Biology 2331 Anatomy and Physiology I "If you want something - - PowerPoint PPT Presentation

Biology 2331 Anatomy and Physiology I

"If you want something you've never had, then you've got to do something you've never done."

Learn and Understand

• A new language
• At this stage, science drives the discipline
• Human A&P is focused but draws upon

knowledge of other disciplines

• Structural and functional hierarchy – the whole

is the sum of its parts

• Systems of the organism attempt to maintain

internal conditions that sustain life while allowing for temporary deviations

What is Biology?

• bios = “life”
• -ology = “study of”
• Greek and Latin important languages in biology and

science in general

• Etymology
• Pronunciation key in glossary (G-1)
• Roots, suffixes and prefixes on last pages of book
• How is science different from other disciplines?

What is Anatomy and Physiology?

• A subset of the larger field of biology
• Anatomy: scientific discipline that investigates the

body’s structure and relationships between its parts

– Readily observable

• Physiology: scientific investigation of the processes or

functions of living things

– At times, not easily observed – based on tested hypotheses which are subject to change when new information comes to light

• Anatomy and physiology are inseparable

– Function always reflects structure – What a structure can do depends on its specific form

What is Anatomy and Physiology?

Like all biology, directly influenced by the fields of

• General chemistry
• General physics
• Biochemistry
• Other fields of biology

Topics of Anatomy

• Gross or macroscopic: structures examined

without a microscope

– Regional: studied area by area – Systemic: studied system by system – Surface: external form and relation to deeper structures

• Microscopic: structures seen with the microscope

– Examples:

• Cytology: cells
• Histology: tissues

Topics of Physiology

• Reveals dynamic nature of living things
• Often focuses on cellular and molecular
• processes. Examples:

–Cell physiology: examines processes in cells –Neurophysiology: examines nervous tissue biochemistry and physics –Cardiovascular physiology: heart and blood vessel tissue biochemistry and physics

Subjects That Encompass Both Anatomy and Physiology

• Pathology: structural and

functional changes caused by disease

• Exercise Physiology: changes in

structure and function caused by exercise

–Example: bone density and training

Figure 1.2 Levels of structural organization.

Figure 1.4a The body’s organ systems and their major functions.

Figure 1.4b The body’s organ systems and their major functions.

Interdependence of Body Cells

• Humans are multicellular

– To function, must keep individual cells alive – Most cells depend on organ systems to meet their survival needs

• All body functions spread among different
• rgan systems
• Organ systems cooperate to maintain life
• Some redundancy will be observed
• Note also, symbiosis with microbes

Figure 1.2 Examples of interrelationships among body organ systems.

Digestive system

Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces) Food O2 CO2 Respiratory system Takes in oxygen and eliminates carbon dioxide Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Blood CO2 O2 Heart Nutrients Interstitial fluid Integumentary system Protects the body as a whole from the external environment Nutrients and wastes pass between blood and cells via the interstitial fluid Feces Urine Urinary system Eliminates nitrogenous wastes and excess ions

Why Do Human Bodies Work the Way They Do?

Humans, like all living things on this planet:

• Are subject to universal laws of chemistry and physics
• Have evolved complex cellular chemistry in order to thrive

within an environment – to function best within a complex environment maximizing survivability and reproduction

– ‘optimized’ for a particular environment

• Have catalogued their complexities as traits present in the

genetic material inherited from parents

• In the natural world, both evolution and environmental change
• ccur very slowly…over tens of thousands of years
• What are the characteristics of the environment humans are

‘adapted’ to?

Homeostasis

• Values of variables

fluctuate around the set point - establish a “normal range”

• Set point: the ideal normal

value of a variable

– essentially an average – But changeable for temporary circumstances

• What is the set point for

body temperature? There are too many body variables to list here

Controlling Body Parameters: Feedback Systems

• Components

– Receptor: monitors the value of some variable; responds to change – Control center: establishes the set point; evaluates change; coordinates appropriate response – Effector: can change the value of the variable; changes feedback on the stimulus

• Stimulus: deviation from the set point; detected

by the receptor

• Response: produced by the effector
• Two examples: negative and positive

Figure 1.4 Interactions among the elements of a homeostatic control system maintain stable internal conditions.

Output: Information sent along efferent pathway to effector. Input: Information sent along afferent pathway to control center. 3 Receptor detects change. 2 Stimulus produces change in variable. 1 4 Response

• f effector

feeds back to reduce the effect of stimulus and returns variable to homeostatic level. 5 Control Center

Afferent pathway Efferent pathway

Receptor Effector BALANCE

Negative Feedback

• Any deviation from the set point is made smaller

(resisted)

• Response reduces or shuts off original stimulus

– Variable changes in opposite direction of initial change

• Most feedback mechanisms in body are NF
• Examples

– Regulation of body temperature – Regulation of blood glucose by insulin – Regulation of blood pressure

Figure 1.5 Body temperature is regulated by a negative feedback mechanism.

Control Center (thermoregulatory center in brain)

Afferent pathway Efferent pathway

Receptors

Temperature-sensitive cells in skin and brain)

Effectors Sweet glands

Sweat glands activated

Response Evaporation of sweat Body temperature falls; stimulus ends Body temperature rises

Stimulus: Heat Response

Body temperature rises; stimulus ends

Effectors Skeletal muscles

Efferent pathway Shivering begins

BALANCE Afferent pathway Control Center

(thermoregulatory center in brain) Receptors Temperature-sensitive cells in skin and brain

Stimulus: Cold

Body temperature falls

Positive Feedback

• When a deviation occurs, the response is to

make the deviation greater - response enhances or exaggerates original stimulus

• Not as common as negative feedback,

purposefully leads away from homeostasis

• Usually controls infrequent events that do not

require continuous adjustment

Positive Feedback

Examples of positive feedback:

• Labor and delivery
• cervical pressure, oxytocin, and uterine contraction
• Blood pressure changes during hemorrhage
• Peripheral blood pressure drops are not resisted in order to

maintain core blood pressure and heart-lung-brain connection

• If blood loss continues - heart’s ability to pump blood

decreases

• Heart and brain starved, death
• Platelet plug formation
• the response to platelet adhesion is more platelet adhesion
• bviously must be carefully controlled

Figure 1.6 A positive feedback mechanism regulates formation of a platelet plug.

Released chemicals attract more platelets. Positive feedback loop Platelets adhere to site and release chemicals. Feedback cycle ends when plug is formed. Platelet plug is fully formed. Break or tear

• ccurs in blood

vessel wall. Positive feedback cycle is initiated.

1 2 3 4