Exam 1 Flashcards
Homeostasis
The body’s ability to detect change, activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions
Positive and Negative feedback loop
negative - A change is sensed and mechanisms to reverse the change are activated – dynamic equilibrium
Positive - Change leads to greater change in the same direction – self-amplifying cycle
endocrine system
Collection of endocrine glands scattered throughout the body
Endocrine glands secrete hormones into bloodstream
Hormones travel through the bloodstream to bind to receptors on target cells
When a hormone binds to target cells receptor, it causes the cell to respond in a specific way
effects hormones have on target cells
Changes in cell membrane permeability and/or membrane potential
Synthesis of proteins or regulatory molecules
Enzyme activation or deactivation
Regulation of secretory activity
Stimulation of mitosis (cell division)
functions of endocrine system
Maintain homeostasis
Storage and utilization of energy (carbohydrates, proteins and fats)
Regulation of growth and reproduction
Control body responses to external stimuli (particularly stress)
steroid hormones
Synthesis – from cholesterol
Storage – produced as needed
Solubility – lipid soluble
Cell membrane permeability – can pass through the cell membrane (simple diffusion)
Location of receptors – inside the cell
Examples – oestrogen, testosterone
amino acid-based hormones
Synthesis – from amino acids
Storage – stored in vesicles
Solubility – water soluble
Cell membrane permeability – cannot pass through the cell membrane
Location of receptors – on the cell membrane
Examples – Antidiuretic hormone, Prolactin
mechanism of steroid hormone actions
- Diffuse through the plasma membrane
- Binds with receptor in cell cytoplasm
- Steroid-receptor complex moves inside the nucleus
- Induces gene expression and protein synthesis
- New protein alters cell function
mechanism of amino acid-based hormones
- Hormone binds with receptor on plasma membrane
- Hormone-receptor complex generates second messenger inside the cell cytoplasm
- Second messenger triggers intracellular chemical to amplify signal (cascade)
- Results in desired cell response
hypothalamus and pituitary gland
Hypothalamus: master endocrine gland
Hypothalamus connects to the pituitary gland via the pituitary gland (infundibulum)
Hypothalamus links the nervous system to the endocrine system via the pituitary gland
Most hormone secretion by the pituitary gland is controlled by hormonal or electrical signals from the hypothalamus
key endocrine glands
Anterior pituitary gland Posterior pituitary gland Pineal gland Thyroid gland Parathyroid gland Adrenal cortex Adrenal medulla Pancreas Ovaries Testes
anterior pituitary gland hormones
Thyroid stimulating hormone
Growth hormone
Adrenocorticotropic hormone
Follicle stimulating hormone
Luteinizing hormone
Prolactin
thyroid stimulating hormone
release from anterior pituitary
Effect: stimulates the cells of the thyroid gland leading to increase production of thyroxine (T4) and Triiodothyronine (T3)
Regulation: Hormonal – produced and released in response to release of thyroid releasing hormone (TRH) from the hypothalamus
growth hormone
release from anterior pituitary
Effect: promotes growth of bone, cartilage and soft tissue
Regulation: hormonal – regulated by the release of growth-hormone releasing hormone and growth-hormone-inhibiting hormone from the hypothalamus
adrenocorticotropic hormone (ACTH)
release from anterior pituitary
Effect: stimulates the production and release of cortisol, androgens and aldosterone from the adrenal cortex
Regulation: hormonal –secreted in response to the secretion of the corticotropin-release hormone (CRH) from the hypothalamus
follicle stimulating hormone
release from anterior pituitary
Effect: stimulates sperm production in males and maturation of ovarian follicles in females
Regulation: hormonal – regulated by the release of gonadotrophin release hormone (GnRH) from the hypothalamus
leuteinizing hormone
release from anterior pituitary
Effect: ovulation in females, and testosterone production in males
Regulation: hormonal – regulated by the release of gonadotrophin release hormone (GnRH) from the hypothalamus
prolactin hormone
Released from: anterior pituitary
Effect: stimulates milk production in the breasts
Regulation: hormonal – secretion is increased by the release of prolactin-releasing hormone from the hypothalamus in response to the baby suckling at the breast
posterior pituitary gland hormones
Oxytocin
Antidiuretic hormone
oxytocin hormone
Released from: posterior pituitary
Effect: increases uterine contractions during childbirth and is responsible for the ‘let down’ response during breastfeeding
