Homeostasis

What are the 3 homeostatic systems?

What are the 3 homeostatic systems?

Nervous, Excretory and endocrine

What are some factors that are regulated?

Temperature, blood sugar, water levels

What is negative feedback?

Negative feedback ensures that conditions remain favourable. A stimuli is detected and a change occurs, integrator will produce signal and send to effector. Effector responds to stimuli. Stimuli is no longer detected and effector stops.

What is positive feedback?

Body senses a change and activates mechanism that accelerates or increases that change. Can be life threatening.

What does a sensory cell do?

Detect stimuli in the environment.

What does an integrator do?

Direct an impulse to produce the appropriate response.

What does an effector do?

It is a muscle or gland that produces the response?

What are the effectors of thermoregulation?

Vasodilatation/sweat and Vasoconstriction/shivering

What is the function of the neurons?

Receives stimuli from the environment and coordinates an appropriate response.

What are glial cells?

Support neurons.

What are the three types of neurons?

Sensory, Interneuron, motor

What is a Sensory neurons?

Detect change

What is a interneuron?

Connects sensory to motor

What is a motor neuron?

Creates the response.

What is a dendrite?

An extension of the beginning of the neuron that connects to other neurons. Receives info.

What is the cell body (soma)?

Contains cell organelle to support function, it processes info from dendrites.

What is an axon?

It sends messages through nerve impulse transmission.

What is the axon terminal?

The end of the neuron.

What is synapse?

The axon terminal linked to dendrite of another neuron.

What are the conditions for action potential?

Ion channels present, no myelin.

Explain the resting membrane.

Lots of K on inside, lots of Na on the outside keeps a charge difference. Pumps will move 3Na ions out and 2K ions in, creates positive charge on outside and negative charge on inside. Some diffusion of K will occur, this makes the outside even more positive.

What is the propagation of impulse?

The movement of impulse down the membrane.

Explain depolarization.

Na channels open and it rushes in, charges have flipped and inside becomes positive. K channels remain closed. A wave of depolarization occurs.

Explain repolarization.

K channels open and K moves out so the pumps can reestablish resting membrane. Na channels remain closed.

Explain the steps of synapse transmissions.

Impulse reaches end of neuron, Ca2 channels open and Ca2 comes into cell. This causes vesicles with NT to move to presynaptic membrane. NT diffuses across synapse and bind to receptor. Na channels open and depolarization begins. Channels close when NT is released.

What is a motor nerve?

Send impulse from brain to all muscles.

What is a sensory nerve?

Send message from muscles to brain.

What is mixed nerve?

Both sensory and motor nerve arranged together.

What is the central nervous system?

Spinal cord and brain, mainly inter neurons, process information.

What is the peripheral nervous system?

Parts of N.S except for brain and spinal. Relay information.

What is the autonomic nervous system?

Controls internal environment. Regulates processes not under conscious control.

What is sympathetic nervous system?

Activate/increase stimulates body.

What is parasympathetic nervous system?

Deactivates body, restores balance.

What is the stomatic nervous system?

Involves external environment, regulates conscious activity.

Parts of the brain stem are…

Medulla oblongata, pons, midbrain, thalamus, hypothalamus, reticular formation.

What is the medulla oblongata?

The lowest part of the brain stem that Controls subconscious body activities.

What is the pons?

It connects 2 halves of the cerebellum and connects cerebrum and medulla.

What is the midbrain?

A relay centre for reflexes from eyes and ears. Connects the area between the spinal cord, the cerebrum and the cerebellum.

What is the thalamus?

The relay centre for impulses going to the cerebrum

What is the hypothalamus?

Controls survival emotions and is a body temp sensor. Regulates the pituitary gland.

What is the reticular formation?

The nerve tract that extends through the brain stem. Selective in the amount & type of nervous stimulation you receive.

What is the cerebellum?

Allows muscles coordination, maintains balance, allows smooth movement.

What is the cerebrum?

5/6 of the brain, the folds increase S.A. Grey matter on outside w lots of connections, White matter on inside that moves info. Has 10 billion neurons & connections but only small % are used.

What are the cortex controls?

Sensory info (sight, hearing, limb positions, taste, touch, odor), Motor info (motion, speech, position of limbs), Thought behaviour (consciousness, attention, memory, reasoning, judgement, emotion, imagination, will power)

What is excretion?

The removal of metabolic waste from blood or ECF.

What is secretion?

The movement of substances from the blood to another location.

What is reabsorption?

Movement of materials back into the blood of ECF.

What is elimination?

The emptying of an organ in which waste is store.

What is egestion?

The elimination of solid waste that never enter cells/blood.

What is diffusion?

Movement of molecules from [high] to [low]

What is osmosis?

Diffusion of water

What is facilitated diffusion?

Membrane that channels specific molecules through. Selective permeability.

What is active diffusion?

uses energy but can move against or with the gradient.

What is the function of the kidney?

Excretion of urine due to protein→ammonia→urea→urine.

Describe how the glomerulus and bowman’s capsule work.

Blood goes into glomerulus, decrease size of blood vessels increases pressure. Dissolved solutes and water are pushed through walls of glomerulus (non-selective filtration) and are picked up by Bowman’s capsule.

Describe the proximal tubule.

It does passive and selective reabsorption of minerals (Na, Cl, HCO3), glucose, aminos and vitamins. This increases water/solvent levels.

Describe the descending tubule.

Reabsorption water. Walls are only permeable to water, not to salt. This decreases water/solvent levels.

Describe the ascending tubule.

Thin section is permeable to salt and not water, this brings water/solvent levels up. The thick section will actively reabsorb salt and fine tunes the levels.

Describe the distal tubule.

Reabsorbs water, Specific and active reabsorption and secretion.

Describe the collecting duct.

Moves waste into kidney and bladder. More water absorption, some urea can be reabsorbed.

What is a molecular messenger?

Chem molecule released when regulator cell detects change in environment. Acts on a target cell.

What are the characteristics of hormones?

1. Produced by a gland

2. Secreted into blood or ECF

3. Works on different cell than what produced it

4. Required in small amounts to trigger target cell

5. Acts only on specific target cells

What is antagonistic effect?

A hormone may be produced to work antagonistically against the other (insulin vs glucagon)

What is a chain reaction effect?

Release of one hormone stimulates the release of a second hormone. Second hormone then inhibits the release of the first one.

What is steroid hormone action?

Steroid enters cell and binds with receptors. Receptor/hormone binds at specific DNA site. Transcription occurs, proteins made via translation, proteins change activity of that cell or secreted into blood to affect other cells.

What is Second messenger?

Bind to cell surface receptors, can’t pass through membrane. Receptor change shape so it binds to cytoplasm protein, causes formation of a reaction activator. Needs an enzyme.