Homeostasis

You should have an understanding of the following:

1. Be able to define physiology and know how it differs from anatomy.

Physiology is the study of function of the body parts, while anatomy is the study of the form and structure. Anatomists would study “form” while physiologists would study “function”

2. Define homeostasis and know what factors must be homeostatically controlled?

Holding each cell’s environment (extracellular fluid) in a steady state

• Concentration of nutrients, O and CO2, waste producs, water and electrolytes

• pH

• Temp

• Volume and pressure of body fluids

3. Know the levels of organization of organisms and the characteristics of all living things have in common.

Chemical → Cellular → Tissue → Organ → Organ System → Organismal

Organization, Metabolism, Growth & Development, Responsiveness, Regulation, Reproduction

4. What body systems are involved in maintaining homeostatic conditions?

All body systems are involved in maintaining homeostasis 

5. You should be able to explain negative feedback, as well as positive feedback.  Which one is more common in the maintenance of homeostasis?

Positive feedback—amplifies the response

Negative feedback—allows regulatory mechanisms to fine-tune homeostatic conditions through small adjustments; most common

6. Know other terms listed in PowerPoints.

Book Notes

1.1 Anatomy & Physiology Compared

Vocab Table

Anatomy, Physiology, and the Scientific Method

• Anatomy — the study of structure and form

  • Anatomists — scientists who study form and structure of organisms

    • Examines relationships among parts of body + structure of individ organs

• Physiology - the study of function of body parts

  • Physiologists - scientists who how organs and body systems typically function + how the functioning of these organs may be altered via medication or disease

• Anatomists v. Physiologist (blood capillaries)

  • Anatomists - describes compsotion of thin wall

  • Physiologist - how thin wall allows for effective gas and nutrient exchange btwn blood and tissue cells

• Scientific Method — Systematic and rigorous process by which scientists

  • Examine natural events/phenomena through observation

  • Develop a hypothesis (possible explanation) for explaining these phenomena

  • Experiment and test hypothesis through data collection

  • Determine if data supports/rejects/modifies hypothesis

  • 
    

Anatomy: Details of Structure and Form

• Anatomy is extremely broad; can be subdivided into more specific fields

  • Microscopic Anatomy - examines structures that cannot be seen by the naked eye

    • Individ cells or thin slices of body structure examined under microscope

    • Cytology — cellular anatomy; the study of body cells and their internal structure

    • Histology — the study of body tissues

  • Gross Anatomy — macroscopic anatomy; investigates structure and relationships of body parts visible to naked eye (intestines, stomach, brain, etc.)

    • Specimens/body parts dissected for examination

    • Systemic Anatomy — studies anatomy of each functional body system (studying urinary system = studying kidneys, ureter, bladder, and urethra)

      • Most undergrad classes taught this way

    • Regional Anatomy — examines all structures in a particular region of the body as a complete unit (studying axillary region would look at blood vessels, nerves, lymph nodes, musculature, CT, and skin)

      • Most med school anatomy classes taught this way

    • Surface Anatomy — focuses on both superficial anatomic markings and internal body structures that relate to the skin covering them

      • Healthcare providers use surface anatomy to ID and locate important landmarks (pulse locations, where to perform CPR)

      • Most classes instruct students on important superficial landmarks

    • Comparative Anatomy — examines similarities and differences in anatomy of different spp.

      • Examine/compare limb structure in humans, chimps, dogs, and cats

    • Embryology — studies developmental changes occurring from conception to birth

• Specialized branches of anatomy focus on diagnosis of medical conditions or advancement of scientific research

  • Pathologic Anatomy — examines all anatomic changes resulting from disease

    • Both gross and microscopic observed

  • Radiographic Anatomy — investigates relationships among internal structures that may be visualized by specific scanning procedures

    • Radiography (x-ray), ultrasound, MRI

Physiology: Details of Function

• Uses a lot of chemistry and cellular biology cries

• Very broad like anatomy; subdivisions focus on a particular body system

  • Cardiovascular Physiology — examines the functioning of the heart, BV, and blood

    • Cardiovascular physiologists examine

      • How heart pumps the blood

      • What are the parameters for healthy BP within BV

      • Details of cellular exchange mechanisms (how respiratory gases, nutrients, and wastes move btwn blood and body structures)

  • Neurophysiology — examines how nerve impulses are propagated throughout nervous system

  • Respiratory Physiology — studies how respiratory gases are transferred by gas exchange btwn lungs and BV

  • Reproductive Physiology — explores how reuglation of sex hormones can drive the reprod cycle and influence sex cell prod and maturation

• Pathophysiology — investigates relationship btwn functioning of an organ system and disease/injury to that organ system

