ANBI Mod 4 Flashcards
What does Homeostasis refer to?
Maintenance of a dynamic equilibrium of the internal environment of the body
- Body Temp
- Acid Base Balance
- Fluid Balance
- Hormonal, Nutrient, Oxygen Level
What are the steps in Homeostasis regulation?
- Stimulus produces change in variables
- Change detected by receptors
- Input: Information sent along afferent pathway
- Output: info sent along efferent pathway
- Response to effector feeds back to influence magnitude of stimulus and returns variable to homeostasis
What are some external stimuli to cause an imbalance?
- Illness, disease (ex, Anemia)
- Overheating/Heat Stress, Cold Stress
- Lactation, Being pregnant, Giving birth
- Stress, Lack of Exercise
What are the two internal communication and regulation systems within animal bodies?
Nervous System
Endocrine System
Describe the Endocrine System
- Secretes that are transmitted to a target cell via the blood or by surrounding interstitial fluid
- causes changes in the metabolic activities in specific cells
- Action is relatively prolonged
- Action is relatively slow (seconds to even days)
a network of glands that produce and release hormones into the bloodstream, which then travel to target organs to regulate various bodily functions like growth, metabolism, and reproduction
Describe the nervous system
- Transmits neurochemical impulses via nerve fibres (Neurotransmitters)
- causes muscular contraction or glands to secrete
- Action is very rapid (milliseconds)
- Effects are relatively brief
What are the 3 Components of the Nervous system?
- Sensory Receptors
- special nervous tissue to collect info that is important to the animal (sensory = afferent neurons)
Leads to
- special nervous tissue to collect info that is important to the animal (sensory = afferent neurons)
- Central Processor (Brain)
- Interprets incoming info and generates a response when needed (motor = efferent nerve)
Leads to
- Interprets incoming info and generates a response when needed (motor = efferent nerve)
- Effectors (Muscle or Glands)
- Organs that can cause change in the body.
What are the 3 Components of the Endocrine system?
- Endocrine gland/cell
a. Secretes Hormones
b. Not anatomically connected - Hormone
a. Chemical Products
b. Released upon stimulation - Target Organ
a. Express Hormone specific receptors
b. Show biological response
What are the Two Divisions of the Classical vertebrate endocrine system
- Neuroendocrine System: Comprised of neurosecretory neurons with nerve terminals that release hormones into the blood or extracellular fluid.
- Ex. Pituitary Gland, hypothalamus, adrenal gland, Pineal Gland
- Peripheral Endocrine System: Present only in higher invertebrates and vertebrates. Comprised of non-neural tissue - No direct link to the nervous system
- Ex. Thyroid, parathyroid, testes/ovaries, pancreas, GI tract, Kidney.
What are some hormone secreting structures shared by all domestic animals?
Hypothalamus and Pituitary Unit/gland
Are Pituitary Hormones produced at all times?
No, as if a feature (lactation for example) is not needed (no child) there’s no need for hormones to be produced to enable that feature of the individuals body.
How are Hormones Regulated through the feedback mechanism?
Release of hormones from the endocrine system can be regulated through a positive and negative feedback mechanism
What is negative feedback to endocrine system?
When the hormone feeds back to decrease its own production
What is positive feedback to the endocrine system?
Characterized by the release of additional hormone in response to an original hormone release
What do Hormones generally do?
Cause changes in cell activity, but they do not make a cell do something it was not previously capable of.
1. Stimulate the making of new proteins
2. Activate or inactivate enzymes
3. Open or close cell membrane channels
4. Cause the cells to secrete/release something
How can endocrine hormones mess with disease?
Many diseases may result from a deficiency or excess of hormones
- Ex. Hyperthyroidism, Hypothyroidism, Cushing’s syndrome, Diabetes
How are Hormones Classified?
Type of Signalling
- Autocrine
- paracrine
- Endocrine
Chemical structure
Solubility: (Water or fat)
What are the classes of hormones?
Steroids
- stress hormones
- Sex Hormones
Peptide Hormones
- Insulin
Amino acid Derivatives
- Thyroid hormones
Ecosinoids
- prostaglandins
How does a cell know to respond to a specific hormone?
Determined by receptors on or inside target cells that provide the specificity for hormone-cell interactions
Describe Water soluble hormones?
Hydrophilic
Hormones that are soluble in aqueous medium
This, they bind to receptor molecules in the outer surface of target cells, initiating reactions within the cell that ultimately modifies the functions of the cells
- Ex. Insulin, Epinephrine
Describe Fat soluble hormones
Lipophilic (fat loving)
Hormones that are not soluble in aqueous medium, but soluble in lipids
They can very easily move across cell membranes
Thus, they target cells inside and can enter the target cell to bind to intracellular receptors
- Ex. Thyroid hormones, Steroid Hormones
What is the difference between Agonist and Antagonist hormones?
- Antagonists bind to a receptor and prevent action. They’re like a blocker on the receptor.
- Agonists bind to receptors activating biological responses.
What defines male or female?
Chromosomes and sexual organs
What is sex determination?
The natural event by which an individual of species becomes male or female
