Chapter 1 An Introduction to the Human Body

Chapter 1 An Introduction to the Human Body • Anatomy – science of structure – relationships revealed by dissection (cutting open)( where a muscle attaches) – imaging techniques • Physiology – science of body functions – How living organisms perform vital functions – How the muscle contracts 1 Structure determines function

Levels of Organization • • • Chemical Cellular Tissue Organs System Level Organismic Level

Levels of Structural Organization • Chemical Level – atomic or molecular level. The smallest stable units of matter. Even at this level form( 3 dimension shape) determines function. • Cellular level – smallest living unit of the body. Molecules can interact to form various organelles. ORGANELLES are the structural and functional component of the cell. • Tissue level – group of cells and the materials surrounding them that work together on one task – 4 basic tissue types • epithelium, muscle, connective tissue, and nerve

Levels of Structural Organization • Organ level – grouping of 2 or more tissue types into a recognizable structure with a specific function. Layers of cardiac tissue in combination with connective tissue form the wall of the heart, a hollow 3 -dimensional organ. • Organ system – collection of related organs with a common function – Each time the heart contracts the heart, blood vessels form the cardiovascular system. 1 of 11 organ systems. • Organismic level- THE HUMAN. All systems must work together in harmony to maintain life, health & wellness.

The 11 Systems • The Neural System- The MASTER SYSTEM. Brain, spinal cord, peripheral nerves, sense organs. • It coordinates activities of other organ systems. • It provides and interprets sensory information about external conditions. • Directs immediate responses to stimuli • First system that develops, gives life to all systems. • Endocrine System- Pituitary gland, thyroid gland, pancreas, adrenals, testes, ovaries. • Directs long term changes in systems. • Adjusts metabolic activity &energy use by they body. • Control structural / functional changes during

Systems Continued • Muscular System- Skeletal muscles, fascia and tendons. • Provides motion • Provides protection and support to other tissues • Generates heat to maintain body temperature • Skeletal System- Bones, cartilages, ligaments, bone marrow. • Provides support and protection for other tissues • Stores calcium and minerals • Forms blood cells

Systems continued • Cardiovascular- Heart, blood vessels • Distributes blood cells, water, nutrients, oxygen, carbon dioxide, and waste products. • Distributes heat and assists in body temperature. • • Integumentary- Skin, hair, sweat glands, nails Protects against environmental hazards. Regulates body temperature Provides sensory information

Systems continued • Lymphatic- Spleen, Thymus, Tonsils, Lymph nodes. • Defends against infections • Returns tissue fluid to the blood stream. • Respiratory- Nasal cavities, Sinuses, Larynx, Trachea, Bronchi, Lungs, Alveoli. • Delivers air to alveoli where gas exchange occurs. • Provides O 2 to bloodstream / removes CO 2. • Produces sound for communication.

Systems Continued • Digestive System- Teeth, tongue, pharynx, esophagus, Stomach, S. I/ L. I, Liver, Gallbladder, Pancreas. • Processes and digests food • Absorbs and conserves water. • Absorbs nutrients and stores energy for reserves. • • Urinary- Kidneys, Ureters, Urinary bladder, Urethra Excretes waste from blood (Blood pressure) Controls water balance Regulates blood ion concentration and PH

Systems Continued • Reproductive Systems- Testes, Prostate Gland, Penis, Scrotum, Ovaries, Uterus, Vagina, Clitoris, Mammary glands. • Produces male sex cells ( Sperm) and hormones • Produces female sex cells ( Oocytes) and hormones • Supports developing embryo from conception to delivery. • Provides milk to nourish newborn infant.

Types of Anatomy • Gross Anatomy- also known as Macroscopic can be see with unaided eye. Surface anatomy- superficial markings Regional anatomy- anatomical regions such as head, neck, trunk Systemic anatomy- Organs that function together. Cardiovascular that distribute blood and nutrients throughout the body

Microscopic Anatomy • Microscopic deals with structures that can’t be seen with the naked eye. • Two major subdivisions: CYTOLOGY & HISTOLOGY • Cytology – Analysis of internal structures of individual cells ( the simplest units of life) Cells are made of chemical substances in various combinations, therefore basic chemistry needs to be looked at before cell structure. • Histology – Examination of TISSUES. Epithelium, muscle, connective tissue, and nerve. Tissues combine to form organs. At the organ level we cross the boundary from microscopic to macroscopic anatomy.

