Chapter 1 The Human Body

Anatomy and Physiology Anatomy – study of the structure of the human body Anatomy – study of the structure of the human body Physiology – study of the function of the human body Physiology – study of the function of the human body

Gross Anatomy Regional – study of structures in an area of the body Regional – study of structures in an area of the body Systemic – study of structures in an organ system Systemic – study of structures in an organ system

Microscopic Anatomy Cytology – study of cells Cytology – study of cells Histology – study of tissues Histology – study of tissues

Developmental Anatomy Study of structural changes in the body throughout life Study of structural changes in the body throughout life Embryology – focuses on changes before birth Embryology – focuses on changes before birth

Physiology Focuses on operation of body systems Focuses on operation of body systems –Renal physiology –Neurophysiology –Cardiovascular physiology

Complementarity of Structure and Function Anatomy and physiology are tied together by this principle Anatomy and physiology are tied together by this principle Structures are “built” a certain way so that they can perform a specific function Structures are “built” a certain way so that they can perform a specific function

Levels of Structural Organization 1. Chemical – simplest level (atoms and molecules) 2. Cellular – cells are smallest units of living things 3. Tissue – groups of cells with common function 4. Organ – contains at least two tissue types 5. Organ system – organs work together to perform certain functions 6. Organism – all organ systems work together to sustain life

Smooth muscle cell Molecules Atoms Smooth muscle tissue Epithelial tissue Heart Blood vessels Smooth muscle tissue Connective tissue Blood vessel (organ) Cardiovascular system Cellular level Cells are made up of molecules. Tissue level Tissues consist of similar types of cells. Organ level Organs are made up of different types of tissues. Organ system level Organ systems consist of different organs that work together closely. Organismal level The human organism is made up of many organ systems. Chemical level Atoms combine to form molecules.

Necessary Life Functions 1. Maintenance of boundaries – internal environment is separate from external environment 2. Movement – can be movement of parts of the body or movement within the body 3. Responsiveness (irritability) – ability to sense changes in the environment and respond to them 4. Digestion – breakdown of foodstuffs

Necessary Life Functions (cont.) 5. Metabolism – all the chemical reactions that occur within the cells of our body –Catabolism = breakdown of substances –Anabolism = synthesis of more complex substances 6. Excretion – removal of waste from the body 7. Reproduction – cellular reproduction and organismal reproduction 8. Growth – increase in size of an organism or part of an organism

Survival Needs These are conditions or substances which the body needs to maintain life These are conditions or substances which the body needs to maintain life 1.Nutrients – needed for chemical reactions 2.Oxygen – chemical reactions require oxygen to occur in the body 3.Water – 60-80% of our body is water, we need it for chemical reactions and secretions 4.Body temperature – this can affect the rate of chemical reactions 5.Atmospheric pressure – the force of air on the body surface

Homeostasis The ability of the human body to maintain a stable internal environment despite a changing external environment The ability of the human body to maintain a stable internal environment despite a changing external environment The body holds internal conditions within narrow limits The body holds internal conditions within narrow limits Examples – maintenance of blood pressure, maintenance of body temperature, elimination of wastes Examples – maintenance of blood pressure, maintenance of body temperature, elimination of wastes

Homeostatic Control Mechanisms Communication must occur for the body to maintain homeostasis Communication must occur for the body to maintain homeostasis This is done with the nervous and endocrine systems This is done with the nervous and endocrine systems –Variable – factor being regulated –Receptor – sensor that detects changes in the environment (stimuli) –Control center – receives input from receptor and determines appropriate response –Effector – responsible for carrying out the response determined by the control center

Change detected by receptor Stimulus: Produces change in variable Input: Information sent along afferent pathway to Receptor (sensor)Effector Control center Variable (in homeostasis) Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis Output: Information sent along efferent pathway to Imbalance

Negative Feedback Mechanisms The output shuts off the original stimulus or decreases its intensity The output shuts off the original stimulus or decreases its intensity The variable changes in a direction opposite to the original change The variable changes in a direction opposite to the original change Negative feedback prevents sudden, dramatic changes within the body Negative feedback prevents sudden, dramatic changes within the body

Figure 1.5 Signal wire turns heater off Response; temperature drops Stimulus: rising room temperature Balance Effector (heater) Receptor-sensor (thermometer In thermostat) Set point Control center (thermostat) Heater off

Figure 1.5 Signal wire turns heater on Response; temperature rises Stimulus: dropping room temperature Balance Effector (heater) Set point Receptor-sensor (thermometer in Thermostat) Control center (thermostat) Heater on

Positive Feedback Mechanisms The response enhances the original stimulus The response enhances the original stimulus Change occurs in the same direction as the initial change Change occurs in the same direction as the initial change Variable moves further and further away from original value Variable moves further and further away from original value Can race out of control Can race out of control