Regulation: neural. Sensory receptors in the cervix and nipple sensory signals to the hypothalamus that results in the release of oxytocin from the posterior pituitary gland
antidiuretic hormone
Released from: posterior pituitary
Effect: increases reabsorption of water in nephrons (functional unit of the kidney)
Regulation: humoral – stimulated by increased plasma osmolality and decreased extracellular fluid volume
pineal gland hormones
melatonin
melatonin hormone
Released from: Pineal gland
Effect: secretion peaks at night. High levels induce drowsiness
Regulation: neural – suppressed by bright light
thyroid gland hormones
Thyroid hormones – Thyroxine (T4) Triiodothyronine (T3)
Calcitonin
Thyroxine (T4) Triiodothyronine (T3)
Released from: thyroid gland
Effect: increases metabolic rate, cell growth and production of body heat
Regulation: hormonal – regulated by the release of thyroid stimulating hormone (TSH) from the anterior pituitary gland
calcitonin hormone
Released from: thyroid gland
Effect: decreases blood calcium levels by increasing calcium excretion, promotes storage of calcium in bone, inhibits calcium absorption by the intestines
Regulation: humoral – controlled directly by blood calcium levels
parathyroid hormone
Released from: parathyroid gland
Effect: increases blood calcium levels by increasing calcium absorption, and stimulating osteoclast activity and therefore reabsorption of calcium from the bones
Regulation: Humoral – controlled directly by blood calcium levels
adrenal gland (adrenal medulla and adrenal cortex)
Adrenal cortex (outside) makes up 85% of the gland, Adrenal Medulla (inside) makes up other 15%
Adrenal cortex (outside)
Cortisol
Aldosterone
Sex hormones
Adrenal Medulla (inside)
Adrenaline
Noradrenaline
cortisol
Released from: adrenal cortex
Effect: increase protein breakdown, glucose formation, depresses the immune response
Regulation: stimulated by the release of adrenocorticotropic hormone from the anterior pituitary gland
aldosterone
Released from: adrenal cortex
Effect: reduces excretion of sodium. Increases the excretion of potassium. Increases water reabsorption and blood volume
Regulation: hormonal – primary control mechanism is the production of angiotensin II in response to reduced blood pressure
sex hormones
Released from: adrenal cortex
Effect: small amounts of weak androgen. In women, then promote libido (sex drive) and are converted into oestrogens (feminizing sex steroids) by other body tissues
Regulation: not fully understood. But the main hormone that stimulates its secretion is ACTH. Therefore, hormonal regulation
adrenaline and noradrenaline
Released from: adrenal medulla
Effect: fight or flight response
Regulation: neural – innovated by the sympathetic nervous system
pancreas
Endocrine part consists of clusters of cells called pancreatic islets
Alpha cells secrete glucagon
Beta cells secrete insulin
insulin
Released from: beta cells of the pancreas
Effect: reduces blood glucose levels. Facilitates the uptake of glucose into muscle and fat. Stimulates the liver to store glucose as glycogen
Regulation: Humoral – increased blood glucose levels
glucagon
Released from: Alpha cells of the pancreas
Effect: increases blood glucose levels. It stimulates the breakdown of glycogen stored in the liver
Regulation: humoral – decreased blood glucose levels
gonads
are the organs that produce gametes – sperm in males and oocytes in females
ovaries
Paired oval bodies located in the pelvic cavity
Hormones:
Oestrogen
Progesterone
testes
Pair structures located outside the abdominal cavity, with in the scrotum
Hormones:
Testosterone
Oestrogen and progesterone
Released from: ovaries
Effect: regulate the menstrual cycle, maintain pregnancy, prepare the mammary glands for lactation, stimulates the development and maintenance of sexual characteristics
Regulation: hormonal – stimulated by FSH and LH
testosterone
Released from: testes
Effect: regulates the production of sperm and stimulates the development and maintenance of sexual characteristics
Regulation: hormonal – stimulated by LH
GI Tract
Mouth
Tongue
Palate
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine
accessory organs
Salivary glands
Liver
Gall bladder
Pancreas
six basic digestive processes
Ingestion: taking food into the mouth
Secretion: release of water, acid, buffers, and enzymes into the lumen of the GI tract
Mixing and propulsion: churning and pushing food through the GI tract
Digestion: mechanical and chemical breakdown of food
Absorption: passage of digested products from the GI tract into the blood and lymph
Defecation: elimination of feces from the GI tract
mechanical and chemical digestion
Mouth
