Lecture 16: Blood 1-3 Flashcards
Blood transports (4)
- O2 from the lungs to the cells of the blood and vice versa
- Nutrients from GI tract to body cells
- Heat and waste products away from the cells
- Hormones from endocrine glands to other body cells
Blood helps to regulate body temperature by
Mainly increasing or decreasing blood flow to the skin for heat exchange
Blood helps to regulate pH through
Buffers
Example:
-Hemoglobin combines with CO2
-Hemoglobin binds H+ ions
Blood helps to regulate electrolytes and water in body fluids by
Influencing dissolved protiens
Pc
Capillary hydrostatic pressure
Pi
Interstitial hydrostatic pressure
(pi)c
Capillary osmotic pressure
(pi)i
Interstitial osmotic pressure
Prevention of blood loss through
clotting
Combats microorganisms and other substances through
white blood cells or specialized plasma proteins
Viscosity of blood vs. water
Because blood contains red blood cells, it is thicker and heavier than water and also flows more slowly than water
Temperature of blood
- Slightly higher than body temperature
- Absorbs heat generated by active skeletal muscle and redistributes it to other tissues
Slight alkalinity of blood
- pH is between 7.35 and 7.45
- Arterial blood is more alkaline than venous because it has less CO2
Plasma proteins normally remain in
plasma
How do plasma proteins act as buffer systems
- Free carboxyl groups (-COOH) at one end of the protein acts like an acid by releasing H+ when pH arises
- Free amino group (-NH2) at the other end of a protein can act as a base by combining with H+ ions when the pH falls
Plasma proteins establish osmotic gradient between
Blood and interstitial fluid
Osmotic pressure is the primary force responsible for
Preventing excessive loss of plasma from the capillaries into the interstitial fluid and thus helps maintain plasma volume
Three primary classes of plasma proteins
Albumin
Globulin
Fibrinogen
Albumins
- Make up 55% percent of plasma proteins
- Major contributors to the osmotic pressure of plasma
- Important in the transport of fatty acids
Globulins percentage
-Make up 38% of plasma proteins
Two types of globulins
- Transport globulins
- Immunoglobulins
Transport globulins
- Thyroid binding globulin (binds and transports thyroxine)
- Transcortin (transports ACTH and cortisol)
- Transferrin (transports ions)
- Lipoproteins (transports lipids)
- Steriod-binding proteins (transports steroid hormones like sex hormones)
Immunoglobulins
Antibodies, crucial to the defense mechanisms of the body
Fibrinogen
- About 7% of plasma proteins
- Functions in blood clotting
Regulatory plasma proteins
Polypeptide hormones such as insulin and thyroid stimulating hormones and prolactin
More than 90% of plasma proteins are produced here, including albumins, fibrinogens, and most of the globulins
Liver
Lymphocytes produce
Immunoglobulins
Plasma hormones are produced by
Many different endocrine organs
Composition of plasma resembles that of
Interstitial fluid
Differ markedly from those found inside living cells
Primary differences between plasma and interstitial fluid
- Concentration of dissolved proteins: Plasma has circulating plasma proteins that cannot cross walls of blood vessels and thus cannot enter interstitial fluid
- Levels of respiratory gases: oxygen enters the blood in the lungs and CO2 enters blood from the tissues
Formed elements are produced through the process of _______ or ______ which takes place in the bone marrow
- Hemopoiesis
- Hematopoiesis
When a hemocytoblast divides, it can either
Replace itself or become committed to a particular pathway, producing myeloid stem cells or lymphoid stem cells
Lymphoid stem cells
After birth, some lymphocytes are formed in the bone marrow, but most are formed from lymphoid stem cells in lymphoid tissue
Under the influence of erythropoietin, myeloid stem cells
develop into reticulocytes and then erythrocytes (RBC)
Under the influence of thrombopoietin, myeloid stem cells
develop into megakaryocytes and then platelets
Under the influence of colony stimulating factors, myeloid stem cells
Develop into basophils, eosinophils, neutrophils, and monocytes (WBC)
Colony stimulating factors include
- Macrophage CSF: stimulates production of monocytes/macrophages
- Granulocytes CSF: stimulates production of granulocytes
- Granulocyte-macrophage CSF: stimulates production of both granulocytes and monocytes
- Multi-CSF: Accelerates production of granulocytes, monocytes, megakaryocytes, and erythrocytes
Erythrocytes are derived from
committed stem cells or hemocytoblasts
Some hemocytoblasts differentiates within the bone marrow into
common myeloid progenitor cells
Some progenitor cells differentiate into _____ and begin synthesizing _____
erythroblasts
hemoglobin
After several divisions, the erythroblast loses its nucleus and becomes an
Immature RBC or reticulocytes
Reticulocytes leave the bone marrow and enter _____ where
bloodstream
they continues to synthesize hemoglobin
Production and destruction of erythrocytes are maintained at an equal rate, thus
if RBC are lost from the circulatory system, the rate of erythropoiesis is increased until the normal erythrocyte number is regained
The main controller of the rate of erythropoiesis is
erythropoietin (EPO), a hormone produced mostly in the kidneys, that operates in a negative feedback system
Reduced oxygen carrying capacity stimulates
EPO release from the kidney which stimulates development of erythrocytes in bone marrow
Shape of erythrocytes
-Flat, disc shaped, indented in the middle on both sides (biconcave)
How does shape influence function in erythrocytes?
- Provides large surface area for diffusion of O2 across membrane
- Thinness of cell allows for rapid diffusion of O2 between the exterior and interior of the cell
- Enables them to bend and flex to travel through the narrow capillaries without rupturing
Purpose of hemoglobin
transports O2
Hemoglobin consists of
- Globin portion made of four highly folded polypeptide chains
- Four iron-containing non-protein heme groups
Each of the four iron atoms can bind
reversibly with one molecule of oxygen
How many O can a hemoglobin bind?
4
Solubility of oxygen in plasma
Poor
About ___% of oxygen is carried in the blood bound to hemoglobin
99
Oxygenated hemoglobin is referred to as
Oxyhemoglobin
The globin portion of hemoglobin binds to CO2 to form
Carbaminohemoglobin
Carbaminohemoglobin carries __% of CO2 in blood
23
The acidic ion H+ of ionized carbonic acid is generated where?
How is it buffered?
- At the tissue level from CO2
- Hemoglobin, so that it minimally alters the pH of the blood
