heart. By Patrick J. Lynch, medical illustrator (Patrick J. Lynch, medical illustrator) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/4/4f/Heart_anterior_large.jpg Cardiovascular System. By Bryan Brandenburg (http://bryanbrandenburg.net/wikpedia-heart-3d//) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/c/cb/Human_Heart_and_Circulatory_System.png David Wiley Photo. Mark A. Philbrick / CC BY http://farm8.staticflickr.com/7264/7754795758_fc7af56605.jpg