Ingestion
Mechanical digestion by teeth
Chemical digestion by salivary amylase
Stomach
Mechanical digestion by churning
Chemical digestion of protein by digestive enzymes and HCI
Liver and pancreas
Secretion of digestive enzymes and bile into duodenum
Small intestine
Mechanical digestion via segmentation
Chemical digestion via digestive enzymes and bile
Major site of absorption
Large intestine
Bacteria breakdown remaining CHO and proteins
Absorption of water
Formation of feces
Rectum and anus
Elimination of feces via defecation
layers of GI tract
Mucosa – inner layer. Lines the lumen and is in contact with digestive products
Submucosa – thick layer of connective tissue. Contains blood vessels and nerves that stimulate gastric glands
Muscularis – inner layer of circular smooth muscle and an outer layer of longitudinal smooth muscle. responsible for motility
Serosa – outer layer. Secrete serous fluid which lubricates and reduces friction
salivary glands
Parotid gland
Sublingual
Submandibular
functions of saliva
Dissolves food (99.5% water)
Lubricates food for swallowing (mucus)
Chemical digestion: salivary amylase – digestion of carbohydrates. Lingual lipase - digestion of lipids
pharynx
The oropharynx and the laryngopharynx are passages for food and respiratory gases
The epiglottis closes off the entrance to the larynx during swallowing, precents food entering the larynx
oesophagus
Muscular tube connection the pharynx to the stomach (approx. 25cm)
Moves bolus from pharynx to stomach via peristalsis
The upper oesophageal sphincter regulates the movement of substances into the oesophagus
Lower oesophageal (cardiac) sphincter regulates movement of substances from the oesophagus to the stomach
peristalsis
Circular muscle behind the food contract
Circular muscle ahead of the food relax
Longitudinal muscle contracts as the food enters that region, reducing the distance the food needs to travel
swallowing (deglutition)
The voluntary (oral) phase – voluntary, movement of the bolus from the oral cavity into the oropharynx
The pharyngeal phase – involuntary, movement of the bolus from the oropharynx into the oesophagus
The oesophageal phase – involuntary, movement of the bolus through the oesophagus and into the stomach
arrector pilli
Small muscles located in the dermis that cause goosebumps
epithelium layers
Simple: one layer of cells, used for absorption and filtration
Stratified: more than one layer of cells, used for protection
Pseudostratified – pseudo (false), stratified (more than one); appears multi-layered but is only made of one layer of cells where all cells connect to the basement membrane, but cell height varies
epithelium shape
Squamous: flat cells, few organelles therefore minimal activity level
Cuboidal: equal in height and width, moderate number of organelles therefore moderate activity level
Columnar: taller than width, multiple organelles therefore high activity level
pancreas
Delivers amylase, trypsin and lipase into duodenum to assist absorption. Bicarbonate – nullify chyme
small intestine
Major site of digestion and absorption of nutrients and water in GIT
large intestine
formation and storage of feces
goblet cells
secrete mucous
gallbladder
Stores, concentrates and delivers bile into the duodenum
absorptive cells
Absorb nutrients
villi
Finger-like projections of mucosa that increase surface area for absorption and digestion
enteroendocrine cells
Secrete secretin and cholecystokinin
microvilli
Microscopic, membrane-covered projections that increase surface area for absorption and digestion
mucous neck cells
secrete mucous
liver
Produces bile (bile salts) necessary for the emulsification and absorption of lipids
parietal cells
Secrete intrinsic factor and hydrochloric acid
chief cells
Secretes pepsinogen and gastric lipase
desmosomes
Desmosomes are localized patches that hold two cells tightly together. They are common in epithelia (e.g., the skin). Desmosomes are attached to intermediate filaments of keratin in the cytoplasm
plasma membrane function
The plasma membrane regulates the transport of materials entering and exiting the cell.
cytosol function
It is involved in signal transduction between the cell membrane and the nucleus and organelles
smooth endoplasmic reticulum funtion
It synthesizes lipids, phospholipids as in plasma membranes, and steroids.
ribosomes function
the site of protein synthesis in the cell
golgi apparatus function
proteins received from the ER are further processed and sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion
lysosomes function
rid cells of waste products
nucleus function
controls and regulates activities of the cell
mitochondria function
generates ATP - power house of the cell
