BODY STRUCTURE/HOMEOSTASIS Flashcards
Organ
Distinct structure of the body composed of two or more tissue types
Organ system
Group of organs that work together to perform major functions in the body or meet physiological needs
Organism
Living being that has a cellular structure and can independently perform all physiological functions necessary for life
Integumentary system function
Encloses internal body structures and the site of many sensory receptors (eg. Hair, skin, nails)
Skeletal system function
Supports the body and enables movement with the muscular system (eg. Cartilage, bones, joints)
Muscular system function
Helps maintain body temperature and enables movement with skeletal system (eg. Tendons, skeletal muscle)
Nervous system function
Detects and processes sensory information and activates bodily responses (eg. Brain, spinal cord, peripheral nerves)
Endocrine system function
Secretes hormones and regulates bodily processes (eg. Thyroid gland, adrenal gland, pituitary gland pancreas, testes)
Cardiovascular system function
Delivers oxygen and nutrients to tissues and equalizes temperature in the body (eg. Heart, blood vessels)
Lymphatic system function
Returns fluid to blood and defends against pathogens (eg. Thymus, lymph nodes, spleen, lymphatic vessels)
Respiratory system function
Removes carbon dioxide from the body and delivers oxygen to blood (eg. Lungs, trachea, nasal passage)
Digestive system function
Processes food for use by the body and removes waste from undigested food (eg. Stomach, liver, gall bladder, large intestine, small intestine)
Urinary system function
Controls water balance in body and removes waste from blood and excretes them (eg. Kidneys, urinary bladder)
Male reproductive system function
Produces sex hormones and gametes and delivers gametes in females (eg. Epididymis and testes)
Female reproductive system function
Produces sex hormones and gametes, supports embryo/fetus until birth, and produces milk for infant (eg. Mammary gland, ovaries, uterus)
Why do anatomists standardize human body
To increase precision and avoid confusion. It allows us to provide a clear and consistent way of describing the human anatomy and physiology
Anatomical position (4):
- The body is standing upright
- Feet are parallel and shoulder width apart
- Toes forward
- Upper limbs held out at each side with the palm forward
Prone
Describes a face down orientation
Supine
Describes a face up orientation
Anterior/ventral
The front of the body or direction towards the front of the body
Posterior/dorsal
The back of the body or direction towards the back of the body
Superior/cranial
Above or higher than another part of the body
Inferior/caudal
Below or lower than another part of the body
Lateral
The side of the body or direction towards the side of the body
Medial
The middle of the body or direction toward the middle of the body
Intermediate
Between a more medial and more lateral structure
Proximal
A position in a limb that is nearer to the point of attachment or the trunk of the body
Distal
A position in a limb that is farther from the point of attachment or the trunk of the body
Central
Towards the middle of a structure
Peripheral
Towards the outer edge of a structure
Superficial
Closer to the surface of the body
Deep
Farther from surface of body
Sectional planes (5):
- Sagittal plane
- Midsagittal plane
- Parasagittal plane
- Frontal/coronal plane
- Transverse plane
Sagittal plane
Divides the body or an organ vertically into right and left sides
Midsagittal plane
A sagittal plane that runs directly down the middle of the body and divides it into EQUAL right and left sides
Parasagittal plane
A sagittal plane that runs vertically away from middle of the body and divides it into two UNEQUAL right and left sides
Frontal/coronal plane
Divides the body or an organ into an anterior portion and a posterior portion
Transverse plane/cross section
Divides the body or organ horizontally into upper and lower portions
Cavities
Membranes, sheaths and other structures that are used to separate the internal body into separate compartments. It is important for protecting delicate internal organs
What are the largest cavities
The dorsal (posterior) cavity and the ventral (anterior) cavity but abdominopelvic cavity is the LARGEST
Dorsal cavity (2):
- Consists of a cranial cavity that houses the brain, and the spinal cavity (or vertebral cavity) that encloses the spinal cord
- Brain and spinal cord are protected by the bones of the skull and vertebral column and are cushioned by cerebrospinal fluid produced by the brain
Ventral cavity (2):
- Consists of two main subdivisions (thoracic cavity and abdominopelvic cavity)
- Ventral cavity allows for significant changes in the size and shape of the organs as they perform their functions
Thoracic cavity
Enclosed by the rib cage and contains the lungs and the heart (latter located in mediastinum)
Abdominopelvic cavity
Largest cavity in the body that is not physically divided by a membrane. However, anatomists distinguish between the abdominal cavity (division housing digestive organs), and pelvic cavity (division housing reproduction organs)
Divisions of the abdominopelvic cavity by health care providers (9):
- Right hypochondriac: Liver, gallbladder
- Epigastric: Liver, stomach
- Left hypochondriac: Stomach, spleen
- Right lumbar: Ascending colon
- Umbilical: Transverse colon, small intestine
- Left lumbar: Descending colon
- Right iliac: Appendix, caecum
- Hypogastric: Lower small intestine, urinary bladder
- Left iliac: Proximal sigmoid colon
Serous membrane (serosa)
One of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavity. It forms fluid filled sacs/cavities that cushions and reduces friction on internal organs when they move like when the lung inflates or heart beats
Parietal layer
Membrane that lines the walls of the body cavity
Visceral layer
Membrane that covers the organs
What is in between the parietal and visceral layers
The cavity, a thin fluid-frilled serous space
Pleura
Serous membrane that surrounds lungs in pleural cavity
Pericardium
Serous membrane that surrounds the heart in the pericardial cavity
Peritoneum
Serous membrane that surrounds several organs in abdominopelvic cavity
Homeostasis
Refers to the relatively stable set of conditions within an organism’s internal environment
Significance of homeostasis
Maintaining a healthy environment for living cells requires maintaining appropriate conditions in the extracellular fluids. The constancy of an internal environment is important in allowing chemical reactions to take place at rates necessary to maintain the body
