PHYSIO 3 EXAM

What do the nervous and endocrine systems have in common?

• Both systems associated with the brain

  • Hypothalamus

  • Epithalamus

• May use same chemical messenger as NTM and hormone

• Two systems are cooperative

What is the mode of transport for the nervous system?

Axon

What is the mode of transport for the endocrine system?

Blood

What is the speed of response for the nervous system?

Instant/Milliseconds

What is the speed of response for the endocrine systems?

Delayed/Seconds

What is the duration of response in the nervous system?

Milliseconds/seconds

What is the duration of response in the endocrine systems?

Minutes/Days

Which system is an amplitude-modulated system?

Endocrine

Which system is a frequency-modulated system?

Nervous

Qualities of what chemical messengers?:

• Produced in small quantities

• Secreted into intercellular space

• Transported some distance in circulatory system

• Acts on target tissues elsewhere in the body

Hormone

Functions of the endocrine system

• Regulation of metabolism

• Control of food intake and digestion

• Modulation of tissue development

• Ion regulation

• Water balance

• HR and BP regulation

• Control of blood glucose and other nutrients

• Control of reproductive functions

• Uterine contractions and milk release

What chemical messengers are released by cells and have a local effect on same cell type from which chemical signals are released?

Autocrine

Example of autocrine chemical messengers

Prostaglandin

What chemical messengers act on cells in immediate vicinity (a narrower kind of paracrine)?

Juxtacrine

Examples of juxtacrine chemical messengers

Cytokines

What chemical messengers are released by cells and affect other cell types locally without being transported in the blood?

Paracrine

Example of paracrine chemical messengers

Somatostatin

What chemical messengers are a type of intercellular signal produced by cells of endocrine glands, enter circulatory system, and affect distant cells?

Endocrine

Example of endocrine chemical messengers

Estrogen

What chemical messengers are produced by neurons and secreted into extracellular spaces by presynaptic nerve terminals, travel short distances, and influence postsynaptic cells?

Neurotransmitter

What type of secretion?:

• Maintenance of relatively constant concentration of hormone

• Ex: thyroid hormone

Chronic hormone secretion

What type of secretion?:

• Big change all at once

• Ex: Epinephrine in response to stress

Acute hormone secretion

What type of secretion?:

• Female reproductive hormones

Episodic (cyclic) hormone secretion

What systems are most hormones controlled by?

Negative feedback systems

Control by what stimuli?:

• Changing blood levels of ions and nutrients directly stimulate secretion of hormones

  • Anything but hormone

Humoral

Example of what stimuli?:
Ca²⁺ in blood

• Declining blood Ca²⁺ conc. stimulates parathyroid glands to secrete PTH

• PTH causes Ca²⁺ conc. to rise, and stimulus is removed

Humoral

Control by what stimuli?:

• Nerve fibers stimulate hormone release

Neural

Example of what stimuli?:

• Sympathetic nervous system fibers stimulate adrenal medulla to secrete catecholamines

Neural

Control by what stimuli?:

• Hormones stimulate other endocrine organs to release their hormones

Hormonal

Example of what stimuli?:

• Ex: hypothalamic hormones stimulate release of most anterior pituitary hormones

• Anterior pituitary hormones stimulates targets to secrete still more hormones

• Hypothalamic-pituitary-target endocrine organ feedback loop

• Hormones from final target organs inhibit release of anterior pituitary hormones

Hormonal

What part of the negative feedback loop has a negative-feedback effect on the anterior pituitary and hypothalamus which causes a decrease in the hormone released from the anterior pituitary gland?

Target endocrine cell

What are common examples of hormones that act with a positive feedback loop?

• Estrogen at end of follicular phase before ovulation

• Oxytocin with contractions

What do water-soluble hormones consist of?

All amino acid-based hormones except thyroid hormone

What kind of hormones dont need to be metabolized before being removed by the kidneys?

Water-soluble

Through what MOA do water-soluble hormones act through?

Second-messenger systems

What is the MOA of lipid-soluble hormones?

Activate genes, causing synthesis of new proteins

What causes downregulation ?

Increase in hormone levels which decrease receptor levels

A hormone bound to a receptor can inc. the rate at which receptor molecules are degraded and this combined form is taken into the cell and then broken down by what process?

Phagocytosis

What causes upregulation?

Decrease in hormone levels which causes an increase in receptors for a better chance at binding

What hormones can diffuse into target cells and bind with intracellular receptors that can access the nucleus?

Lipid-soluble steroid and thyroid hormones

What kind of hormones exert effects through second-messenger systems like cylic AMP and PIP₂-calcium?

Amino acid-based

What G-protein coupled pathway involves phospholipase C, IP3, and DAG?

G_q

What are the products of the cleavage of PIP2 by phospholipase C?

• Diacylglycerol (DAG) activates protein kinases

• Inositol triphosphate (IP3) cause Ca²⁺ release from intracellular storage sites

What is the main function of the JAK/STAT pathway?

Induce growth and cell division

In what hormones does signal amplification happen more significantly?

Water-soluble

What hormones have more signal amplification, but are slower to effect cells?

Water-soluble

What hormones have less signal amplification, but are faster to effect cells?

Steroidal

Where do the nervous and endocrine systems interact?

