Recognize the importance of regulating the extracellular fluid in multicellular organisms, and that such regulation of the internal environment is referred to ‘homeostasis’.
Extracellular fluid(ECF) supplies correct temperature, pH etc. and is the route for nutrient delivery and waste disposal. Hence it is important to maintain these variables in a constant manner so that the organism will be able to survive.
Homestasis is the ability of organisms to maintain the ECF within limits required for survival, in the face of varying external environments.
Define:
- controlled variable: variable that the system tries to keep stable
- set point: target value for controlled variable
- reference range: target value for controlled variable.
Account for the variability within individuals over time.
Genetic factor accounts for variation between different individuals. Each individuals have their own biological rhythm and do their own activity each day.
Describe how negative feedback and feed-forward control systems operate to achieve homeostasis.
Negative feedback
Components are: sensor(monitor actual value of controlled variable), integration center(compare actual with set point value), effectors(produce response).
Negative feedback control systems help inhibit an effect to control a variable to be in its set point reference range.
Feed-forward
Actions taken in advance to prevent or minimize changes in controlled variable involves making prediction to controlled variable in future. Feed forward can be physiological(anticipated physiological adjustments and biological rhythms) or behavioural (learnt behavior).
Feed forward helps by anticipating a certain action which can change a variable in the body and creates an action in order to minimize the change in that variable.
Negative feedback and Feedforward feedback systems are important concepts. They are always (ALWAYS) covered in the finals. Remember:
1) definition of negative and feedforward feedback
2) learn how to describe what happens in these feedback systems (ie. the components like sensor, integration etc.)
3) why ECF needs to be maintained
4) definition of set point
All of these may be tested in short answers style.
Types of Synovial Joints
1. Plane joints
• Articular surfaces are essentially flat
• Allow only slipping or gliding movements
• Only examples of nonaxial joints
2. Hinge joints
• Cylindrical projections of one bone fits into a trough-shaped surface on another
• Motion is along a single plane
• Uniaxial joints permit flexion and extension only
• Examples: elbow and interphalangeal joints
3. Pivot Joints
• Rounded end of one bone protrudes into a “sleeve,” or ring, composed of bone (and possibly ligaments) of another
• Only uniaxial movement allowed
• Examples: joint between the axis and the dens, and the proximal radioulnar joint
4. Condyloid, or Ellipsoidal, Joints
• Oval articular surface of one bone fits into a complementary depression in another
• Both articular surfaces are oval
• Biaxial joints permit all angular motions
• Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle) joints
5. Saddle Joints
• Similar to condyloid joints but with greater movement
• Each articular surface has both a concave and a convex surface
• Example: carpometacarpal joint of the thumb
6. Ball-and-Socket Joints
• A spherical or hemispherical head of one bone articulates with a cuplike socket of another
• Multiaxial joints permit the most freely moving synovial joints
• Examples: shoulder and hip joints
Information on musculoskeletal system.
• The three types of muscle tissue are skeletal, cardiac, and smooth
• These types differ in structure, location, function, and means of activation
• Skeletal and smooth muscle cells are elongated and are called muscle fibers
• Muscle contraction depends on two kinds of myofilaments – actin and myosin
• Muscle terminology is similar: Sarcolemma – muscle plasma membrane; Sarcoplasm – cytoplasm of a muscle cell
• Prefixes – myo, and sarco all refer to muscle
3 main types of muscle:
Skeletal Muscle Tissues
• Packaged in skeletal muscles that attach to and cover the bony skeleton
• Has obvious stripes called striations
• Is controlled voluntarily (i.e., by conscious control)
• Contracts rapidly but tires easily
• Is responsible for overall body motility
• Is extremely adaptable and can exert forces over a range from a fraction of an ounce to over 70 pounds
Cardiac Muscle Tissue
• Occurs only in the heart
• Is striated like skeletal muscle but is not voluntary
• Contracts at a fairly steady rate set by the heart’s pacemaker
• Neural controls allow the heart to respond to changes in bodily needs
Smooth Muscle Tissue
• Found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages
• Forces food and other substances through internal body channels
• It is not striated and is involuntary
Muscle Function
• Skeletal muscles are responsible for all locomotion
• Cardiac muscle is responsible for coursing the blood through the body
• Smooth muscle helps maintain blood pressure, and squeezes or propels substances (i.e., food, feces) through organs
• Muscles also maintain posture, stabilize joints, and generate heat
Know the difference between the different range of movement for the different types of joints. Though in exams, they normally wont explicitly ask you to explain what those joints are, but a question which portrays a picture of a certain part of a body and you may be ask to identify the type of joint and type of movement allowed. Example: a picture of a femur and hip may be shown and you will need to identify that it is a ball and socket joint and allows multiaxial movements including rotation.
Other notes on nervous system, musculoskeletal system etc. will be provided in the hubs191 blogspot at $10. For purchase, please email hsfyadmin@gmail.com. Cheers!
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