Types of Physiology • Human physiology is the study of human functions. • CELL PHYSIOLOGY- Is the cornerstone of human physiology. It considers events at the chemical and molecular level. Chemical processes within cells and between cells. • Specialized physiology- specific ORGANS. Example is cardiac physiology dealing with heart function. • Systemic physiology- Specific organ systems. Respiratory physiology, cardiovascular physiology. • Pathophysiology- Pathos=disease. The effects of disease on organ or system functions

Week 1 Lecture 2 Homeostasis • The adjustment of physiological systems to maintain balance. 2 types: Auto-regulation & extrinsic regulation • Auto-regulation- when an organ system adjusts automatically in response to environmental change. If O 2 levels drop in tissues, then cells release chemicals that will dilate the blood vessels. This will increase rate of flow and provide more O 2 to the region. • Extrinsic- results from Neural or Endocrine systems. When one exercises The NS commands the heart rate to increase, and reduces flow to digestive tract.

Control of Homeostasis • Homeostasis is continually being disrupted by – external stimuli or • intense heat, cold , and lack of oxygen – internal stimuli • psychological stresses • Exercise • Disruptions are usually mild & temporary • If homeostasis is not maintained, death may result

Neural and Endocrine Controls • Process of maintaining a controlled condition – sensory receptors detect change in a monitored variable – nervous system and/or endocrine system responds – Effector- activity either enhances or opposes stimulus • Example of control of blood gas level – exercise increases blood CO 2 levels – sensory receptors detect change – nervous system increases heart and breathing rates to remove excess CO 2 – adrenal gland releases epinephrine to increase heart and breathing rates

Components of Feedback Loop • Receptor – monitors a controlled condition • Control center – determines next action • Effector – receives directions from the control center – produces a response that changes the controlled condition

Negative & Positive Feedback Loops • Negative feedback loop – original stimulus reversed – most feedback systems in the body are negative – used for conditions that need frequent adjustment – body temperature( thermoregulation- Hypothalamus)) , blood sugar levels, blood pressure • Positive feedback loop – original stimulus intensified – seen during normal childbirth

Homeostasis of Blood Pressure • Pressure receptors in walls of certain arteries detect an increase in BP – blood Pressure = force of blood on walls of vessels • Brain receives input and signals heart and blood vessels • Heart rate slows and arterioles dilate (increase in diameter) • BP returns to normal • NEGATIVE FEED BACK

Negative feedback If body temperature rises to high, the SKIN and HYPOTHALMUS send info to the control center to the 2 effectors 1) muscle tissue of the blood vessels supplying the skin and 2) sweat glands. Muscle tissue relaxes and dilates blood vessels, sweat glands accelerate their secretion. The skin acts like a radiator by losing heat to the environment and the evaporation of sweat speeds up the process. Body temperature returns to normal temperature at the hypothalamus declines, and thermoregulatory control center becomes less active.

Positive Feedback during Childbirth • Stretch receptors in walls of uterus send signals to the brain • Brain releases hormone (oxytocin) into bloodstream • Uterine smooth muscle contracts more forcefully • More stretch, more hormone, more contraction etc. • Cycle ends with birth of the baby & decrease in stretch

Positive feedback • Positive feedback loops are typically found when a potentially dangerous process must be completed before homeostasis can be restored. • One seldom encounters + feedback in daily life b/c it tends to produce extreme responses. • Example- blood loss due to a severe cut can lower blood pressure so the body’s response: release chemicals to begin the process of clotting. As clotting gets under way, each step RELEASES CHEMICALS TO ACCELERATE THE PROCESS. The process ends with the formation of the clot.

Homeostatic Imbalances • Disorder = abnormality of function • Disease = homeostatic imbalance with distinct – symptoms---changes in body function felt by the patient such as nausea – signs----changes in body function that can be observed by the doctor such as rash or fever • Diagnosis---skill of distinguishing one disease from another