3 important conditions that must be met to maintain a constant internal environment:
- Maintaining proper concentrations of gases, nutrients, water, and salts
- Maintaining an optimum temperature of 37C for chemical reaction rates and proper protein shapes
- Maintaining an optimum pressure for the proper concentrations of various substances and the rates they move through the body
Internal environment
Internal environment is the environment in which the cells are found
Intracellular fluid
Fluid inside the cells (cytoplasm)
Extracellular fluid
Fluid outside the cells in the body
Plasma
Liquid portion of blood and functions to move red and white blood cells, platelets, nutrients, molecules, gases, electrolytes and wastes throughout circulatory system
Interstitial fluid
Fluid that surrounds living cells within tissues
Internal environment homeostasis (4):
- Homeostasis is maintained within the internal environment of the body
- It is the fluid inside the body but outside of cells
- Continually subjected to disturbances that if left unchecked could lead to illness or death
Cells function in homeostasis
Responsible for controlling bodily activities and controlling the composition of the materials that surround them
Cells are surrounded by __
Cells are surrounded by extracellular materials that is mostly fluid
Stressor
Any stimulus that causes an imbalance in the internal environment
External stressor
Stressors occurring outside the body (eg. lack of environmental oxygen, extreme environmental temperatures)
Internal stressor
Stressors occurring inside the body (eg. rapid changes in blood pressure, changes in nutrient levels)
Maintaining homeostasis (4):
- Requires the body continuously monitoring internal conditions
- Each physiological condition has a particular set point (the physiological value around which the normal range fluctuates)
- Normal range is a restricted set of values that is healthful and stable
- Feedback systems!
Set point
Physiological value around which the normal range fluctuates
Normal range
Restricted set of values that is healthful and stable
Feedback system
Regulatory mechanism that monitors and adjusts a process based on the information received about its current state.
5 components of feedback system:
- Sensor
- Control center
- Effector
- Response
- Normal range
- A SENSOR detects when the stressor/stimulus produces a deviation in a physiological value away from set point and reports to control center
- The CONTROL CENTER compares the current value to the normal range and if it deviates too much, then the control center activates an effector
- An EFFECTOR produces a response
- A RESPONSE causes return of the physiological value to its NORMAL RANGE
Negative feedback system (6):
- Mechanism that reverses a deviation from set point
- Body parameters maintained within normal range
- Functioning in body at all times
- The effected response works opposite to the stressor/stimulus
- Eg. Insulin lowers blood sugar when levels are high, and glucagon raising blood sugar when levels are low
- Eg. Elevated (heat gain) or decreased (heat loss) body temperatures maintained by negative feedback
What happens when body temperature increases too much:
- Sensors detect the increase in body temperature and send to the control center (hypothalamus) of the brain
- The hypothalamus stimulates a cluster of brain cells called thermoregulatory center with THREE consequences
- The 3 consequences contribute to the response and lowers body temperature as heat is lost
Hypothalamus
Control center of the brain
Thermoregulatory center
Cluster of brain cells stimulated by the hypothalamus
3 mechanisms for INCREASED TEMP
- Blood vessels dilating in the skin (effector); allowing more blood to flow to the surface and radiate heat
- Sweat glands activated (effector); increase production and secretion of sweat and evaporates and releases heat
- Depth of respiration increases (effector); increasing heat loss from the lungs
Decreased body temperature (3):
- Sensors detect the decrease in body temperature and send to the control center (hypothalamus) of the brain
- The hypothalamus stimulates a cluster of brain cells called thermoregulatory center with FOUR consequences
- The 4 consequences contribute to the response and increases body temperature as heat is produced
4 mechanisms for DECREASED BODY TEMPERATURE
- Blood vessels constricting in the skin (effector); Less blood to skin trapping heat in the core
- Skeletal muscles contract - shivering (effector); generates heat while using ATP
- Thyroid gland releases thyroid hormone (effector); increasing metabolic activity and heat production
- Adrenal glands release epinephrine (effector); glucose produced to increase metabolism
Beta cells (receptors)
Endocrine cells in the pancreas that detect excess glucose (stimulus/stressor) in the blood stream
Beta cells (control center)
Responds to the increase blood glucose by releasing insulin
Insulin
Signals skeletal muscle fibers, adipocytes, and liver cells to take up the excess glucose
Positive feedback system (2):
- Intensifies a change in the body’s physiological condition rather than reversing it
- Eg. Childbirth, blood clotting, urination
Childbirth as positive feedback
Enormous changes in the mother’s body is required to expel the baby at the end of pregnancy and the events of childbirth must progress rapidly to a conclusion once begun to avoid risk. The extreme muscular work of labor and delivery are the result of a positive feedback system
Childbirth steps in positive feedback system (7):
- Contractions of labor (stimulus) push baby towards cervix
- Cervix contains stretch sensitive nerve cells that monitor the degree or stretching (sensors)
- The sensors sends messages to the brain that causes the pituitary gland (control center) to release oxytocin in blood stream
- Oxytocin causes stronger contractions of the smooth muscles in the uterus (the effectors) and pushes baby further down the birth canal
- This causes even greater stretching of the cervix (response)
- The cycle of stretching, oxytocin release, and the forceful contractions stops when the baby is born
- As the stretching of the cervix halts, it stops the release of oxytocin
Blood clotting in positive feedback
The body responds to the most immediate threat of excessive blood loss after a penetrating wound, and releases substances in the injured blood vessel wall that begins process of blood clotting until eventually sealing off the damaged area
