Physiology Overview - Vertebrates Chapter 40

What you need to know  The four types of tissues and their general functions  The importance of homeostasis and examples  How feedback systems control homeostasis and 1 example of positive feedback and 1 example of negative feedback

Organ Systems (On AP Test) 1. Digestive System (nutrition/solid waste) 2. Endocrine System (regulation) 3. Respiratory System (gas exchange) 4. Circulatory System (transport) 5. Excretory System (homeostasis, liquid waste)

Organ Systems 6. Integumentary System (Cartilage, connective tissues) 7. Nervous System (integration of body and environment through senses) 8. Muscular System (locomotion) 9. Lymphatic Immune System (defense) 10. Reproductive System 11. Skeletal System (bones)

Hierarchy  Cells  tissues  organs  organ systems  Example:  Neurons  nervous tissue  brain  nervous system

Specialized Cells/Tissue 1. Epithelial cells (endoderm & ectoderm):  Cells that cover interior and exterior body surfaces including glands  Skin, lining of lungs, and all other organs  Tight junctions 2. Connective Tissue (mesoderm):  Supports the body, and connects parts together  Connective, adipose, cartilage, bone, and blood  Loose connections

Specialized Cells/Tissue 3. Nervous tissue (ectoderm):  Conducts impulses throughout the body  Nerve cells, brain cells, and spinal cord 4. Muscle tissue (mesoderm):  Actin/myosin cytoskeleton parts in cytoplasm of muscle cells convert ATP into movement  Skeletal muscles, smooth muscles, and cardiac muscles

Metabolism  ATP production through cellular respiration  Metabolic rates in organisms determined by ATP requirements for survival  High in endothermic  Low in exothermic (approx. 90% lower)

Homeostasis  Dynamic set of mechanisms that regulate internal environment

Homeostasis – steady state  All organisms do homeostasis  Isolation from environment is impossible for survival  External environment changes the internal environment  Wide fluctuations in external environment  Stable internal environment promotes healthy metabolism

Feedback Loops  Regulate body functions 1. Receptor  detects change 2. Control center  receives info from the receptor and directs response  Usually hypothalamus 3. Effector  Carries out response

Negative Feedback Loops  Effectors reduce change, preventing small changes from becoming big changes  Most homeostatic mechanisms are negative feedback loops: temp, blood sugar, pH, hydration, and oxygen supply

Negative Feedback Example

Positive Feedback Loops  Change stimulates response that further amplifies change (rare)  Childbirth:  Stimulus: pressure of head on cervix  Response: increased contractions

Thermoregulation/Endotherms  Source of body heat = intense metabolism  Metabolism increases 2x every 10 0 Celsius  Body temp is independent of environment  Mostly high temperatures that are narrowly regulated  High food consumption  Body surface area/volume ratio is important  Mammals and Birds

Variations of Thermoregulation  Poikilotherms: large variation of body temperature  Marine fish tend to have body temperatures higher than water due to high metabolisms  Hibernation in some mammals  Homeotherm: stable body temperature  Humans

Heat Production/Conservation  Insulation: fur, feathers, blubber  Acclimations: seasonal change of winter/summer coat, and membrane fluidity (regulated by fatty acids)  Shivering: muscle contractions regulated by hormones (adrenalin, thyroxin)  Insects shiver and/or rub their wings

Heat Regulation Mechanisms  Counter current exchange  temperature exchange between incoming and outgoing blood flow  Bird feet, fish fins, marine mammal flippers  Vasoconstriction: smooth muscle nodes around capillaries reduce blood flow to extremities (conservation)  Vasodilation: relaxation of smooth muscles increases blood flow (radiation)

Heat Regulation Mechanisms  Hibernation: lowering of body temp and activity level to save food stores  Behaviors: avoiding/seeking heat, shade, cool water  Sweating: heat loss through evaporation from skin  Panting: heat loss through evaporation of saliva

Heat Regulation Mechanisms  Large extremities: ears/tail for heat loss  Small extremities: for heat retention  Hypothalamus: Thermo-regulator in the brain

Hypothalamus  Nerve cells in the hypothalamus can detect if blood temperature is off  Below set point: induction of shivering and vasoconstriction of tissues in extremities (raise/conserve core temperature)  Above set point: induction (adrenalin and glucagon) of sweating, panting, and vasodilation (lower core temperature)

Endocrine System  Produces hormones that regulate homeostasis, reproduction, and development  Characteristics of hormones include:  Transported by blood  Minute amounts required to stimulate body wide response  Are either steroids, peptides, or amino acids