  • A pathophysiologist would examine how contractile force of heart, BP, and gas and nutrient exchange may be affected in an individ w/ heart disease

1.4 The Body’s Levels of Organization

Vocab

Characteristics Common to Living Things

• Several distinctive properties are common to all orgs, including humans

  • Organization

    • All organisms exhibit a complex structure and order

  • Metabolism

    • All organisms engage in metabolism

      • Metabolism consists of both anabolism (small → big) and catabolism (big → small)

  • Growth & Development

    • Organisms assimilate materials from their environ and exhbit incd size (growth) and incd specialization as related to form and function (development)

  • Responsiveness

    • All organisms exhibit responsiveness (reacting to stimuli)

    • Occurs at almost all levels of organization

  • Regulation

    • All orgs must be able to adjust

    • Body temp rises → more blood circulated to body’s surface for heat loss → Body temp returns to normal

      • Example of homeostasis

  • Reproduction

    • All organisms produce new cells for growth, maintenance, and repair

    • Somatic - mitosis

    • Gametes - meiosis; could turn into a new living organism

• Human organizational levels

  • Chemical → Cellular → Tissue → Organ → Organ System → Organismal

    • Chemical

      • Simplest level; atoms and molecules (macromolecules = complex molecules; biological macromolecules)

      • Biological macromolecule classes

        • Proteins, carbohydrates, nucleic acids (DNA & RNA), and lipids

      • Macromolecules also form organelles

    • Cellular

      • Consists of cells, which are formed from atoms and molecules

      • Structures vary widely according to specialization (skeletal muscle cell v. RBC)

    • Tissue

      • Consists of tissues (shocker)

      • 4 major types

        • Epithelial—covers exposed surfaces and lines body cavities

        • Connective—protects, supports, and binds structures and organs

        • Muscle—produces movement

        • Nervous—propagates nerve impulses for comms

    • Organ

      • Composed of organs (also a shocker)

      • Small intestine contains all 4 tissue types

    • Organ System

      • Multiple related organs that work together to coordinate activities and achieve a common function

    • Organismal

      • Highest level of structural organization

      • All body systems function interdependently in an organism

Introduction to Organ Systems

• All orgs must exchange nutrients, wastes, and gases w/ environ to stay alive and healthy (from bacteria to humans)

• People maintain a healthy body through intricate organ systems

  • Integumentary—provides protection, prevents water loss/gain, synthesizes Vit. D, releases secretions, regulates body temp, houses sensory receptors

  • Skeletal—provides support and protection, site of hematopoiesis, stores calcium and phosphorus, provides sites for ligament and muscle attachments

  • Muscular—produces body mvmt, generates heat when muscles contract

  • Nervous—responds to sensory stimuli, controls muscles and some glands, responsible for consciousness/intelligence/memory

  • Endocrine—consists of glands and cell clusters that secrete hormones, maintains blood composition and volume, controls digestive processes, regulates reprod functions

  • Cardiovascular—consists of the heart (a pump) and BV; distributes hormones, nutrients, gases, and picks up waste products

  • Lymphatic—transports and filters lymph; may participate in immune responses

  • Respiratory—responsible for gas exchange (O2 and CO2) btwn blood and air in lungs

  • Urinary—filters blood to remove waste prods and biologically active molecules; concentrates waste prods in urine, and expels it from body

  • Digestive—mechanically and chemically digests food, absorbs nutrients, and expels waste prods

  • Reproductive—gonads (testes/ovaries) produce sex cells (sperm/oocytes) and sex hormones (androgens, estrogen, progesterone)

1.6 Homeostasis: Keeping Internal Conditions Stable

Vocab

Intro

• Homeostasis critical for a healthy organism

  • 2 principles central to homeostasis

    • Homeostatic systems

    • System regulation via negative (most common) or positive feedback

Components of Homeostatic Systems

• The ability to maintain homeostasis within a body occurs through homeostatic systems

• Homeostatic systems have 3 components: receptor, control center, and effector

  • Receptor — body structure that detects a stimulus (a variable that is changing)

    • Ex. Eye’s retina (receptor) detects a change in light entering the eye (stimulus)

  • Control Center — the structure that both interprets input from the receptor and initiates changes through the effector; the ‘middleman’

    • Generally a portion of nervous system (brain/spinal cord) or an organ of the endocrine system (hormones)

    • Nervous system—Quick to respond to change (but usually dissipates quickly)

    • Endocrine system—More sustained response over several hours or days

    • Sometimes control center is the same as the receptor (parathyroid gland detecting an inc in blood calcium, then releases PTH in response)

  • Effector — the structure that brings about the change to alter the stimulus; causes an “effect”

    • Most body structures can act as effectors, but muscles and exocrine glands are often effectors

