2Jon Krakauer Read about his climb up Mount Everest He reached the highest and one of the coolest places on EarthWind chill temperatures average -53C.Some people survive the climb and some do not. Why?
3How is the human body organized? Like a car or a computer, the human body is made up of many parts working together in a coordinated fashion.The parts are organized hierarchically, so that smaller components are organized into increasingly larger units, which are themselves organized into more complex systems.
4How is the human body organized? Anatomyis the study of the physical structures that make up an organism.Human bodies have an anatomical structure that well adapted to living in certain environments and performing certain functionsWe evolved in the hot, flat savannahs of AfricaEnvironment favored big brains, bipedal posture, etc.We don’t do well swimming at bottom of ocean or living on mountaintops.
5How is the human body organized? For all living things, the smallest anatomical unit is the cell. Human bodies are made up of trillions of cells, each of which can be classified as one of a few hundred different types.
6How is the human body organized? Cells are organized into tissues – layers of specialized cells working together to execute a particular function.Humans and other animals have four different kinds of specialized tissue – epithelial, connective, muscle, and nervous.
7How is the human body organized? An organ is a structure made up of different tissue types working together to carry out a common function.Stomach is composed of four different tissues for digestion.
8How is the human body organized? At the highest level of organization, organs interact chemically and physically as part of organ systems.
9How is the human body organized? Physiology is the study of the way a living organism’s physical parts function.Physiologists want to understand how organ systems cooperate to accomplish basic tasks,such as obtaining energy from foodtaking in nutrients to build new molecules during growth and repairand ridding the body of wastes.
10Maintaining Homeostasis The body is an integrated system for processing inputs and outputs and maintaining homeostasis – the maintenance of a relatively stable internal environment.
11Maintaining Homeostasis: Thermoregulation Like many animals, humans have an optimal temperature and are sensitive to temperature changes.We can toleration external temperature changes over a wide range.We are extremely sensitive to changes in our internal temperature.Through thermoregulation – the maintenance of a relatively stable internal body temperature – our body temperature is kept at a consistent 37°C (98.6°F).This is just one example of how the body tries to maintain homeostasis.
12Maintaining Homeostasis: Thermoregulation How do we respond to cold temperature???Conserving heat and generating moreTo conserve heat, the body performs peripheral vasoconstriction – the reduction in diameter of blood vessels just below the surface of the skin.This pushes blood from the skin to the body core, where the internal organs are, decreasing the amount of heat loss from your skin to the environment.
14Maintaining Homeostasis: Thermoregulation To generate more heat, the body shivers.Shivering is the involuntary contraction of normally voluntary muscles.When muscles contract through shivering, they create heat.
15Maintaining Homeostasis: Thermoregulation To help prevent overheating, peripheral vasodilation, or the expansion in diameter of blood vessels, increases blood flow to the skin, and evaporative cooling (otherwise known as sweating) cools the body by releasing heat to the air.We are doing a lot of sweating this summer?
16BalanceIf vasoconstriction goes on for too long (helping to retain heat), frostbite may occurDeath of tissues caused by lack of blood flowDuring the Everest climb, they had more than the cold to deal with? What else?
17AltitudeAt high altitudes, the percentage of oxygen molecules in the air is the same as sea level20% oxygen at sea levelProblem is with barometric pressure of oxygen is much lower, as it is with all molecules at high altitudes.Number of oxygen molecules banging around in a given volume of the atmosphereLower pressure means few oxygen molecules bind to hemoglobin in bloodLow oxygen in blood is termed hypoxiaHave serious effects on brain
18How do you cope with low oxygen For condition of low oxygen, climbers train or acclimate their bodies to the low oxygen condition.AcclimatizationThe process of physiologically adjusting to an environmental change over a period of time. Generally reversibleHow long did they train? What did they have as a backup for the climb?Body increases output of red blood cells
19Maintaining Homeostasis: Feedback Loops Thermoregulation does not require conscious thought.Automated response (thermostat)The body’s thermostat is the hypothalamusThe hypothalamus is a structure that sits at the base of the brain, right above the brain stem.The hypothalamus is responsible for a variety of physiological functions.It receives signals from many different sensors – specialized cells that detect changes in the internal and external environment.temperature, pressure, or solute concentration.
20Maintaining Homeostasis: Feedback Loops The hypothalamus acts as a thermostat. It has a specific temperature set point below which a warning message is triggered that body temperature is dropping when cold outside.When that happens, the hypothalamus essentially tells the body to take corrective action.- What happens to blood vessels? What else happens?Signals are sent from the hypothalamus to their target tissues along nerve fibers.
21Maintaining Homeostasis: Feedback Loops An effector is a cell or tissue that acts to exert a response on the basis of information relayed from a sensor.They act to cause a change in the internal environment.Once effectors have raised the body temperature, the sensors sense the changed conditions and the signals are turned off.
22Maintaining Homeostasis: Feedback Loops A feedback loop is a pathway that involves input from a sensor, a response via an effector, and detection of the response by the sensor.
23Maintaining Homeostasis: Feedback Loops In a negative feedback loop, the output of the circuit inhibits the input of the circuit, thereby helping to bring the system back to its set point.Opposite effectTemperature goes up, bring temperature back down to set point.