Hypothalamus and pituitary gland

How is the hypothalamus connected to the pituitary gland?

Infundibulum

How many major hormones does the pituitary gland secrete after being triggered either directly or indirectly by the thalamus?

8

What lobe of the pituitary gland is neural tissue derived from a downgrowth of the brain (hypothalamus)?

Posterior lobe

How does the posterior pituitary gland maintain its neural connection to the hypothalamus?

Hypothalamic-hypophyseal tract

What hormones does the posterior pituitary gland secrete?

• Oxytocin

• Antidiuretic hormone (ADH)

Where are hormones stored in the posterior pituitary gland?

Axon terminals

When are hormones released from the posterior pituitary gland?

When neurons fire

What lobe of the pituitary gland is glandular tissue derived from an out-pocketing of oral mucosa?

Anterior lobe

Vascularity connected to the hypothalamus via hypophyseal portal system consisting of?

• Primary capillary plexus

• Secondary capillary plexus

• Hypophyseal portal veins

What lobe of the pituitary gland has the true gland cells?

Anterior lobe

What hormones does the anterior pituitary gland release?

• Growth hormone releasing hormone

• Thyrotropic releasing hormone

• Corticotropin release hormone

• Gonadotropin release hormone

• Prolactin release hormone

• Dopamine

What pituitary lobe consists of axon terminals of neurons from hypothalamic neurons?

Posterior lobe

What neurons within the posterior pituitary gland produce oxytocin?

Paraventricular neurons

What neurons within the posterior pituitary gland produce ADH?

Supraoptic neurons

What two hormones?:

• Each composed of 9 amino acids

• Almost identical but differ in two amino acids

• Oxytocin

• ADH

If there is a high blood osmolality, what is the posterior pituitary triggered to secrete?

ADH

What hormone targets kidney tubules to reabsorb more water to inhibit or prevent urine formation?

ADH (Vasopressin)

High concentrations of ADH causes what?

Vasoconstriction

What hormone is a strong stimulant of uterine contractions released during childbirth and also acts as a hormonal trigger for milk ejection?

Oxytocin

Through what system does oxytocin operate on?

Positive feedback mechanisms

What hormone also acts as a NTM in the brain?

Oxytocin

What are the different parts of the pancreas?

• Uncinate process

• Head

• Neck

• Body

• Tail

What is the blood supply to the pancreas?

Branches from celiac trunk and SMA

What nervous system is the primary innervation of the pancreas?

Autonomic nervous system

Sympathetic innervation of the pancreas

T6-T12 thoracic splanchnic nerves and celiac plexus

Parasympathetic innervation of pancreas

Vagus nerve

What are pancreatic secretions predominantly regulated by?

Other hormone products and chemical signals

Relating to or denoting glands which secrete hormones or other products directly into the blood

Endocrine

A gland that makes substances such as sweat, tears, saliva, milk, and digestive juices, and releases them through a duct or opening to a body surface

Exocrine

What is an exocrine gland’s way of maintaining contact with the body surface?

By a duct

What portion of the pancreas composes approximately 80-90% of the organ’s tissue?

Exocrine pancreas

What are the grape-like clusters that form sacs around terminal ends of pancreatic ducts and that are the functional unit of exocrine pancreas?

Acini

Acini are made up of cetroacinar cells which

• Produce and secrete enzymes and zymogens

• Have dense granules at their apical ends (contain secretory products)

What are the dense granules at the apical ends of the acini containing?

Secretory products

What is the main job of the exocrine pancreas?

Digestive activity

How does exocrine glands secrete their products?

Network of ducts or lumen

What does the exocrine pancreas produce?

Pancreatic enzymes and bicarbonate

What are components of pancreatic juice?

• Water and electrolytes

• Enzymes

• Zymogens

• Sodium bicarbonate

What are the enzymes in the pancreatic juice?

• Pancreatic amylase

• Pancreatic lipase

• Ribonuclease and deoxyribonuclease

What enzyme is involved in digestion of carbohydrates/starch?

Pancreatic amylase

What enzyme is involved in digestion of fats?

Pancreatic lipase

What enzymes degrade RNA and DNA, respectively?

Ribonuclease and deoxyribonuclease

What are enzymes that are altered after secretion to become active and their function is to digest proteins?

Zymogens

When would the activation of zymogens be a problem?

If activation occurs before receiving duodenum

What secretes sodium bicarbonate?

Ductal epithelial cells in the pancreas

What is the function of sodium bicarbonate in the pancreatic juice?

Neutralizes hydrochloric acid (HCl) from the stomach

What protein?:

• Produced in the duodenum and proximal jejunum

• Stimulates acinar secretion

• Triggered by gastric acid, long-chain fatty acids, and essential amino acids (meals)

Cholecystokinin

What protein?:

• Produced in the S cells of duodenal mucosa

• Release stimulated by gastric acid (pH < 4.5), prompting production and secretion of bicarbonate

Secretin

What are examples of inhibitory neuropeptides?

• Somatostatin

• Pancreatic polypeptide

• Calcitonin

• Glucagon

Which of the following is a component of the exocrine portion of the pancreas?

Acini

Hormone secretions directly secreted into the bloodstream

Endocrine

How is endocrine pancreatic tissue arranged?

Circular islets of Langerhans