The Human Body chapter 1

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Survival Needs

Atmospheric Pressure

Specific air pressure is needed for adequate breathing and gas exchange in the lungs

Normal Body Temperature

If body temp falls below or goes above 37°C, rates of chemical reactions are affected

Water

The most abundant molecule in the body: Provides the watery environment needed for chemical reactions → Also is the fluid base for secretions and excretions

Oxygen

Essential for release of energy from foods → The body can survive only a few minutes without oxygen

Nutrients

Chemicals for energy and cell building → Carbs: Major source of energy → Proteins: Needed for cell building and enzyme activity → Fats: Long-term energy storage → Minerals and vitamins: involved in chemical reactions as well as for structural purposes

Homeostasis

Homeostatic Imbalance

Normally smooth layers can become rough and even can stick together, resulting in excruciating pain

Serous membranes can become inflamed as a result of infection or other causes

Control systems become less efficient → If negative feedback mechanisms become overwhelmed, destructive positive feedback mechanisms lower → e.g heart failure

Disturbance of homeostasis → Increases risk of disease: pathology → Contributes to changes associated with aging

Homeostatic Controls

Positive Feedback - Response enhances the original stimulus - May exhibit a cascade or amplifying effect as feedback causes variable to continue in the same direction as the initial change - Usually controls infrequent events that don’t require continuous adjustment 1. Enhancements of labor contractions by oxycontin 2. Platelet plug formation and blood clotting

Negative Feedback - Most-used feedback mechanism in the body - Response reduces or shuts off original stimulus - Variable changes in opposite direction of initial change 1. Regulation of blood glucose by insulin 2. Regulation of body temperature

Regulation of blood glucose – Receptors sense increased blood glucose (blood sugar) – Pancreas (control center) secretes insulin into the blood – Insulin causes body cells (effectors) to absorb more glucose, which decreases blood glucose levels

Effector - Receivers output from the control center - Provides the means to respond

Control Center - Determines set point at which variable is maintained - Receives input from receptor

Receptor (sensor) - Monitors environment - responds to stimuli

The body must constantly be monitored and regulated to maintain homeostasis → Nervous Systems → Variables

Homeostasis is the maintenance of relatively stable internal conditions despite continuous changes in environment

Any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival

Anatomical Terms, Position and Direction

Regional Terms

Appendicular → Libs (legs and arms)

Axial → Head, neck, and trunk

Regional terms designate specific areas within body divisions

PICTURE https://medictests.com/units/standard-anatomical-terms-and-planes

Directional Terms describe one body structure in relation to another body structure → Direction is always based on standard anatomical position → Right and left refer to the body being viewed, not right and left of the observer

Standard Anatomical Position → Body erect, feet slightly apart, palms facing forward with thumbs pointing away from the body

Body planes and Sections

Sections → cuts of sections made along a body plane

surfaces along which body or structures may be cut for anatomical study → Three most common planes: Sagittal Plane Frontal (coronal) plane Transverse Plane

Oblique Section → Result of cuts and angles other than 90° to a vertical plane

Transverse (Horizontal) plane → Divides body horizontally (90° to the vertical plane) into superior and inferior (top and bottom) → Produces a cross-section

Frontal (coronal) plane → Divides body vertically into anterior and posterior parts (front and back) → Produces a frontal or coronal section

Parasagittal Plane → The cut was off-centered, not on the midline

Midsagittal (median) plane → The cut was made perfectly on the midline

Sagittal Plane → Divides body vertically into right and left parts → Produces a sagittal section if cut along this plane

Body Cavities

Two sets of Cavities

Ventral Body Cavity

Membranes in the ventral body cavity → Serosa (also called serous membrane Thin, double-layered membranes that cover surfaces in the ventral body cavity -Parietal serosa lines internal body cavity walls -Visceral serosa covers internal organs (viscera) Double layers are separated by a slit-like cavity filled with serous fluid Fluid secreted by both layers of membrane

Pleural Cavity

Abdominal Pelvic Cavity

Dorsal Body Cavity

Vertebral Cavity

Cranial Cavity

A body cavity is a fluid-filled space inside the body that holds and protects internal organs

Body contains internal cavities that are closed to an environment Cavities provide different degrees of protection to organs within them

The Body’s Organ Systems and Their Major Functions

Female Reproductive System

Mammary glands, Ovary, Uterus, Vagina, Uterine tube

Overall function is offspring. Ovaries produce eggs and female sex hormones

Male Reproductive System

Prostate, Penis, Testis, Scrotum, Ductus deferens

Overall function is production of offspring. Testes produce sperm and male sex hormones

Urinary System

Urinary Bladder, Kidney, Urethra

Eliminates nitrogenous wastes from the body. Regulates water, electrolyte, and acid-base balance of the blood

Digestive System

Liver, Stomach, Large/Small Intestine

Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible food are eliminated as feces

Respiratory System

Lungs, Nasal Cavity, Pharynx, Trachea, Bronchus

Keeps blood constantly supplied with oxygen and removes carbon dioxide. Occurs within the walls of the lungs

Lymphatic system

Redbone Marrow, Thymus, Spleen, Lymph nodes

Picks up fluids leaked from blood vessels and returns it to blood. Houses white blood cells (involved with immunity).

Cardiovascular System

Blood Vessels, Heart

Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood

Endocrine System

Ovary, Testis, Adrenal gland, Pancreas

Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use

Nervous System

Nerves, Brain, Spinal cord

Responds to internal and external changes by activating appropriate muscles and glands

Muscular System

Muscles in body: Obliques, Biceps, Pec

Allows manipulation of the environment, locomotion, facial expression, etc

Skeletal system

Bones, Joints

Protects and supports body organs. Blood cells are formed within bones

Integumentary System

Hair, Skin, Nails

Synthesizes vitamin D and houses pain, pressure, etc receptors along with sweat and oil glands

Requirements for life

Growth

Increase in size of a body part or of the organism

Reproduction

At the cellular level, reproduction involves the division of cells for growth or repair At the organismal level, reproduction is the production of offspring

Excretion

Removal of wastes from metabolism and digestion E.g Urea (from breakdown of proteins), carbon dioxide (from metabolism), feces (unabsorbed food)

Metabolism

All chemical reactions that occur in body cells. Sum of all catabolism (breakdown of molecules) and anabolism (synthesis of molecules)

Digestion

Mechanical and enzymatic breakdown of ingested food, followed by absorption of simple molecules (monomers) into blood/lymphatics

Responsiveness

Ability to sense and respond to stimuli

Movement

The muscular System allows movement of body parts via skeletal muscles and of substances via cardiac muscle (blood) and smooth muscle (digestion, urination)

Maintaining Boundaries

Separation between internal and external environments (E,g Plasma membranes, Skin separates organism from environment)

Structural Organization

Organismal Level

All Organ Systems Combined to Make the Whole Organism

Organ System

Organs That Work Closely Together

Organ Level

Contains 2+ Types of Tissues

Tissue Level

Groups of Similar Cells

Cellular Level

Single Cell

Chemical Level

Atoms, Molecules, Organelles

Anatomy and Physiology

The two are Inseprable

- Function always reflects structure - What a structure can do depends on its specific form - Known as the principle of complementarity of structure and function

Physiology

Looks at how the body’s abilities are dependent on chemical reactions in individual cells

Often focuses on cellular and molecular levels of the body

Based on organ systems

Study of the function of body parts; how they work to carry out life-sustaining activities