24Maintaining Homeostasis: Feedback Loops In a positive feedback loop, the output of a system acts to further increase the input of the system.Delivery of child, blood clotting
25Maintaining Homeostasis: Feedback Loops Hypothalamus regulates many body functions: hunger, thirst, and sleep.Body’s main homeostasis control centerKey part of nervous system and endocrine systemRight below the hypothalamus is the pituitary gland that releases hormones for homeostasis.
26What happened on the climb down Everest? HypothermiaA drop of body temperature below 35C (95F) which causes enzyme malfunction and eventually, death
27Thermoregulation cannot do so indefinitely Work takes energy. Need food for fuelThe body uses the sugar glucose, a breakdown product of carbohydrate digestion, as fuel.When we eat carbohydrates, sugars are released and absorbed into circulation, and blood sugar increases.
28Maintaining Homeostasis: Feedback Loops Some of this sugar may be used immediately as fuel for aerobic respiration in cells of the body.Whatever is not needed right away will be converted into glycogen – an energy-storing carbohydrate – which is stored in muscles and the liver.By converting excess glucose to glycogen, the body maintains a relatively stable blood-glucose level.
30Maintaining Homeostasis: Feedback Loops Blood-glucose levels are controlled by endocrine tissue in the pancreas, an organ that functions in both the endocrine and digestive systems.
31Maintaining Homeostasis: Feedback Loops In response to high blood sugar, the pancreas produces the hormone insulin, which binds to receptors on muscle and liver cells, signaling them to remove sugar from the blood.Insulin also signals these cells to make glycogen, using the sugars taken up from the blood.
32Maintaining Homeostasis: Feedback Loops When blood-sugar levels are low, the body first prompts us to eat by sending a signal to the hypothalamus. If eating isn’t an option, the body begins to break down its stored glycogen.Glucagon, a hormone produced by the pancreas in response to low blood sugar, triggers muscle and liver cells to convert their stored glycogen to glucose.
33Organ SystemsThe integumentary system serves to protect the body from damage. It includes the skin, hair, fat, and nails.
34Organ SystemsThe muscular system is responsible for the movement of body parts. Skeletal limbs, the heart, and other internal organs all move with the aid of this system.
35Organ SystemsThe skeletal system provides structural support for the body and includes the bones, cartilage, ligaments, and tendons.
36Organ SystemsThe circulatory system pumps blood between the lungs and the body cells using the heart, blood, and blood vessels. These organs transport molecules all over the body.
37Organ SystemsThe endocrine system provides communication within the body using hormones made by tissues including the hypothalamus, pituitary, thyroid, and adrenal glands.
38Organ SystemsThe nervous system includes organs that sense and respond to information from all over the body. This system includes the brain, spinal cord, and peripheral nerves.
39Organ SystemsThe lymphatic system transfers lymph fluid from tissues into the blood and includes the cells and organs of the immune system, such as the lymph nodes, spleen, and bone marrow.
40Organ SystemsThe respiratory system is involved in the exchange of oxygen and carbon dioxide between the air and the blood. Respiratory system organs include the trachea, lungs, and diaphragm.
41Organ SystemsThe digestive system breaks down and absorbs food molecules using organs such as salivary glands, stomach, small intestine, liver, and large intestine.
42Organ SystemsThe urinary system is involved in the regulation of fluid balance in the body and the elimination of waste in urine. The kidneys and bladder are key organs in this system.
43Organ SystemsThe reproductive system is involved in the development of offspring. Male organs include the testes and penis. Female organs include the ovaries and uterus.
44Maintaining Homeostasis: Feedback Loops Osmolarity is the concentration of dissolved solutes in the blood.Among the solutes dissolved in the blood are electrolytes – ions such as sodium and potassium that are critical for nerve signaling and muscle contraction.
46Maintaining Homeostasis: Feedback Loops Osmolarity is monitored by the hypothalamus as part of osmoregulation.When you are dehydrated – when you have less fluid in your blood – the concentration of dissolved solutes is higher.
47Maintaining Homeostasis: Feedback Loops If the hypothalamus registers that the concentration of solutes in the blood is high, it will trigger a sense of thirst, as well as triggering the release of antidiuretic hormone (ADH) from the pituitary, which travels through the bloodstream and acts on the kidneys.The kidneys are the organ involved in osmoregulation, filtration of blood to remove wastes, and production of several important hormones.
48Maintaining Homeostasis: Feedback Loops ADH signals the kidneys to excrete less water in the urine.By reducing the amount of water lost in urine, ADH causes more water to be reabsorbed by the kidneys back into the bloodstream.Water in the bloodstream dilutes dissolved solutes and lowers the osmolarity.
49Maintaining Homeostasis: Feedback Loops Osmoregulation also depends on sensors that detect changes in blood volume and pressure, both of which depend on the amount of water in the blood.
50How do other organisms thermoregulate? Because humans use internal metabolic heat to thermoregulate, humans are classified as endotherms.
51How do other organisms thermoregulate? Animals that rely on environmental sources of heat, such as sunlight, to maintain body temperature are classified as ectotherms.
52How do other organisms thermoregulate? Some organisms generate heat from nonshivering thermogenesis.