    • Ex. Smooth muscle in walls of bronchioles incs airflow in and out; salivary glands inc saliva output when eating

Homeostatic Systems Regulated by Negative Feedback

• Most bodily processes controlled by negative feedback

  • Variables maintained within specific parameters

• Changes regulated by negative feedback loop

• Ex. Blood glucose and insulin

  • Pancreas is receptor and control cnter

  • If blood glucose elevates past set point, pancreas releases insulin → decs blood glucose

  • If blood glucose drops past set point, pancreas releases glucagon → incs blood glucose

• Ex. Withdrawal reflex from injury, regulating HR and BP, changing breathing rate in response to incd blood CO2 levels

• Temperature Regulation

  • Maintaining a body temp at its set point occurs through negative feedback homeostatic systems

    • Cold day → skin sensory receptors send nerve impulses to hypothalamus → hypothalamus compares skin sensory input to body temp set point (98.6F/37C) → hypothalamus initiates impulses for vasoconstriction → decs amount of blood circulating to surface → heat loss is reduced

      • Other actions are taken (shivering, goose bumps, etc.)

      • Stimulus = cold; receptors = sensory receptors in skin and hypothalamus (hypoth can monitor blood temp); effectors = BV, skeletal muscles, arrector pili muscles

    • Hot day/exercise → incd body temp detected by skin sensory receptors or hypoth. → hypoth. compares incd body temp to body temp set point → initiates vasodilation, sweating → cools body

      • Stimulus = heat/exercise; receptors = sensory receptors in skin or hypoth.; effectors = BV, sweat glands

• Endocrine homeostatic systems

  • Adrenal gland releasing aldosterone in response to incd blood K levels

  • Kidney releasing erythropoietin hormone in response to decd blood O2 levels

Homeostatic Systems Regulated by Positive Feedback

• Homeostatic systems could also be regulated by positive feedback

  • Much less common than negative

• Positive feedback loop will continue until interrupted by an event or change in stimulus

• Ex. Mother delivering baby

  • Pressure of baby’s head on cervix → nerve impulses sent from cervix to hypoth. → hypoth. signals pituitary to release oxytocin → oxytocin stimulates uterine to contract

    • Stimulus = pressure of baby’s head; receptors = cervix; control center = hypoth.; effector = pituitary

    • As long as stimulus (baby’s head pressing into cervix) remains present, positive feedback loop will continue

• Ex. Breastfeeding

  • Baby suckling → nerve impulses relayed from breast to hypoth. → initiates pituitary to release oxytocin → milk ejectoin

    • Stimulus = baby suckling; receptors = skin sensory receptors in nipple region; control center = hypothalamus; effector = pituitary

• Ex. blood-clotting cascade and platelet plug formation

  • Blood clotting ceases w/ formation of blood clot; platelet plug formation ceases when platelets plug dmged BV

Lecture Notes

• Physiology: Function of the human body

• Goal of body: Maintain Homeostasis

  • Holding all body components (cells, tissues, organs) in a consistent environ

• Characteristics of Living Things

  • Organization

  • Metabolism

    • Anabolic Metabolism—building larger molecules from smaller ones

      • Building new muscle tissue (proteins) from the amino acids in your food

      • These rxns require energy (endergonic process)

    • Catabolic Metabolism—breaking large molecules into smaller ones

      • Digesting nutrients in food to release the energy stored in them

      • These rxns release energy for body (exergonic process)

  • Growth & Development

  • Responsiveness (stimulus → response)

  • Regulation

    • Adjusts internal bodily functions to maintain homeostasis despite disruptive changes

  • Reproduction

    • Somatic/mitosis—produce new cells for maintenance, growth, and repair

    • Gametes/meiosis—produce eggs and sperm for reproduction of a new org

• Homeostasis—holding each cell’s environment (extracellular fluid) in a steady state

  • Done through different control mechanisms

  • Negative feedback—allows regulatory mechanisms to fine-tune homeostatic conditions through small adjustments

    • Most common control mechanism

    • If deviation occurs in homeostasis, multiple things adjust so homeostasis can be restored; once homeostasis is restored, the things stop

    • Stimulus (a change occurs) → Receptor (detects change) →receptor sends info to control center→ Control center (integrates input and initiates change through effector) →control center sends output info to effector→ Effector (struc that brings about a change to the stimulus) → Homeostasis

  • Positive feedback—amplifies response

    • Uncommon

    • Breasfeeding

      • Stimulus (baby suckles) → Receptor (skin receptor detects suckling and sends impulses to hypothalamus) → Control Center (hypoth. signals posterior pituitary to release oxytocin) → Effector (oxytocin stimules milk ejection from breast) → baby continues suckling