Integration and endocrinology Flashcards
List the four basic methods of cell-to-cell communication
Gap junctions
Contact-dependent signals
Autocrine signals
Paracrine signals
These methods facilitate various forms of communication between cells in different contexts.
Gap junctions
Gap junctions – direct transfer of ions or molecules between cells through protein channels.
Contact-dependent signals
Contact-dependent signals – membrane proteins on one cell bind to membrane proteins on another.
Autocrine signals
Autocrine signals – a cell releases a chemical that acts on itself.
Paracrine signals
Paracrine signals – a cell releases a chemical that acts on nearby cells.
Describe the general pattern of a signal pathway
- Signal molecule (ligand) binds to a receptor.
- This activates the receptor.
- The receptor starts a cascade of events (transduction of the signal) inside the cell (often involving second messengers).
- A cellular response occurs (e.g. secretion, gene activation, etc.).
This pattern outlines how signals are processed within cells.
Describe how signalling molecules interact with target-cell receptors
Signaling molecules bind to specific receptors on target cells, the shape of the receptor must match the shape of the signal (like a lock and key). Binding triggers a response inside the cell. initiating a cellular response.
This interaction is crucial for the activation of signal transduction pathways.
What is the difference and relationship between chemical and electrical signals?
Chemical signals: involve molecules like hormones or neurotransmitters moving through blood or between cells.
Electrical signals: involve changes in voltage (action potentials) across neuron membranes.
Electrical signals in neurons can trigger the release of chemical signals (neurotransmitters).
Both types of signals are essential for communication within the nervous system and endocrine system.
List the differences between endocrine and neural control
- Speed: Endocrine is slower than neural
- Duration: Endocrine effects last longer
- Specificity: Neural control is more specific
- Mode of transmission: Endocrine uses blood, neural uses nerves
What are the control pathways for neural reflexes?
Neural reflex: stimulus → sensor → sensory neuron → CNS → motor neuron → effector → response
Diagrams help visualize the interactions and feedback mechanisms within these pathways.
What are the control pathways for neuroendocrine reflexes?
Neuroendocrine reflex: stimulus → sensor → CNS → hormone release from brain → target → response
What are the control pathways for endocrine reflexes?
Endocrine reflex: stimulus → endocrine cell → hormone → target → response
Distinguish between endocrine and exocrine glands
Endocrine glands secrete hormones directly into the bloodstream e.g. Thyroid, pituitary
Exocrine glands secrete substances through ducts to external surfaces e.g. Sweat, salivary glands
This distinction is important for understanding hormone distribution and function.
Compare the two chemical classes of hormones based on their solubility
Lipid-soluble hormones (e.g., steroids e.g. cortisol) - receptor inside cell - circulate bound to transport proteins
Water-soluble hormones (e.g., peptides, amines e.g. insulin) - receptor on membrane - circulate freely in the plasma
The solubility affects hormone transport, receptor interaction, and mechanism of action.
Describe the two general mechanisms of hormone action
Lipid-soluble hormones bind to receptors within target cells -> change gene expression in nucleus
Water-soluble hormones bind to receptors on the exterior surface of the target cell ->activate enzymes or second messengers
These mechanisms explain how hormones exert their effects on target cells.
Describe the locations of and relationships between the hypothalamus and pituitary gland
The hypothalamus controls the pituitary gland and is located in the ventral brain below the third ventricle and above the pituitary gland.
This anatomical relationship is crucial for the regulation of many endocrine functions.
What is the funtion of the anterior pituitary gland
Makes and releases hormones.
What is the function of the posterior pituitary gland
Stores and releases hormones made by the hypothalamus.
Describe the mechanism of control of hormone secretion
Hormone secretion is regulated by feedback loops, neural signals, and other hormones.
Stimuli can be:
Neural
Hormonal
Humoral (like low calcium or glucose levels)
Control mechanisms ensure homeostasis and appropriate physiological responses.
Describe the location, histology, hormones, and functions of the anterior pituitary
- Anterior pituitary: Located in the brain, contains glandular tissue, secretes hormones like ACTH, TSH, LH, FSH, GH, and PRL
The anterior and posterior pituitary play distinct roles in hormone regulation.
Describe the location, histology, hormones, and functions of the posterior pituitary
- Posterior pituitary: Located in the brain, contains neural tissue, releases hormones like oxytocin and ADH
Describe the location, histology, hormones, and functions of the thyroid gland
- Thyroid gland: Located in the neck, composed of follicular cells, secretes thyroxine (T4) and triiodothyronine (T3) to control metabolism and calcitonin to lower calcium
These glands are vital for metabolism, stress response, and electrolyte balance.
Describe the location, histology, hormones, and functions of the adrenal gland
- Adrenal gland: Located atop the kidneys, composed of cortex and medulla, secretes cortisol (stress), aldosterone (salt balance), and adrenaline (fight or flight)
Describe how the body responds to stress
The body responds to stress through the activation of the hypothalamic-pituitary-adrenal (HPA) axis, leading to the release of cortisol and other stress hormones. Cortisol increases glucose, reduces inflammation, suppresses immune function.
Short-term stress also triggers adrenaline (fight or flight).
This response is crucial for managing acute and chronic stress.