Figure 1.6 Released chemicals attract more platelets Clotting occurs as platelets adhere to site and release chemicals Break or tear in blood vessel wall Feedback cycle initiated Feedback cycle ends after clot seals break Clotting proceeds; newly forming clot grows

Anatomical Position Body is erect Body is erect Feet slightly apart Feet slightly apart Palms face forward Palms face forward Thumbs point away from the body Thumbs point away from the body Figure 1.7a

Table 1.1a

Table 1.1b

Body Planes Sagittal plane – vertical, divides body into right and left parts Sagittal plane – vertical, divides body into right and left parts –Midsaggital plane Frontal plane – vertical, divides body into front and back parts Frontal plane – vertical, divides body into front and back parts Transverse plane – horizontal, divides body into upper and lower parts Transverse plane – horizontal, divides body into upper and lower parts

Body Planes Figure 1.8

Body Cavities Two main body cavities Two main body cavities 1. Dorsal – protects nervous system Cranial cavity – holds the brain Cranial cavity – holds the brain Vertebral cavity – holds spinal cord Vertebral cavity – holds spinal cord

Body Cavities 2. Ventral – larger, more anterior Thoracic cavity – surrounded by ribs Thoracic cavity – surrounded by ribs –Pleural cavities – encase the lungs –Mediastinum – contains pericardial cavity and other thoracic organs Abdominopelvic cavity – in abdominal region, divided from thoracic cavity by diaphragm Abdominopelvic cavity – in abdominal region, divided from thoracic cavity by diaphragm –Abdominal cavity – contains stomach, intestines, liver, and spleen –Pelvic cavity – contains bladder, reproductive organs, and rectum

Cranial cavity (contains brain) Dorsal body cavity Diaphragm Abdominal cavity (contains digestive viscera) Pelvic cavity (contains bladder, reproductive organs, and rectum) Vertebral cavity (contains spinal cord) Key: Dorsal body cavity Ventral body cavity Thoracic cavity (contains heart and lungs) (a) Lateral view Figure 1.9a

Figure 1.9b Ventral body cavity (thoracic and abdomino- pelvic cavities) Abdomino- pelvic cavity Superior mediastinum Pleural cavity Cranial cavity Vertebral cavity Pericardial cavity within the mediastinum Diaphragm Abdominal cavity (contains digestive viscera) Pelvic cavity (contains bladder, reproductive organs, and rectum) Thoracic cavity (contains heart and lungs) (b) Anterior view Key: Dorsal body cavity Ventral body cavity

Membranes Ventral body cavity has double-layered membranes called serous membranes Ventral body cavity has double-layered membranes called serous membranes Parietal serosa – attached to body wall Parietal serosa – attached to body wall Visceral serosa – covers organs Visceral serosa – covers organs Serous fluid – found between the layers Serous fluid – found between the layers

Serous Membrane Relationship Figure 1.10a

Membranes of Specific Regions Serous membranes are the general term Serous membranes are the general term Parietal pericardium and visceral pericardium refer to the heart Parietal pericardium and visceral pericardium refer to the heart Parietal pleura and visceral pleura refer to the lungs Parietal pleura and visceral pleura refer to the lungs Parietal peritoneum and visceral peritoneum refer to the abdominopelvic cavity Parietal peritoneum and visceral peritoneum refer to the abdominopelvic cavity

Heart Serosae Figure 1.10b

Other Body Cavities Oral cavity – contains teeth and tongue Oral cavity – contains teeth and tongue Digestive cavity – cavities of the digestive organs Digestive cavity – cavities of the digestive organs Nasal cavity – located within and posterior to the nose Nasal cavity – located within and posterior to the nose Orbital cavities – house the eyes Orbital cavities – house the eyes Middle ear cavities – contains bones (ossicles) that transmit sound vibrations Middle ear cavities – contains bones (ossicles) that transmit sound vibrations Synovial cavities – joint cavities Synovial cavities – joint cavities

Figure 1.13

Abdominopelvic Regions Used to pinpoint specific areas of the abdominopelvic cavity Used to pinpoint specific areas of the abdominopelvic cavity Nine separate regions Nine separate regions 1.Umbilical region – around navel, central region 2.Epigastric region – above umbilical region 3.Hypogastric region – below umbilical region

Abdominopelvic Regions (cont.) 4., 5. Right and Left Iliac (inguinal) regions – lateral to hypogastric region 6., 7. Right and Left Lumbar regions – lateral to umbilical region 8., 9. Right and Left Hypochondriac regions – lateral to epigastric region

Abdominopelvic Regions Figure 1.11a

Organs of the Abdominopelvic Regions Figure 1.11b

Abdominopelvic Quadrants Right upper (RUQ) Right upper (RUQ) Left upper (LUQ) Left upper (LUQ) Right lower (RLQ) Right lower (RLQ) Left lower (LLQ) Left lower (LLQ) Figure 1.12